ALBERT

Description: 〈span〉〈div〉Summary〈/div〉Seismic free oscillations, or normal modes, provide a convenient tool to calculate low-frequency seismograms in heterogeneous Earth models. A procedure called ‘full mode coupling’ allows the seismic response of the Earth to be computed. However, in order to be theoretically exact, such calculations must involve an infinite set of modes. In practice, only a finite subset of modes can be used, introducing an error into the seismograms. By systematically increasing the number of modes beyond the highest frequency of interest in the seismograms, we investigate the convergence of full-coupling calculations. As a rule-of-thumb, it is necessary to couple modes 1–2 mHz above the highest frequency of interest, although results depend upon the details of the Earth model. This is significantly higher than has previously been assumed. Observations of free oscillations also provide important constraints on the heterogeneous structure of the Earth. Historically, this inference problem has been addressed by the measurement and interpretation of splitting functions. These can be seen as secondary data extracted from low frequency seismograms. The measurement step necessitates the calculation of synthetic seismograms, but current implementations rely on approximations referred to as self- or group-coupling and do not use fully accurate seismograms. We therefore also investigate whether a systematic error might be present in currently published splitting functions. We find no evidence for any systematic bias, but published uncertainties must be doubled to properly account for the errors due to theoretical omissions and regularization in the measurement process. Correspondingly, uncertainties in results derived from splitting functions must also be increased. As is well known, density has only a weak signal in low-frequency seismograms. Our results suggest this signal is of similar scale to the true uncertainties associated with currently published splitting functions. Thus, it seems that great care must be taken in any attempt to robustly infer details of Earth's density structure using current splitting functions.〈/span〉

Description: 〈span〉〈div〉Summary〈/div〉In this paper, we propose a new wavelet-based 3-D inversion method for frequency-domain airborne electromagnetic (FDAEM) data. Instead of inverting the model in the space domain using a smoothing constraint, this new method recovers the model in the wavelet domain based on a sparsity constraint. In the wavelet domain, the model is represented by two types of coefficients, which contain both large- and fine-scale informations of the model, meaning the wavelet-domain inversion has inherent multiresolution. In order to accomplish a sparsity constraint, we minimize an L〈sub〉1〈/sub〉-norm measure in the wavelet domain that mostly gives a sparse solution. The final inversion system is solved by an iteratively reweighted least-squares method. We investigate different orders of Daubechies wavelets to accomplish our inversion algorithm, and test them on synthetic frequency-domain AEM data set. The results show that higher order wavelets having larger vanishing moments and regularity can deliver a more stable inversion process and give better local resolution, while the lower order wavelets are simpler and less smooth, and thus capable of recovering sharp discontinuities if the model is simple. At last, we test this new inversion algorithm on a frequency-domain helicopter EM (HEM) field data set acquired in Byneset, Norway. Wavelet-based 3-D inversion of HEM data is compared to L〈sub〉2〈/sub〉-norm-based 3-D inversion's result to further investigate the features of the new method.〈/span〉

Description: 〈span〉〈div〉Summary〈/div〉A monitoring method to grasp the spatio-temporal change in the interplate coupling in a subduction zone based on the spatial gradients of surface displacement rate fields is proposed. I estimated the spatio-temporal change in the interplate coupling along the plate boundary in northeastern (NE) Japan by applying the proposed method to the surface displacement rates based on global positioning system observations. The gradient of the surface velocities is calculated in each swath configured along the direction normal to the Japan Trench for time windows such as 0.5, 1, 2, 3 and 5 yr being shifted by one week during the period of 1997–2016. The gradient of the horizontal velocities is negative and has a large magnitude when the interplate coupling at the shallow part (less than approximately 50 km in depth) beneath the profile is strong, and the sign of the gradient of the vertical velocity is sensitive to the existence of the coupling at the deep part (greater than approximately 50 km in depth). The trench-parallel variation of the spatial gradients of a displacement rate field clearly corresponds to the trench-parallel variation of the amplitude of the interplate coupling on the plate interface, as well as the rupture areas of previous interplate earthquakes. Temporal changes in the trench-parallel variation of the spatial gradient of the displacement rate correspond to the strengthening or weakening of the interplate coupling. We can monitor the temporal change in the interplate coupling state by calculating the spatial gradients of the surface displacement rate field to some extent without performing inversion analyses with applying certain constraint conditions that sometimes cause over- and/or underestimation at areas of limited spatial resolution far from the observation network. The results of the calculation confirm known interplate events in the NE Japan subduction zone, such as the post-seismic slip of the 2003 M8.0 Tokachi-oki and 2005 M7.2 Miyagi-oki earthquakes and the recovery of the interplate coupling around the rupture area of the 1994 M7.6 Sanriku-Haruka-oki earthquake. The results also indicate the semi-periodic occurrence of slow slip events and the expansion of the area of slow slip events before the 2011 Tohoku-oki earthquake (M9.0) approaching the hypocentre of the Tohoku-oki earthquake.〈/span〉

Description: 〈span〉〈div〉Summary〈/div〉We image the internal structure of the San Jacinto fault zone (SJFZ) in the trifurcation area southeast of Anza, California, with seismic records from dense linear and rectangular arrays. The examined data include recordings from more than 20 000 local earthquakes and nine teleseismic events. Automatic detection algorithms and visual inspection are used to identify 〈span〉P〈/span〉 and 〈span〉S〈/span〉 body waves, along with 〈span〉P〈/span〉- and 〈span〉S〈/span〉-types fault zone trapped waves (FZTW). The location at depth of the main branch of the SJFZ, the Clark fault, is identified from systematic waveform changes across lines of sensors within the dense rectangular array. Delay times of 〈span〉P〈/span〉 arrivals from teleseismic and local events indicate damage asymmetry across the fault, with higher damage to the NE, producing a local reversal of the velocity contrast in the shallow crust with respect to the large-scale structure. A portion of the damage zone between the main fault and a second mapped surface trace to the NE generates 〈span〉P〈/span〉- and 〈span〉S〈/span〉-types FZTW. Inversions of high-quality 〈span〉S〈/span〉-type FZTW indicate that the most likely parameters of the trapping structure are width of ∼70 m, 〈span〉S〈/span〉-wave velocity reduction of 60 per cent, 〈span〉Q〈/span〉 value of 60 and depth of ∼2 km. The local reversal of the shallow velocity contrast across the fault with respect to large-scale structure is consistent with preferred propagation of earthquake ruptures in the area to the NW.〈/span〉

Description: 〈span〉〈div〉Summary〈/div〉The computational cost of quasi-〈span〉P〈/span〉 wave extrapolation depends on the complexity of the medium, and specifically the anisotropy. Our effective-model method splits the anisotropic dispersion relation into an isotropic background and a correction factor to handle this dependency. The correction term depends on the slope (measured using the gradient) of current wavefields and the anisotropy. As a result, the computational cost is independent of the nature of anisotropy, which makes the extrapolation efficient. A dynamic implementation of this approach decomposes the original pseudo-differential operator into a Laplacian, handled using the low-rank approximation of the spectral operator, plus an angular dependent correction factor applied in the space domain to correct for anisotropy. We analyse the role played by the correction factor and propose a new spherical decomposition of the dispersion relation. The proposed method provides accurate wavefields in phase and more balanced amplitudes than a previous spherical decomposition. Also, it is free of 〈span〉SV〈/span〉-wave artefacts. Applications to a simple homogeneous transverse isotropic medium with a vertical symmetry axis (VTI) and a modified Hess VTI model demonstrate the effectiveness of the approach. The Reverse Time Migration applied to a modified BP VTI model reveals that the anisotropic migration using the proposed modelling engine performs better than an isotropic migration.〈/span〉

Description: 〈span〉〈div〉Summary〈/div〉Over the past 15 yr, numerical models of convection in Earth’s mantle have made a leap forward: they can now produce self-consistent plate-like behaviour at the surface together with deep mantle circulation. These digital tools provide a new window into the intimate connections between plate tectonics and mantle dynamics, and can therefore be used for tectonic predictions, in principle. This contribution explores this assumption. First, initial conditions at 30, 20, 10 and 0 Ma are generated by driving a convective flow with imposed plate velocities at the surface. We then compute instantaneous mantle flows in response to the guessed temperature fields without imposing any boundary conditions. Plate boundaries self-consistently emerge at correct locations with respect to reconstructions, except for small plates close to subduction zones. As already observed for other types of instantaneous flow calculations, the structure of the top boundary layer and upper-mantle slab is the dominant character that leads to accurate predictions of surface velocities. Perturbations of the rheological parameters have little impact on the resulting surface velocities. We then compute fully dynamic model evolution from 30 and 10 to 0 Ma, without imposing plate boundaries or plate velocities. Contrary to instantaneous calculations, errors in kinematic predictions are substantial, although the plate layout and kinematics in several areas remain consistent with the expectations for the Earth. For these calculations, varying the rheological parameters makes a difference for plate boundary evolution. Also, identified errors in initial conditions contribute to first-order kinematic errors. This experiment shows that the tectonic predictions of dynamic models over 10 My are highly sensitive to uncertainties of rheological parameters and initial temperature field in comparison to instantaneous flow calculations. Indeed, the initial conditions and the rheological parameters can be good enough for an accurate prediction of instantaneous flow, but not for a prediction after 10 My of evolution. Therefore, inverse methods (sequential or data assimilation methods) using short-term fully dynamic evolution that predict surface kinematics are promising tools for a better understanding of the state of the Earth’s mantle.〈/span〉

Description: Minerals, Vol. 7, Pages 200: Adsorption of Scandium and Neodymium on Biochar Derived after Low-Temperature Pyrolysis of Sawdust Minerals doi: 10.3390/min7100200 Authors: Konstantinos Komnitsas Dimitra Zaharaki Georgios Bartzas Georgios Alevizos The objective of this study was to investigate the adsorption of two rare earth elements (REEs), namely scandium (Sc) and neodymium (Nd), on biochar produced after low temperature pyrolysis (350 °C) of wood sawdust. The biochar was characterized with the use of several analytical techniques, namely X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric (TG) analysis, while the pH at point of zero charge (pHPZC) was also determined. The experimental conditions were: absorbent concentration 1–10 g L−1, REE concentration in solution 20 mg L−1, contact time for equilibrium 24 h, temperature 25 °C and stirring speed 350 rpm. The efficiency of biochar was compared to that of a commercial activated carbon. Geochemical modelling was carried out to determine speciation of Nd and Sc species in aqueous solutions using PHREEQC-3 equipped with the llnl database. The experimental results indicated the potential of low temperature produced biochar, even though inferior to that of activated carbon, to adsorb efficiently both REEs. The equilibrium adsorption data were very well fitted into the Freundlich isotherm model, while kinetic data suggested that the removal of both REEs follows the pseudo-second order kinetic reaction. Finally, the most probable adsorption mechanisms are discussed.

