ALBERT

Description: Hyrrokkin sarcophaga is a parasitic foraminifera that is commonly found in cold-water coral reefs where it infests the file clam Acesta excavata and the scleractinian coral Desmophyllum pertusum (formerly known as Lophelia pertusa). Here, we present measurements of the trace element and isotopic composition of these parasitic foraminifera, analyzed by inductively coupled optical emission spectrometry (ICP-OES), electron probe microanalysis (EPMA) and mass spectrometry (gas-source MS and inductively-coupled-plasma MS). Our results reveal that the geochemical signature of H. sarcophaga depends on the host organism it infests. Sr / Ca ratios are 1.1 mmol mol−1 higher in H. sarcophaga that infest D. pertusum, which could be an indication that dissolved host carbonate material is utilized in shell calcification, given that the aragonite of D. pertusum has a naturally higher Sr concentration compared to the calcite of A. excavata. Similarly, we measure 3.1 ‰ lower δ13C and 0.25 ‰ lower δ18O values in H. sarcophaga that lived on D. pertusum, which might be caused by the direct uptake of the host's carbonate material with a more negative isotopic composition or different pH regimes in these foraminifera (pH can exert a control on the extent of CO2 hydration/hydroxylation) due to the uptake of body fluids of the host. We also observe higher Mn / Ca ratios in foraminifera that lived on A. excavata but did not penetrate the host shell compared to specimen that penetrated the shell, which could be interpreted as a change in food source, changes in the calcification rate, Rayleigh fractionation or changing oxygen conditions. While our measurements provide an interesting insight into the calcification process of this unusual foraminifera, these data also indicate that the geochemistry of this parasitic foraminifera is unlikely to be a reliable indicator of paleoenvironmental conditions using Sr / Ca, Mn / Ca, δ18O or δ13C unless the host organism is known and its geochemical composition can be accounted for.

Description: In this work we have performed a detailed study of vectors to ore to a representative volcanic-rock-hosted replacive volcanogenic massive sulfide (VMS) deposit located in the northern Iberian Pyrite Belt (Spain), the Aguas Teñidas deposit. The investigated vectors include the following: (1) mineralogical zoning, (2) host sequence characterization and mineralized unit identification based on whole rock geochemistry discrimination diagrams, (3) study of the characteristics and behaviour of whole rock geochemical anomalies around the ore (e.g. alteration-related compositional changes, characteristics and extent of geochemical halos of indicative elements such as Cu, Zn, Pb, Sb, Tl, and Ba around the deposit), and (4) application of portable X-ray fluorescence (p-XRF) analysis to the detection of the previous vectors. In the footwall, a concentric cone-shaped hydrothermal alteration zone bearing the stockwork passes laterally, from core to edge, from quartz (only local) to chlorite–quartz, sericite–chlorite–quartz, and sericite–quartz alteration zones. The hydrothermal alteration is also found in the hanging wall despite being tectonically allochthonous to the orebody: a proximal sericite alteration zone is followed by a more distal albite-rich one. Whole rock major elements show an increase in alteration indexes (e.g. AI, CCPI) towards the mineralization, a general SiO2 enrichment, and FeO enrichment as well as K2O and Na2O depletion towards the centre of the hydrothermal system, with MgO showing a less systematic behaviour. K2O and Na2O leached from the centre of the system are transported and deposited in more external areas. Copper, Pb, and Zn produce proximal anomalies around mineralized areas, with the more mobile Sb, Tl, and Ba generating wider halos. Whereas Sb and Tl halos form around all mineralized areas, Ba anomalies are restricted to areas around the massive sulfide body. Our results show that proposed vectors, or adaptations designed to overcome p-XRF limitations, can be confidently used by analysing unprepared hand specimens, including the external rough curved surface of drill cores. The data presented in this work are not only applicable to VMS exploration in the Iberian Pyrite Belt, but on a broader scale they will also contribute to improving our general understanding of vectors to ore in replacive-type VMS deposits.

Description: Seismic facies analysis can generate a map to describe the spatial distribution characteristics of reservoirs, and therefore plays a critical role in seismic interpretation. To analyse the characteristics of the horizon of interest, it is usually necessary to extract seismic waveforms along the target horizon using a selected time window. The inaccuracy of horizon interpretation often produces some inconsistent phases and leads to inaccurate classification. Therefore, the developed adaptive phase K-means algorithm proposed a sliding time window to extract seismic waveforms. However, setting the maximum offset of the sliding window is difficult in a real data application. A value that is too large may cause the cross-layer problem, whereas a value that is too small reduces the flexibility of the algorithm. To address this disadvantage, this paper proposes a robust K-means (R-K-means) algorithm with a Gaussian-weighted sliding window for seismic waveform classification. The used weights punish those windows distant from the interpretation horizon in the objective function, consequently producing a smaller range of horizon adjustments even when using relatively large maximum offsets and benefitting the generation of stable and reliable seismic facies maps. The application of real seismic data from the F3 block proves the effectiveness of the proposed algorithm.

Description: We combine satellite data products to provide a first and general overview of the physical sea ice conditions along the drift of the international Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition and a comparison with previous years (2005–2006 to 2018–2019). We find that the MOSAiC drift was around 20 % faster than the climatological mean drift, as a consequence of large-scale low-pressure anomalies prevailing around the Barents–Kara–Laptev sea region between January and March. In winter (October–April), satellite observations show that the sea ice in the vicinity of the Central Observatory (CO; 50 km radius) was rather thin compared to the previous years along the same trajectory. Unlike ice thickness, satellite-derived sea ice concentration, lead frequency and snow thickness during winter months were close to the long-term mean with little variability. With the onset of spring and decreasing distance to the Fram Strait, variability in ice concentration and lead activity increased. In addition, the frequency and strength of deformation events (divergence, convergence and shear) were higher during summer than during winter. Overall, we find that sea ice conditions observed within 5 km distance of the CO are representative for the wider (50 and 100 km) surroundings. An exception is the ice thickness; here we find that sea ice within 50 km radius of the CO was thinner than sea ice within a 100 km radius by a small but consistent factor (4 %) for successive monthly averages. Moreover, satellite acquisitions indicate that the formation of large melt ponds began earlier on the MOSAiC floe than on neighbouring floes.

Description: Across the Qinghai–Tibet Plateau (QTP) there is a narrow engineering corridor with widely distributed slopes called the Qinghai–Tibet Engineering Corridor (QTEC), where a variety of important infrastructures are concentrated. These facilities are transportation routes for people, materials, energy, etc. from inland China to the Tibet Autonomous Region. From Golmud to Lhasa, the engineering corridor covers 632 km of permafrost containing the densely developed Qinghai–Tibet Railway and Qinghai–Tibet Highway, as well as power and communication towers. Slope failure in permafrost regions, caused by permafrost degradation, ground ice melting, etc., affects the engineering construction and permafrost environments in the QTEC. We implement a variety of sensors to monitor the hydrological and thermal deformation between permafrost slopes and permafrost engineering projects in the corridor. In addition to soil temperature and moisture sensors, the global navigation satellite system (GNSS), terrestrial laser scanning (TLS), and unmanned aerial vehicles (UAVs) were adopted to monitor the spatial distribution and changes in thermal deformation. An integrated dataset of hydrological and thermal deformation in permafrost engineering and slopes in the QTEC from the 1950s to 2020, including meteorological and ground observations, TLS point cloud data, and RGB and thermal infrared (TIR) images, can be of great value for estimating the hydrological and thermal impact and stability between engineering and slopes under the influence of climate change and engineering disturbance. The dataset and code were uploaded to the Zenodo repository and can be accessed through https://zenodo.org/communities/qtec (last access: 23 June 2021), including meteorological and ground observations at https://doi.org/10.5281/zenodo.5009871 (Luo et al., 2020d), TLS measurements at https://doi.org/10.5281/zenodo.5009558 (Luo et al., 2020a), UAV RGB and TIR images at https://doi.org/10.5281/zenodo.5016192 (Luo et al., 2020b), and R code for permafrost indices and visualisation at https://doi.org/10.5281/zenodo.5002981 (Luo et al., 2020c).

Description: We present the first incorporation of the Common Representative Intermediates version 2.2 tropospheric chemistry mechanism, CRI v2.2, combined with stratospheric chemistry, into the global chemistry–climate United Kingdom Chemistry and Aerosols (UKCA) model to give the CRI-Strat 2 mechanism. A rigorous comparison of CRI-Strat 2 with the earlier version, CRI-Strat, is performed in UKCA in addition to an evaluation of three mechanisms, CRI-Strat 2, CRI-Strat and the standard UKCA chemical mechanism, StratTrop v1.0, against a wide array of surface and airborne chemical data. CRI-Strat 2 comprises a state-of-the-art isoprene scheme, optimized against the Master Chemical Mechanism v3.3.1, which includes isoprene peroxy radical isomerization, HOx recycling through the addition of photolabile hydroperoxy aldehydes (HPALDs), and isoprene epoxy diol (IEPOX) formation. CRI-Strat 2 also features updates to several rate constants for the inorganic chemistry, including the reactions of inorganic nitrogen and O(1D). The update to the isoprene chemistry in CRI-Strat 2 increases OH over the lowest 500 m in tropical forested regions by 30 %–50 % relative to CRI-Strat, leading to an improvement in model–observation comparisons for surface OH and isoprene relative to CRI-Strat and StratTrop. Enhanced oxidants also cause a 25 % reduction in isoprene burden and an increase in oxidation fluxes of isoprene and other biogenic volatile organic compounds (BVOCs) at low altitudes with likely impacts on subsequent aerosol formation, atmospheric lifetime, and climate. By contrast, updates to the rate constants of O(1D) with its main reactants relative to CRI-Strat reduces OH in much of the free troposphere, producing a 2 % increase in the methane lifetime, and increases the tropospheric ozone burden by 8 %, primarily from reduced loss via O(1D)+H2O. The changes to inorganic nitrogen reaction rate constants increase the NOx burden by 4 % and shift the distribution of nitrated species closer to that simulated by StratTrop. CRI-Strat 2 is suitable for multi-decadal model integrations and the improved representation of isoprene chemistry provides an opportunity to explore the consequences of HOx recycling in the United Kingdom Earth System Model (UKESM1). This new mechanism will enable a re-evaluation of the impact of BVOCs on the chemical composition of the atmosphere and further probe the feedback between the biosphere and the climate.

Description: The use of mass flow simulations in volcanic hazard zonation and mapping is often limited by model complexity (i.e. uncertainty in correct values of model parameters), a lack of model uncertainty quantification, and limited approaches to incorporate this uncertainty into hazard maps. When quantified, mass flow simulation errors are typically evaluated on a pixel-pair basis, using the difference between simulated and observed (“actual”) map-cell values to evaluate the performance of a model. However, these comparisons conflate location and quantification errors, neglecting possible spatial autocorrelation of evaluated errors. As a result, model performance assessments typically yield moderate accuracy values. In this paper, similarly moderate accuracy values were found in a performance assessment of three depth-averaged numerical models using the 2012 debris avalanche from the Upper Te Maari crater, Tongariro Volcano, as a benchmark. To provide a fairer assessment of performance and evaluate spatial covariance of errors, we use a fuzzy set approach to indicate the proximity of similarly valued map cells. This “fuzzification” of simulated results yields improvements in targeted performance metrics relative to a length scale parameter at the expense of decreases in opposing metrics (e.g. fewer false negatives result in more false positives) and a reduction in resolution. The use of this approach to generate hazard zones incorporating the identified uncertainty and associated trade-offs is demonstrated and indicates a potential use for informed stakeholders by reducing the complexity of uncertainty estimation and supporting decision-making from simulated data.

Description: In this study, we analyse the climatology of ionosphere over Nepal based on GPS-derived vertical total electron content (VTEC) observed from four stations as defined in Table 1: KKN4 (27.80∘ N, 85.27∘ E), GRHI (27.95∘ N, 82.49∘ E), JMSM (28.80∘ N, 83.74∘ E) and DLPA (28.98∘ N, 82.81∘ E) during the years 2008 to 2018. The study illustrates the diurnal, monthly, annual, seasonal and solar cycle variations in VTEC during all times of solar cycle 24. The results clearly reveal the presence of equinoctial asymmetry in TEC, which is more pronounced in maximum phases of solar cycle in the year 2014 at KKN4 station, followed by descending, ascending and minimum phases. Diurnal variations in VTEC showed the short-lived day minimum which occurs between 05:00 to 06:00 LT (local time) at all the stations considered, with diurnal peaks between 12:00 and 15:00 LT. The maximum value of TEC is observed more often during the spring equinox than the autumn equinox, with a few asymmetries. Seasonal variation in TEC is observed to be a manifestation of variations in solar flux, particularly regarding the level of solar flux in consecutive solstices.

Description: This paper successfully applied the geoengineering workflow for integrated well-test analysis to characterise fluid flow in a newly discovered fractured reservoir in the Barents Sea. A reservoir model containing fractures and matrix was built and calibrated using this workflow to match complex pressure transients measured in the field. We outline different geological scenarios that could potentially reproduce the pressure response observed in the field, highlighting the challenge of non-uniqueness when analysing well-test data. However, integrating other field data into the analysis allowed us to narrow the range of uncertainty, enabling the most plausible geological scenario to be taken forward for more detailed reservoir characterisation and history matching. The results provide new insights into the reservoir geology and the key flow processes that generate the pressure response observed in the field. This paper demonstrates that the geoengineering workflow used here can be applied to better characterise naturally fractured reservoirs. We also provide reference solutions for interpreting well-tests in fractured reservoirs where troughs in the pressure derivative are recognisable in the data.

Description: We report on applications of the ultraviolet-light-emitting-diode-based incoherent broadband cavity-enhanced absorption spectroscopy (UV-LED-IBBCEAS) technique for optical monitoring of HONO, NO2 and CH2O in a simulation chamber. Performance intercomparison of UV-LED-IBBCEAS with a wet chemistry-based NitroMAC sensor and a Fourier transform infrared (FTIR) spectrometer has been carried out on real-time simultaneous measurement of HONO, NO2 and CH2O concentrations during the reaction of NO2 with H2O vapour in CESAM (French acronym for Experimental Multiphasic Atmospheric Simulation Chamber). The 1σ (signal-to-noise ratio (SNR) = 1) detection limits of 112 pptv for NO2, 56 pptv for HONO and 41 ppbv for CH2O over 120 s were found for the UV-LED-IBBCEAS measurement. On the contrary to many set-ups where cavities are installed outside the simulation chamber, we describe here an original in situ permanent installation. The intercomparison results demonstrate that IBBCEAS is a very well suitable technique for in situ simultaneous measurements of multiple chemically reactive species with high sensitivity and high precision even if the absorption bands of these species are overlapped. It offers excellent capacity for non-invasive optical monitoring of chemical reactions without any perturbation. For the application to simulation chambers, it has the advantage to provide a spatially integrated measurement across the reactor and hence to avoid point-sampling-related artefacts.

