ALBERT

Description: 〈b〉Monitoring the crisis of a rock glacier with repeated UAV surveys〈/b〉〈br〉 Sebastián Vivero and Christophe Lambiel〈br〉 Geogr. Helv., 74, 59-69, https://doi.org/10.5194/gh-74-59-2019, 2019〈br〉 〈p〉In this study, rapid topographic changes and high creeping rates caused by the destabilisation of an active rock glacier in a steep mountain flank were investigated in detail with five unmanned aerial vehicle (UAV) surveys between June 2016 and September 2017. State-of-the-art photogrammetric techniques were employed to derived high-density point clouds and high-resolution orthophoto mosaics from the studied landform. The accuracy of the co-registration of subsequent point clouds was carefully examined and adjusted based on comparing stable areas outside the rock glacier, which minimised 3-D alignment errors to a mean of 0.12 m. Elevation and volumetric changes in the destabilised rock glacier were quantified over the study period. Surface kinematics were estimated with a combination of image correlation algorithms and visual inspection of the orthophoto mosaics. Between June 2016 and September 2017, the destabilised part of the rock glacier advanced up to 60–75 m and mobilised a volume of around 27 000 m〈span〉〈sup〉3〈/sup〉〈/span〉 of material which was dumped over the lower talus slope. This study has demonstrated a robust and customisable monitoring approach that allows a detailed study of rock glacier geometric changes during a crisis phase.〈/p〉

Description: 〈b〉ESD Reviews: Thermodynamic optimality in Earth sciences. The missing constraints in modeling Earth system dynamics?〈/b〉〈br〉 Martijn Westhoff, Axel Kleidon, Stan Schymanski, Benjamin Dewals, Femke Nijsse, Maik Renner, Henk Dijkstra, Hisashi Ozawa, Hubert Savenije, Han Dolman, Antoon Meesters, and Erwin Zehe〈br〉 Earth Syst. Dynam. Discuss., doi:10.5194/esd-2019-6,2019〈br〉 〈b〉Manuscript under review for ESD〈/b〉 (discussion: open, 0 comments)〈br〉 Even models relying on physical laws have parameters that need to be measured or estimated. Thermodynamic optimality principles potentially offer a way to reduce the number of estimated parameters by stating that a system evolves to an optimum state. These principles have been applied successfully within the Earth system, but it is often unclear what to optimize and how. In this review paper we identify commonalities between different successful applications as well as some doubtful applications.

Description: 〈b〉Seismic Hazard of L'Aquila downtown (central Italy): new insights for 3D geological model based on high-resolution seismic reflection profile and borehole stratigraphy〈/b〉〈br〉 Marco Tallini, Marco Spadi, Domenico Cosentino, Marco Nocentini, Luca Macerola, Giuseppe Cavuoto, and Vincenzo Di Fiore〈br〉 Solid Earth Discuss., https//doi.org/10.5194/se-2019-25,2019〈br〉 〈b〉Manuscript under review for SE〈/b〉 (discussion: open, 0 comments)〈br〉 The interpretation of a 1 km-long high-resolution seismic reflection profile integrated with borehole stratigraphy was useful to reconstruct the geological subsoil model of L'Aquila downtown which was struck by the 6/4/2009 Mw 6.1 earthquake, and thus to provide indication on the seismic site effects and the faults activity. This information was essential to design urban masterplan able to mitigate the Seismic Hazard of cultural heritage cities of central Italy, such as the case study site.

Description: 〈b〉Seismic Hazard of L'Aquila downtown (central Italy): new insights for 3D geological model based on high-resolution seismic reflection profile and borehole stratigraphy〈/b〉〈br〉 Marco Tallini, Marco Spadi, Domenico Cosentino, Marco Nocentini, Luca Macerola, Giuseppe Cavuoto, and Vincenzo Di Fiore〈br〉 Solid Earth Discuss., https//doi.org/10.5194/se-2019-25,2019〈br〉 〈b〉Manuscript under review for SE〈/b〉 (discussion: open, 0 comments)〈br〉 The interpretation of a 1 km-long high-resolution seismic reflection profile integrated with borehole stratigraphy was useful to reconstruct the geological subsoil model of L'Aquila downtown which was struck by the 6/4/2009 Mw 6.1 earthquake, and thus to provide indication on the seismic site effects and the faults activity. This information was essential to design urban masterplan able to mitigate the Seismic Hazard of cultural heritage cities of central Italy, such as the case study site.