Description: 〈b〉Friedrich Robert Helmert, founder of modern geodesy, on the occasion of the centenary of his death〈/b〉〈br〉 Johannes Ihde and Andreas Reinhold〈br〉 Hist. Geo Space. Sci., 8, 79-95, https://doi.org/10.5194/hgss-8-79-2017, 2017〈br〉 Friedrich Robert Helmert died in Potsdam in 1917. He was, for over 30 years, director of the Royal Prussian Geodetic Institute and of the Central Bureau of the Internationale Erdmessung, today's IAG. He dedicated his life and his scientific career to the field of geodesy. His teachings on theoretical and physical geodesy were incorporated into university curricula around the world and hence into international endeavours to measure planet Earth.

Description: 〈b〉Scientific Drilling at Lake Tanganyika, Africa: A Transformative Record for Understanding Evolution in Isolation and the Biological History of the African Continent, University of Basel, 6–8 June 2016〈/b〉〈br〉 Andrew S. Cohen and Walter Salzburger〈br〉 Sci. Dril., 22, 43-48, https://doi.org/10.5194/sd-22-43-2017, 2017〈br〉 A workshop was held in Basel, Switzerland, to discuss the scientific opportunities for evolutionary biology, paleobiology and paleoecology of a drilling project at Lake Tanganyika, one of the oldest and most biodiverse lakes on Earth. A record of the numerous endemic organisms collected from the lake coupling body fossils, environmental history and potentially aDNA or ancient protein records would be transformative for understanding evolution in isolation and the biogeographic history of Africa.

Description: 〈b〉Fifteen years of the Chinese Continental Scientific Drilling Program〈/b〉〈br〉 Zhiqin Xu, Jingsui Yang, Chengshan Wang, Zhisheng An, Haibing Li, Qin Wang, and Dechen Su〈br〉 Sci. Dril., 22, 1-18, https://doi.org/10.5194/sd-22-1-2017, 2017〈br〉 The 5158 m deep borehole of the Chinese Continental Scientific Drilling (CCSD) Project in the Sulu ultrahigh-pressure metamorphic terrain marked the starting point of the CCSD Program. Since then, several continental scientific drilling projects were conducted with funding of the Chinese government and partially with support of ICDP, resulting in a total drilling depth of more than 35 000 m. This paper reviews the history and major progress of the CCSD Program in the past 15 years.

Description: 〈b〉GONAF – the borehole Geophysical Observatory at the North Anatolian Fault in the eastern Sea of Marmara〈/b〉〈br〉 Marco Bohnhoff, Georg Dresen, Ulubey Ceken, Filiz Tuba Kadirioglu, Recai Feyiz Kartal, Tugbay Kilic, Murat Nurlu, Kenan Yanik, Digdem Acarel, Fatih Bulut, Hisao Ito, Wade Johnson, Peter Eric Malin, and Dave Mencin〈br〉 Sci. Dril., 22, 19-28, https://doi.org/10.5194/sd-22-19-2017, 2017〈br〉 GONAF (Geophysical Observatory at the North Anatolian Fault) has been installed around the eastern Sea of Marmara section where a 〈i〉M〈/i〉〈i〉〉〈/i〉7 earthquake is pending to capture the seismic and strain activity preceding, during, and after such an anticipated event. GONAF is currently comprised of seven 300 m deep vertical seismic profiling stations and four collocated 100 m deep borehole strain meters. GONAF is the first ICDP-driven project with a primary focus on long-term fault-zone monitoring.

Description: 〈b〉Regional estimation of Curie-point depths and succeeding geothermal parameters from recently acquired high-resolution aeromagnetic data of the entire Bida Basin, north-central Nigeria〈/b〉〈br〉 Levi I. Nwankwo and Abayomi J. Sunday〈br〉 Geoth. Energ. Sci., 5, 1-9, https://doi.org/10.5194/gtes-5-1-2017, 2017〈br〉 The recent aeromagnetic data over the Bida Basin, Nigeria, have been used to estimate the Curie-point depths (CPDs), geothermal gradients (GGs), and near-surface crustal heat flow (HF) of the basin. The result shows that the CPD varies between 15.57 and 29.62 km, GG varies between 19.58 and 37.25 °C km〈sup〉−1〈/sup〉, and HF varies between 48.41 and 93.12 mW m〈sup〉−2〈/sup〉. Regions are observed in the basin with shallow CPDs and corresponding high HFs, thus suggesting anomalous geothermal conditions.

Description: 〈b〉A statistical approach to latitude measurements: Ptolemy's and Riccioli's geographical works as case studies〈/b〉〈br〉 Luca Santoro〈br〉 Hist. Geo Space. Sci., 8, 69-77, https://doi.org/10.5194/hgss-8-69-2017, 2017〈br〉 Historical geographical works typically contain many latitude measurements of locations: all show measurement errors and some of these refer to lost cities. How can we estimate errors? How can we know the right position of lost cities? This work shows a general approach to give a scientific answer to these questions in two particular case studies: Ptolemy's Geography and Riccioli's work on geography.

Description: 〈b〉Steponas Kolupaila's contribution to hydrological science development〈/b〉〈br〉 Gintaras Valiuškevičius〈br〉 Hist. Geo Space. Sci., 8, 57-67, https://doi.org/10.5194/hgss-8-57-2017, 2017〈br〉 This article presents the most important facts on the life and scientific achievements of Steponas Kolupaila (1892–1964) – one of the most famous hydrologists of the 20th century. This Lithuanian scientist is especially well known for his book 〈i〉Bibliography of Hydrometry〈/i〉.

Description: 〈b〉Ball lightning: a Renaissance account from Zafra (Spain)〈/b〉〈br〉 José M. Vaquero〈br〉 Hist. Geo Space. Sci., 8, 53-56, https://doi.org/10.5194/hgss-8-53-2017, 2017〈br〉 An analysis is given of the account of a 〈q〉globe of fire〈/q〉 observed in Zafra (Spain) in the middle of the 16th century. During a strong storm, Conde Don Pedro observed what he described as a 〈q〉globe of fire〈/q〉 that was directed against the city and abruptly changed course. He attributed the change in course to a miracle. He described neither any damage nor sound.

Description: 〈b〉Franz Kossmat – 〈i〉Subdivision of the Variscan Mountains〈/i〉 – a translation of the German text with supplementary notes〈/b〉〈br〉 Guido Meinhold〈br〉 Hist. Geo Space. Sci., 8, 29-51, https://doi.org/10.5194/hgss-8-29-2017, 2017〈br〉 This work is in honour of Franz Kossmat (1871–1938) and his esteemed paper the 〈i〉Gliederung des varistischen Gebirgsbaues〈/i〉 published 1927 in 〈i〉Abhandlungen des Sächsischen Geologischen Landesamts〈/i〉, Volume 1, pages 1 to 39. It constitutes the foundation of the general subdivision of the Central European Variscides into several geotectonic zones and the idea of large-scale nappe transport of individual units. In the English translation presented here an attempt is made to provide a readable text, which should still reflect Kossmat's style but would also be readable for a non-German speaking community either working in the Variscan Mountains or having specific interests in historical aspects of geosciences. Supplementary notes provide information about Kossmat's life and the content of the text. Kossmat's work is a superb example of how important geological fieldwork and mapping are for progress in geoscientific research.

Description: 〈b〉Report on the ICDP workshop DIVE (Drilling the Ivrea–Verbano zonE)〈/b〉〈br〉 Mattia Pistone, Othmar Müntener, Luca Ziberna, György Hetényi, and Alberto Zanetti〈br〉 Sci. Dril., 23, 47-56, https://doi.org/10.5194/sd-23-47-2017, 2017〈br〉 The Ivrea–Verbano Zone is the most complete, time-integrated crust–upper mantle archive in the world. It is a unique target for assembling data on the deep crust and Moho transition zone to unravel the formation, evolution, and modification of the continental crust through space and time across the Earth. Four drilling operations in the Ivrea-Verbano Zone crustal section represent the scientifically most promising solution to achieve the major goals of DIVE Project.

Description: 〈b〉Scientific Exploration of Induced SeisMicity and Stress (SEISMS)〈/b〉〈br〉 Heather M. Savage, James D. Kirkpatrick, James J. Mori, Emily E. Brodsky, William L. Ellsworth, Brett M. Carpenter, Xiaowei Chen, Frédéric Cappa, and Yasuyuki Kano〈br〉 Sci. Dril., 23, 57-63, https://doi.org/10.5194/sd-23-57-2017, 2017〈br〉 The Scientific Exploration of Induced SeisMicity and Stress (SEISMS) meeting brought together earthquake scientists from around the world. Discussion focused on field-scale experiments for understanding earthquake nucleation, propagation, and arrest.

Description: 〈b〉Facility for testing ice drills〈/b〉〈br〉 Dennis L. Nielson, Chris Delahunty, John W. Goodge, and Jeffery P. Severinghaus〈br〉 Sci. Dril., 22, 29-33, https://doi.org/10.5194/sd-22-29-2017, 2017〈br〉 The North American Testing (NAT) was designed to test critical functions of a Rapid Access Ice Drill (RAID) at a site in northern Utah. The RAID was designed to rapidly drill in Antarctica through over 2500 m of ice and then take a core sample of the bedrock. The system has many innovative features that required field testing before the system was shipped to Antarcitca. The NAT facility consisted of a borehole where we froze a column of ice to test drilling and fluid circulation functions.

Description: 〈b〉IODP workshop: developing scientific drilling proposals for the Argentina Passive Volcanic Continental Margin (APVCM) – basin evolution, deep biosphere, hydrates, sediment dynamics and ocean evolution〈/b〉〈br〉 Roger D. Flood, Roberto A. Violante, Thomas Gorgas, Ernesto Schwarz, Jens Grützner, Gabriele Uenzelmann-Neben, F. Javier Hernández-Molina, Jennifer Biddle, Guillaume St-Onge, and APVCM workshop participants〈br〉 Sci. Dril., 22, 49-61, https://doi.org/10.5194/sd-22-49-2017, 2017〈br〉 The Argentine margin contains important sedimentological, paleontological and chemical records of regional and local tectonic evolution, sea level, climate evolution and ocean circulation since the opening of the South Atlantic in the Late Jurassic–Early Cretaceous as well as the present-day results of post-depositional chemical and biological alteration. Despite its important location, which underlies the exchange of southern- and northern-sourced water masses, the Argentine margin has not been investigated in detail using scientific drilling techniques, perhaps because the margin has the reputation of being erosional. However, a number of papers published since 2009 have reported new high-resolution and/or multichannel seismic surveys, often combined with multi-beam bathymetric data, which show the common occurrence of layered sediments and prominent sediment drifts on the Argentine and adjacent Uruguayan margins. There has also been significant progress in studying the climatic records in surficial and near-surface sediments recovered in sediment cores from the Argentine margin. Encouraged by these recent results, our 3.5-day IODP (International Ocean Discovery Program) workshop in Buenos Aires (8–11 September 2015) focused on opportunities for scientific drilling on the Atlantic margin of Argentina, which lies beneath a key portion of the global ocean conveyor belt of thermohaline circulation. Significant opportunities exist to study the tectonic evolution, paleoceanography and stratigraphy, sedimentology, and biosphere and geochemistry of this margin.