Description: Assimilation of weather radar measurements including radar reflectivity and radial wind data has been operational at the Deutscher Wetterdienst, with a diagonal observation error (OE) covariance matrix. For an implementation of a full OE covariance matrix, the statistics of the OE have to be a priori estimated, for which the Desroziers method has been often used. However, the resulted statistics consists of contributions from different error sources and are difficult to interpret. In this work, we use an approach that is based on samples for truncation error in radar observation space to approximate the representation error due to unresolved scales and processes (RE) and compare its statistics with the OE statistics estimated by the Desroziers method. It is found that the statistics of the RE help the understanding of several important features in the variances and correlation length scales of the OE for both reflectivity and radial wind data and the other error sources from the microphysical scheme, radar observation operator and the superobbing technique may also contribute, for instance, to differences among different elevations and observation types. The statistics presented here can serve as a guideline for selecting which observations are assimilated and for assignment of the OE covariance matrix that can be diagonal or full and correlated.

Description: Determining controls on the temperature sensitivity of heterotrophic soil respiration remains critical to incorporating soil–climate feedbacks into climate models. Most information on soil respiratory responses to temperature comes from laboratory incubations of isolated soils and typically subsamples of individual horizons. Inconsistencies between field and laboratory results may be explained by microbial priming supported by cross-horizon exchange of labile C or N. Such exchange is feasible in intact soil profiles but is absent when soils are isolated from surrounding depths. Here we assess the role of soil horizon connectivity, by which we mean the degree to which horizons remain layered and associated with each other as they are in situ, on microbial C and N substrate use and its relationship to the temperature sensitivity of respiration. We accomplished this by exploring changes in C : N, soil organic matter composition (via C : N, amino acid composition and concentration, and nuclear magnetic resonance spectroscopy), and the δ13C of respiratory CO2 during incubations of organic horizons collected across boreal forests in different climate regions where soil C and N compositions differ. The experiments consisted of two treatments: soil incubated (1) with each organic horizon separately and (2) as a whole organic profile, permitting cross-horizon exchange of substrates during the incubation. The soils were incubated at 5 and 15 ∘C for over 430 d. Enhanced microbial use of labile C-rich, but not N-rich, substrates were responsible for enhanced, whole-horizon respiratory responses to temperature relative to individual soil horizons. This impact of a labile C priming mechanism was most emergent in soils from the warmer region, consistent with these soils' lower C bioreactivity relative to soils from the colder region. Specifically, cross-horizon exchange within whole soil profiles prompted increases in mineralization of carbohydrates and more 13C-enriched substrates and increased soil respiratory responses to warming relative to soil horizons incubated in isolation. These findings highlight that soil horizon connectivity can impact microbial substrate use in ways that affect how soil effluxes of CO2 are controlled by temperature. The degree to which this mechanism exerts itself in other soils remains unknown, but these results highlight the importance of understanding mechanisms that operate in intact soil profiles – only rarely studied – in regulating a key soil–climate feedback.

Description: Plumes from the boreal spring biomass burning (BB) in northern peninsular Southeast Asia (nPSEA) are lifted into the subtropical jet stream and transported and deposited across nPSEA, South China, Taiwan and even the western North Pacific Ocean. This paper as part of the Seven SouthEast Asian Studies (7-SEAS) project effort attempts to improve the chemical weather prediction capability of the Weather Research and Forecasting coupled with the Community Multiscale for Air Quality (WRF–CMAQ) model over a vast region, from the mountainous near-source burning sites at nPSEA to its downwind region. Several sensitivity analyses of plume rise are compared in the paper, and it is discovered that the initial vertical allocation profile of BB plumes and the plume rise module (PLMRIM) are the main reasons causing the inaccuracies of the WRF–CMAQ simulations. The smoldering emission from the Western Regional Air Partnership (WRAP) empirical algorithm included has improved the accuracies of PM10, O3 and CO at the source. The best performance at the downwind sites is achieved with the inline PLMRIM, which accounts for the atmospheric stratification at the mountainous source region with the FINN burning emission dataset. Such a setup greatly improves not only the BB aerosol concentration prediction over near-source and receptor ground-based measurement sites but also the aerosol vertical distribution and column aerosol optical depth of the BB aerosol along the transport route. The BB aerosols from nPSEA are carried by the subtropical westerlies in the free troposphere to the western North Pacific, while BB aerosol has been found to interact with the local pollutants in the Taiwan region through three conditions: (a) overpassing western Taiwan and entering the central mountain area, (b) mixing down to western Taiwan, (c) transport of local pollutants upwards and mixing with a BB plume on higher ground. The second condition, which involves the prevailing high-pressure system from Asian cold surge, is able to impact most of the population in Taiwan.

Description: The German Bight located within the central North Sea is a hydro- and morphodynamically highly complex system of estuaries, barrier islands, and part of the world's largest coherent tidal flats, the Wadden Sea. To identify and understand challenges faced by coastal stakeholders, such as harbor operators or governmental agencies, to maintain waterways and employ numerical models for further analyses, it is imperative to have a consistent database for both bathymetry and surface sedimentology. Current commercial and public data products are insufficient in spatial and temporal resolution and coverage for recent analysis methods. Thus, this first part of a two-part publication series of the German joint project EasyGSH-DB describes annual bathymetric digital terrain models at a 10 m gridded resolution for the German North Sea coast and German Bight from 1996 to 2016 (Sievers et al., 2020a, https://doi.org/10.48437/02.2020.K2.7000.0001), as well as surface sedimentological models of discretized cumulative grain size distribution functions for 1996, 2006, and 2016 on 100 m grids (Sievers et al., 2020b, https://doi.org/10.48437/02.2020.K2.7000.0005). Furthermore, basic morphodynamic and sedimentological processing analyses, such as the estimation of, for example, bathymetric stability or surface maps of sedimentological parameters, are provided (Sievers et al., 2020a, b, see respective download links).

Description: The Phanerozoic tectonothermal evolution of the SW slope of the East European Platform (EEP) in Poland is reconstructed by means of thermal maturity, low-temperature thermochronometry, and thermal modelling. We provide a set of new thermochronometric data and integrate stratigraphic and thermal maturity information to constrain the burial and thermal history of sediments. Apatite fission track (AFT) analysis and zircon (U-Th)/He (ZHe) thermochronology have been carried out on samples of sandstones, bentonites, diabase, and crystalline basement rocks collected from 17 boreholes located in central and NE Poland. They penetrated sedimentary cover of the EEP subdivided from the north to south into the Baltic, Podlasie, and Lublin basins. The average ZHe ages from Proterozoic basement rocks as well as Ordovician to Silurian bentonites and Cambrian to lower Carboniferous sandstones range from 848 ± 81 to 255 ± 22 Ma with a single early Permian age of 288 Ma, corresponding to cooling after a thermal event. The remaining ZHe ages represent partial reset or source ages. The AFT ages of samples are dispersed in the range of 235.8 ± 17.3 Ma (Middle Triassic) to 42.1 ± 11.1 Ma (Paleogene) providing a record of Mesozoic and Cenozoic cooling. The highest frequency of the AFT ages is in the Jurassic and Early Cretaceous prior to Alpine basin inversion. Thermal maturity results are consistent with the SW-ward increase of the Paleozoic and Mesozoic sediments thickness. An important break in a thermal maturity profile exists across the base Permian–Mesozoic unconformity. Thermal modelling showed that significant heating of Ediacaran to Carboniferous sedimentary successions occurred before the Permian with maximum paleotemperatures in the earliest and latest Carboniferous for Baltic–Podlasie and Lublin basins, respectively. The results obtained suggest an important role of early Carboniferous uplift and exhumation at the SW margin of the EEP. The SW slope of the latter was afterward overridden in the Lublin Basin by the Variscan orogenic wedge. Its tectonic loading interrupted Carboniferous uplift and caused resumption of sedimentation in the late Viséan. Consequently, a thermal history of the Lublin Basin is different from that in the Podlasie and Baltic basins but similar to other sections of the Variscan foreland, characterized by maximum burial at the end of Carboniferous. The Mesozoic thermal history was characterized by gradual cooling from peak temperatures at the transition from Triassic to Jurassic due to decreasing heat flow. Burial caused maximum paleotemperatures in the SW part of the study area, where the EEP was covered by an extensive sedimentary pile. However, further NE, due to low temperatures caused by shallow burial, the impact of fluids can be detected by vitrinite reflectance, illite/smectite, and thermochronological data. Our new results emphasize the importance of using multiple low-temperature thermochronometers and thermal modelling in connection with thermal maturity analysis to elucidate the near-surface evolution of platform margins.

Description: Snow stands out from materials at the Earth’s surface owing to its unique optical properties. Snow optical properties are sensitive to the snow microstructure, triggering potent climate feedbacks. The impacts of snow microstructure on its optical properties such as reflectance are, to date, only partially understood. However, precise modelling of snow reflectance, particularly bidirectional reflectance, are required in many problems, e.g. to correctly process satellite data over snow-covered areas. This study presents a dataset that combines bidirectional reflectance measurements over 500–2500 nm and the X-ray tomography of the snow microstructure for three snow samples of two different morphological types. The dataset is used to evaluate the stereological approach from Malinka (2014) that relates snow optical properties to the chord length distribution in the snow microstructure. The mean chord length and specific surface area (SSA) retrieved with this approach from the albedo spectrum and those measured by the X-ray tomography are in excellent agreement. The analysis of the 3D images has shown that the random chords of the ice phase obey the gamma distribution with the shape parameter m taking the value approximately equal to or a little greater than 2. For weak and intermediate absorption (high and medium albedo), the simulated bidirectional reflectances reproduce the measured ones accurately but tend to slightly overestimate the anisotropy of the radiation. For such absorptions the use of the exponential law for the ice chord length distribution instead of the one measured with the X-ray tomography does not affect the simulated reflectance. In contrast, under high absorption (albedo of a few percent), snow microstructure and especially facet orientation at the surface play a significant role in the reflectance, particularly at oblique viewing and incidence.

Description: Attribution in its general definition aims to quantify drivers of change in a system. According to IPCC Working Group II (WGII) a change in a natural, human or managed system is attributed to climate change by quantifying the difference between the observed state of the system and a counterfactual baseline that characterizes the system's behavior in the absence of climate change, where “climate change refers to any long-term trend in climate, irrespective of its cause” (IPCC, 2014). Impact attribution following this definition remains a challenge because the counterfactual baseline, which characterizes the system behavior in the hypothetical absence of climate change, cannot be observed. Process-based and empirical impact models can fill this gap as they allow us to simulate the counterfactual climate impact baseline. In those simulations, the models are forced by observed direct (human) drivers such as land use changes, changes in water or agricultural management but a counterfactual climate without long-term changes. We here present ATTRICI (ATTRIbuting Climate Impacts), an approach to construct the required counterfactual stationary climate data from observational (factual) climate data. Our method identifies the long-term shifts in the considered daily climate variables that are correlated to global mean temperature change assuming a smooth annual cycle of the associated scaling coefficients for each day of the year. The produced counterfactual climate datasets are used as forcing data within the impact attribution setup of the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP3a). Our method preserves the internal variability of the observed data in the sense that factual and counterfactual data for a given day have the same rank in their respective statistical distributions. The associated impact model simulations allow for quantifying the contribution of climate change to observed long-term changes in impact indicators and for quantifying the contribution of the observed trend in climate to the magnitude of individual impact events. Attribution of climate impacts to anthropogenic forcing would need an additional step separating anthropogenic climate forcing from other sources of climate trends, which is not covered by our method.

Description: Biocides used in film protection products leaching from facades are known to be a potential threat to the environment. This study identifies individual sources and entry pathways in a small-scale urban area. We investigate emissions of commonly used biocides (terbutryn, diuron, and octylisothiazolinone – OIT) and some of their transformation products (TPs; diuron-desmethyl, terbumeton, terbuthylazine-2-hydroxy, and terbutryn-desethyl) from a 2 ha residential area 13 years after construction has ended. Sampling utilizes existing urban water infrastructure representative for decentralized storm water management in central and northern Europe and applies a two-step approach to (a) determine the occurrence of biocides above water quality limits (i.e., predicted no-effect concentration, PNEC) and (b) identify source areas and characterize entry pathways into surface and groundwater. Monitoring focuses on the analysis of selected biocides and TPs by liquid chromatography–mass spectrometry/mass spectrometry (LC-MS/MS) in water samples taken from facades, rainwater pipes, drainage, and storm water infiltration systems. In standing water in a swale, we found high concentrations of diuron (174 ng L−1) and terbutryn (40 ng L−1) above PNEC for surface water. We confirmed expected sources, i.e., facades. Sampling of rain downpipes from flat roofs identified additional sources of all biocides and two TPs of terbutryn and one TP of diuron. Diuron and terbutryn were found in three drainage pipes representing different entry pathways of biocides. In one drainage pipe collecting road runoff, only diuron-desmethyl and terbutryn-desethyl were detected. In two other drainage pipes collecting infiltrated water through soil, terbuthylazine-2-hydroxy was additionally detected. One of the pipes collecting infiltrated water through soil concentration showed the highest concentrations of terbutryn and two of its TPs (terbutryn-desethyl and terbuthylazine-2-hydroxy). This suggests a high leaching potential of terbutryn. The applied two-step approach determined sources and pathways of biocide and their TPs. This study contributes to expanding knowledge on their entry and distribution and, thus, eventually towards reducing emissions.

Description: Regional anomalies of steric sea level are either due to redistribution of heat and freshwater anomalies or due to ocean–atmosphere buoyancy fluxes. Interannual to decadal variability in sea level across the tropical Pacific is mainly due to steric variations driven by wind stress anomalies. The importance of air–sea buoyancy fluxes is less clear. We use a global, eddy-permitting ocean model and a series of sensitivity experiments with quasi-climatological momentum and buoyancy fluxes to identify the contribution of buoyancy fluxes for interannual to decadal sea level variability in the tropical Pacific. We find their contribution on interannual timescales to be strongest in the central tropical Pacific at around a 10∘ latitude in both hemispheres and also relevant in the very east of the tropical domain. Buoyancy-flux-forced anomalies are correlated with variations driven by wind stress changes, but their effect on the prevailing anomalies and the importance of heat and freshwater fluxes vary locally. In the eastern tropical basin, interannual sea level variability is amplified by anomalous heat fluxes, while the importance of freshwater fluxes is small, and neither has any impact on decadal timescales. In the western tropical Pacific, the variability on interannual and decadal timescales is dampened by both heat and freshwater fluxes. The mechanism involves westward-propagating Rossby waves that are triggered during El Niño–Southern Oscillation (ENSO) events by anomalous buoyancy fluxes in the central tropical Pacific and counteract the prevailing sea level anomalies once they reach the western part of the basin.