Description: 〈b〉Two decades observing smoke above clouds in the south-eastern Atlantic Ocean: Deep Blue algorithm updates and validation with ORACLES field campaign data〈/b〉〈br〉 Andrew M. Sayer, N. Christina Hsu, Jaehwa Lee, Woogyung V. Kim, Sharon Burton, Marta A. Fenn, Richard A. Ferrare, Meloë Kacenelenbogen, Samuel LeBlanc, Kristina Pistone, Jens Redemann, Michal Segal-Rozenhaimer, Yohei Shinozuka, and Si-Chee Tsay〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2019-58,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 Aerosols are small particles in the atmosphere such as dust or smoke. They are routinely monitored by satellites due to their importance for climate and air quality. However aerosols above clouds are more difficult to monitor. This study describes an improvement to a technique to monitor light-absorbing aerosols above clouds from four Earth-orbiting satellite instruments. The improved method is evaluated using data from the ORACLES field campaign, which measured these aerosols from aircraft.

Description: 〈b〉Precision of continuous GPS velocities from statistical analysis of synthetic time series〈/b〉〈br〉 Christine Masson, Stephane Mazzotti, and Philippe Vernant〈br〉 Solid Earth, 10, 329-342, https://doi.org/10.5194/se-10-329-2019, 2019〈br〉 We use statistical analyses of synthetic position time series to estimate the potential precision of GPS velocities. Regression tree analyses show that the main factors controlling the velocity precision are the duration of the series, the presence of offsets, and the noise. Our analysis allows us to propose guidelines which can be applied to actual GPS data that constrain the velocity accuracies.

Description: 〈b〉Precision of continuous GPS velocities from statistical analysis of synthetic time series〈/b〉〈br〉 Christine Masson, Stephane Mazzotti, and Philippe Vernant〈br〉 Solid Earth, 10, 329-342, https://doi.org/10.5194/se-10-329-2019, 2019〈br〉 We use statistical analyses of synthetic position time series to estimate the potential precision of GPS velocities. Regression tree analyses show that the main factors controlling the velocity precision are the duration of the series, the presence of offsets, and the noise. Our analysis allows us to propose guidelines which can be applied to actual GPS data that constrain the velocity accuracies.

Description: 〈b〉Assessment of Sub-Shelf Melting Parameterisations Using theOcean-Ice Sheet Coupled Model NEMO(v3.6)-Elmer/Ice(v8.3)〈/b〉〈br〉 Lionel Favier, Nicolas C. Jourdain, Adrian Jenkins, Nacho Merino, Gaël Durand, Olivier Gagliardini, Fabien Gillet-Chaulet, and Pierre Mathiot〈br〉 Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2019-26,2019〈br〉 〈b〉Manuscript under review for GMD〈/b〉 (discussion: open, 0 comments)〈br〉 The melting due to oceanic forcing at the base of ice shelves is the main driver of current Antarctic marine terminating glaciers. We assess various melting parameterisations ranging from simple scalings with far-field thermal driving to emulators of box and plume models, using a new Ocean-Ice Sheet coupled model. Two types of quadratic dependencies to thermal forcing show the best trade-off between the simplicity of the approach and the results accuracy in comparison to the coupled model.

Description: 〈b〉Development and evaluation of pollen source methodologies for the Victorian Grass Pollen Emissions Module VGPEM1.0〈/b〉〈br〉 Kathryn M. Emmerson, Jeremy D. Silver, Edward Newbigin, Edwin R. Lampugnani, Cenk Suphioglu, Alan Wain, and Elizabeth Ebert〈br〉 Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2019-43,2019〈br〉 〈b〉Manuscript under review for GMD〈/b〉 (discussion: open, 0 comments)〈br〉 We present the first representation of grass pollen in a 3D dispersion model anywhere in Australia, tested using observations from eight counting sites in Victoria. The capability was developed in response to the severe thunderstorm asthma event which took place in Melbourne in November 2016. Ten pollen emission methodologies were developed and evaluated. The best results were obtained using statistical methods that combine elements of the satellite derived Enhanced Vegetation Index.

Description: 〈b〉Design and dynamic analysis of metal rubber isolators between satellite and carrier rocket system〈/b〉〈br〉 Xibin Cao, Cheng Wei, Jiqiu Liang, and Lixu Wang〈br〉 Mech. Sci., 10, 71-78, https://doi.org/10.5194/ms-10-71-2019, 2019〈br〉 For launching satellite, with the needs of mobility and rapid-responsibility, the vehicle is used for launching. The system inevitably undergoes random vibrations caused by uneven ground excitation, while the camera and other high-precision payloads of the satellite cannot withstand the harsh mechanical environment without isolators. Due to the superior damping properties of MR, this paper designs the simple MR components and provides a feasible design method to absorb vibrations.