Description: 〈b〉A comparison of the use of X-ray and neutron tomographic core scanning techniques for drilling projects: insights from scanning core recovered during the Alpine Fault Deep Fault Drilling Project〈/b〉〈br〉 Jack N. Williams, Joseph J. Bevitt, and Virginia G. Toy〈br〉 Sci. Dril., 22, 35-42, https://doi.org/10.5194/sd-22-35-2017, 2017〈br〉 We compare images of drillcore from the Alpine Fault in New Zealand that were collected using X-ray computed tomography (CT) and neutron tomography (NT). Both techniques provide 3-D images of the core's internal structure, which would not be possible through visual analysis alone. We find that CT scans are more beneficial, as they can image a wider range of rock types, and this scanning technique is more practical. Nevertheless, NT provides complementary scans over limited intervals of core.

Description: 〈b〉Foramina in plesiosaur cervical centra indicate a specialized vascular system〈/b〉〈br〉 Tanja Wintrich, Martin Scaal, and P. Martin Sander〈br〉 Foss. Rec., 20, 279-290, https://doi.org/10.5194/fr-20-279-2017, 2017〈br〉 Plesiosaurians retain a very long neck but greatly reduce neck flexibility, and the cervicals have large, paired, and highly symmetrical foramina on the ventral side of the centrum, traditionally termed 〈q〉subcentral foramina〈/q〉, and on the floor of the neural canal. We found that these dorsal and the ventral foramina are connected by a canal. The foramen are not for nutrient transfer; they are the osteological correlates of a highly paedomorphic vascular system in the neck of plesiosaurs.

Description: Long-term vegetation monitoring in Great Britain – the Countryside Survey 1978–2007 and beyond Claire M. Wood, Simon M. Smart, Robert G. H. Bunce, Lisa R. Norton, Lindsay C. Maskell, David C. Howard, W. Andrew Scott, and Peter A. Henrys Earth Syst. Sci. Data Discuss., doi:10.5194/essd-2017-17,2017 Manuscript under review for ESSD (discussion: open, 0 comments) The Countryside Survey (CS) of Great Britain consists of an extensive set of repeated ecological measurements at a national scale, covering a time span of 29 years. CS was first undertaken in 1978 to monitor ecological and land use change in Britain using standardised procedures for recording ecological data from representative 1 km squares throughout the country. The vegetation component has subsequently been repeated in 1990, 1998 and 2007, and changes may be related to a range of drivers.

Description: Long-term vegetation monitoring in Great Britain – the Countryside Survey 1978–2007 and beyond Claire M. Wood, Simon M. Smart, Robert G. H. Bunce, Lisa R. Norton, Lindsay C. Maskell, David C. Howard, W. Andrew Scott, and Peter A. Henrys Earth Syst. Sci. Data Discuss., doi:10.5194/essd-2017-17,2017 Manuscript under review for ESSD (discussion: open, 0 comments) The Countryside Survey (CS) of Great Britain consists of an extensive set of repeated ecological measurements at a national scale, covering a time span of 29 years. CS was first undertaken in 1978 to monitor ecological and land use change in Britain using standardised procedures for recording ecological data from representative 1 km squares throughout the country. The vegetation component has subsequently been repeated in 1990, 1998 and 2007, and changes may be related to a range of drivers.

Description: Measurement experiences with FluxSet digital D/I station László Hegymegi, János Szöllősy, Csaba Hegymegi, and Ádám Domján Geosci. Instrum. Method. Data Syst. Discuss., doi:10.5194/gi-2017-14,2017 Manuscript under review for GI (discussion: open, 0 comments) The authors developed and built a digital non-magnetic declination inclination magnetometer which gives all measurement data in digital form. Use of this instrument significantly decreases possibility of observation errors and minimizes handwork. We showed that this device is suitable for absolute magnetic control measurements, and its more convenient, user friendly and effective than the traditional ones.

Description: Possibilities of further improvement of 1-second fluxgate variometers Andriy Marusenkov Geosci. Instrum. Method. Data Syst. Discuss., doi:10.5194/gi-2017-12,2017 Manuscript under review for GI (discussion: open, 0 comments) The paper discusses the possibility to improve quality of geomagnetic variations monitoring at the ground observatories. The new fluxgate sensor as well as electronics with upgraded temperature and noise characteristics are described. It is supposed that the application of the discussed in the paper results and recommendations will allow creating an fluxgate magnetometer with outstanding level of parameters.

Description: Measurement experiences with FluxSet digital D/I station László Hegymegi, János Szöllősy, Csaba Hegymegi, and Ádám Domján Geosci. Instrum. Method. Data Syst. Discuss., doi:10.5194/gi-2017-14,2017 Manuscript under review for GI (discussion: open, 0 comments) The authors developed and built a digital non-magnetic declination inclination magnetometer which gives all measurement data in digital form. Use of this instrument significantly decreases possibility of observation errors and minimizes handwork. We showed that this device is suitable for absolute magnetic control measurements, and its more convenient, user friendly and effective than the traditional ones.

Description: Explicit and parametrised representation of under ice shelf seas in a z * coordinate ocean model Pierre Mathiot, Adrian Jenkins, Christopher Harris, and Gurvan Madec Geosci. Model Dev. Discuss., doi:10.5194/gmd-2017-37,2017 Manuscript under review for GMD (discussion: open, 0 comments) Ice shelf/ocean interactions are a major source of fresh water on the Antarctic continental shelf and have a strong impact on ocean properties, ocean circulation and sea ice. However, climate models based on the ocean/sea ice model NEMO currently do not include these interactions in any detail. The capability of explicitly simulating the circulation beneath ice shelves is introduced in the non-linear free surface model NEMO. Its implementation into the NEMO framework and its assessment in an idealised and realistic circum-Antarctic configuration is described in this study. Compared with the current prescription of ice shelf melting (i.e. at the surface) inclusion of open sub-ice-shelf leads to a decrease sea ice thickness along the coast, a weakening of the ocean stratification on the shelf, a decrease in salinity of HSSW on the Ross and Weddell Sea shelves and an increase in the strength of the gyres that circulate within the over-deepened basins on the West Antarctic continental shelf. Mimicking the under ice shelf seas overturning circulation by introducing the meltwater over the depth range of the ice shelf base, rather than at the surface is also tested. It yields similar improvements in the simulated ocean properties and circulation over the Antarctic continental shelf than the explicit ice shelf cavity representation. With the ice shelf cavities opened, the widely-used “3 equations” ice shelf melting formulation enables an interactive computation of melting that has been assessed. Comparison with observational estimates of ice shelf melting indicates realistic results for most ice shelves. However, melting rates for Amery, Getz and George VI ice shelves are considerably overestimated.

Description: Multiple domain evaluation of watershed hydrology models Karthik Kumarasamy and Patrick Belmont Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2017-121,2017 Manuscript under review for HESS (discussion: open, 0 comments) Watershed scale models simulating hydrology and water quality have advanced rapidly in sophistication. Given the importance of these models to support decision-making for a wide range of environmental issues, the hydrology community is compelled to improve the metrics used to evaluate model performance. We introduce a suite of new tools and metrics for model evaluation. We propose general guidelines for selecting parameters that should be included for matching predicted flow with measured flow.

Description: Moment-based Metrics for Global Sensitivity Analysis of Hydrological Systems Aronne Dell'Oca, Monica Riva, and Alberto Guadagnini Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2017-90,2017 Manuscript under review for HESS (discussion: open, 0 comments) We propose new metrics to assist global sensitivity analysis of Earth systems. Our approach allows assessing the impact of model parameters on the first four statistical moments of a target model output, allowing to ascertain which parameters can affect some moments of the model output pdf while being uninfluential to others. Our approach is fully compatible with analysis in the context of model complexity reduction, design of experiment, uncertainty quantification and risk assessment.

Description: Interannual variation, decadal trend, and future change in ozone outflow from East Asia Jia Zhu, Hong Liao, Yuhao Mao, Yang Yang, and Hui Jiang Atmos. Chem. Phys., 17, 3729-3747, doi:10.5194/acp-17-3729-2017, 2017 Asian O 3 outflow exhibited a small and statistically insignificant decadal trend with large interannual variations from 1986–2006. The latter were mainly caused by variations in the meteorological conditions. Future climate change will aggravate the effects of the increases in anthropogenic emissions on future changes in the Asian O 3 outflow. These findings help us to understand the variations in tropospheric O 3 in the regions downwind of East Asia on different timescales.

Description: Tracing changes in atmospheric moisture supply to the drying Southwest China Chi Zhang, Qiuhong Tang, Deliang Chen, Laifang Li, Xingcai Liu, and Huijuan Cui Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2017-147,2017 Manuscript under review for ACP (discussion: open, 0 comments) Precipitation over Southwest China (SWC) decreased significantly in recent years. By attributing precipitation to its sources, we found that the reduced precipitation is resulted from the reduced moisture supply from regions influenced by the South Asian Summer Monsoon and the westerlies. Further study revealed the dynamic variations in circulation dominate the interannual variations in precipitation over SWC. Changes in circulation systems may be related to the recent changes in SSTs.

Description: Potential impact of carbonaceous aerosols on the Upper Troposphere and Lower Stratosphere (UTLS) during Asian summer monsoon in a global model simulation Suvarna Fadnavis, Gayatry Kalita, K. Ravi Kumar, Blaz Gasparini, and Jui-Lin Frank Li Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2017-197,2017 Manuscript under review for ACP (discussion: open, 0 comments) In this study, the model simulations show that monsoon convection over the Bay of Bengal, the South China Sea and Southern flanks of the Himalayas transport Asian carbonaceous aerosol into the UTLS. Carbonaceous aerosol induces enhancement in heating rate, vertical velocity and water vapor transport in the UTLS.Doubling of BC + OC aerosols creates an anomalous warming over the TP. It elicits monsoon Hadley circulation and thus increases precipitation over India and northeast China.

Description: An improved parameterisation of ozone dry deposition to the ocean and its impact in a global climate–chemistry model Ashok K. Luhar, Ian E. Galbally, Matthew T. Woodhouse, and Marcus Thatcher Atmos. Chem. Phys., 17, 3749-3767, doi:10.5194/acp-17-3749-2017, 2017 Dry deposition of tropospheric ozone relates to its destruction at the Earth’s surface. An improved model scheme for such deposition to the ocean is formulated backed up by field data. It results in the oceanic dry deposition of ozone to be 12 % of the global total, which is much lower than the current model estimate of about 30 %. This result has implications for modelling global tropospheric ozone budget and its radiative forcing, and ozone mixing ratios, especially in the Southern Hemisphere.

Description: Potential impact of carbonaceous aerosols on the Upper Troposphere and Lower Stratosphere (UTLS) during Asian summer monsoon in a global model simulation Suvarna Fadnavis, Gayatry Kalita, K. Ravi Kumar, Blaz Gasparini, and Jui-Lin Frank Li Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2017-197,2017 Manuscript under review for ACP (discussion: open, 0 comments) In this study, the model simulations show that monsoon convection over the Bay of Bengal, the South China Sea and Southern flanks of the Himalayas transport Asian carbonaceous aerosol into the UTLS. Carbonaceous aerosol induces enhancement in heating rate, vertical velocity and water vapor transport in the UTLS.Doubling of BC + OC aerosols creates an anomalous warming over the TP. It elicits monsoon Hadley circulation and thus increases precipitation over India and northeast China.