Description: The Nioghalvfjerdsfjorden glacier (also known as the 79∘ North Glacier) drains approximately 8 % of the Greenland Ice Sheet. Supraglacial lakes (SGLs), or surface melt ponds, are a persistent summertime feature and are thought to drain rapidly to the base of the glacier and influence seasonal ice velocity. However, seasonal development and spatial distribution of SGLs in the north-east of Greenland are poorly understood, leaving a substantial error in the estimate of meltwater and its impacts on ice velocity. Using results from an automated detection of melt ponds, atmospheric and surface mass balance modelling, and reanalysis products, we investigate the role of specific climatic conditions in melt onset, extent, and duration from 2016 to 2019. The summers of 2016 and 2019 were characterised by above-average air temperatures, particularly in June, as well as a number of rainfall events, which led to extensive melt ponds to elevations up to 1600 m. Conversely, 2018 was particularly cold, with a large accumulated snowpack, which limited the development of lakes to altitudes less than 800 m. There is evidence of inland expansion and increases in the total area of lakes compared to the early 2000s, as projected by future global warming scenarios.

Description: Coincident wide-angle and multi-channel seismic data acquired within the scope of the PAMELA Moz3-5 project allow us to reconsider the formation mechanism of East African margins offshore of southern Mozambique. This study specifically focuses on the sedimentary and deep-crustal architecture of the Limpopo margin (LM) that fringes the eastern edge of the Mozambique’s Coastal Plain (MCP) and its offshore southern prolongation the North Natal Valley (NNV). It relies primarily on the MZ3 profile that runs obliquely from the northeastern NNV towards the Mozambique basin (MB) with additional inputs from a tectonostratigraphy analysis of industrial onshore–offshore seismic lines and nearby or crossing velocity models from companion studies. Over its entire N–S extension the LM appears segmented into (1) a western domain that shows the progressive eastward crustal thinning and termination of the MCP/NNV continental crust and its overlying pre-Neocomian volcano-sedimentary basement and (2) a central corridor of anomalous crust bounded to the east by the Mozambique fracture zone (MFZ) and the oceanic crust of the MB. A prominent basement high marks the boundary between these two domains. Its development was most probably controlled by a steep and deeply rooted fault, i.e., the Limpopo fault. We infer that strike-slip or slightly transtensional rifting occurred along the LM and was accommodated along this Limpopo fault. At depth we propose that ductile shearing was responsible for the thinning of the continental crust and an oceanward flow of lower crustal material. This process was accompanied by intense magmatism that extruded to form the volcanic basement and gave the corridor its peculiar structure and mixed nature. The whole region remained at a relative high level during the rifting period and a shallow marine environment dominated the pre-Neocomian period during the early phase of continent–ocean interaction. It is only some time after break-up in the MB and the initiation of the MFZ that decoupling occurred between the MCP/NNV and the corridor, allowing for the latter to subside and become covered by deep marine sediments. A scenario for the early evolution and formation of the LM is proposed taking into account both recent kinematic and geological constraints. It implies that no or little change in extensional direction occurred between the intra-continental rifting and subsequent phase of continent–ocean interaction.

Description: As the robustness for the wave equation-based inversion methods, wave equation migration velocity analysis (WEMVA) is stable for overcoming the multipathing problem and has become popular in recent years. As a rapidly developed method, differential semblance optimisation (DSO) is convenient to implement and can automatically detect the moveout existing in common image gathers (CIGs). However, by implementing in the image domain with the target of minimising moveouts and improving coherence of the CIGs, the DSO method often suffers from imaging artefacts caused by uneven illumination and irregular observation geometry, which may produce poor velocity updates with artefact contamination. To deal with this issue, in this paper, by introducing Wiener-like filters, we modify the conventional image matching-based objective function to a new one by introducing the quadratic Wasserstein metric technique. The new misfit function measures the distance of two distributions obtained by the convolutional filters and target functions. With the new misfit function, the adjoint sources and the corresponding gradients are improved. We apply the new method to two numerical examples and one field dataset. The corresponding results indicate that the new method is robust to compensate low frequency components of velocity models.

Description: Models are an important tool to predict Earth system dynamics. An accurate prediction of future states of ecosystems depends on not only model structures but also parameterizations. Model parameters can be constrained by data assimilation. However, applications of data assimilation to ecology are restricted by highly technical requirements such as model-dependent coding. To alleviate this technical burden, we developed a model-independent data assimilation (MIDA) module. MIDA works in three steps including data preparation, execution of data assimilation, and visualization. The first step prepares prior ranges of parameter values, a defined number of iterations, and directory paths to access files of observations and models. The execution step calibrates parameter values to best fit the observations and estimates the parameter posterior distributions. The final step automatically visualizes the calibration performance and posterior distributions. MIDA is model independent, and modelers can use MIDA for an accurate and efficient data assimilation in a simple and interactive way without modification of their original models. We applied MIDA to four types of ecological models: the data assimilation linked ecosystem carbon (DALEC) model, a surrogate-based energy exascale earth system model: the land component (ELM), nine phenological models and a stand-alone biome ecological strategy simulator (BiomeE). The applications indicate that MIDA can effectively solve data assimilation problems for different ecological models. Additionally, the easy implementation and model-independent feature of MIDA breaks the technical barrier of applications of data–model fusion in ecology. MIDA facilitates the assimilation of various observations into models for uncertainty reduction in ecological modeling and forecasting.

Description: Atlantic salmon (Salmo salar) populations throughout the North Atlantic have declined in recent decades largely due to reduced marine survival, yet our understanding of marine distribution patterns and migratory routes remains limited. Here, we assigned archived individual samples (n = 3891) collected over a half century (1968–2018) throughout the North Atlantic to region of origin using range-wide genetic assignment. In the Northwest Atlantic, the distribution of assignments reinforced the importance of the Labrador Sea as an aggregation area, with 73% of all reporting groups detected. Moreover, individuals from six European reporting groups were identified in the Northwest Atlantic, and detections decreased with decreasing latitude spanning an area from Greenland to southern Newfoundland. In the Northeast Atlantic, six North American reporting groups were detected in samples from around the Faroe Islands. Based on the distribution of samples, estimates of trans-Atlantic migration distance averaged 3861 and 2889 km for North American and European salmon respectively. Our analysis highlights the widespread importance of the Labrador Sea and Faroe Islands to the species marine distribution patterns, and the prevalence of long-distance trans-Atlantic migration. Ultimately, the results suggest that environmental conditions experienced by many Atlantic salmon populations span much of the North Atlantic Ocean.

Description: Heterotrophic protists are essential components of the marine ecosystem, yet they are often excluded from monitoring programmes. With limited resources, monitoring strategies need to be optimised considering both scientific knowledge and available resources. In doing so, it is crucial to understand how sampling frequency affects the value of the data. We analysed 11 years of weekly heterotrophic protist time-series data from Station L4 in the Western English Channel to explore how different sampling intervals impact data quality. In the L4 dataset, comprising 55 protist taxa, the reduction of sampling frequency from weekly to four times a year at specific seasons decreased the number of taxa encountered by 38% for ciliates and 29% for heterotrophic dinoflagellates while the mean annual biomass or its mean variation were not affected. Furthermore, when samples were taken only four times a year, biomass peaks of the ten most important taxa were often missed. The primary motivator for this study was furthering the development of the heterotrophic protist monitoring in temperate and subarctic marine areas, e.g. the Baltic Sea. Based on our findings, we give recommendations on sampling frequency to optimise the value of heterotrophic protist monitoring.

Description: The Lafaye orbicular body was emplaced in the Villatange tonalite-granodiorite unit of the Guéret magmatic complex (Massif Central, France). It consists of plagioclasic orbicules (4–35 cm diameter) embedded in homogeneous cordierite granodiorite. Orbicule cores consist mostly of residual metasedimentary xenoliths or autolithic plagioclasic cumulates. Rims (0.7–8 cm thickness) are single- or multi-layered; layers, mostly comb-textured, comprise alternating sheets dominated by cordierite (XFe = 0.32–0.37) or plagioclase (mostly An25–30). Additional mineral phases are minor biotite (XFe = 0.52; AlVI = 0.58–0.92 atoms per formula unit) and interstitial quartz. Plagioclase and cordierite morphologies (needle-like, skeletal, branching or fan-shaped) indicate growth under high initial supersaturation. However, the final polyhedral shapes and primary zoning of many individual plagioclase crystals, as well as evidence of partial recrystallization, imply significant textural maturation. Whole-rock major and trace element data (A/CNK = 1.12–1.46) and Sr and Nd isotopic compositions (εNd(355 Ma)  = −8.6 to −7.4; 87Sr/86Sr(355 Ma) = 0.7110–0.7147) suggest that the parental magma of the orbicules resulted from bulk assimilation of aluminous metasediments by a Villatange-type granodioritic magma. Heterogeneous nucleation and growth of plagioclase and cordierite around xenoliths/autoliths are interpreted in terms of (1) adiabatic decompression of magma pulses ascending in dykes leading to superheating and resorption of early solids, and (2) volatile exsolution, inducing undercooling, supersaturation, and rim crystallization. The variability of layers (number, thickness, mineral distribution, and texture) is considered to result from oscillatory crystallization combined with variable plagioclase growth rates linked to changes in the degree of supersaturation as a function of the extent of melt degassing, itself linked to magma transfer dynamics.

Description: The high fluxes of iron minerals associated with aeolian dry deposition may result in an anomalously high reactive iron content and the rapid reoxidation of hydrogen sulfide in sediments. This will prevent the formation of pyrite and result in a ‘cryptic’ sulfur cycle. We studied the cycling of iron and sulfur in deep water (〉800 m water depth) sediments of the Red Sea and its northern extension, the Gulf of Aqaba. We found that the reactive iron content in the surface sediments of the Gulf of Aqaba and the Red Sea is high, whereas the amount of sulfur-bound iron is very low and decreases with the water depth. The presence of trace amounts of pyrite and zero-valent sulfur, as well as the isotopic compositions of sulfate and pyrite, which are consistent with sulfate reduction under substrate-limiting conditions, suggest that cryptic sulfur cycling is likely to be a result of the rapid reoxidation of hydrogen sulfide rather than the suppression of microbial sulfate reduction. The low amount of reactive iron and high organic carbon content in the sediments of the Shaban Deep, which are overlain by hypersaline hydrothermal brines, result in a non-cryptic sulfur cycle characterized by the preservation of pyrite in the sediments.Supplementary material: Data for sulfur speciation, iron speciation and sulfur isotope composition are available at https://doi.org/10.6084/m9.figshare.c.5508155Thematic collection: This article is part of the Sulfur in the Earth system collection available at: https://www.lyellcollection.org/cc/sulfur-in-the-earth-system

Description: La Réunion Island includes two major volcanic systems. About 0·5 Myr ago, Piton des Neiges volcano declined, while Piton de la Fournaise volcano grew on its flank. Since then the Piton de la Fournaise shield volcano has produced homogeneous lavas with chemical compositions transitional between alkali and tholeiitic basalts. In April 2007, the volcano emitted a very small volume of trachytic pumice during its largest historical eruption. We conducted a comprehensive petrological and geochemical study of the pumice to understand the occurrence of such silicic melt in the feeding system of this highly active basaltic volcano. Isotopes of Sr, Nd, Pb and O, together with trace elements, indicate that the trachyte is genetically related to the La Réunion mantle plume and derives from crystallization of a typical basalt. The trachyte chemistry records a long and complex history of differentiation and outgassing. The extensive depletion of moderately volatile elements (F, Cl, B, Cs, Cu, Li) and less volatile uranium is consistent with exsolution of dense fluids at depths of several kilometres. Lithium isotopes point to closed-system degassing during the very late stages of crystallization. U-series isotopes and radiogenic 208Pb*/206Pb* constrain the age of U loss to between 0·4 and 2·1 Ma. This age is as old as or older than the Piton de la Fournaise shield edifice. The 2007 trachyte could thus be a liquid remnant of an extinct volcano, such as Piton des Neiges or Les Alizés (Piton de la Fournaise proto-volcano). It could also result from partial melting of an old syenite intrusion or remobilization of interstitial melts not fully solidified. Thermal modelling indicates that the sustained heat flux from hot basaltic magmas rising from the mantle can maintain temperatures above 800 °C in the central feeding system, and prevent total solidification of magmas trapped in this hot core.

Description: Fisheries management is usually supported by technical and financial measurements (i.e. logbooks and market data), which are helpful for ecological or economic assessments. Yet this information is not able to address social heterogeneity and fisher motivations, which are key to understanding fisher behaviour. This case study of the demersal segment in the Netherlands shows that combining quantitative analysis of logbooks with qualitative data collected by engaging with fishers can capture both fishing activity and its motivations, generating a more social understanding of fisher behaviour. A métier analysis of logbook data describes five dominant fishing practices among the selected segment. Twenty-five in-depth interviews with fishers along with focus groups including other experts identify three social factors that influence fisher behaviour in the Dutch demersal fleet: business structure, working rhythm, and polyvalence. The results show that motivations for fisher behaviour are more complex than complying with regulations or seeking profit: social factors also influence fishing activity. Furthermore, these social factors have real implications for the impacts of management measures on both the fishing communities and the environment, especially in times of change. These results are useful for management strategy development or evaluation because they are feasibly observable through existing data collection protocols.

Description: Harbour seals are surveyed aerially when they haul-out to moult in August. The proportion of the population hauled out throughout the year is related to temporal, environmental, and meteorological variables. Thus, monitoring is conducted under predefined ranges of conditions. Effects of variation within these ranges are rarely reviewed. We used linear models to assess effects of time, date and weather on the difference between counts predicted by a population growth model and observed counts, based on a 30-year time-series. Our top-ranked model explained 34.4% of the variance. Survey date and its interaction with survey year were the most important variables, with higher counts earlier in August, particularly early in the time series, where surveys may not have been timed optimally to capture the peak in the moult. Cloud cover, wind speed, temperature, and interactions between these were of lesser importance; there were fewer seals on land during cloudy, windy days and on clear, warm days. These effects of weather are likely related to temperature regulation. Power analyses suggested that correction for survey conditions would allow detection of a one percentage point annual change in population growth rate with 80% power 4 years sooner than without taking survey conditions into account.