Description: 〈b〉Correcting atmospheric CO〈sub〉2〈/sub〉 and CH〈sub〉4〈/sub〉 mole fractions obtained with Picarro analyzers for sensitivity of cavity pressure to water vapor〈/b〉〈br〉 Friedemann Reum, Christoph Gerbig, Jost V. Lavric, Chris W. Rella, and Mathias Göckede〈br〉 Atmos. Meas. Tech., 12, 1013-1027, https://doi.org/10.5194/amt-12-1013-2019, 2019〈br〉 Atmospheric CO〈sub〉2〈/sub〉 and CH〈sub〉4〈/sub〉 mole fractions are often measured using greenhouse gas analyzers manufactured by Picarro, Inc. We report biases in these measurements that are related to pressure changes in the optical cavity of the analyzers and occur mainly at low water vapor mole fractions. We provide a method to correct the biases, which contributes to keeping the overall accuracy of CO〈sub〉2〈/sub〉 and CH〈sub〉4〈/sub〉 measurements with Picarro analyzers within the WMO interlaboratory compatibility goals.

Description: 〈b〉GCAM v5.1: representing the linkages between energy, water, land, climate, and economic systems〈/b〉〈br〉 Katherine Calvin, Pralit Patel, Leon Clarke, Ghassem Asrar, Ben Bond-Lamberty, Ryna Yiyun Cui, Alan Di Vittorio, Kalyn Dorheim, Jae Edmonds, Corinne Hartin, Mohamad Hejazi, Russell Horowitz, Gokul Iyer, Page Kyle, Sonny Kim, Robert Link, Haewon McJeon, Steven J. Smith, Abigail Snyder, Stephanie Waldhoff, and Marshall Wise〈br〉 Geosci. Model Dev., 12, 677-698, https://doi.org/10.5194/gmd-12-677-2019, 2019〈br〉 This paper describes GCAM v5.1, an open source model that represents the linkages between energy, water, land, climate, and economic systems. GCAM examines the future evolution of these systems through the end of the 21st century. It can be used to examine, for example, how changes in population, income, or technology cost might alter crop production, energy demand, or water withdrawals, or how changes in one region’s demand for energy affect energy, water, and land in other regions.

Description: 〈b〉GCAM v5.1: representing the linkages between energy, water, land, climate, and economic systems〈/b〉〈br〉 Katherine Calvin, Pralit Patel, Leon Clarke, Ghassem Asrar, Ben Bond-Lamberty, Ryna Yiyun Cui, Alan Di Vittorio, Kalyn Dorheim, Jae Edmonds, Corinne Hartin, Mohamad Hejazi, Russell Horowitz, Gokul Iyer, Page Kyle, Sonny Kim, Robert Link, Haewon McJeon, Steven J. Smith, Abigail Snyder, Stephanie Waldhoff, and Marshall Wise〈br〉 Geosci. Model Dev., 12, 677-698, https://doi.org/10.5194/gmd-12-677-2019, 2019〈br〉 This paper describes GCAM v5.1, an open source model that represents the linkages between energy, water, land, climate, and economic systems. GCAM examines the future evolution of these systems through the end of the 21st century. It can be used to examine, for example, how changes in population, income, or technology cost might alter crop production, energy demand, or water withdrawals, or how changes in one region’s demand for energy affect energy, water, and land in other regions.

Description: 〈b〉Inconsistencies between observed, reconstructed, and simulated precipitation indices for England since the year 1650 CE〈/b〉〈br〉 Oliver Bothe, Sebastian Wagner, and Eduardo Zorita〈br〉 Clim. Past, 15, 307-334, https://doi.org/10.5194/cp-15-307-2019, 2019〈br〉 Our understanding of future climate changes increases if different sources of information agree on past climate variations. Changing climates particularly impact local scales for which future changes in precipitation are highly uncertain. Here, we use information from observations, model simulations, and climate reconstructions for regional precipitation over the British Isles. We find these do not agree well on precipitation variations over the past few centuries.

Description: 〈b〉Factors controlling pCO〈sub〉2〈/sub〉 variability in the eastern Gulf of Cádiz (SW Iberian Península)〈/b〉〈br〉 Dolores Jiménez-López, Ana Sierra, Teodora Ortega, Soledad Garrido, Nerea Hernández-Puyuelo, Ricardo Sánchez-Leal, and Jesús Forja〈br〉 Ocean Sci. Discuss., https//doi.org/10.5194/os-2019-6,2019〈br〉 〈b〉Manuscript under review for OS〈/b〉 (discussion: open, 0 comments)〈br〉 The present study describes the surface distribution of the partial pressure of CO〈sub〉2〈/sub〉 in the continental shelf of the eastern Gulf of Cádiz. For this, eight oceanographic cruises were carried out between March 2014 and February 2016. This distribution presents a linear dependence with the temperature and it decreases with distance from the coast. The Gulf of Cádiz acts as a sink of CO〈sub〉2〈/sub〉 with a mean value for the study period of −0.18 ± 20 1.32 mmol m〈sup〉−2〈/sup〉 d〈sup〉−1〈/sup〉.