Description: Ice Crystal Characterization in Cirrus Clouds: A Sun-tracking Camera System and Automated Detection Algorithm for Halo Displays Linda Forster, Meinhard Seefeldner, Matthias Wiegner, and Bernhard Mayer Atmos. Meas. Tech. Discuss., doi:10.5194/amt-2017-17,2017 Manuscript under review for AMT (discussion: open, 0 comments) Halo displays are produced by scattering of sunlight by smooth, hexagonal ice crystals. Consequently, the presence of a halo should contain information on particle shape. This study presents HaloCam, a novel sun-tracking camera system, and an automated detection algorithm to collect and evaluate long-term halo observations. Two-year HaloCam observations revealed that about 25 % of the detected cirrus clouds occurred together with a 22° halo indicating the presence of smooth, hexagonal crystals.

Description: Since the late 1990s, land surface temperatures over Japan have increased during the summer and autumn, while global mean temperatures have not risen in this duration (i.e., the global warming hiatus). In contrast, winter and spring temperatures in Japan have decreased. To assess the impact of both global warming and global-scale decadal variability on this enhanced seasonal temperature contrast, we analyzed the outputs of 100 ensemble simulations of historical and counterfactual non-warming climate simulations conducted using a high-resolution atmospheric general circulation model (AGCM). Our simulations showed that atmospheric fields impacted by the La Nina-like conditions associated with Interdecadal Pacific Oscillation (IPO) have predominantly contributed to the seasonal temperature contrast over Japan. Compared with the impact of negative IPO, the influence of global warming on seasonal temperature contrasts in Japan was small. In addition, atmospheric variability has also had a large impact on temperatures in Japan over a decadal timescale. The results of this study suggest a future increase in heatwave risk during the summer and autumn when La Nina-like decadal phenomena and atmospheric perturbations coincide over a background of global warming.

Description: Risk assessment of liquefaction-induced hazards using Bayesian network based on standard penetration test data Xiao-Wei Tang, Jiang-Nan Qiu, and Ji-Lei Hu Nat. Hazards Earth Syst. Sci. Discuss., doi:10.5194/nhess-2017-80,2017 Manuscript under review for NHESS (discussion: open, 0 comments) Liquefaction-induced hazards are responsible for considerable damages to engineering structures during major earthquakes. Presently, there is not any effective empirical approach that can assess different liquefaction-induced hazards in one model, such as sand boils, ground cracks, settlement, and lateral spreading, due to the uncertainties and complexity of multiple related factors of seismic liquefaction and liquefaction-induced hazards. This study used Bayesian network method to integrate multiple important factors of seismic liquefaction, sand boils, ground cracks, settlement and lateral spreading into a model based on standard penetration test historical data, so that the constructed Bayesian network model can assess the four different liquefaction-induced hazards together for free fields. In the study case, compared with the artificial neural network technology and the Ishihara and Yoshimine simplified method, the Bayesian network method performed a better classification ability, because its prediction probabilities of Accuracy , Brier score , Recall , Precision , and area under the curve of receiver operating characteristic ( AUC of ROC ) are better, which illustrated that the Bayesian network method is a good alternative tool for risk assessment of liquefaction-induced hazards. Furthermore, the performances of the application of the BN model in estimating liquefaction-induced hazards in the Japan's Northeast Pacific Offshore Earthquake also prove the correctness and reliability of it compared with the liquefaction potential index approach. Except for assessing the severity of hazards induced by soil liquefaction, the proposed Bayesian network model can also predict whether the soil is liquefied or not after an earthquake, and it can deduce the process of a chain reaction of the liquefaction-induced hazards and do backward reasoning, the assessment results from the proposed model could provide informative guidelines for decision-makers to detect damage state of a field induced by liquefaction.

Description: On the deep convection events and Antarctic Bottom Water formation in ocean reanalysis products Wilton Aguiar, Mauricio M. Mata, and Rodrigo Kerr Ocean Sci. Discuss., doi:10.5194/os-2017-9,2017 Manuscript under review for OS (discussion: open, 0 comments) In ocean models, Antarctic Bottom Water (AABW) formation is frequently misrepresented. Hence, assessing the causes of spurious formation is important to assure accurate future simulations. Only one of the state-of-art reanalysis investigated showed AABW formation accurately. Spurious formation in the other two products resulted from opening of large ice-free areas. The relatively accurate AABW formation in one of the products is an important advance on the simulation of deep ocean circulation.

Description: In this paper, the composite additive of CaF2/CaO was used to extract vanadium from stone coal, and the effect of roasting and leaching kinetics were studied. The purpose of this manuscript is to realize and improve the vanadium recovery from stone coal using the composite additive. The experimental results indicated that the roasted clinker can be obtained under the conditions of CaF2/CaO at a mass ratio of 2:3 and a total additive amount of 10 wt %, a roasting temperature 850 °C, and a roasting time of 90 min. The leaching rate of vanadium can reach 86.74%, which increased by 16.4% compared with that of blank roasting under the conditions including a leaching temperature of 950 °C, a sulfuric acid concentration of 15% (v/v), a leaching time of 2 h, and a ratio of liquid to solid of 3 mL/g. The phase transformation analysis indicated that the muscovite structure was effectively destroyed during the roasting process comparing with no additives, which provided the basis for vanadium dissociation. Roasting can promote the formation of calcium vanadate, which is beneficial to the leaching of vanadium. The vanadium leaching kinetic analysis indicated that the activation energy of the acid leaching reaction decreased from 42.50 KJ/mol in the blank roasting to 22.56 KJ/mol in the calcified roasting, and the reaction order, with respect to the sulfuric acid concentration, decreased from 1.15 to 0.85. Calcified roasting has a better mineral activation than blank roasting, which can accelerate the leaching of vanadium and reduce the dependence on high-temperature and high acid levels in the leaching process.

Description: Strain heterogeneities at the ductile to brittle transition; a case study on ice Thomas Chauve, Maurine Montagnat, Cédric Lachaud, David Georges, and Pierre Vacher Solid Earth Discuss., doi:10.5194/se-2017-24,2017 Manuscript under review for SE (discussion: open, 0 comments) For the first time, Digital Image Correlation was used to follow strain field development during micro cracking, at the ductile to brittle transition in polycrystalline ice. Owing to the high temperature conditions of the tests, dynamic recrystallization mechanisms (nucleation and sub-grain rotation) efficiently participate to the stress redistribution during and after crack opening, and even lead to local crack closure.

Description: Strain heterogeneities at the ductile to brittle transition; a case study on ice Thomas Chauve, Maurine Montagnat, Cédric Lachaud, David Georges, and Pierre Vacher Solid Earth Discuss., doi:10.5194/se-2017-24,2017 Manuscript under review for SE (discussion: open, 0 comments) For the first time, Digital Image Correlation was used to follow strain field development during micro cracking, at the ductile to brittle transition in polycrystalline ice. Owing to the high temperature conditions of the tests, dynamic recrystallization mechanisms (nucleation and sub-grain rotation) efficiently participate to the stress redistribution during and after crack opening, and even lead to local crack closure.

Description: Impact of icebergs on net primary productivity in the Southern Ocean Shuang-Ye Wu and Shugui Hou The Cryosphere, 11, 707-722, doi:10.5194/tc-11-707-2017, 2017 The primary productivity in the Southern Ocean (SO) is limited by the amount of iron available for biological activities. Recent studies show that icebergs could be a main source of iron to the SO. Based on remote sensing data, our study shows that iceberg presence is associated with elevated levels of ocean productivity, particularly in iron-deficient regions. This impact could serve as a negative feedback to the climate system.

Description: Bromine, iodine and sodium in surface snow along the 2013 Talos Dome–GV7 traverse (northern Victoria Land, East Antarctica) Niccolò Maffezzoli, Andrea Spolaor, Carlo Barbante, Michele Bertò, Massimo Frezzotti, and Paul Vallelonga The Cryosphere, 11, 693-705, doi:10.5194/tc-11-693-2017, 2017 Sea ice is a crucial parameter within Earth's climate system. Understanding its dynamics and its response to other climatic variables is therefore of primary importance in view of a warming climate and sea ice decline. In this work we investigate some features of a chemical parameter in ice cores, bromine enrichment, which is linked to sea ice and can therefore be used to reconstruct sea ice in the past.

Description: Application of a two-step approach for mapping ice thickness to various glacier types on Svalbard Johannes Jakob Fürst, Fabien Gillet-Chaulet, Toby J. Benham, Julian A. Dowdeswell, Mariusz Grabiec, Francisco Navarro, Rickard Pettersson, Geir Moholdt, Christopher Nuth, Björn Sass, Kjetil Aas, Xavier Fettweis, Charlotte Lang, Thorsten Seehaus, and Matthias Braun The Cryosphere Discuss., doi:10.5194/tc-2017-30,2017 Manuscript under review for TC (discussion: open, 0 comments) For the large majority of glaciers and ice caps, there is no information on the thickness of the ice cover. Any attempt to predict glacier demise under climatic warming and to estimate the future contribution to sea-level rise is limited as long as the glacier thickness is not well constrained. Here, we present a two-step mass-conservation approach for mapping ice thickness. Measurements are naturally reproduced. The reliability is readily assessible from a complementary map of error estimates.

Description: Bromine, iodine and sodium in surface snow along the 2013 Talos Dome–GV7 traverse (northern Victoria Land, East Antarctica) Niccolò Maffezzoli, Andrea Spolaor, Carlo Barbante, Michele Bertò, Massimo Frezzotti, and Paul Vallelonga The Cryosphere, 11, 693-705, doi:10.5194/tc-11-693-2017, 2017 Sea ice is a crucial parameter within Earth's climate system. Understanding its dynamics and its response to other climatic variables is therefore of primary importance in view of a warming climate and sea ice decline. In this work we investigate some features of a chemical parameter in ice cores, bromine enrichment, which is linked to sea ice and can therefore be used to reconstruct sea ice in the past.

Description: Application of a two-step approach for mapping ice thickness to various glacier types on Svalbard Johannes Jakob Fürst, Fabien Gillet-Chaulet, Toby J. Benham, Julian A. Dowdeswell, Mariusz Grabiec, Francisco Navarro, Rickard Pettersson, Geir Moholdt, Christopher Nuth, Björn Sass, Kjetil Aas, Xavier Fettweis, Charlotte Lang, Thorsten Seehaus, and Matthias Braun The Cryosphere Discuss., doi:10.5194/tc-2017-30,2017 Manuscript under review for TC (discussion: open, 0 comments) For the large majority of glaciers and ice caps, there is no information on the thickness of the ice cover. Any attempt to predict glacier demise under climatic warming and to estimate the future contribution to sea-level rise is limited as long as the glacier thickness is not well constrained. Here, we present a two-step mass-conservation approach for mapping ice thickness. Measurements are naturally reproduced. The reliability is readily assessible from a complementary map of error estimates.