Description: Sargassum forests play an important role in coastal waters as habitats for marine organisms, including commercial species. However, human activities have negatively affected their distribution causing a worldwide decline of Sargassum forests. Mapping and monitoring the distribution and biomass of these habitats using acoustic remote sensing techniques is key for their conservation. Nonetheless, most researches based on acoustic remote sensing methods focus on estimations of macrophyte area and its canopy height, and less researches reporting 3D visualization of these habitats. This study demonstrates the use of high-resolution multibeam echosounder (MBES) bathymetric data to visualize the 3D structure of Sargassum forests. Comparing acoustic data and underwater camera photos collected in field surveys, we identified Sargassum individuals as vertical clusters of contiguous sounding points with a base close to the sea bottom in the sounding data of the MBES. Using this criterion, we could distinguish Sargassum echoes, visualize the 3D structure of Sargassum forests and estimate the number of Sargassum individuals in the survey area. Using the relation between thallus length and dry weight of sampled Sargassum plants, standing stock and biomass could be estimated assuming the thallus length was the height of Sargassum plants identified with the MBES.

Description: This paper reviews application of the Daily Egg Production Method (DEPM) to sardine (Sardinops sagax) off southern Australia between 1995 and 2019. Coefficients of variation (CVs) of estimates of spawning biomass (SB) were reduced from 23–59% to 8–12% by: (i) estimating mean daily egg production (P0), spawning fraction (S), and sex ratio (R) from all historical data rather than annually; and (ii) combining batch fecundity (F) and female weight (W) into a single parameter, relative fecundity (F′ = F^/W). Total daily egg production was estimated most precisely from annual estimates of spawning area (A) and estimates of P0 obtained from historical data. Both S and R were estimated most precisely from historical data. Estimating W and F from historical data did not increase precision. F′ had lower CVs than both W and F, and was stable across years and a wide range of W. Findings demonstrate that A can be converted into a precise estimates of SB using estimates of P0, S, R, and F′ obtained from historical data. However, the possibility that DEPM parameters may change in the future cannot be discounted. Future monitoring should include annual estimation of P0 and periodic (e.g. 3–5 years) re-estimation of adult parameters.

Description: In his 1953 paper, Harald Sverdrup argued that the development of a spring bloom in the ocean depends on the juxtaposition of two depth horizons: the mixed-layer depth and the critical depth. Mixed-layer depth shallower than the critical depth favours phytoplankton growth in the layer and vice versa. However, mathematically, Sverdrup left the problem unsolved in the form of a transcendental equation. In spite of the high number of citations that this paper has garnered, the solution to this equation has not been found, until now. In this work, we present an analytical solution for the critical depth, as originally defined by Sverdrup. The paper opens with the definition of the critical depth and the description of the Lambert W function. The analytical solution for critical depth follows. Sverdrup’s original model is extended to include the effect of light attenuation by phytoplankton and the analytical solution for steady-state biomass in the mixed layer is derived. The expression for mixed-layer production at steady state is also presented. Two novel variants of the critical depth are defined: the optically uncoupled critical depth and the optically coupled critical depth. It is demonstrated that at steady state the optically coupled critical depth equals the mixed-layer depth and that the irradiance at the base of the mixed layer equals the irradiance at the optically uncoupled critical depth. Competitive exclusion is demonstrated to hold and the optically uncoupled critical depth is linked to the critical light intensity in multi-species competition. Finally, a conservation principle for the critical depth is found.

Description: Fishery bycatch poses a serious threat to seabird populations globally. Traditional haul-only post-capture observations are inadequate and inefficient to document seabird bycatch due to the substantial bycatch loss known to occur. Pre-capture observations offer an alternative by documenting seabird interactions leading up to captures. Based on the long-term large-scale dedicated field observations, this study revealed significant risk factors for the pre-capture stages of the seabird bycatch process in pelagic longline fisheries using Bayesian methods. Rough sea conditions were found to correlate with more seabirds following fishing vessels. Species identity, density effect, inter-species effect, and sea condition were found to significantly affect how frequently seabirds aggregated around a fishing vessel engage in bait-taking interactions. Intra-species competition was found to be the dominant type of density effect. Moreover, a web of inter-species interactions was identified to facilitate the bait-taking of superior competitors at the expense of inferior ones. The findings of this study are relevant to fishery managers in updating current data collection protocols to alleviate data issues caused by bycatch loss, to conservation biologists in quantifying bycatch risks for susceptible seabird populations, and in aiding the design and evaluation of bycatch mitigation measures.

Description: Fishing and translocation of marine species for use in aquaculture is widespread. Corkwing, goldsinny, and ballan wrasse (Symphodus melops, Ctenolabrus rupestris, and Labrus bergylta) are fished on the Swedish west coast for use as cleaner-fish in Norwegian salmon farms. Here, we aim to provide knowledge and recommendations to support ecosystem-based management for wrasse fisheries in Sweden. We compared fished and non-fished areas to test if current fishery levels have led to stock depletion. To gain insight on the role of wrasse in the algal belt trophic chain, we analysed the gut contents of goldsinny and corkwing using metabarcoding. Finally, we analysed the trophic interactions of wrasse and potential prey in a mesocosm study. We could not detect any signs of stock depletion or altered size structure in fished areas compared to the protected control area. Gut analyses confirmed both goldsinny and corkwing as non-specialized, omnivorous opportunists and revealed, with 189 prey taxa detected, a broader spectrum of prey than previously known. Common prey items included mesoherbivores such as small gastropods and crustaceans, but also insects and algae. We conclude that there are no visible signs of stock depletion at the current removal level of wrasses by the fishery. However, this emerging fishery should be closely monitored for potential cascading effects on the algal belt ecosystem, and our study could provide a baseline for future monitoring.

Description: Target strength model inputs including morphometry, material properties, lipid composition, and in situ orientations were measured for sub-Arctic krill (Euphausia pacifica, Thysanoessa spinifera, T. inermis, and T. raschii) in the eastern Bering Sea (EBS, 2016) and Gulf of Alaska (GOA, 2017). Inter-species and -regional animal lengths were significantly different (F1,680 = 114.10, p 

Description: Atlantic cod (Gadus morhua) is one of the most commercially important fish species in the North Atlantic. Environmental factors, such as water temperatures, influence growth of individuals over time, thus forming population-specific growth patterns across climatic regions. Here we develop an integrative approach to investigate the role of temperature in shaping geographic differences of cod growth in the Celtic Sea, North Sea, Iceland, and Barents Sea. We combine a physiology-based growth model and 50-years observational temperature data of 0.5 × 0.5° spatial resolution to simulate continuous growth of cod. The model generated weight-at-age data for the period 1959–2007 which we compared to observational data from fishery-independent scientific surveys. In the Celtic and the northern North Sea, simulated growth matches well observational data. We also show that relatively warm temperatures in the Celtic Sea facilitate maximum growth rates; future warming is likely to have a negative impact on growth of these cod stocks. Growth simulations in Icelandic waters and the Barents Sea are less consistent with local observational data. More complex growth patterns in these regions are probably shaped by ontogenetic shifts in temperature regimes, feeding conditions and physiological adaptations. These findings should stimulate further research on critical processes to be considered in population-specific projections of growth of cod and productivity.

Description: In designing and performing surveys of animal abundance, monitoring programs often struggle to determine the sampling intensity and design required to achieve their objectives, and this problem greatly increases in complexity for multispecies surveys with inherent trade-offs among species. To address these issues, we conducted a multispecies stratified random survey design optimization using a spatiotemporal operating model and a genetic algorithm that optimizes both the stratification (defined by depth and longitude) and the minimum optimal allocation of samples across strata subject to prespecified precision limits. Surveys were then simulated under those optimized designs and performance was evaluated by calculating the precision and accuracy of a resulting design-based abundance index. We applied this framework to a multispecies fishery-independent bottom trawl survey in the Gulf of Alaska, USA. Incorporating only spatial variation in the optimization failed to produce population estimates within the prespecified precision constraints, whereas including additional spatiotemporal variation ensured that estimates were both unbiased and within prespecified precision constraints. In general, results were not sensitive to the number of strata in the optimized solutions. This optimization approach provides an objective quantitative framework for designing new, or improving existing, survey designs for many different ecosystems.

Description: Changes in animal movement and behaviour at fine scales (tens of metres) in immediate proximity to tidal stream turbine structures are largely unknown and have implications for risks of animal collision with turbine blades. This study used upward-facing multibeam echosounder data to detect and track animal movement comprising fish, diving seabirds, and marine mammals. Measurements over spring-neap tidal cycles at a turbine structure (no blades present) are compared to a neighbouring reference area with no structure and comparable conditions, with measurements consecutive in time to maximize comparability. The majority of tracked animals (93.4% around turbine structure and 99.1% without turbine structure) were observed swimming against the flow, with 87.5% and 97.8%, respectively, making ground and showing capability of manoeuvring in tidal stream flow speeds. Track tortuosity increased around the turbine structure compared to the reference site, particularly in the wake and at low flow speeds, indicating animal station-holding or milling behaviour. These data also evidence the benefits of multibeam echosounders to measure animal movement through larger measurement volumes rather than relying on single-beam echosounders to measure animal presence alone, including to avoid large biases overestimating the size of schools swimming against the flow measured by time-in-beam.

Description: The Antarctic Peninsula is one of the most rapidly warming regions on earth, and it is likely that the abundance and distribution of marine predators will change as a result.Procellariiform seabirds are highly mobile predators, which target specific habitat characteristics associated with underlying distributions of prey and areas of increased prey availability. We use ship surveys and hurdle models, to estimate the summer distribution and relative density of 11 seabird species within the northern Antarctic Peninsula marine ecosystem. Models differed among species; however, sea surface temperature and depth were frequently associated with seabird occurrence and had the greatest explanatory power across many species. Null models based on observation data were better at predicting seabird density than models that included environmental covariates. This suggests that the main driver of distribution patterns is the broad-scale habitat features, and fine-scale aggregations within these ranges are harder to predict. Our seabird distribution models reflect known habitat associations, species hotspots, and community organization relative to oceanic and coastal marine processes. Application of species distribution models will benefit the assessments of critical habitat and potential responses to climate change and anthropogenic disturbance, which will provide insight into how species may change in polar ecosystems.

Description: Many data-limited fish stocks worldwide require management advice. Simple empirical management procedures have been used to manage data-limited fisheries but do not necessarily ensure compliance with maximum sustainable yield objectives and precautionary principles. Genetic algorithms are efficient optimization procedures for which the objectives are formalized as a fitness function. This optimization can be included when testing management procedures in a management strategy evaluation. This study explored the application of a genetic algorithm to an empirical catch rule and found that this approach could substantially improve the performance of the catch rule. The optimized parameterization and the magnitude of the improvement were dependent on the specific stock, stock status, and definition of the fitness function. The genetic algorithm proved to be an efficient and automated method for tuning the catch rule and removed the need for manual intervention during the optimization process. Therefore, we conclude that the approach could also be applied to other management procedures, case-specific tuning, and even data-rich stocks. Finally, we recommend the phasing out of the current generic ICES “2 over 3” advice rule in favour of case-specific catch rules of the form tested here, although we caution that neither works well for fast-growing stocks.

Description: Ocean grabbing occurs when traditional users, such as small-scale fishers, are pushed aside by new development activities. This grabbing must be prevented to avoid sea uses that maintain or increase social inequity. In this paper, we show that in tropical Atlantic countries, such as Brazil and Senegal, examples of ocean grabbing already occur. In this context, we analyse if Maritime Spatial Planning (MSP) may be an opportunity to limit ocean grabbing or, to the contrary, poses a risk to increase it. MSP calls for an ecosystem approach that requires integrated coastal and marine management and involves stakeholders in developing a shared vision of the future, where society and environment are preserved. However, recent studies have shown that MSP is a process to be used cautiously to ensure equitable decisions. Meanwhile, the concept is spreading worldwide including in tropical Atlantic countries. We highlight that context matters and the specificities of the tropical Atlantic must be taken into account when deploying MSP processes. In the tropical Atlantic context, there is increased imbalances of stakeholder power, traps from decision support tools, and a need for adaptive management. These specific features must be addressed when deploying MSP in a way to avoid ocean grabbing.

Description: The influence of oceanographic variables on assemblages of meso- and bathypelagic fish was investigated along a Northeastern Atlantic Ocean transect (Cape Verde to the Bay of Biscay) during May 2019. Fish were collected using a mrozooplankton trawl during daylight hours at ten stations. Along the transect, 17 hydrographic stations were also performed with a CTD (Conductivity, Temperature, and Depth). A total of 130 fish taxa were identified. The dominant family was Gonostomatidae, with four species (Cyclothone braueri, Cyclothone microdon, Cyclothone pseudopallida, and Cyclothone pallida) being responsible of more than 78% of the total density. The most frequent species that appeared to be ubiquitous were C. braueri and C. pseudopallida, while Myctophidae was the most diverse family. Multivariate analyses revealed two clusters related with the latitudinal gradient. The fish community in the southern stations (25–37°N) was more diverse than in the northern stations (42–48°N). Temperature from 300 to 700 m depth explained 65% of variation in terms of density and 58% in terms of biomass, both statistically significant. The investigated variation in the deep-pelagic ecosystems on a large spatial scale gives essential information to ecosystem management approhes and marine spatial planning.

Description: In the European Union (EU), the ecosystem approach to fisheries is implemented through several directives and polices, which are overarched by the Marine Strategy Framework Directive (MSFD). The MSFD requires the assessment of the environmental status of exploited fish and shellfish stocks, among others, to advise the EU Common Fisheries Policy (CFP) on sustainable catch options. The stock assessments for the CFP and the MSFD are supposed to be congruent, yet they differ in several substantial subjects. While the annual CFP assessment is based on two indicators, fishing mortality (F) and spawning stock biomass (SSB), in its Descriptor 3 (D3) the MSFD requires the assessment of three criteria (F, SSB, and age or size structure) within a six year period. Assessing exploited fish and shellfish stocks under the MSFD by using existing CFP assessments has therefore been a half-completed task, which had to be fulfilled by the member states of the EU. This paper suggests six easy steps, referred to as “quick wins” (QW), which are based on existing information from CFP stock assessments. The implementation of these six QW would allow for assessments of exploited fish and shellfish stocks that are compliant to D3. These QW are to (i) assess length/age structure within a stock, (ii) analyse and assess selectivity by fisheries, (iii) use all available information to assess a stock, (iv) use response indicators to assess environmental targets, (v) provide integrated stock-specific advice, and (vi) provide assessments with a mid-term perspective over a-period of six years. International Council for the Exploration of the Sea (ICES) combines the infrastructure and expertise to produce stock-specific assessment products tailored to the requirements of MSFD D3. Thereby, ICES could provide a valuable service to EU member states in the north-east Atlantic region by providing scientifically validated, quality-assured, and MSFD-compliant single-stock assessment products. This would be a big advancement towards implementing the ecosystem approach to fisheries management within Europe.