Description: 〈b〉Role of Microbial Communities in the Weathering and Stalactite Formation in Karst Topography〈/b〉〈br〉 Tung-Yi Huang, Bing-Mu Hsu, Cheng-Wei Fan, Hsin-Chi Tsai, Chien-Yi Tung, and Jung-Sheng Chen〈br〉 Biogeosciences Discuss., https//doi.org/10.5194/bg-2019-12,2019〈br〉 〈b〉Manuscript under review for BG〈/b〉 (discussion: open, 0 comments)〈br〉 This study surveyed the bacterial genetic material from environment around a limestone gulch, namely scrapes on speleothem surface, dripping water through speleothem, earth under a plan limestone wall, and scrapes from the plan wall. By the estimation of bioinformatics prediction, the relative abundance of bacteria inducing calcium precipitation in scrapes of speleothems and the water were about 100 times higher than the plan wall, while weathering related bacteria were plenty on the plan wall.

Description: 〈b〉Hyposalinity tolerance inthecoccolithophorid 〈i〉Emiliania huxleyi〈/i〉 under the influence of ocean acidification involves enhanced photosynthetic performance〈/b〉〈br〉 Jiekai Xu, John Beardall, and Kunshan Gao〈br〉 Biogeosciences Discuss., https//doi.org/10.5194/bg-2019-4,2019〈br〉 〈b〉Manuscript under review for BG〈/b〉 (discussion: open, 0 comments)〈br〉 A lot of papers studying Ocean acidification (OA) have been published while no related reports can be found on the combined effects of OA with decreased salinity on coccolithophores yet.Thus, we investigated the physiological responses of an Emiliania huxleyi strain grown at 2CO〈sub〉2〈/sub〉 concentrations and 3 levels of salinity and found cells could tolerate reduced salinity under OA as its increased light capturing capability, which suggests a potential niche extension of coccolithophores in the future.

Description: 〈b〉Causes for increased flood frequency in central Europe in the 19th century〈/b〉〈br〉 Stefan Brönnimann, Luca Frigerio, Mikhaël Schwander, Marco Rohrer, Peter Stucki, and Jörg Franke〈br〉 Clim. Past Discuss., https//doi.org/10.5194/cp-2019-17,2019〈br〉 〈b〉Manuscript under review for CP〈/b〉 (discussion: open, 0 comments)〈br〉 During the 19th century flood frequency was high in Central Europe, but it was low in the mid-20th century. This paper tracks these decadal changes in flood frequency for the case of Switzerland from peak discharge data back to precipitation data and daily weather reconstructions. We find an increased frequency of flood-prone weather types during large parts of the 19th century and decreased frequency in the mid-20th century. Sea-surface temperature anomalies can only explain a small part of it.

Description: 〈b〉Statistical modelling of co-seismic knickpoint formation and river response to fault slip〈/b〉〈br〉 Philippe Steer, Thomas Croissant, Edwin Baynes, and Dimitri Lague〈br〉 Earth Surf. Dynam. Discuss., https//doi.org/10.5194/esurf-2019-5,2019〈br〉 〈b〉Manuscript under review for ESurf〈/b〉 (discussion: open, 0 comments)〈br〉 We use a statistical earthquake generator to investigate the influence of fault activity on river profile development and on the formation of co-seismic knickpoints. We find that the height distribution of knickpoints resulting from a purely seismic fault is homogeneous. Shallow aseismic slip favors knickpoints generated by large magnitude earthquakes nucleating at depth. Accounting for fault burial by alluvial cover can modulate the topographic expression of earthquakes and fault activity.

Description: 〈b〉Past and future dynamics of the Brunt Ice Shelf from seabed bathymetry and ice shelf geometry〈/b〉〈br〉 Dominic A. Hodgson, Tom A. Jordan, Jan De Rydt, Peter T. Fretwell, Samuel A. Seddon, David Becker, Kelly A. Hogan, Andrew M. Smith, and David G. Vaughan〈br〉 The Cryosphere, 13, 545-556, https://doi.org/10.5194/tc-13-545-2019, 2019〈br〉 The Brunt Ice Shelf in Antarctica is home to Halley VIa, the latest in a series of six British research stations that have occupied the ice shelf since 1956. A recent rapid growth of rifts in the Brunt Ice Shelf signals the onset of its largest calving event since records began. Here we consider whether this calving event will lead to a new steady state for the ice shelf or an unpinning from the bed, which could predispose it to accelerated flow or collapse.