Description: Impact of icebergs on net primary productivity in the Southern Ocean Shuang-Ye Wu and Shugui Hou The Cryosphere, 11, 707-722, doi:10.5194/tc-11-707-2017, 2017 The primary productivity in the Southern Ocean (SO) is limited by the amount of iron available for biological activities. Recent studies show that icebergs could be a main source of iron to the SO. Based on remote sensing data, our study shows that iceberg presence is associated with elevated levels of ocean productivity, particularly in iron-deficient regions. This impact could serve as a negative feedback to the climate system.

Description: Sensitivity of transatlantic dust transport to chemical aging and related atmospheric processes Mohamed Abdelkader, Swen Metzger, Benedikt Steil, Klaus Klingmüller, Holger Tost, Andrea Pozzer, Georgiy Stenchikov, Leonard Barrie, and Jos Lelieveld Atmos. Chem. Phys., 17, 3799-3821, doi:10.5194/acp-17-3799-2017, 2017 We present a modeling study on the impacts of the key processes (dust emission flux, convection and dust aging parameterizations) that control the transatlantic dust transport using an advanced version of the EMAC atmospheric chemistry general circulation model. We define the direct effect of dust aging as an increase in the AOD as a result of hygroscopic growth. We define the indirect effect as a reduction in the dust AOD due to the higher removal of the aged dust particles.

Description: Using the Weather Research and Forecasting (WRF) – Advanced Research WRF (ARW) mesoscale model (WRF–ARW), we investigate how two nocturnal offshore rainbands occurring in the Mediterranean basin are modified in a warmer sea surface temperature (SST). After sunset, the thermal difference between land and sea air increases. Driven by drainage winds or land breeze, the inland cold air interacts with the relatively warmer and moister air over the sea. Vertical movement of sea air over the boundary between the two air masses may induce cloud and rain bands offshore. When an increase of SST is prescribed in the WRF simulations, a change in the precipitation pattern is simulated. The numerical experiments show an increase both in the extension and location of the rainbands and in the precipitation rate. These changes, induced by the modified SST, are analyzed by estimating and comparing several parameters such as the location of level of free convection (LFC), Convective Available Potential Energy (CAPE), or the triggering, deceleration and blockage terms of simplified conceptual models.

Description: Simultaneous multicopter-based air sampling and sensing of meteorological variables Caroline Brosy, Karina Krampf, Matthias Zeeman, Benjamin Wolf, Wolfgang Junkermann, Klaus Schäfer, Stefan Emeis, and Harald Kunstmann Atmos. Meas. Tech. Discuss., doi:10.5194/amt-2017-60,2017 Manuscript under review for AMT (discussion: open, 0 comments) Vertical and horizontal sounding of the planetary boundary layer can be complemented by unmanned aerial vehicles (UAV). Utilizing a multicopter-type UAV spatial sampling of air and simultaneously sensing of meteorological variables is possible for the study of surface exchange processes. During stable atmospheric conditions, vertical methane gradients of about 300 ppb were found. This approach extended the vertical profile height of existing tower-based infrastructure by a factor of five.

Description: Linking diverse nutrient patterns to different water masses within anticyclonic eddies in the upwelling system off Peru Yonss Saranga José, Heiner Dietze, and Andreas Oschlies Biogeosciences, 14, 1349-1364, doi:10.5194/bg-14-1349-2017, 2017 This study aims to investigate the diverse subsurface nutrient patterns observed within anticyclonic eddies in the upwelling system off Peru. Two simulated anticyclonic eddies with opposing subsurface nitrate concentrations were analysed. The results show that diverse nutrient patterns within anticyclonic eddies are related to the presence of water mass from different origins at different depths, responding to variations in depth of the circulation strength at the edge of the eddy.

Description: Gas chromatography vs. quantum cascade laser-based N 2 O flux measurements using a novel chamber design Christian Brümmer, Bjarne Lyshede, Dirk Lempio, Jean-Pierre Delorme, Jeremy J. Rüffer, Roland Fuß, Antje M. Moffat, Miriam Hurkuck, Andreas Ibrom, Per Ambus, Heinz Flessa, and Werner L. Kutsch Biogeosciences, 14, 1365-1381, doi:10.5194/bg-14-1365-2017, 2017 We present a novel chamber design for measuring soil–atmosphere N 2 O fluxes and compare the performance of a commonly applied gas chromatography (GC) setup with laser-based (QCL) concentration detection. While GC was still a useful method for longer-term investigations, we found that closure times of 10 min and sampling every 5 s is sufficient when using a QCL system. Further, extremely low standard errors (

Description: Drivers of multi-century trends in the atmospheric CO 2 mean annual cycle in a prognostic ESM Jessica Liptak, Gretchen Keppel-Aleks, and Keith Lindsay Biogeosciences, 14, 1383-1401, doi:10.5194/bg-14-1383-2017, 2017 We analyzed the evolution of the atmospheric CO 2 mean annual cycle simulated during 1950–2300 under three scenarios designed to separate the effects of climate change, CO 2 fertilization, and land use change. CO 2 fertilization in boreal and temperate ecosystems drove mean annual cycle amplification over the NH midlatitudes during 1950–2300. Boreal and Arctic climate change drove high-latitude amplification before 2200, after which CO 2 fertilization contributed nearly equally to amplification.

Description: Accurate and high resolution bathymetric data is a necessity for a wide range of coastal oceanographic research topics. Active sensing methods, such as ship-based soundings and Light Detection and Ranging (LiDAR), are expensive and time consuming solutions. Therefore, the significance of Satellite-Derived Bathymetry (SDB) has increased in the last ten years due to the availability of multi-constellation, multi-temporal, and multi-resolution remote sensing data as Open Data. Effective SDB algorithms have been proposed by many authors, but there is no ready-to-use software module available in the Geographical Information System (GIS) environment as yet. Hence, this study implements a Geographically Weighted Regression (GWR) based SDB workflow as a Geographic Resources Analysis Support System (GRASS) GIS module (i.image.bathymetry). Several case studies were carried out to examine the performance of the module in multi-constellation and multi-resolution satellite imageries for different study areas. The results indicate a strong correlation between SDB and reference depth. For instance, case study 1 (Puerto Rico, Northeastern Caribbean Sea) has shown an coefficient of determination (R2) of 0.98 and an Root Mean Square Error (RMSE) of 0.61 m, case study 2 (Iwate, Japan) has shown an R2 of 0.94 and an RMSE of 1.50 m, and case study 3 (Miyagi, Japan) has shown an R2 of 0.93 and an RMSE of 1.65 m. The reference depths were acquired by using LiDAR for case study 1 and an echo-sounder for case studies 2 and 3. Further, the estimated SDB has been used as one of the inputs for the Australian National University and Geoscience Australia (ANUGA) tsunami simulation model. The tsunami simulation results also show close agreement with post-tsunami survey data. The i.mage.bathymetry module developed as a part of this study is made available as an extension for the Open Source GRASS GIS to facilitate wide use and future improvements.

Description: Episodic Neoglacial expansion and rapid 20th Century retreat of a small ice cap on Baffin Island, Arctic Canada and modeled temperature change Simon L. Pendleton, Gifford H. Miller, Robert A. Anderson, Sarah E. Crump, Yafang Zhong, Alexandra Jahn, and Áslaug Geirsdottir Clim. Past Discuss., doi:10.5194/cp-2017-27,2017 Manuscript under review for CP (discussion: open, 0 comments) Recent warming in the high latitudes has prompted the accelerated retreat of ice caps and glaciers, especially in the Canadian Arctic. Here we use the radiocarbon age of preserved plants being exposed by shrinking ice caps that once entombed them. These ages help us to constrain the timing and magnitude of climate change on southern Baffin Island over the past ~ 2000 years. Our results show episodic cooling up until ~ 1900 CE, followed by accelerated warming through present.

Description: Episodic Neoglacial expansion and rapid 20th Century retreat of a small ice cap on Baffin Island, Arctic Canada and modeled temperature change Simon L. Pendleton, Gifford H. Miller, Robert A. Anderson, Sarah E. Crump, Yafang Zhong, Alexandra Jahn, and Áslaug Geirsdottir Clim. Past Discuss., doi:10.5194/cp-2017-27,2017 Manuscript under review for CP (discussion: open, 0 comments) Recent warming in the high latitudes has prompted the accelerated retreat of ice caps and glaciers, especially in the Canadian Arctic. Here we use the radiocarbon age of preserved plants being exposed by shrinking ice caps that once entombed them. These ages help us to constrain the timing and magnitude of climate change on southern Baffin Island over the past ~ 2000 years. Our results show episodic cooling up until ~ 1900 CE, followed by accelerated warming through present.

Description: Seasonal forecasting of hydrological drought in the Limpopo Basin: a comparison of statistical methods Mathias Seibert, Bruno Merz, and Heiko Apel Hydrol. Earth Syst. Sci., 21, 1611-1629, doi:10.5194/hess-21-1611-2017, 2017 Seasonal early warning is vital for drought management in arid regions like the Limpopo Basin in southern Africa. This study shows that skilled seasonal forecasts can be achieved with statistical methods built upon driving factors for drought occurrence. These are the hydrological factors for current streamflow and meteorological drivers represented by anomalies in sea surface temperatures of the surrounding oceans, which combine to form unique combinations in the drought forecast models.

Description: A sprinkling experiment to quantify celerity-velocity differences at the hillslope scale Willem J. van Verseveld, Holly R. Barnard, Chris B. Graham, Jeffrey J. McDonnell, J. Renée Brooks, and Markus Weiler Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2017-125,2017 Manuscript under review for HESS (discussion: open, 0 comments) How stream water responds immediately to a rainfall or snow event while the average time it takes water to travel through the hillslope can be years or decades, is poorly understood. We assessed this difference by combining a 24 day sprinkler experiment (a tracer was applied at the start) with a process based hydrologic model. Immobile soil water, deep groundwater contribution and soil depth variability explained this difference at our hillslope site.

Description: Groundwater impacts on surface water quality and nutrient loads in lowland polder catchments: monitoring the greater Amsterdam area Liang Yu, Joachim Rozemeijer, Boris M. van Breukelen, Maarten Ouboter, Corné van der Vlugt, and Hans Peter Broers Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2017-99,2017 Manuscript under review for HESS (discussion: open, 0 comments) The study shows the importance of the connection between groundwater and surface water nutrient chemistry in a lowland delta area – the greater Amsterdam area. We expect that taking account of groundwater-surface water interaction is also important in other subsiding and urbanising deltas around the world, where water is managed intensively in order to enable agricultural productivity and achieve water sustainable cities.