Description: Managers, stakeholders, and scientists recognize the need for collaborative, transparent, integrated approaches to complex resource management issues, and frameworks to address these complex issues are developing. Through the course of 2019, the Mid-Atlantic Fishery Management Council developed a conceptual model of ecosystem linkages and risks for summer flounder, a species of recreational and commercial fisheries importance. The proximal aim of the model was to develop a list of integrated management questions that could be refined and addressed through a future quantitative management strategy evaluation. As such, this conceptual model served as a scoping tool. However, the true value of the conceptual model lays elsewhere: familiarizing resource managers historically focused on single-species management with the potential utility of an ecosystem approach to management. This paper details the goals and development of the conceptual model and situates this process in the broader context of best practices for collaborative open science and scientific reproducibility. Further, it highlights a successful path by which the shift towards ecosystem-based management can be actuated.

Description: Understanding the competitive interactions of ecological similar species is essential to determine their role and niche in the ecosystem. Using both conventional dietary methods and stable isotope analysis, we examined the feeding ecology, trophic position and possible niche partitioning of Northeast Atlantic mackerel (Scomber scombrus), Icelandic summer spawning (ISS) herring (Clupea harengus), and Norwegian spring spawning (NSS) herring from Icelandic waters during the spring and summer 2012 and 2014. The stomach analysis showed differences in prey preferences among the species during summer, where mackerel diets were almost exclusively calanoid copepods, while herring ate larger zooplankton, i.e. euphausiids and amphipods. Analysis of isotopic diet contribution of mackerel and herring using Bayesian mixing models, representing mainly the spring consumption, revealed that euphausiids were the main dietary contributor of both mackerel and herring. Fish prey were also an important dietary source for ISS herring, and amphipods were important to the diet of NSS herring. In addition, mackerel encompassed a broad isotopic niche, whereas the two herring stocks had narrower and separated niches from each other. The results from this analysis reveal new and holistic information into the diet of these species, which have various ecological implications.

Description: Theoretical size at the onset of maturity (TSOM) for female Norway lobster was estimated by a new methodology based on the probability distributions of mature individuals built on physiological maturity measures. Onset of maturity using TSOM varied from 18.4- to 33.7-mm carapace length for the Irish functional management units (FUs). These estimates showed a significant negative linear relationship (R2 = 0.60) with population density and a significant positive linear relationship with average size in females (R2 = 0.84). The size class at which 50% of the females are sexually mature (L50) was linked to the new TSOM metric by a significant positive linear relationship (R2 = 0.40). This set of linear relationships ultimately allowed TSOM and L50 to be estimated without a requirement for maturity stages to be distinguished. As well as contributing to the stock assessment and management of Nephrops (e.g. in data-limited FUs) and its potential for the calibration of more routinely used estimates, TSOM might be applied in new species and meta-analyses where size of maturity data are scarce. This new metric also better-defines the maturity process since, taken together, TSOM, L50, and smallest berried female represent sequential maturity events: (i) onset of maturity, (ii) 50% mature (from gonad staging), and (iii) berried females.

Description: Although gelatinous zooplankton are an important component of marine ecosystems, gelatinous mesozooplankton that are

Description: The carapace length (CL) at which American lobster (Homarus americanus) females reach maturity can be used to evaluate egg production, growth patterns, and the overall health of lobster stocks. The female maturity datasets used to represent Gulf of Maine (GOM) lobsters in the 2015 Atlantic States Marine Fisheries Commission American Lobster Stock Assessment were collected in the 1990s by the Maine Department of Marine Resources at two coastal sites. Many studies have demonstrated an inverse relationship between temperature and the size at maturity in female lobsters, and GOM waters have warmed significantly over this period. To update these GOM maturity datasets, we used ovarian staging to determine the maturity status of over 1200 females from fives sites over 3 years. Broad application of this methodology in tandem with key growth measurements on females 50–120 mm CL allowed us to characterize reproductive development and generate maturity ogives (proportion mature at a given CL). We observed a latitudinal gradient in the size at maturity across this coastal region of the GOM and quantified a decrease in this size over 25 years. These findings have implications for future stock assessment approaches and management measures implemented to sustain this valuable fishery.

Description: The carbonate chemistry in coastal waters is more variable compared with that of open oceans, both in magnitude and time scale of its fluctuations. However, knowledge of the responses of coastal phytoplankton to dynamic changes in pH/pCO2 has been scarcely documented. Hence, we investigated the physiological performance of a coastal isolate of the coccolithophore Emiliania huxleyi (PML B92/11) under fluctuating and stable pCO2 regimes (steady ambient pCO2, 400 μatm; steady elevated pCO2, 1200 μatm; diurnally fluctuating elevated pCO2, 600–1800 μatm). Elevated pCO2 inhibited the calcification rate in both the steady and fluctuating regimes. However, higher specific growth rates and lower ratios of calcification to photosynthesis were detected in the cells grown under diurnally fluctuating elevated pCO2 conditions. The fluctuating pCO2 regime alleviated the negative effects of elevated pCO2 on effective photochemical quantum yield and relative photosynthetic electron transport rate compared with the steady elevated pCO2 treatment. Our results suggest that growth of E. huxleyi could benefit from diel fluctuations of pH/pCO2 under future-projected ocean acidification, but its calcification was reduced by the fluctuation and the increased concentration of CO2, reflecting a necessity to consider the influences of dynamic pH fluctuations on coastal carbon cycles associated with ocean global changes.

Description: Millions of people’s livelihoods rely on artisanal fisheries. However, in many regions fishers are increasingly facing ciguatera poisoning, a seafood-borne illness. The toxin, produced by benthic dinoflagellates, can spread through marine food webs and to humans by direct consumption. Ciguatera risk can play a major role in fisher’s activities but has never been considered in any marine spatial plans thus far. To fill this gap, we examined if integrating ciguatera in systematic conservation plans could affect these decisions. We developed through map-based interviews, a novel seven-step framework to collect and map local knowledge on ciguatera risk and fisheries activities with two innovations: (i) better mapping of fishing grounds by combining geomorphological habitat and fishing gear information, and (ii) integrating ciguatera risk directly into systematic spatial planning designs and scenarios conceived to maximize benthic habitat conservation while minimizing impacts to fishers. The approach is illustrated for Raivavae Island, in French Polynesia, Pacific Ocean. We found that integrating ciguatera significantly improved prioritization solutions with a 24–38% decrease of costs to fishers compared with scenarios based solely on fishery data. This framework was designed for scientists and managers to optimize the implementation of conservation plans and could be generalized to ciguatera-prone areas.

Description: Deep-sea marine fishes support important fisheries but estimates of their distributions are often incomplete as the data behind them may reflect fishing practices, access rights, or political boundaries, rather than actual geographic distributions. We use a simple suitable habitat model based on bottom depth, temperature, and salinity to estimate the potential distribution of Greenland halibut (Reinhardtius hippoglossoides). A large presence-only dataset is examined using multivariate kernel densities to define environmental envelopes, which we link to spatial distribution using a pan-Arctic oceanographic model. Occurrences generally fit the model well, although there were gaps in the predicted circum-Arctic distribution likely due to limited survey activity in many of the ice-covered seas around the Arctic Ocean. Bottom temperature and depth were major factors defining model fit to observations, but other factors, such as ecosystem interactions and larval drift could also influence distribution. Model predictions can be tested by increasing sampling effort in poorly explored regions and by studying the connectivity of putative populations. While abundances of Greenland halibut in the High Arctic are currently low, some areas are predicted to be suitable habitat for this species, suggesting that on-going sea-ice melt may lead to fisheries expansion into new areas.

Description: On the continental shelf, New Zealand bryozoans dominate ecologically-important three-dimensional benthic habitat providing structural complexity which hosts a wide variety of fauna, including economically valuable species (e.g. oysters and blue cod). The association between these species and bryozoan-dominated biogenic habitat commonly results in trawling damage to the benthos; eliminating pressure from destructive fishing practices could support bryozoan regrowth. In 2002, a voluntary fishing restriction was designated over part of one such bryozoan-dominated biogenic habitat, but the efficacy of this ban has not been assessed. Statutory marine protected areas have been proposed in the same area; they aim to achieve bryozoan protection and recovery. A comparison of the bryozoan fauna using benthic images from 2003 and 2019 from the Otago shelf, South Island, New Zealand/Te Waipounamu, Aotearoa shows that a 17-year voluntary fishing ban has been ineffective at increasing the cover and richness of bryozoan-dominated biogenic habitat on the Otago shelf. This study provides a baseline for future monitoring and develops useful metrics for recovery, while calling for further research on the biology and ecology of habitat-forming bryozoans.

Description: Ecosystem-based management is generally viewed as one of the most promising avenues for addressing the various anthropogenic pressures facing the world’s marine ecosystems. These approaches have been developed to varying degrees by individual countries or international organisations, but there remain a large proportion of marine ecosystems, particularly in developing regions, that have not yet been the subject of such research. In these areas, lack of effective regulation and the often high importance of the marine environment in providing food and economic opportunities, together create conditions where marine resources and habitats come under unsustainable levels of pressure. Here, we present a data-limited assessment approach to discern marine ecological patterns, in this case for the exclusive economic zone of Vietnam. By combining data from environmental and biological surveys from the Vietnamese national survey dataset and local oceanographic models, we have identified a series of 12 candidate ecological production units, delineated by their environmental characteristics, and the key commercial species that exist within them. These units are suggested as a possible foundation for a spatial management structure in the Vietnamese exclusive economic zone including considerations such as placement of marine protected areas, or ecological boundaries of key areas of socio-economic importance.

Description: This paper explores the possibility of using the ensemble modelling paradigm to fully capture assessment uncertainty and improve the robustness of advice provision. We identify and discuss advantages and challenges of ensemble modelling approaches in the context of scientific advice. There are uncertainties associated with every phase in the stock assessment process: data collection, assessment model choice, model assumptions, interpretation of risk, up to the implementation of management advice. Additionally, the dynamics of fish populations are complex, and our incomplete understanding of those dynamics and limited observations of important mechanisms, necessitate that models are simpler than nature. The aim is for the model to capture enough of the dynamics to accurately estimate trends and abundance, and provide the basis for robust advice about sustainable harvests. The status quo approach to assessment modelling has been to identify the “best” model and generate advice from that model, mostly ignoring advice from other model configurations regardless of how closely they performed relative to the chosen model. We discuss and make suggestions about the utility of ensemble models, including revisions to the formal process of providing advice to management bodies, and recommend further research to evaluate potential gains in modelling and advice performance.

Description: Climate effects on marine fish depend on life stage, particularly when life stages differ in habitat utilization. In the present study, we investigated life stage-dependent responses of lesser sandeel (Ammodytes marinus) to temperature at contrasting geographical scales. We related population density and individual growth to temperature and found different temperature responses between the first and the second years of life. During the first year of life, fish size was the single most important factor influencing sandeel abundances, indicating a positive relationship between growth and survival. In contrast, during the second year of life, autumn bottom temperature was negatively correlated with sandeel abundance, suggesting elevated mortality in warm years. Southerly areas, experiencing higher temperatures in general, were also the areas showing the strongest response to temperature. This study sheds light on how warming impacts population dynamics of one of the most important forage fishes in the North Sea and supports the discussion of underlying mechanisms.

Description: Recent ichnological analysis conducted in two sections (Rodiles and Lastres) of the Asturian Basin revealed the presence of Halimedides Lorenz von Liburnau 1902, which occurs just above the black shales related to the end of the T-OAE. Halimedides is associated with the recovery of the tracemaker community after the reestablishment of favourable, oxic, conditions. The appearance of Halimedides after the T-OAE event, previously not registered, supports the close relationship of the tracemaker with oxygen conditions, as occurs in other anoxic events including the Cretaceous OAE-1a and OAE-2. Also a relation between morphometric and paleoenvironmental parameters is observed, occurring larger and densely chambered specimens in darker, weakly oxygenated facies, while smaller and sparsely chambered forms are registered in lighter, better oxygenated sediments.

Description: The geometry, distribution, and rock properties (i.e. porosity and permeability) of turbidite reservoirs, and the processes associated with turbidity current deposition, are relatively well known. However, less attention has been given to the equivalent properties resulting from laminar sediment gravity-flow deposition, with most research limited to cogenetic turbidite-debrites (i.e. transitional flow deposits) or subsurface studies that focus predominantly on seismic-scale mass-transport deposits (MTDs). Thus, we have a limited understanding of the ability of sub-seismic MTDs to act as hydraulic seals and their effect on hydrocarbon production, and/or carbon storage. We investigate the gap between seismically resolvable and sub-seismic MTDs, and transitional flow deposits on long-term reservoir performance in this analysis of a small (

Description: The northern Antarctic Peninsula (NAP) is a highly dynamic transitional zone between the subpolar-polar and oceanic-coastal environments, and it is located in an area affected by intense climate change, including intensification and spatial shifts of the westerlies as well as atmospheric and oceanic warming. In the NAP area, the water masses originate mainly from the Bellingshausen and Weddell seas, which create a marked regional dichotomy thermohaline characteristic. Although the NAP area has relatively easy access when compared to other Southern Ocean environments, our understanding of the water masses' distribution and the dynamical processes affecting the variability of the region is still limited. That limitation is closely linked to the sparse data coverage, as is commonly the case in most Southern Ocean environments. This work provides a novel seasonal three-dimensional high-resolution hydrographic gridded data set for the NAP (version 1), namely the NAPv1.0. Hydrographic measurements from 1990 to 2019 comprising data collected by conductivity, temperature, depth (CTD) casts; sensors from the Marine Mammals Exploring the Oceans Pole to Pole (MEOP) consortium; and Argo floats have been optimally interpolated to produce maps of in situ temperature, practical salinity, and dissolved oxygen at ∼ 10 km spatial resolution and 90 depth levels. The water masses and oceanographic features in this regional gridded product are more accurate than other climatologies and state estimate products currently available. The data sets are available in netCDF format at https://doi.org/10.5281/zenodo.4420006 (Dotto et al., 2021). The novel and comprehensive data sets presented here for the NAPv1.0 product are a valuable tool to be used in studies addressing climatological changes in the unique NAP region since they provide accurate initial conditions for ocean models and improve the end of the 20th- and early 21st-century ocean mean-state representation for that area.