Description: 〈b〉Evaluating solar radiation forecast uncertainty〈/b〉〈br〉 Minttu Tuononen, Ewan J. O'Connor, and Victoria A. Sinclair〈br〉 Atmos. Chem. Phys., 19, 1985-2000, https://doi.org/10.5194/acp-19-1985-2019, 2019〈br〉 Many applications require accurate forecasts of the amount of solar radiation reaching the surface, such as solar energy and UV radiation forecasts. This also means that cloud must be correctly forecast. We investigated the skill of these forecasts over Helsinki, Finland, using cloud and solar radiation observations. We found that there were errors in the model radiation forecast even when the clouds were correctly forecast, which we attribute to incorrect representation of the cloud properties.

Description: 〈b〉Mapping trends in woody cover throughout Namibian savanna with MODIS seasonal phenological metrics and field inventory data〈/b〉〈br〉 Vladimir R. Wingate, Nikolaus J. Kuhn, Stuart R. Phinn, and Cornelis van der Waal〈br〉 Biogeosciences Discuss., https//doi.org/10.5194/bg-2019-28,2019〈br〉 〈b〉Manuscript under review for BG〈/b〉 (discussion: open, 0 comments)〈br〉 〈p〉Woody vegetation is an integral component of savannas. Here, two main change processes alter woody vegetation, namely shrub encroachment and deforestation. Both impact a range of ecosystem services and functions across scales. Accurate estimates of change, including spatial extent, rate and drivers are lacking. This is primarily due to savanna vegetation comprising woody and herbaceous vegetation, each of which exhibit divergent phenological characteristics, and vary importantly in their response to climatic and environmental factors. This study uses phenological metrics derived from the MODIS MOD13Q1 NDVI time-series to model woody cover as a function of field measurements, and to map trends across Namibia. These metrics enhance the contrasting phenological characteristics of woody and herbaceous vegetation, and standardizes their annual response to climatic and environmental factors by integrating short term variation. Trends in woody cover are excellent indicators of shrub encroachment and deforestation. Trend significance was computed using the Mann-Kendall test, while change statistics, including the rate and spatial extent of change were derived using the Theil-Sen slope. Change was evaluated in relation to drivers including land-use, population, biomes and precipitation. An overall decrease in woody cover was identified, with the most pronounced decreases found in urban and densely populated areas. Decreases in woody cover were not homogenously distributed; losses predominated in tropical desert and dry forests, but gains were found across shrub lands.〈/p〉

Description: 〈b〉On the timescales and length scales of the Arctic sea ice thickness anomalies: a study based on 14 reanalyses〈/b〉〈br〉 Leandro Ponsoni, François Massonnet, Thierry Fichefet, Matthieu Chevallier, and David Docquier〈br〉 The Cryosphere, 13, 521-543, https://doi.org/10.5194/tc-13-521-2019, 2019〈br〉 The Arctic is a main component of the Earth's climate system. It is fundamental to understand the behavior of Arctic sea ice coverage over time and in space due to many factors, e.g., shipping lanes, the travel and tourism industry, hunting and fishing activities, mineral resource extraction, and the potential impact on the weather in midlatitude regions. In this work we use observations and results from models to understand how variations in the sea ice thickness change over time and in space.