Description: Parameter optimisation for a better representation of drought by LSMs: inverse modelling vs. sequential data assimilation Hélène Dewaele, Simon Munier, Clément Albergel, Carole Planque, Nabil Laanaia, Dominique Carrer, and Jean-Christophe Calvet Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2017-120,2017 Manuscript under review for HESS (discussion: open, 0 comments) Soil Maximum Available Water Content (MaxAWC) is a key parameter in land surface models. Being difficult to measure, this parameter is usually unavailable. A fifteen-year time-series of satellite-derived observations of Leaf Area Index (LAI) is used to retrieve MaxAWC for rainfed croplands over France. LAI is sequentially assimilated into the ISBA LSM. MaxAWC is retrieved minimizing LAI analyses increments. Annual maximum LAI observations correlate with MaxAWC.

Description: Analysis of streamflow response to land use land cover changes using satellite data and hydrological modelling: case study of Dinder and Rahad tributaries of the Blue Nile (Ethiopia/Sudan) Khalid Hassaballah, Yasir Mohamed, Stefan Uhlenbrook, and Khalid Biro Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2017-128,2017 Manuscript under review for HESS (discussion: open, 0 comments) The Dinder and Rahad experienced significant hydrological changes during recent years. This is claimed to be due to land use land cover changes (LULCC). Specific studies on LULCC in the Dinder and Rahad basins are still missing. This paper aims to understand the LULCC in the Dinder and Rahad and its implications on streamflow using satellite data and hydrological modelling. We expect that this study will be of high importance for decision making related to water resources planning and management.

Description: A conceptual prediction model of seasonal drought processes using atmospheric and oceanic Standardized Anomalies: application in four recent severe drought events in China Zhenchen Liu, Guihua Lu, Hai He, Zhiyong Wu, and Jian He Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2017-136,2017 Manuscript under review for HESS (discussion: open, 0 comments) Process prediction of seasonal drought is the goal of our study. We developed a drought prediction model based on atmospheric/oceanic anomalies. It is essentially the synchronous statistical relationship between atmospheric/oceanic anomalies and precipitation anomalies, forced by seasonal climate forecast models. It can predict seasonal drought development very well, despite its weakness in drought severity.

Description: A national-scale seasonal hydrological forecast system: development and evaluation over Britain Victoria A. Bell, Helen N. Davies, Alison L. Kay, Anca Brookshaw, and Adam A. Scaife Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2017-154,2017 Manuscript under review for HESS (discussion: open, 0 comments) The research presented here provides the first evaluation of the skill of a seasonal hydrological forecast for the UK. The forecast scheme combines rainfall forecasts from the Met Office GloSea5 forecast system with a national-scale hydrological model to provide estimates of river flows 1 to 3 months ahead. The skill in the combined model is assessed for different seasons and regions of Britain, and the analysis indicates that Autumn/Winter flows can be forecast with reasonable confidence.

Description: A national-scale seasonal hydrological forecast system: development and evaluation over Britain Victoria A. Bell, Helen N. Davies, Alison L. Kay, Anca Brookshaw, and Adam A. Scaife Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2017-154,2017 Manuscript under review for HESS (discussion: open, 0 comments) The research presented here provides the first evaluation of the skill of a seasonal hydrological forecast for the UK. The forecast scheme combines rainfall forecasts from the Met Office GloSea5 forecast system with a national-scale hydrological model to provide estimates of river flows 1 to 3 months ahead. The skill in the combined model is assessed for different seasons and regions of Britain, and the analysis indicates that Autumn/Winter flows can be forecast with reasonable confidence.

Description: High-magnitude flooding across Britain since AD 1750 Neil Macdonald and Heather Sangster Hydrol. Earth Syst. Sci., 21, 1631-1650, doi:10.5194/hess-21-1631-2017, 2017 We use historical records to extend current understanding of flood risk, examining past spatial and temporal variability and ask are the perceived high-magnitude flood events witnessed in recent years really unprecedented? We identify that there are statistically significant relationships between the British flood index and climatic drivers, whereby the largest floods often transcend single catchments affecting regions and that the current flood-rich period is not unprecedented.

Description: A conceptual prediction model of seasonal drought processes using atmospheric and oceanic Standardized Anomalies: application in four recent severe drought events in China Zhenchen Liu, Guihua Lu, Hai He, Zhiyong Wu, and Jian He Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2017-136,2017 Manuscript under review for HESS (discussion: open, 0 comments) Process prediction of seasonal drought is the goal of our study. We developed a drought prediction model based on atmospheric/oceanic anomalies. It is essentially the synchronous statistical relationship between atmospheric/oceanic anomalies and precipitation anomalies, forced by seasonal climate forecast models. It can predict seasonal drought development very well, despite its weakness in drought severity.

Description: Analysis of streamflow response to land use land cover changes using satellite data and hydrological modelling: case study of Dinder and Rahad tributaries of the Blue Nile (Ethiopia/Sudan) Khalid Hassaballah, Yasir Mohamed, Stefan Uhlenbrook, and Khalid Biro Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2017-128,2017 Manuscript under review for HESS (discussion: open, 0 comments) The Dinder and Rahad experienced significant hydrological changes during recent years. This is claimed to be due to land use land cover changes (LULCC). Specific studies on LULCC in the Dinder and Rahad basins are still missing. This paper aims to understand the LULCC in the Dinder and Rahad and its implications on streamflow using satellite data and hydrological modelling. We expect that this study will be of high importance for decision making related to water resources planning and management.

Description: High-magnitude flooding across Britain since AD 1750 Neil Macdonald and Heather Sangster Hydrol. Earth Syst. Sci., 21, 1631-1650, doi:10.5194/hess-21-1631-2017, 2017 We use historical records to extend current understanding of flood risk, examining past spatial and temporal variability and ask are the perceived high-magnitude flood events witnessed in recent years really unprecedented? We identify that there are statistically significant relationships between the British flood index and climatic drivers, whereby the largest floods often transcend single catchments affecting regions and that the current flood-rich period is not unprecedented.

Description: Mineral leaching chemicals transport with runoff and sediment from severely eroded rare earth tailings in southern China Huizhong Lu, Longxi Cao, Yin Liang, Jiuqin Yuan, Yayun Zhu, Yi Wang, Yalan Gu, and Qiguo Zhao Solid Earth Discuss., doi:10.5194/se-2017-28,2017 Manuscript under review for SE (discussion: open, 0 comments) Rare earth mining has led to severe soil erosion in southern China. Furthermore, the presence of the mineral leaching chemical ammonium sulfate in runoff and sediment poses a serious environmental threat to downstream water bodies. To study the transport characteristics of mineral leaching chemicals, soil on rare earth tailings was sampled in different positions, and runoff and sediment samples were collected along flow routes during three typical rainfall events. The results demonstrated that the NH 4 + contents in the surface sediment deposits increased from the top of the heap (6.56 mg/kg) to the gully (8.23 mg/kg) and outside the tailing heap (13.03 mg/kg). The contents of SO 4 2− in the different locations of the tailing heaps ranged from 27.71 to 40.33 mg/kg. During typical rainfall events, the absorbed NH4+ concentrations (2.05, 1.26 mg/L) in runoff were higher than the dissolved concentrations (0.93, 1.04 mg/L), while the absorbed SO 4 2− concentrations (2.87, 1.92 mg/L) were lower than the dissolved concentrations (6.55, 7.51 mg/L). The dissolved NH 4 + and SO 4 2− concentrations in runoff displayed an exponentially decreasing tendency with increasing transport distance (Y=1.02*exp(-0.00312X), Y=3.34*exp(-0.0185X)). No clear trend with increasing distance was observed for the absorbed NH 4 + and SO 4 2− contents in transported sediment. The NH 4 + and SO 4 2− contents had positive correlations with the silt and clay ratio in transported sediment but negative correlations with the sand ratio. These results provide a better understanding of the transport processes and can be used to develop equations to predict the transport of mineral leaching chemicals in rare earth tailings.

Description: Ice-shelf damming in the glacial Arctic Ocean: dynamical regimes of a basin-covering kilometre thick ice shelf Johan Nilsson, Martin Jakobsson, Chris Borstad, Nina Kirchner, Göran Björk, Raymond T. Pierrehumbert, and Christian Stranne The Cryosphere Discuss., doi:10.5194/tc-2017-37,2017 Manuscript under review for TC (discussion: open, 0 comments) Recent data suggest that a one-kilometre thick ice shelf extended over the glacial Arctic Ocean during MIS 6, about 140 000 years ago. Here, we theoretically analyse the development and equilibrium features of such an ice shelf. The ice shelf was effectively dammed by the Fram Strait and the mean ice-shelf thickness was controlled primarily by the horizontally-integrated mass balance. Our results can aid to resolve some outstanding questions of the state of the glacial Arctic Ocean.

Description: Ice-shelf damming in the glacial Arctic Ocean: dynamical regimes of a basin-covering kilometre thick ice shelf Johan Nilsson, Martin Jakobsson, Chris Borstad, Nina Kirchner, Göran Björk, Raymond T. Pierrehumbert, and Christian Stranne The Cryosphere Discuss., doi:10.5194/tc-2017-37,2017 Manuscript under review for TC (discussion: open, 0 comments) Recent data suggest that a one-kilometre thick ice shelf extended over the glacial Arctic Ocean during MIS 6, about 140 000 years ago. Here, we theoretically analyse the development and equilibrium features of such an ice shelf. The ice shelf was effectively dammed by the Fram Strait and the mean ice-shelf thickness was controlled primarily by the horizontally-integrated mass balance. Our results can aid to resolve some outstanding questions of the state of the glacial Arctic Ocean.

Description: Community-based early warning systems for flood risk mitigation in Nepal Paul J. Smith, Sarah Brown, and Sumit Dugar Nat. Hazards Earth Syst. Sci., 17, 423-437, doi:10.5194/nhess-17-423-2017, 2017 Risks from flooding are of global importance. Experience gained in Nepal is presented to demonstrate that empowering the communities impacted by flooding to be active participants in risk mitigation can have significant positive impacts. In part this is achieved through community involvement in the provision of warnings based on observations of river flow upstream. The success of simple, robust methodology for the early provision of such warnings based on predicting future river flows is shown.

Description: Global distribution of CO 2 in the upper troposphere and stratosphere Mohamadou Diallo, Bernard Legras, Eric Ray, Andreas Engel, and Juan A. Añel Atmos. Chem. Phys., 17, 3861-3878, doi:10.5194/acp-17-3861-2017, 2017 We construct a new monthly zonal mean CO 2 distribution from the upper troposphere to the stratosphere over the 2000–2010 period. The main features of the CO 2 distribution are consistent with expected variability due to the transport of long-lived trace gases by the Brewer–Dobson circulation. The method used to construct this CO 2 product is unique and should be useful for model and satellite validation in the upper troposphere and stratosphere.

Description: On biases in atmospheric CO inversions assimilating MOPITT satellite retrievals Yi Yin, Frederic Chevallier, Philippe Ciais, Gregoire Broquet, Anne Cozic, Sophie Szopa, and Yilong Wang Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2017-166,2017 Manuscript under review for ACP (discussion: open, 0 comments) CO inverse modelling studies have so far reported significant discrepancies between model concentrations optimised with the Measurement of Pollution in the Troposphere (MOPITT) satellite retrievals and surface in-situ measurements. Here, we assess how well a global CTM fits a large variety of independent CO observations before and after assimilating MOPITTv6 retrievals to optimise CO sources/sink and discuss potential sources of errors and their implications for global CO modelling studies.