Description: A method is proposed for determining the height of the turbulent mixing layer on the basis of the vertical profiles of the dissipation rate of turbulent energy, which is estimated from lidar measurements of the radial wind velocity using conical scanning by a probe beam around the vertical axis. The accuracy of the proposed method is discussed in detail. It is shown that for the estimation of the mixing layer height (MLH) with the acceptable relative error not exceeding 20 %, the signal-to-noise ratio should be no less than −16 dB, when the relative error of lidar estimation of the dissipation rate does not exceed 30 %. The method was tested in a 6 d experiment in which the wind velocity turbulence was estimated in smog conditions due to forest fires in Siberia in summer 2019. The results of the experiment reveal that the relative error of determination of the MLH time series obtained by this method does not exceed 10 % in the period of turbulence development. The estimates of the turbulent mixing layer height by the proposed method are in a qualitative agreement with the MLH estimated from the distributions of the Richardson number in height and time obtained during the comparison experiment in spring 2020.

Description: Micritic sediments containing dark, discrete, organic-rich burrows, situated in a light grey background carbonate mud, were deposited over a broad geographic area in deep-shelf, bathyal, and basinal environments in the western margin of the Tethys Ocean during the Early and Middle Jurassic. These hemipelagic deposits represent a distinct depositional regime marked by low-energy, soft-bottom and only locally dysoxic environments. Still, it is unclear whether the trace fossil assemblages occurring in these deposits pertain to a network of several community types -the ichnotaxa differing from basin to basin- or else a single community of environmentally broad-ranging, burrow-producing species. Lower Jurassic trace-fossil assemblages are found in the Western Carpathians and in the Subbetic, Betic Cordillera, i.e. in basins separated by more than 2,000 km in their original palaeogeographic areas. The stereotypical Chondrites and Zoophycos trace-fossil assemblages that occur in the analysed deposits share two ichnogenera of distinctive morphology (Lamellaeichnus, Teichichnus). Agglutinated foraminifera Bathysiphon occurs together with the described trace fossil assemblage and determines epibenthic palaeoenvironmental conditions. In the Western Carpathians, a Lamellaeichnus-dominated assemblage alternates with a Zoophycos-dominated assemblage in small, metre-scale cycles in the upper Pliensbachian, and the proportion of the Zoophycos assemblage increases stratigraphically upwards, probably owing to reduced basin ventilation during the early Toarcian. Within the southern Iberian Palaeomargin, represented by the Betic Cordillera, Zoophycos is scarce in the facies.

Description: In the 2019/2020 austral summer, the surface melt duration and extent on the northern George VI Ice Shelf (GVIIS) was exceptional compared to the 31 previous summers of distinctly lower melt. This finding is based on analysis of near-continuous 41-year satellite microwave radiometer and scatterometer data, which are sensitive to meltwater on the ice shelf surface and in the near-surface snow. Using optical satellite imagery from Landsat 8 (2013 to 2020) and Sentinel-2 (2017 to 2020), record volumes of surface meltwater ponding were also observed on the northern GVIIS in 2019/2020, with 23 % of the surface area covered by 0.62 km3 of ponded meltwater on 19 January. These exceptional melt and surface ponding conditions in 2019/2020 were driven by sustained air temperatures ≥0 ∘C for anomalously long periods (55 to 90 h) from late November onwards, which limited meltwater refreezing. The sustained warm periods were likely driven by warm, low-speed (≤7.5 m s−1) northwesterly and northeasterly winds and not by foehn wind conditions, which were only present for 9 h total in the 2019/2020 melt season. Increased surface ponding on ice shelves may threaten their stability through increased potential for hydrofracture initiation; a risk that may increase due to firn air content depletion in response to near-surface melting.

Description: In the Pliocene Model Intercomparison Project Phase 2 (PlioMIP2), coupled climate models have been used to simulate an interglacial climate during the mid-Piacenzian warm period (mPWP; 3.264 to 3.025 Ma). Here, we compare the Atlantic Meridional Overturning Circulation (AMOC), poleward ocean heat transport and sea surface warming in the Atlantic simulated with these models. In PlioMIP2, all models simulate an intensified mid-Pliocene AMOC. However, there is no consistent response in the simulated Atlantic ocean heat transport nor in the depth of the Atlantic overturning cell. The models show a large spread in the simulated AMOC maximum, the Atlantic ocean heat transport and the surface warming in the North Atlantic. Although a few models simulate a surface warming of ∼ 8–12 ∘C in the North Atlantic, similar to the reconstruction from Pliocene Research, Interpretation and Synoptic Mapping (PRISM) version 4, most models appear to underestimate this warming. The large model spread and model–data discrepancies in the PlioMIP2 ensemble do not support the hypothesis that an intensification of the AMOC, together with an increase in northward ocean heat transport, is the dominant mechanism for the mid-Pliocene warm climate over the North Atlantic.

Description: Recently, time-lapse seismic (4D seismic) has been steadily used to demonstrate the relation between field depletion and 4D seismic response, subsequently to have more efficient field management. A key component of the reservoir monitoring is the knowledge of fluid movement and pressure variations. This information is vital to assist infill drillings and a trustworthy source to update reservoir models, consequently improving model-based reservoir management and decision-making process. However, in practice the 4D seismic interpretation of reservoirs with multipart production regime possesses ambiguities through different levels of uncertainty. Complex nature of some 4D seismic signals emphasizes the roles of competing effects, geology, rock and fluid interactions. Hence, a reliable 4D interpretation requires an interdisciplinary approach entailing data analysis and insights from geophysics, engineering and geology. In this research, a step-wise workflow was introduced to reduce uncertainties in the 4D seismic interpretation and provide diagnoses to perform better reservoir surveillance. In parallel, the workflow expresses the use of engineering data analysis to conduct a consistent interpretation and encompasses the 3D and 4D seismic attributes with engineering data analysis. This study is implemented in a Brazilian heavy-oil offshore field where production started in 2013. The field experienced intense production activity up to 2016, making the deep-water field an ideal candidate to explore the challenges in interpreting complex 4D signals. Beyond these challenges, significant understanding of reservoir behavior is obtained and suggestions are made to improve the reservoir simulation model, which could support reservoir engineers with data assimilation applications.

Description: A ground-based network of more than 1200 Global Navigation Satellite System (GNSS) Continuously Operating Reference Stations (CORS) was analysed using GIPSY-OASIS II software package for the documentation of time and space variations of water vapor in atmosphere during the North Atlantic Waveguide and Downstream impact EXperiment (NAWDEX) during fall 2016. The network extends throughout the North Atlantic, from the Caribbeans to Morocco through Greenland. This paper presents the methodology used for GNSS data processing, screening, and conversion of Zenith Tropospheric Delay (ZTD) estimates to Integrated Water Vapor content (IWV) using surface parameters from reanalysis. The retrieved IWV are used to evaluate the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalyses ERAI and ERA5. ERA5 shows an overall improvement over ERAI in representing the spatial and temporal variability of IWV over the study area. The mean bias is decreased from 0.31±0.63 to 0.19±0.56 kg m−2 (mean ±1σ over all stations) and the standard deviation reduced from 2.17±0.67 to 1.64±0.53 kg m−2 combined with a slight improvement in correlation coefficient from 0.95 to 0.97. At regional scale, both reanalyses show a general wet bias at mid and northern latitudes but a dry bias in the Caribbeans. We hypothesize this results from the different nature of data being assimilated over the tropical oceans. This GNSS IWV data set is intended to be used for a better description of the high impact weather events that occurred during the NAWDEX experiment.

Description: The deep chlorophyll maximum (DCM) is a well-known feature of the global ocean. However, its description and the study of its formation are a challenge, especially in the peculiar environment that is the Black Sea. The retrieval of chlorophyll a (chl a) from fluorescence (Fluo) profiles recorded by Biogeochemical Argo (BGC-Argo) floats is not trivial in the Black Sea, due to the very high content of coloured dissolved organic matter (CDOM) which contributes to the fluorescence signal and produces an apparent increase in the chl a concentration with depth. Here, we revised Fluo correction protocols for the Black Sea context using co-located in situ high-performance liquid chromatography (HPLC) and BGC-Argo measurements. The processed set of chl a data (2014–2019) is then used to provide a systematic description of the seasonal DCM dynamics in the Black Sea and to explore different hypotheses concerning the mechanisms underlying its development. Our results show that the corrections applied to the chl a profiles are consistent with HPLC data. In the Black Sea, the DCM begins to form in March, throughout the basin, at a density level set by the previous winter mixed layer. During a first phase (April–May), the DCM remains attached to this particular layer. The spatial homogeneity of this feature suggests a hysteresis mechanism, i.e. that the DCM structure locally influences environmental conditions rather than adapting instantaneously to external factors. In a second phase (July–September), the DCM migrates upward, where there is higher irradiance, which suggests the interplay of biotic factors. Overall, the DCM concentrates around 45 % to 65 % of the total chlorophyll content within a 10 m layer centred around a depth of 30 to 40 m, which stresses the importance of considering DCM dynamics when evaluating phytoplankton productivity at basin scale.

Description: In four study areas within different lithological settings and rockfall activity, lidar data were applied for a morphometric analysis of block sizes, block shapes and talus cone characteristics. This information was used to investigate the dependencies between block size, block shape and lithology on the one hand and runout distances on the other hand. In our study, we were able to show that lithology seems to have an influence on block size and shape and that gravitational sorting did not occur on all of the studied debris cones but that other parameters apparently control the runout length of boulders. Such a parameter seems to be the block shape, as it plays the role of a moderating parameter in two of the four study sites, while we could not confirm this for our other study sites. We also investigated the influence of terrain parameters such as slope inclination, profile curvature and roughness. The derived roughness values show a clear difference between the four study sites and seem to be a good proxy for block size distribution on the talus cones and thus could be used in further studies to analyse a larger sample of block size distribution on talus cones with different lithologies.

Description: Understanding the vertical distribution of aerosol helps to reduce the uncertainty in the aerosol life cycle and therefore in the estimation of the direct and indirect aerosol forcing. To improve our understanding, we use measurements from four deployments of the Atmospheric Tomography (ATom) field campaign (ATom1–4) which systematically sampled aerosol and trace gases over the Pacific and Atlantic oceans with near pole-to-pole coverage. We evaluate the UK Earth System Model (UKESM1) against ATom observations in terms of joint biases in the vertical profile of three variables related to new particle formation: total particle number concentration (NTotal), sulfur dioxide (SO2) mixing ratio and the condensation sink. The NTotal, SO2 and condensation sink are interdependent quantities and have a controlling influence on the vertical profile of each other; therefore, analysing them simultaneously helps to avoid getting the right answer for the wrong reasons. The simulated condensation sink in the baseline model is within a factor of 2 of observations, but the NTotal and SO2 show much larger biases mainly in the tropics and high latitudes. We performed a series of model sensitivity tests to identify atmospheric processes that have the strongest influence on overall model performance. The perturbations take the form of global scaling factors or improvements to the representation of atmospheric processes in the model, for example by adding a new boundary layer nucleation scheme. In the boundary layer (below 1 km altitude) and lower troposphere (1–4 km), inclusion of a boundary layer nucleation scheme (Metzger et al., 2010) is critical to obtaining better agreement with observations. However, in the mid (4–8 km) and upper troposphere (〉 8 km), sub-3 nm particle growth, pH of cloud droplets, dimethyl sulfide (DMS) emissions, upper-tropospheric nucleation rate, SO2 gas-scavenging rate and cloud erosion rate play a more dominant role. We find that perturbations to boundary layer nucleation, sub-3 nm growth, cloud droplet pH and DMS emissions reduce the boundary layer and upper tropospheric model bias simultaneously. In a combined simulation with all four perturbations, the SO2 and condensation sink profiles are in much better agreement with observations, but the NTotal profile still shows large deviations, which suggests a possible structural issue with how nucleation or gas/particle transport or aerosol scavenging is handled in the model. These perturbations are well-motivated in that they improve the physical basis of the model and are suitable for implementation in future versions of UKESM.

Description: Stratospheric ozone and water vapour are key components of the Earth system, and past and future changes to both have important impacts on global and regional climate. Here, we evaluate long-term changes in these species from the pre-industrial period (1850) to the end of the 21st century in Coupled Model Intercomparison Project phase 6 (CMIP6) models under a range of future emissions scenarios. There is good agreement between the CMIP multi-model mean and observations for total column ozone (TCO), although there is substantial variation between the individual CMIP6 models. For the CMIP6 multi-model mean, global mean TCO has increased from ∼ 300 DU in 1850 to ∼ 305 DU in 1960, before rapidly declining in the 1970s and 1980s following the use and emission of halogenated ozone-depleting substances (ODSs). TCO is projected to return to 1960s values by the middle of the 21st century under the SSP2-4.5, SSP3-7.0, SSP4-3.4, SSP4-6.0, and SSP5-8.5 scenarios, and under the SSP3-7.0 and SSP5-8.5 scenarios TCO values are projected to be ∼ 10 DU higher than the 1960s values by 2100. However, under the SSP1-1.9 and SSP1-1.6 scenarios, TCO is not projected to return to the 1960s values despite reductions in halogenated ODSs due to decreases in tropospheric ozone mixing ratios. This global pattern is similar to regional patterns, except in the tropics where TCO under most scenarios is not projected to return to 1960s values, either through reductions in tropospheric ozone under SSP1-1.9 and SSP1-2.6, or through reductions in lower stratospheric ozone resulting from an acceleration of the Brewer–Dobson circulation under other Shared Socioeconomic Pathways (SSPs). In contrast to TCO, there is poorer agreement between the CMIP6 multi-model mean and observed lower stratospheric water vapour mixing ratios, with the CMIP6 multi-model mean underestimating observed water vapour mixing ratios by ∼ 0.5 ppmv at 70 hPa. CMIP6 multi-model mean stratospheric water vapour mixing ratios in the tropical lower stratosphere have increased by ∼ 0.5 ppmv from the pre-industrial to the present-day period and are projected to increase further by the end of the 21st century. The largest increases (∼ 2 ppmv) are simulated under the future scenarios with the highest assumed forcing pathway (e.g. SSP5-8.5). Tropical lower stratospheric water vapour, and to a lesser extent TCO, shows large variations following explosive volcanic eruptions.