Description: 〈b〉Regulation of N〈sub〉2〈/sub〉O emissions from acid organic soil drained for agriculture: Effects of land use and season〈/b〉〈br〉 Arezoo Taghizadeh-Toosi, Lars Elsgaard, Tim J. Clough, Rodrigo Labouriau, Vibeke Ernstsen, and Søren O. Petersen〈br〉 Biogeosciences Discuss., https//doi.org/10.5194/bg-2019-14,2019〈br〉 〈b〉Manuscript under review for BG〈/b〉 (discussion: open, 0 comments)〈br〉 〈p〉Drained organic soils are extensively used for cereal and high-value cash crop production or as grazing land, but emissions of nitrous oxide (N〈sub〉2〈/sub〉O) are enhanced by the drainage and cultivation. A study was conducted to investigate the regulation of N〈sub〉2〈/sub〉O emissions in a raised bog area drained for agriculture. The area has been classified as potentially acid sulfate soil, and we hypothesised that pyrite oxidation was a potential driver of N〈sub〉2〈/sub〉O emissions. Two sites with rotational grass, and two sites with a potato crop, were equipped for monitoring of N〈sub〉2〈/sub〉O emissions, as well as sub-soil N〈sub〉2〈/sub〉O concentrations at 5, 10, 20, 50 and 100 cm depth, during spring and autumn 2015. Precipitation, air and soil temperature, soil moisture, water table (WT) depth, and soil mineral N were recorded during weekly field campaigns. In late April and early September, intact cores were collected to 1 m depth at adjacent grassland and potato sites for analysis of soil properties, which included acid volatile sulfide (AVS) and chromium-reducible sulfur (CRS) to quantify, respectively, iron monosulfide (FeS) and pyrite (FeS〈sub〉2〈/sub〉), as well as total reactive iron (TRFe) and nitrite (NO〈sub〉2〈/sub〉〈sup〉−〈/sup〉). Soil organic matter composition and total reduction capacity was also determined. The soil pH varied between 4.7 and 5.4. Equivalent soil gas phase concentrations of N〈sub〉2〈/sub〉O ranged from around 10 µL L〈sup〉−1〈/sup〉 at grassland sites to several hundred µL L〈sup〉−1〈/sup〉 at potato sites, in accordance with lower soil mineral N concentrations at grassland sites. Total N〈sub〉2〈/sub〉O emissions during 152–174 days were 3–6 kg N〈sub〉2〈/sub〉O-N ha〈sup〉−1〈/sup〉 for rotational grass, and 19–21 kg N〈sub〉2〈/sub〉O-N ha〈sup〉−1〈/sup〉 for potato sites. Statistical analyses by graphical models showed that soil N〈sub〉2〈/sub〉O concentration in the capillary fringe was the strongest predictor for N〈sub〉2〈/sub〉O emissions in spring, and for grassland sites also in the autumn. For potato sites in the autumn, nitrate (NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉) availability in the top soil, together with temperature, were the main controls on N〈sub〉2〈/sub〉O emissions. Pyrite oxidation coupled with NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 reduction could not be dismissed as a source of N〈sub〉2〈/sub〉O, but the total reduction capacity of the peat soil was much higher than explained by the FeS〈sub〉2〈/sub〉 concentration. The concentrations of TRFe were also much higher than pyrite concentrations, and potentially chemodenitrification could have been a source of N〈sub〉2〈/sub〉O during WT drawdown in spring. The N〈sub〉2〈/sub〉O emissions associated with rapid soil wetting and WT rise in autumn were consistent with biological denitrification. Soil N availability and seasonal WT changes were important controls of N〈sub〉2〈/sub〉O emissions.〈/p〉

Description: 〈b〉Palaeoenvironmental response of mid-latitudinal wetlands to PETM climate change (Schöningen lignite deposits, Germany)〈/b〉〈br〉 Katharina Methner, Olaf Lenz, Walter Riegel, Volker Wilde, and Andreas Mulch〈br〉 Clim. Past Discuss., https//doi.org/10.5194/cp-2019-20,2019〈br〉 〈b〉Manuscript under review for CP〈/b〉 (discussion: open, 0 comments)〈br〉 We describe the presence of a carbon isotope excursion (CIE) in Paleogene lignites (Schöningen, DE) that we attribute to reflect the Paleocene-Eocene Thermal Maximum (PETM). Palynological data point to minor PETM-related paleovegetation changes. Paleo-North Sea wetland deposits (Schöningen; Cobham; Vasterival) therefore, share major characteristics of increased fire activity (pre-PETM), minor plant species changes, a reduced CIE, and drowning of near-coastal mires during the PETM.

Description: 〈b〉Application of Factor and Cluster Analyses to Determine Source–Receptor Relationships of Industrial Volatile Organic Odor Species in a Dual-Optical Sensing System〈/b〉〈br〉 Jen-Chih Yang, Pao-Erh Chang, Chi-Chang Ho, and Chang-Fu Wu〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-344,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 A new approach for the determination of source–receptor relationships of volatile organic odor species in an industrial odor nuisance site is proposed. A dual-optical sensing system and a meteorological station were used collaboratively to generate both receptor and source data. Factor and cluster analyses were employed to improve the quality and completeness of the source profiles. The major odor emission source was identified and future emission reductions can be accomplished accordingly.