Description: The Variability of Relationship between Black Carbon and Carbon Monoxide over the Eastern Coast of China: BC Aging during Transport Qingfeng Guo, Min Hu, Song Guo, Zhijun Wu, Jianfei Peng, and Yusheng Wu Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2017-56,2017 Manuscript under review for ACP (discussion: open, 0 comments) To characterize primary emissions over the eastern coast of China, a cascade of field campaign was conducted. The high loadings of both BC and CO imply the severe anthropogenic pollution over the areas. The slopes between BC and CO at different areas reveal the vehicular emission as the common source and the distinct fuel structures between North and South China. The comparisons of slopes and correlation coefficient among these areas indicate the more aging of BC in East China Sea.

Description: Temporal characteristics of atmospheric ammonia and nitrogen dioxide over China based on emission data, satellite observations and atmospheric transport modeling since 1980 Lei Liu, Xiuying Zhang, Wen Xu, Xuejun Liu, Yi Li, Xuehe Lu, Yuehan Zhang, and Wuting Zhang Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2017-106,2017 Manuscript under review for ACP (discussion: open, 0 comments) We conducted the temporal trend analysis of atmospheric NH 3 and NO 2 in China since 1980 based on emission data (during 1980–2010), satellite observations (for NH 3 since 2008 and for NO 2 since 2005) and atmospheric chemistry transport modeling (during 2008–2015). Our findings provided an overall insight on the temporal trends of both NO 2 and NH 3 since 1980 and the multivariate data used in this study have implications for estimating long-term Nr deposition datasets.

Description: Global distribution of CO 2 in the upper troposphere and stratosphere Mohamadou Diallo, Bernard Legras, Eric Ray, Andreas Engel, and Juan A. Añel Atmos. Chem. Phys., 17, 3861-3878, doi:10.5194/acp-17-3861-2017, 2017 We construct a new monthly zonal mean CO 2 distribution from the upper troposphere to the stratosphere over the 2000–2010 period. The main features of the CO 2 distribution are consistent with expected variability due to the transport of long-lived trace gases by the Brewer–Dobson circulation. The method used to construct this CO 2 product is unique and should be useful for model and satellite validation in the upper troposphere and stratosphere.

Description: Sulfate geoengineering: a review of the factors controlling the needed injection of sulfur dioxide Daniele Visioni, Giovanni Pitari, and Valentina Aquila Atmos. Chem. Phys., 17, 3879-3889, doi:10.5194/acp-17-3879-2017, 2017 This review paper summarizes the state-of-the-art knowledge of the direct and indirect side effects of sulfate geoengineering, that is, the injection of sulfur dioxide into the stratosphere in order to offset the warming caused by the anthropic increase in greenhouse gasses. An overview of the various effects and their uncertainties, using results from published scientific articles, may help fine-tune the best amount of sulfate to be injected in an eventual realization of the experiment.

Description: Upper tropospheric cloud systems derived from IR sounders: properties of cirrus anvils in the tropics Sofia E. Protopapadaki, Claudia J. Stubenrauch, and Artem G. Feofilov Atmos. Chem. Phys., 17, 3845-3859, doi:10.5194/acp-17-3845-2017, 2017 Upper tropospheric clouds cover about 30 % of the Earth and play a key role in the climate system by modulating the Earth's energy budget and heat transport. In this article, we study upper tropospheric cloud systems using cloud properties deduced from infrared sounders. Our analyses show that the size of the systems as well as the fraction of thin cirrus over the total anvil area increases with increasing convective depth.

Description: On the spatio-temporal representativeness of observations Nick Schutgens, Svetlana Tsyro, Ed Gryspeerdt, Daisuke Goto, Natalie Weigum, Michael Schulz, and Philip Stier Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2017-149,2017 Manuscript under review for ACP (discussion: open, 0 comments) Using high-resolution simulations, we estimate representativeness errors on time-scales of hours to a year and length-scales of 50 to 200 km for a variety of observing systems (in-situ or remote sensing ground sites, satellites with imagers or LIDARs, etc) and show how to reduce them. This study is relevant to the use of observations in constructing satellite L3 products, observational inter comparison and model evaluation.

Description: Top-down and Bottom-up aerosol-cloud-closure: towards understanding sources of uncertainty in deriving cloud radiative flux Kevin J. Sanchez, Greg C. Roberts, Radiance Calmer, Keri Nicoll, Eyal Hashimshoni, Daniel Rosenfeld, Jurgita Ovadnevaite, Jana Preissler, Darius Ceburnis, Colin O'Dowd, and Lynn M. Russell Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2017-201,2017 Manuscript under review for ACP (discussion: open, 0 comments) Top-down and bottom-up aerosol-cloud-radiative flux closures were conducted at the Mace Head atmospheric research station in Galway, Ireland in August 2015. This study is part of the BACCHUS (Impact of Biogenic versus Anthropogenic emissions on Clouds and Climate: towards a Holistic UnderStanding) European collaborative project, with the goal of understanding key processes affecting aerosol-cloud-radiative flux closures to improve future climate predictions and develop sustainable policies for Europe. Instrument platforms include ground-based, unmanned aerial vehicles (UAV), and satellite measurements of aerosols, clouds and meteorological variables. The ground-based and airborne measurements of aerosol size distributions and cloud condensation nuclei (CCN) concentration were used to initiate a 1D microphysical aerosol-cloud parcel model (ACPM). UAVs were equipped for a specific science mission, with an optical particle counter for aerosol distribution profiles, a cloud sensor to measure cloud extinction, or a 5-hole probe for 3D wind vectors. UAV cloud measurements are rare and have only become possible in recent years through the miniaturization of instrumentation. These are the first UAV measurements at Mace Head. ACPM simulations are compared to in-situ cloud extinction measurements from UAVs to quantify closure in terms of cloud radiative flux. Two out of seven cases exhibit sub-adiabatic vertical temperature profiles within the cloud, which suggests that entrainment processes affect cloud microphysical properties and lead to an overestimate of simulated cloud radiative flux. Including an entrainment parameterization and explicitly calculating the entrainment fraction in the ACPM simulations both improved cloud-top radiative closure. Entrainment reduced the difference between simulated and observation-derived cloud-top radiative flux (δRF) by between 30 W m −2 and 40 W m −2 . After accounting for entrainment, satellite-derived cloud droplet number concentrations (CDNC) were within 30 % of simulated CDNC. In cases with a well-mixed boundary layer, δRF is less than 25 W m −2 after accounting for cloud-top entrainment, compared to less than 50 W m −2 when entrainment is not taken into account. In cases with a decoupled boundary layer, cloud microphysical properties are inconsistent with ground-based aerosol measurements, as expected, and δRF is as high as 88 W m −2 , even after accounting for cloud-top entrainment. This work demonstrates the need to take in-situ measurements of aerosol properties for cases where the boundary layer is decoupled as well as consider cloud-top entrainment to accurately model stratocumulus cloud radiative flux.

Description: Upper tropospheric cloud systems derived from IR sounders: properties of cirrus anvils in the tropics Sofia E. Protopapadaki, Claudia J. Stubenrauch, and Artem G. Feofilov Atmos. Chem. Phys., 17, 3845-3859, doi:10.5194/acp-17-3845-2017, 2017 Upper tropospheric clouds cover about 30 % of the Earth and play a key role in the climate system by modulating the Earth's energy budget and heat transport. In this article, we study upper tropospheric cloud systems using cloud properties deduced from infrared sounders. Our analyses show that the size of the systems as well as the fraction of thin cirrus over the total anvil area increases with increasing convective depth.

Description: On biases in atmospheric CO inversions assimilating MOPITT satellite retrievals Yi Yin, Frederic Chevallier, Philippe Ciais, Gregoire Broquet, Anne Cozic, Sophie Szopa, and Yilong Wang Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2017-166,2017 Manuscript under review for ACP (discussion: open, 0 comments) CO inverse modelling studies have so far reported significant discrepancies between model concentrations optimised with the Measurement of Pollution in the Troposphere (MOPITT) satellite retrievals and surface in-situ measurements. Here, we assess how well a global CTM fits a large variety of independent CO observations before and after assimilating MOPITTv6 retrievals to optimise CO sources/sink and discuss potential sources of errors and their implications for global CO modelling studies.

Description: Importance of the Saharan Heat Low on the control of the North Atlantic free tropospheric humidity deduced from IASI δD observations Jean-Lionel Lacour, Cyrille Flamant, Camille Risi, Cathy Clerbaux, and Pierre-François Coheur Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2017-152,2017 Manuscript under review for ACP (discussion: open, 0 comments) We present temporal and spatial δD distributions derived from IASI obtained above the North Atlantic in the vicinity of West Africa. We show that the seasonality of δD in the North Atlantic is closely associated with the installation of the Saharan Heat Low (SHL). We provide an interpretation of the temporal and spatial variations of δD and show that the interactions between the large scale subsidence, the ITCZ and the SHL can be disentangled thanks to the added information contained in δD.

Description: Lower tropospheric distributions of O 3 and aerosol over Raoyang, a rural site in the North China Plain Rui Wang, Xiaobin Xu, Shihui Jia, Ruisheng Ma, Liang Ran, Zhaoze Deng, Weili Lin, Ying Wang, and Zhiqiang Ma Atmos. Chem. Phys., 17, 3891-3903, doi:10.5194/acp-17-3891-2017, 2017 Knowledge about the vertical distributions of air pollutants is limited. We present first unmanned aerial vehicle (UAV) observations of vertical profiles of O 3 and size-resolved aerosol number concentrations over a rural site in the North China Plain. We show the determination of mixed and residual layer depth and characterization of diurnal O 3 and aerosol number concentrations in the mixed and residual layer. We confirm a rapid increase of O 3 in the lower troposphere during the recent decade.

Description: Improved OSIRIS NO 2 retrieval algorithm: description and validation Christopher E. Sioris, Landon A. Rieger, Nicholas D. Lloyd, Adam E. Bourassa, Chris Z. Roth, Douglas A. Degenstein, Claude Camy-Peyret, Klaus Pfeilsticker, Gwenaël Berthet, Valéry Catoire, Florence Goutail, Jean-Pierre Pommereau, and Chris A. McLinden Atmos. Meas. Tech., 10, 1155-1168, doi:10.5194/amt-10-1155-2017, 2017 A new OSIRIS NO 2 retrieval algorithm is described and validated using 〉 40 balloon-based profile measurements. The validation results indicate a slight improvement relative to the existing operational algorithm in terms of the bias versus the balloon data, particularly in the lower stratosphere. The implication is that this new algorithm should replace the operational one. The motivation was to combine spectral fitting and the SaskTRAN radiative transfer model to achieve an improved product.