Description: High-quality and long-term soil moisture products are significant for hydrologic monitoring and agricultural management. However, the acquired daily Advanced Microwave Scanning Radiometer 2 (AMSR2) soil moisture products are incomplete in global land (just about 30 %–80 % coverage ratio), due to the satellite orbit coverage and the limitations of soil moisture retrieval algorithms. To solve this inevitable problem, we develop a novel spatio-temporal partial convolutional neural network (CNN) for AMSR2 soil moisture product gap-filling. Through the proposed framework, we generate the seamless daily global (SGD) AMSR2 long-term soil moisture products from 2013 to 2019. To further validate the effectiveness of these products, three verification methods are used as follows: (1) in situ validation, (2) time-series validation, and (3) simulated missing-region validation. Results show that the seamless global daily soil moisture products have reliable cooperativity with the selected in situ values. The evaluation indexes of the reconstructed (original) dataset are a correlation coefficient (R) of 0.685 (0.689), root-mean-squared error (RMSE) of 0.097 (0.093), and mean absolute error (MAE) of 0.079 (0.077). The temporal consistency of the reconstructed daily soil moisture products is ensured with the original time-series distribution of valid values. The spatial continuity of the reconstructed regions is in accordance with the spatial information (R: 0.963–0.974, RMSE: 0.065–0.073, and MAE: 0.044–0.052). This dataset can be downloaded at https://doi.org/10.5281/zenodo.4417458 (Zhang et al., 2021).

Description: The intertropical convergence zone (ITCZ) is an important component of the tropical rain belt. Climate models continue to struggle to adequately represent the ITCZ and differ substantially in its simulated response to climate change. Here we employ complex network approaches, which extract spatiotemporal variability patterns from climate data, to better understand differences in the dynamics of the ITCZ in state-of-the-art global circulation models (GCMs). For this purpose, we study simulations with 14 GCMs in an idealized slab-ocean aquaplanet setup from TRACMIP – the Tropical Rain belts with an Annual cycle and a Continent Model Intercomparison Project. We construct network representations based on the spatial correlation patterns of monthly surface temperature anomalies and study the zonal-mean patterns of different topological and spatial network characteristics. Specifically, we cluster the GCMs by means of the distributions of their zonal network measures utilizing hierarchical clustering. We find that in the control simulation, the distributions of the zonal network measures are able to pick up model differences in the tropical sea surface temperature (SST) contrast, the ITCZ position, and the strength of the Southern Hemisphere Hadley cell. Although we do not find evidence for consistent modifications in the network structure tracing the response of the ITCZ to global warming in the considered model ensemble, our analysis demonstrates that coherent variations of the global SST field are linked to ITCZ dynamics. This suggests that climate networks can provide a new perspective on ITCZ dynamics and model differences therein.

Description: Recent seismicity in Alberta and north-east British Columbia has been attributed to ongoing oil and gas development in the area, due to its temporal and spatial correlation. Prior to such development, the area was seismically quiescent. Here, we show evidence that latent seismicity may occur in areas where previous operations have occurred, even during a shutdown in operations. The global COVID-19 pandemic furnished the unique opportunity to study seismicity during a long period of anthropogenic quiescence. Within the Kiskatinaw area of British Columbia, 389 events were detected from April to August 2020, which encompasses a period with very little hydraulic fracturing operations. This reduction in operations was the result of a government-imposed lockdown severely restricting the movement of people as well as a downturn in the economic market causing industry stock prices to collapse. Except for a reduction in the seismicity rate and a lack of temporal clustering that is often characteristic of hydraulic fracturing induced sequences, the general characteristics of the observed seismicity were similar to the preceding time period of active operations. During the period of relative quiescence, event magnitudes were observed between ML −0.7 and ML 1.2, which is consistent with previous event magnitudes in the area. Hypocentres occurred in a corridor orientated NW–SE, just as seismicity had done in previous years, and were located at depths associated with the target Montney formation or shallower (

Description: We have applied multiscale deformable-layer tomography (DLT) to build a laterally varying velocity model, using a single-offset vertical seismic profile (VSP) data set acquired for a salt proximity survey in southern Texas. The purpose of the VSP survey is to delineate the 2D salt flank using the P-wave reflections. Previous study has identified an anhydrate layer as the cap rock of the salt dome. The large impedance contrasts of this anhydrite layer generate strong downgoing P (sediment)-S (anhydrite)-P (salt) waves recorded by downhole geophones. Incidentally, the P-S-P-waves have similar traveltimes as those of the P-wave salt flank reflections, thus contaminating the imaging of the salt flank. Identifying shear-mode contamination requires an accurate velocity model of anhydrite. However, the extremely poor coverage of the single-offset VSP greatly challenges tomographic techniques to determine the lateral velocity variation. We tackle this problem using multiscale DLT, which characterizes the velocity field by a set of deformable layers. We constrain the layer velocities using the check-shot data and invert for the geometric variation. The inverted model indicates that the anhydrite layer has a “thick-thin-thick” lateral variation with offset, and the S-wave in the anhydrite layer helps in imaging the P-S-P-waves along the well track. The estimated anhydrite layer geometry is validated by the kinematic accuracies of P-waves in the data domain and P-S-P-waves in the image domain. Some in-salt dipping structures are determined by multiscale DLT as well. This field data example indicates that multiscale DLT is feasible for estimating velocities using VSP data of the single-offset situation. An accurate velocity model is the key for modeling and adaptive subtraction of the shear-mode contamination related to the salt geometry.

Description: Amplitude variation with incidence angle (AVA) analysis is an essential tool for discriminating lithology in the hydrocarbon reservoirs. Compared with the traditional AVA inversion using only P-wave information, joint AVA inversion using PP and PS seismic data provides better estimation of rock properties (e.g., density, P- and S-wave velocities). At present, the most used AVA inversions depend on the approximations of Zoeppritz equations (e.g., Shuey and Aki-Richards approximations), which are not suitable for formations with strong contrast interfaces and seismic data with large incidence angles. Based on the previous derivation of accurate Jacobian matrix, we find that the sign of each partial derivative of reflection coefficient with respect to P-, S-wave velocities and density changes across the interface, represents good indicator for the reflection interfaces. Accordingly, we propose an adaptive stratified joint PP and PS AVA inversion using the accurate Jacobian matrix that can automatically obtain the layer information and can be further used as a constraint in the inversion of in-layer rock properties (density, P- and S-wave velocities). Due to the use of the exact Zoeppritz equations and accurate Jacobian matrix, this proposed inversion method is more accurate than traditional AVA inversion methods, has higher computational efficiency and can be applied to seismic wide-angle reflection data or seismic data acquired for formations with strong contrast interfaces. The model study shows that this proposed inversion method works better than the classical Shuey and Aki-Richards approximations at estimating reflection interfaces and in-layer rock properties. It also works well in handling a part of the complex Marmousi 2 model and real seismic data.

Description: Satellite observations (International Satellite Cloud Climatology Project (ISCCP), 1983–2009) of linear trends in cloud cover are compared to those in global precipitation (Global Precipitation Climatology Project (GPCP) pentad V2.2, 1983–2009), to investigate possible cause(s) of the linear trends in both cloud cover and precipitation. The spatial distributions of the linear trends in total cloud cover and precipitation are both characterized primarily by a broadening of the major ascending zone of Hadley circulation. Our correlation studies suggest that global warming, Atlantic Multidecadal Oscillation (AMO) and Pacific Decadal Oscillation (PDO) can explain 67 %, 49 % and 38 %, respectively, of the spatial variabilities in the linear trends in cloud cover, but causality is harder to establish. Further analysis of the broadening of the major ascending zone of Hadley circulation shows that the trend in global temperature, rather than those in AMO and PDO, is the primary contributor to the observed linear trends in total cloud cover and precipitation in 1983–2009. The underlying mechanism driving this broadening is proposed to be the moisture–convection–latent-heat feedback cycle under global warming conditions. The global analysis is extended by investigating connections between clouds and precipitation in China, based on a large number of long-running, high-quality surface weather stations in 1957–2005. This reveals a quantitative matching relationship between the reduction in light precipitation and the reduction in total cloud cover. Furthermore, our study suggests that the reduction in cloud cover in China is primarily driven by global temperature; PDO plays a secondary role, while the contribution from AMO and Niño3.4 is insignificant, consistent with the global analysis.

Description: This study was performed in the framework of HyMeX (Hydrological cycle in the Mediterranean Experiment), which aimed to study the heavy precipitation that regularly affects the Mediterranean area. A reanalysis with a convective-scale model AROME-WMED (Application of Research to Operations at MEsoscale western Mediterranean) was performed, which assimilated most of the available data for a 2-month period corresponding to the first special observation period of the field campaign (Fourrié et al., 2019). Among them, observations related to the low-level humidity flow were assimilated. Such observations are important for the description of the feeding of the convective mesoscale systems with humidity (Duffourg and Ducrocq, 2011; Bresson et al., 2012; Ricard et al., 2012). Among them there were a dense reprocessed network of high-quality Global Navigation Satellite System (GNSS) zenithal total delay (ZTD) observations, reprocessed data from wind profilers, lidar-derived vertical profiles of humidity (ground and airborne) and Spanish radar data. The aim of the paper is to assess the impact of the assimilation of these four observation types on the analyses and the forecasts from the 3 h forecast range (first guess) up to the 48 h forecast range. In order to assess this impact, several observing system experiments (OSEs) or so-called denial experiments, were carried out by removing one single data set from the observation data set assimilated in the reanalysis. Among the evaluated observations, it is found that the ground-based GNSS ZTD data set provides the largest impact on the analyses and the forecasts, as it represents an evenly spread and frequent data set providing information at each analysis time over the AROME-WMED domain. The impact of the reprocessing of GNSS ZTD data also improves the forecast quality, but this impact is not statistically significant. The assimilation of the Spanish radar data improves the 3 h precipitation forecast quality as well as the short-term (30 h) precipitation forecasts, but this impact remains located over Spain. Moreover, marginal impact from wind profilers was observed on wind background quality. No impacts have been found regarding lidar data, as they represent a very small data set, mainly located over the sea.

Description: Systematic measurements of the atmospheric Ar∕N2 ratio have been made at ground-based stations in Japan and Antarctica since 2012. Clear seasonal cycles of the Ar∕N2 ratio with summertime maxima were found at middle- to high-latitude stations, with seasonal amplitudes increasing with increasing latitude. Eight years of the observed Ar∕N2 ratio at Tsukuba (TKB) and Hateruma (HAT), Japan, showed interannual variations in phase with the observed variations in the global ocean heat content (OHC). We calculated secularly increasing trends of 0.75 ± 0.30 and 0.89 ± 0.60 per meg per year from the Ar∕N2 ratio observed at TKB and HAT, respectively, although these trend values are influenced by large interannual variations. In order to examine the possibility of the secular trend in the surface Ar∕N2 ratio being modified significantly by the gravitational separation in the stratosphere, two-dimensional model simulations were carried out by arbitrarily modifying the mass stream function in the model to simulate either a weakening or an enhancement of the Brewer–Dobson circulation (BDC). The secular trend of the Ar∕N2 ratio at TKB, corrected for gravitational separation under the assumption of weakening (enhancement) of BDC simulated by the 2-D model, was 0.60 ± 0.30 (0.88 ± 0.30) per meg per year. By using a conversion factor of 3.5 × 10−23 per meg per joule by assuming a one-box ocean with a temperature of 3.5 ∘C, average OHC increase rates of 17.1 ± 8.6 ZJ yr−1 and 25.1 ± 8.6 ZJ yr−1 for the period 2012–2019 were estimated from the corrected secular trends of the Ar∕N2 ratio for the weakened- and enhanced-BDC conditions, respectively. Both OHC increase rates from the uncorrected- and weakened-BDC secular trends of the Ar∕N2 ratio are consistent with 12.2 ± 1.2 ZJ yr−1 reported by ocean temperature measurements, while that from the enhanced-BDC is outside of the range of the uncertainties. Although the effect of the actual atmospheric circulation on the Ar∕N2 ratio is still unclear and longer-term observations are needed to reduce uncertainty of the secular trend of the surface Ar∕N2 ratio, the analytical results obtained in the present study imply that the surface Ar∕N2 ratio is an important tracer for detecting spatiotemporally integrated changes in OHC and BDC.

Description: Understanding the evolution of, and the interactions between, ice sheets and the global climate over geological timescales is important for being able to project their future evolution. However, direct observational evidence of past CO2 concentrations, and the implied radiative forcing, only exists for the past 800 000 years. Records of benthic δ18O date back millions of years but contain signals from both land ice volume and ocean temperature. In recent years, inverse forward modelling has been developed as a method to disentangle these two signals, resulting in mutually consistent reconstructions of ice volume, temperature, and CO2. We use this approach to force a hybrid ice-sheet–climate model with a benthic δ18O stack, reconstructing the evolution of the ice sheets, global mean sea level, and atmospheric CO2 during the late Pliocene and the Pleistocene, from 3.6 million years (Myr) ago to the present day. During the warmer-than-present climates of the late Pliocene, reconstructed CO2 varies widely, from 320–440 ppmv for warm periods to 235–250 ppmv for the early glacial excursion ∼3.3 million years ago. Sea level is relatively stable during this period, with maxima of 6–14 m and minima of 12–26 m during glacial episodes. Both CO2 and sea level are within the wide ranges of values covered by available proxy data for this period. Our results for the Pleistocene agree well with the ice-core CO2 record, as well as with different available sea-level proxy data. For the Early Pleistocene, 2.6–1.2 Myr ago, we simulate 40 kyr glacial cycles, with interglacial CO2 decreasing from 280–300 ppmv at the beginning of the Pleistocene to 250–280 ppmv just before the Mid-Pleistocene Transition (MPT). Peak glacial CO2 decreases from 220–250 to 205–225 ppmv during this period. After the MPT, when the glacial cycles change from 40 to 80 120 kyr cyclicity, the glacial–interglacial contrast increases, with interglacial CO2 varying between 250–320 ppmv and peak glacial values decreasing to 170–210 ppmv.