Description: 〈b〉Deformation mechanisms in mafic amphibolites and granulites: record from the Semail metamorphic sole during subduction infancy〈/b〉〈br〉 Mathieu Soret, Philippe Agard, Benoît Ildefonse, Benoît Dubacq, Cécile Prigent, and Claudio Rosenberg〈br〉 Solid Earth Discuss., https//doi.org/10.5194/se-2019-28,2019〈br〉 〈b〉Manuscript under review for SE〈/b〉 (discussion: open, 0 comments)〈br〉 This study sheds light on the mineral-scale mechanisms controlling the progressive deformation of sheared amphibolites from the Oman metamorphic sole during subduction initiation, and unravels how strain is localized and accommodated in (hydrated) mafic rocks at high temperature conditions. Our results indicate how metamorphic reactions and pore-fluid pressures driven by changes in pressure–temperature conditions and/or water activity control the rheology of mafic rocks.

Description: 〈b〉Is water vapor a key player of the wintertime haze in North China Plain?〈/b〉〈br〉 Jiarui Wu, Naifang Bei, Bo Hu, Suixin Liu, Meng Zhou, Qiyuan Wang, Xia Li, Lang Liu, Tian Feng, Zirui Liu, Yichen Wang, Junji Cao, Xuexi Tie, Jun Wang, Luisa T. Molina, and Guohui Li〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1289,2019〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 The near-surface PM〈sub〉2.5〈/sub〉 contribution of the ALW total effect is 17.5 % in NCP, indicating that ALW plays an important role in the PM〈sub〉2.5〈/sub〉 formation during the wintertime haze pollution. Moreover, the ALW-HET overwhelmingly dominates the PM〈sub〉2.5〈/sub〉 enhancement due to the ALW. The ALW does not consistently enhance near-surface [PM〈sub〉2.5〈/sub〉] with increasing RH. When the RH exceeds 80 %, the contribution of the ALW commences to decrease caused by the high occurrence frequencies of precipitation.

Description: 〈b〉The Geodynamic World Builder: a solution for complex initial conditions in numerical modelling〈/b〉〈br〉 Menno Fraters, Cedric Thieulot, Arie van den Berg, and Wim Spakman〈br〉 Solid Earth Discuss., https//doi.org/10.5194/se-2019-24,2019〈br〉 〈b〉Manuscript under review for SE〈/b〉 (discussion: open, 0 comments)〈br〉 Three-dimensional numerical modelling of geodynamic processes may benefit strongly from using realistic 3D starting models that approximate e.g. natural subduction settings in the geological past or at present. To this end we developed the Geodynamic World Builder (GWB) which enables relatively straight-forward parameterization of complex 3D geometric structures associated with geodynamic processes. The GWB is an open source community code designed to easily interface with geodynamic codes.

Description: 〈b〉Application of Factor and Cluster Analyses to Determine Source–Receptor Relationships of Industrial Volatile Organic Odor Species in a Dual-Optical Sensing System〈/b〉〈br〉 Jen-Chih Yang, Pao-Erh Chang, Chi-Chang Ho, and Chang-Fu Wu〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-344,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 A new approach for the determination of source–receptor relationships of volatile organic odor species in an industrial odor nuisance site is proposed. A dual-optical sensing system and a meteorological station were used collaboratively to generate both receptor and source data. Factor and cluster analyses were employed to improve the quality and completeness of the source profiles. The major odor emission source was identified and future emission reductions can be accomplished accordingly.

Description: 〈b〉Reanalysis of the 1761 transatlantic tsunami〈/b〉〈br〉 Martin Wronna, Maria Ana Baptista, and Jorge Miguel Miranda〈br〉 Nat. Hazards Earth Syst. Sci., 19, 337-352, https://doi.org/10.5194/nhess-19-337-2019, 2019〈br〉 We investigate the source of the 1761 earthquake and tsunami. The reanalysis of the tsunami travel times agrees with an earlier suggested source area. We check the geodynamic setting of the area and place a fault as an extension to an identified fault and use numerical modelling to distinguish between two candidate sources. One of our theories is compatible with the geodynamic setting and reproduces well the observed tsunami parameters.

Description: 〈b〉A dataset of 30-meter annual vegetation phenology indicators (1985–2015) in urban areas of the conterminous United States〈/b〉〈br〉 Xuecao Li, Yuyu Zhou, Lin Meng, Ghassem R. Asrar, Chaoqun Lu, and Qiusheng Wu〈br〉 Earth Syst. Sci. Data Discuss., https//doi.org/10.5194/essd-2019-9,2019〈br〉 〈b〉Manuscript under review for ESSD〈/b〉 (discussion: open, 0 comments)〈br〉 We generated a long-term (1985-2015) and fine-resolution (30m) product of vegetation phenology indicators in urban domains in the conterminous United States, using Landsat satellite observations. The derived phenology indicators agree well with in-situ observations and show more spatial details in complex urban areas compared to the existing moderate resolution phenology product. The published data are of great use for urban phenology studies (e.g., pollen-induced respiratory allergies).