Description: Viable cold-tolerant iron-reducing microorganisms in geographically diverse subglacial environments Sophie L. Nixon, Jon P. Telling, Jemma L. Wadham, and Charles S. Cockell Biogeosciences, 14, 1445-1455, doi:10.5194/bg-14-1445-2017, 2017 Despite their permanently cold and dark characteristics, subglacial environments (glacier ice–sediment interface) are known to harbour active microbial communities. However, the role of microbial iron cycling in these environments is poorly understood. Here we show that subglacial sediments harbour active iron-reducing microorganisms, and they appear to be cold-adapted. These results may have important implications for global biogeochemical iron cycling and export to marine ecosystems.

Description: Can land degradation drive differences in the C exchange of two similar semiarid ecosystems? Ana López-Ballesteros, Cecilio Oyonarte, Andrew S. Kowalski, Penélope Serrano-Ortiz, Enrique P. Sánchez-Cañete, M. Rosario Moya, and Francisco Domingo Biogeosciences Discuss., doi:10.5194/bg-2017-77,2017 Manuscript under review for BG (discussion: open, 0 comments) The concept of land degradation stems from the loss of an ecosystem's biological productivity, which in turn relies on several degradation processes, such as long-term loss of natural vegetation, depletion of soil nutrients, soil compaction or water and wind erosion, to which drylands are especially vulnerable. Currently, drylands occupy more than one third of the global terrestrial surface and will probably expand under future climate change scenarios. Drylands' key role in the global C balance has been recently demonstrated, but the effects of land degradation on C sequestration by these ecosystems needs further research. In the present study, we compare net carbon exchange, together with satellite data and meteorological, ambient and vadose zone (CO 2 , water content and temperature) variables, between two nearby (~23 km) experimental sites representing natural (i.e. site of reference) and degraded grazed semiarid grasslands located in SE Spain, via eddy covariance measurements over 6 years, with highly variable precipitation magnitude and distribution. Results show a striking difference in the annual C balances with an average release of 196 ± 40 and −23 ± 20 g C m −2 yr −1 for the degraded and natural sites, respectively. At the seasonal scale, differing patterns in net CO 2 fluxes were detected over both growing and dry seasons. As expected, during the growing seasons, greater net C uptake over longer periods was observed in the natural site, however, much greater net C release was measured in the degraded site during drought periods. We tested differences in all monitored meteorological and soil variables and found it most relevant that CO 2 at 1.50 m belowground was around 1000 ppm higher in the degraded site. Thus, we believe that subterranean ventilation of this vadose zone CO 2 , previously observed at both sites, largely drives the differences in C dynamics between them, especially during the dry season maybe due to enhanced subsoil-atmosphere interconnectivity in the degraded site. Overall, the 12 site-years of data allow direct exploration of the roles of climate and land degradation in the biological and non-biological processes that ultimately control the C sequestration capacity of semiarid ecosystems.

Description: The Pacific–North American plate boundary in California is composed of a 400-km-wide network of faults and zones of distributed deformation. Earthquakes, even large ones, can occur along individual or combinations of faults within the larger plate boundary system. While research often focuses on the primary and secondary faults, holistic study of the plate boundary is required to answer several fundamental questions. How do plate boundary motions partition across California faults? How do faults within the plate boundary interact during earthquakes? What fraction of strain accumulation is relieved aseismically and does this provide limits on fault rupture propagation? Geodetic imaging, broadly defined as measurement of crustal deformation and topography of the Earth’s surface, enables assessment of topographic characteristics and the spatio-temporal behavior of the Earth’s crust. We focus here on crustal deformation observed with continuous Global Positioning System (GPS) data and Interferometric Synthetic Aperture Radar (InSAR) from NASA’s airborne UAVSAR platform, and on high-resolution topography acquired from lidar and Structure from Motion (SfM) methods. Combined, these measurements are used to identify active structures, past ruptures, transient motions, and distribution of deformation. The observations inform estimates of the mechanical and geometric properties of faults. We discuss five areas in California as examples of different fault behavior, fault maturity and times within the earthquake cycle: the M6.0 2014 South Napa earthquake rupture, the San Jacinto fault, the creeping and locked Carrizo sections of the San Andreas fault, the Landers rupture in the Eastern California Shear Zone, and the convergence of the Eastern California Shear Zone and San Andreas fault in southern California. These examples indicate that distribution of crustal deformation can be measured using interferometric synthetic aperture radar (InSAR), Global Navigation Satellite System (GNSS), and high-resolution topography and can improve our understanding of tectonic deformation and rupture characteristics within the broad plate boundary zone.

Description: MicroHH 1.0: a computational fluid dynamics code for direct numerical simulation and large-eddy simulation of atmospheric boundary layer flows Chiel C. van Heerwaarden, Bart J. H. van Stratum, Thijs Heus, Jeremy A. Gibbs, Evgeni Fedorovich, and Juan-Pedro Mellado Geosci. Model Dev. Discuss., doi:10.5194/gmd-2017-41,2017 Manuscript under review for GMD (discussion: open, 0 comments) MicroHH ( ww.microhh.org ) is a new and open source computational fluid dynamics code for the simulation of turbulent flows in the atmosphere. It is made the simulate atmospheric flows up to the finest detail levels at very high resolution. It has been designed from scratch in order to use a modern design that allows the code to run on more than 10.000 cores, as well as on a Graphical Processing Unit.

Description: The ophiolitic rocks of the Attic-Cycladic crystalline belt are considered of key importance for understanding the Mesozoic tectonic evolution of the Aegean region. Unresolved questions concern their tectono-stratigraphic relationships across the region. The mode of occurrence of the Cycladic ophiolites varies, as they appear as: (a) dismembered blocks (olistoliths) within the supra-detachment units of Paros and Naxos; (b) mélange formations in the upper structural unit of western Samos and Skyros; and (c) meta-ophiolitic mélange in the Cycladic Blueschist Unit (CBU) from central Samos. The trace element geochemistry and Pb-Sr-Nd isotopes of the mafic ophiolitic rocks indicate four geochemical groups: (a) the upper unit metabasites from Paros and western Samos (Kallithea) display an evolved basaltic composition (Mg# 40.2–59.6), with low Zr/Nb values (5–16) and high Ce/Y values (1.3 to 2.6) compared to MORB, indicating island-arc tholeiite affinities; (b) Naxos upper unit metabasalts show spider diagrams patterns indicating ocean island basalt (OIB-type) affinities; (c) Central Samos metagabbros (CBU) are primitive rocks with Back-Arc Basin basalt affinities; (d) the Skyros metadolerites and Tinos (Mt Tsiknias) and S. Evia (CBU) metagabbros, cluster as a separate geochemical group; they exhibit high MgO values (>10 wt %), very low TiO2 values (0.1–0.2 wt %), Y and Yb, and depleted trace element N-MORB normalized patterns, similar to volcanic rocks formed in modern oceanic fore-arc settings, such as boninites. A combination of the Pb- and Sr-isotopic compositions of Cycladic metabasites indicate that the Pb and Sr incorporated in the Cycladic ophiolites correspond to mixtures of magmatic fluids with seawater (206Pb/204Pb = 18.51–18.80; 207Pb/204Pb = 15.59–15.7; 208Pb/204Pb = 39.03–39.80 and initial 87Sr/86Sr80 = 0.705–0.707). Furthermore, peridotite relicts from Samos, Paros, and Naxos—irrespective of the structural unit—display chemical affinities of ocean floor peridotites formed in a supra-subduction zone. The characteristics of harzburgite relicts in Cycladic serpentinites and Skyros indicate a highly residual nature of the mantle source. Geochemical data from this study shed further light on the complex structure of the oceanic lithosphere from which the Cycladic ophiolites originated.

Description: Historical (1750–2014) anthropogenic emissions of reactive gases and aerosols from the Community Emission Data System (CEDS) Rachel M. Hoesly, Steven J. Smith, Leyang Feng, Zbigniew Klimont, Greet Janssens-Maenhout, Tyler Pitkanen, Jonathan J. Seibert, Linh Vu, Robert J. Andres, Ryan M. Bolt, Tami C. Bond, Laura Dawidowski, Nazar Kholod, Jun-ichi Kurokawa, Meng Li, Liang Liu, Zifeng Lu, Maria Cecilia P. Moura, Patrick R. O'Rourke, and Qiang Zhang Geosci. Model Dev. Discuss., doi:10.5194/gmd-2017-43,2017 Manuscript under review for GMD (discussion: open, 0 comments) Historical emission trends are key inputs to earth systems and atmospheric chemistry models. We present a new data set of historical (1750–2014) anthropogenic gases (CO, CH 4 , NH 3 , NO X , SO 2 , NMVOC, BC, OC, and CO 2 ) developed with the Community Emissions Database System (CEDS). This improves on existing inventories as it uses consistent methods and data across emissions species, has annual resolution for a longer and more recent time series, and is designed to be transparent and reproducible.

Description: Modelling of sediment transport and morphological evolution under the combined action of waves and currents Guilherme Franz, Matthias T. Delpey, David Brito, Lígia Pinto, Paulo Leitão, and Ramiro Neves Ocean Sci. Discuss., doi:10.5194/os-2017-8,2017 Manuscript under review for OS (discussion: open, 0 comments) The paper describes a numerical modelling methodology capable of reproducing the hydrodynamics, sediment transport and morphological evolution of coastal zones under the combined action of waves and currents. The long-term beach response to different designs of coastal defence structures was assessed, as well as the formation of multiple sandbars on the beach slope. The methodology can be applied in engineering studies in order to evaluate the best solution to protect the coast against erosion.

Description: Evaluating the effect of alternative carbon allocation schemes in a land surface model (CLM4.5) on carbon fluxes, pools and turnover in temperate forests Francesc Montané, Andrew M. Fox, Avelino F. Arellano, Natasha MacBean, M. Ross Alexander, Alex Dye, Daniel A. Bishop, Valerie Trouet, Flurin Babst, Amy E. Hessl, Neil Pederson, Peter D. Blanken, Gil Bohrer, Christopher M. Gough, Marcy E. Litvak, Kimberly A. Novick, Richard P. Phillips, Jeffrey D. Wood, and David J. P. Moore Geosci. Model Dev. Discuss., doi:10.5194/gmd-2017-74,2017 Manuscript under review for GMD (discussion: open, 0 comments) How carbon is allocated to different plant tissues (leaves, stem, and roots) determines carbon residence time and thus remains a central challenge for understanding the global carbon cycle. In this paper, we used a state-of-the-art land surface model (CLM4.5) with its standard carbon allocation scheme, and we implemented alternative carbon allocation schemes based on published papers. One of the alternative allocation schemes improved aboveground biomass estimates in most of our sites.

Description: Heterogeneity measures in hydrological frequency analysis: review and new developments Ana I. Requena, Fateh Chebana, and Taha B. M. J. Ouarda Hydrol. Earth Syst. Sci., 21, 1651-1668, doi:10.5194/hess-21-1651-2017, 2017 The notion of a measure to quantify the degree of heterogeneity of a region from which information is required to estimate the magnitude of events at ungauged sites is introduced. These heterogeneity measures are needed to compare regions, evaluate the impact of particular sites, and rank the performance of delineating methods. A framework to define and assess their desirable properties is proposed. Several heterogeneity measures are presented and/or developed to be assessed, giving guidelines.