Description: In urban areas, road traffic is a dominant source of nitrogen oxides (NOx=NO+NO2). Although the emissions from individual vehicles are regulated by the European emission standards, real driving emissions often exceed these limits. In this study, two multi-axis differential optical absorption spectroscopy (MAX-DOAS) instruments on opposite sides of the motorway were used to measure the NO2 absorption caused by road traffic at the A60 motorway close to Mainz, Germany. In combination with wind data, the total NOx emissions for the occurring traffic volume can be estimated. Hereto, the ozone-dependent photochemical equilibrium between NO and NO2 is considered. We show that for 10 May 2019 the measured emissions exceed the maximum expected emissions calculated from the European emission standards for standardised test cycles by a factor of 11±7. One major advantage of the method used here is that MAX-DOAS measurements are very sensitive to the integrated NO2 concentration close to the surface. Thus, all emitted NO2 molecules are detected independently from their altitude, and therefore the whole emission plume originating from the nearby motorway is captured, which is a key advantage compared to other approaches such as in situ measurements.

Description: Summary Landslides can cause devastating damage. In particular, heavy rainfall-triggered landslides pose a chain of natural hazards. However, such events are often difficult to detect, leaving the physical processes poorly understood. Here we apply a novel surface-wave detector to detect and locate landslides during the transit of Typhoon Talas 2011. We identify multiple landslides triggered by Typhoon Talas, including a landslide in the Tenryu Ward, Shizuoka prefecture, Japan, ∼400 km east from the typhoon track. The Tenryu landslide displaced a total volume of 1.2 − −1.5 × 106 m. The landslide is much smaller than those detected by using globally recorded surface waves, yet the event generated coherent seismic signals propagating up to 3000 km away. Our observations show that attributes of small and large landslides may follow the same empirical scaling relationships, indicating possible invariant failure mechanisms. Our results also suggest an alerting technology to detect and locate landslides with a sparse seismic network.

Description: Summary We studied the broad-band spectra of the 8 largest earthquakes that have occurred in Chile in the last 25 years using strong-motion records and 1-Hz high-rate GNSS (cGNSS) data. To avoid the numerical instability problem with the double integration of the accelerograms, we computed velocity spectra integrating the acceleration time series in the spectral domain and compared them to time-differentiated the cGNSS displacement records. To compute the velocity spectrum, we used a multitaper algorithm so as to provide stability over the entire spectral band. We found that the velocity spectra of records obtained close to the main rupture of the earthquakes are different from classical Aki and Brune spectra. The velocity spectrum of large events in Chile presents a flat trend at low frequencies produced by the near-field waves. This trend converges at low frequencies to the static displacement as determined from GNSS data. For different magnitude earthquakes, we observe a transition in the ground-velocity spectrum from a decay of ${f^{ - 1}}$ at high frequencies and a flat trend at low frequencies to a more classical model with a peak at the corner frequency. The source-station distance influences the shape of the velocity spectrum at low frequencies, but there is no simple rule for the records available at present. At intermediate frequencies, the spectra are controlled by surface waves and S waves. We found a transition in the velocity spectrum for the 2014 Iquique earthquake, which indicates a change in the decay of the spectrum for stations at distances greater than ∼200 km. Finally, we show that the flat low-frequency trend of the velocity spectra determined from accelerograms, and the peak ground-displacement (PGD) determined from GNSS data scales with the moment to the power 2/3.

Description: To provide long-term air pollutant exposure estimates for epidemiological studies, it is essential to test the feasibility of developing land-use regression (LUR) models using only routine air quality measurement data and to evaluate the transferability of LUR models between nearby cities. In this study, we developed and evaluated the intercity transferability of annual-average LUR models for ambient respirable suspended particulates (PM10), fine suspended particulates (PM2.5), nitrogen dioxide (NO2) and ozone (O3) in the Taipei–Keelung metropolitan area of northern Taiwan in 2019. Ambient PM10, PM2.5, NO2 and O3 measurements at 30 fixed-site stations were used as the dependent variables, and a total of 156 potential predictor variables in six categories (i.e., population density, road network, land-use type, normalized difference vegetation index, meteorology and elevation) were extracted using buffer spatial analysis. The LUR models were developed using the supervised forward linear regression approach. The LUR models for ambient PM10, PM2.5, NO2 and O3 achieved relatively high prediction performance, with R2 values of 〉 0.72 and leave-one-out cross-validation (LOOCV) R2 values of 〉 0.53. The intercity transferability of LUR models varied among the air pollutants, with transfer-predictive R2 values of 〉 0.62 for NO2 and

Description: The species Selenogonus narinoensis was described by Stirton (1947) based on a single specimen which comes from sediments cropping out in the Cocha Verde locality, Nariño Department (Colombia), tentatively referred to the late Pliocene–Pleistocene (MGN 931; IGM p002118, Museo Geológico Nacional, Servicio Geológico Colombiano, Bogotá). However, morphological studies and comparative morphometric observations of the specimen suggest that (1) no diagnostic character supports the validity of the species Selenogonus narinoensis (here considered species inquirenda); (2) a combination of features (e.g., the mandibular condyle located behind the posterior edge of the vertical mandibular ramus, the angular process which projects laterally outwards, a bunolophodont crown morphology, a mesodont crown height, and a simple crown morphology of the third lobe of m3) indicates it belongs to the genus Platygonus; (3) this specimen corresponds to one of the largest South American peccaries; (4) taking into account certain anatomical characters as well as its morphometric range, this specimen is assigned to Platygonus cf. marplatensis. Even though the stratigraphic provenance of the specimen is still doubtful, it can be proposed that (1) it could be one of the most ancient records of tayassuids in South America, as would be expected given its geographical position, and (2) considering the new taxonomic proposal, this specimen represents the first record of Platygonus cf. marplatensis in Colombia and represents one of the northernmost South American records of the genus. This new interpretation would be of great relevance in the Great American Biotic Interchange due to its strategic geographical proximity to the Isthmus of Panama.

Description: We experimentally quantified the impact of cloud fraction and cloud type on the heating rate (HR) of black and brown carbon (HRBC and HRBrC). In particular, we examined in more detail the cloud effect on the HR detected in a previous study (Ferrero et al., 2018). High-time-resolution measurements of the aerosol absorption coefficient at multiple wavelengths were coupled with spectral measurements of the direct, diffuse and surface reflected irradiance and with lidar–ceilometer data during a field campaign in Milan, Po Valley (Italy). The experimental set-up allowed for a direct determination of the total HR (and its speciation: HRBC and HRBrC) in all-sky conditions (from clear-sky conditions to cloudy). The highest total HR values were found in the middle of winter (1.43 ± 0.05 K d−1), and the lowest were in spring (0.54 ± 0.02 K d−1). Overall, the HRBrC accounted for 13.7 ± 0.2 % of the total HR, with the BrC being characterized by an absorption Ångström exponent (AAE) of 3.49 ± 0.01. To investigate the role of clouds, sky conditions were classified in terms of cloudiness (fraction of the sky covered by clouds: oktas) and cloud type (stratus, St; cumulus, Cu; stratocumulus, Sc; altostratus, As; altocumulus, Ac; cirrus, Ci; and cirrocumulus–cirrostratus, Cc–Cs). During the campaign, clear-sky conditions were present 23 % of the time, with the remaining time (77 %) being characterized by cloudy conditions. The average cloudiness was 3.58 ± 0.04 oktas (highest in February at 4.56 ± 0.07 oktas and lowest in November at 2.91 ± 0.06 oktas). St clouds were mostly responsible for overcast conditions (7–8 oktas, frequency of 87 % and 96 %); Sc clouds dominated the intermediate cloudiness conditions (5–6 oktas, frequency of 47 % and 66 %); and the transition from Cc–Cs to Sc determined moderate cloudiness (3–4 oktas); finally, low cloudiness (1–2 oktas) was mostly dominated by Ci and Cu (frequency of 59 % and 40 %, respectively). HR measurements showed a constant decrease with increasing cloudiness of the atmosphere, enabling us to quantify for the first time the bias (in %) of the aerosol HR introduced by the simplified assumption of clear-sky conditions in radiative-transfer model calculations. Our results showed that the HR of light-absorbing aerosol was ∼ 20 %–30 % lower in low cloudiness (1–2 oktas) and up to 80 % lower in completely overcast conditions (i.e. 7–8 oktas) compared to clear-sky ones. This means that, in the simplified assumption of clear-sky conditions, the HR of light-absorbing aerosol can be largely overestimated (by 50 % in low cloudiness, 1–2 oktas, and up to 500 % in completely overcast conditions, 7–8 oktas). The impact of different cloud types on the HR was also investigated. Cirrus clouds were found to have a modest impact, decreasing the HRBC and HRBrC by −5 % at most. Cumulus clouds decreased the HRBC and HRBrC by −31 ± 12 % and −26 ± 7 %, respectively; cirrocumulus–cirrostratus clouds decreased the HRBC and HRBrC by −60 ± 8 % and −54 ± 4 %, which was comparable to the impact of altocumulus (−60 ± 6 % and −46 ± 4 %). A higher impact on the HRBC and HRBrC suppression was found for stratocumulus (−63 ± 6 % and −58 ± 4 %, respectively) and altostratus (−78 ± 5 % and −73 ± 4 %, respectively). The highest impact was associated with stratus, suppressing the HRBC and HRBrC by −85 ± 5 % and −83 ± 3 %, respectively. The presence of clouds caused a decrease of both the HRBC and HRBrC (normalized to the absorption coefficient of the respective species) of −11.8 ± 1.2 % and −12.6 ± 1.4 % per okta. This study highlights the need to take into account the role of both cloudiness and different cloud types when estimating the HR caused by both BC and BrC and in turn decrease the uncertainties associated with the quantification of their impact on the climate.

Description: Extensive and rigorous model intercomparison is of great importance before model application due to the uncertainties in current land surface models (LSMs). Without considering the uncertainties in forcing data and model parameters, this study designed an ensemble of 55 296 experiments to evaluate the Noah LSM with multi-parameterization (Noah-MP) for snow cover events (SCEs), soil temperature (ST) and soil liquid water (SLW) simulation, and investigated the sensitivity of parameterization schemes at a typical permafrost site on the Qinghai–Tibet Plateau (QTP). The results showed that Noah-MP systematically overestimates snow cover, which could be greatly resolved when adopting the sublimation from wind and a semi-implicit snow/soil temperature time scheme. As a result of the overestimated snow, Noah-MP generally underestimates ST, which is mostly influenced by the snow process. A systematic cold bias and large uncertainties in soil temperature remain after eliminating the effects of snow, particularly in the deep layers and during the cold season. The combination of roughness length for heat and under-canopy (below-canopy) aerodynamic resistance contributes to resolving the cold bias in soil temperature. In addition, Noah-MP generally underestimates top SLW. The runoff and groundwater (RUN) process dominates the SLW simulation in comparison to the very limited impacts of all other physical processes. The analysis of the model structural uncertainties and characteristics of each scheme would be constructive to a better understanding of the land surface processes in the permafrost regions of the QTP as well as to further model improvements towards soil hydrothermal regime modeling using LSMs.

Description: Organic nitrates are secondary species in the atmosphere. Their fate is related to the chemical transport of pollutants from polluted areas to more distant zones. While their gas-phase chemistry has been studied, their reactivity in condensed phases is far from being understood. However, these compounds represent an important fraction of organic matter in condensed phases. In particular, their partition to the aqueous phase may be especially important for oxidized organic nitrates for which water solubility increases with functionalization. This work has studied for the first time the aqueous-phase ⚫OH-oxidation kinetics of four alkyl nitrates (isopropyl nitrate, isobutyl nitrate, 1-pentyl nitrate, and isopentyl nitrate) and three functionalized organic nitrates (α-nitrooxyacetone, 1-nitrooxy-2-propanol, and isosorbide 5-mononitrate) by developing a novel and accurate competition kinetic method. Low reactivity was observed, with kOH ranging from 8×107 to 3.1×109 L mol−1 s−1 at 296±2 K. Using these results, a previously developed aqueous-phase structure–activity relationship (SAR) was extended, and the resulting parameters confirmed the extreme deactivating effect of the nitrate group, up to two adjacent carbon atoms. The achieved extended SAR was then used to determine the ⚫OH-oxidation rate constants of 49 organic nitrates, including hydroxy nitrates, ketonitrates, aldehyde nitrates, nitrooxy carboxylic acids, and more functionalized organic nitrates such as isoprene and terpene nitrates. Their multiphase atmospheric lifetimes towards ⚫OH oxidation were calculated using these rate constants, and they were compared to their gas-phase lifetimes. Large differences were observed, especially for polyfunctional organic nitrates: for 50 % of the proposed organic nitrates for which the ⚫OH reaction occurs mainly in the aqueous phase (more than 50 % of the overall removal), their ⚫OH-oxidation lifetimes increased by 20 % to 155 % under cloud/fog conditions (liquid water content LWC = 0.35 g m−3). In particular, for 83 % of the proposed terpene nitrates, the reactivity towards ⚫OH occurred mostly (〉98 %) in the aqueous phase, while for 60 % of these terpene nitrates, their lifetimes increased by 25 % to 140 % compared to their gas-phase reactivity. We demonstrate that these effects are of importance under cloud/fog conditions but also under wet aerosol conditions, especially for the terpene nitrates. These results suggest that considering aqueous-phase ⚫OH-oxidation reactivity of biogenic nitrates is necessary to improve the predictions of their atmospheric fate.

Description: Early Paleozoic trondhjemites, gneissic granites and alkali granites in southern Yunnan preserve important records of the tectonic evolution of the Prototethyan Ocean and regional correlations. Zircon ages suggest that these granitoids were emplaced from 476 to 436 Ma. The trondhjemites are characterized by high Na2O and low K2O contents, with εNd(t) values of −1.9 to −3.5 and εHf(t) values of −2.8 to +3.9. The trondhjemites were derived from an amphibolite source with a juvenile mafic component. The gneissic granites belong to the metaluminous low-K calc-alkaline series with an εNd(t) value of −6.2 and εHf(t) values of −5.0 to −0.4. The alkali granites belong to the high-K calc-alkaline series and yield εNd(t) values of −10.1 to −10.7 and εHf(t) values of −7.9 to −2.3. The gneissic granites were derived from an ‘ancient' lower mafic crust, whereas the alkali granites were derived from a meta-sedimentary source. These granitoids were formed during the subduction of the Prototethyan Ocean beneath the Simao Block and can be compared with similar igneous rocks from the Truong Son and Tam Ky-Phuoc Son zones in southern Laos. Our study, along with Early Paleozoic igneous suites from southern Laos, central Vietnam and the Malay Peninsula, suggests an arc–back-arc system along the northern margin of Gondwana.Supplementary material: Tables of zircon U–Pb and in-situ Hf and geochemical data are available at https://doi.org/10.6084/m9.figshare.c.5322386