Description: 〈b〉Linear Optimal Runoff Aggregate (LORA): a global gridded synthesis runoff product〈/b〉〈br〉 Sanaa Hobeichi, Gab Abramowitz, Jason Evans, and Hylke E. Beck〈br〉 Hydrol. Earth Syst. Sci., 23, 851-870, https://doi.org/10.5194/hess-23-851-2019, 2019〈br〉 〈p〉No synthesized global gridded runoff product, derived from multiple sources, is available, despite such a product being useful for meeting the needs of many global water initiatives. We apply an optimal weighting approach to merge runoff estimates from hydrological models constrained with observational streamflow records. The weighting method is based on the ability of the models to match observed streamflow data while accounting for error covariance between the participating products. To address the lack of observed streamflow for many regions, a dissimilarity method was applied to transfer the weights of the participating products to the ungauged basins from the closest gauged basins using dissimilarity between basins in physiographic and climatic characteristics as a proxy for distance. We perform out-of-sample tests to examine the success of the dissimilarity approach, and we confirm that the weighted product performs better than its 11 constituent products in a range of metrics. Our resulting synthesized global gridded runoff product is available at monthly timescales, and includes time-variant uncertainty, for the period 1980–2012 on a 0.5〈span〉〈sup〉∘〈/sup〉〈/span〉 grid. The synthesized global gridded runoff product broadly agrees with published runoff estimates at many river basins, and represents the seasonal runoff cycle for most of the globe well. The new product, called Linear Optimal Runoff Aggregate (LORA), is a valuable synthesis of existing runoff products and will be freely available for download on 〈span〉https://geonetwork.nci.org.au/geonetwork/srv/eng/catalog.search#/metadata/f9617_9854_8096_5291〈/span〉 (last access: 31 January 2019).〈/p〉

Description: 〈b〉Temporal variability in foraminiferal morphology and geochemistry at the West Antarctic Peninsula: a sediment trap study〈/b〉〈br〉 Anna Mikis, Katharine R. Hendry, Jennifer Pike, Daniela N. Schmidt, Kirsty M. Edgar, Victoria Peck, Frank J. C. Peeters, Melanie J. Leng, Michael P. Meredith, Chloe L. Todd, Sharon Stammerjohn, and Hugh Ducklow〈br〉 Biogeosciences Discuss., https//doi.org/10.5194/bg-2019-19,2019〈br〉 〈b〉Manuscript under review for BG〈/b〉 (discussion: open, 0 comments)〈br〉 Antarctic marine calcifying organisms are threatened by regional climate change and ocean acidification. Future projections of regional carbonate production are challenging due to the lack of historical data combined with complex climate variability. We present a six-year record of flux, morphology, and geochemistry of an Antarctic planktonic foraminifera, which shows that their growth is most sensitive to sea-ice dynamics, and is linked with the El Niño Southern Oscillation.

Description: 〈b〉Towards an advanced observation system for the marine Arctic in the framework of the Pan-Eurasian Experiment (PEEX)〈/b〉〈br〉 Timo Vihma, Petteri Uotila, Stein Sandven, Dmitry Pozdnyakov, Alexander Makshtas, Alexander Pelyasov, Roberta Pirazzini, Finn Danielsen, Sergey Chalov, Hanna K. Lappalainen, Vladimir Ivanov, Ivan Frolov, Anna Albin, Bin Cheng, Sergey Dobrolyubov, Viktor Arkhipkin, Stanislav Myslenkov, Tuukka Petäjä, and Markku Kulmala〈br〉 Atmos. Chem. Phys., 19, 1941-1970, https://doi.org/10.5194/acp-19-1941-2019, 2019〈br〉 The Arctic marine climate system, ecosystems, and socio-economic systems are changing rapidly. This calls for the establishment of a marine Arctic component of the Pan-Eurasian Experiment (MA-PEEX), for which we present a plan. The program will promote international collaboration; sustainable marine meteorological, sea ice, and oceanographic observations; advanced data management; and multidisciplinary research on the marine Arctic and its interaction with the Eurasian continent.

Description: 〈b〉Variations in the summer oceanic 〈i〉p〈/i〉CO〈sub〉2〈/sub〉 and carbon sink in Prydz Bay using the self-organizing map analysis approach〈/b〉〈br〉 Suqing Xu, Keyhong Park, Yanmin Wang, Liqi Chen, Di Qi, and Bingrui Li〈br〉 Biogeosciences, 16, 797-810, https://doi.org/10.5194/bg-16-797-2019, 2019〈br〉 In this study we applied the self-organizing map (SOM) method to estimate the oceanic 〈i〉p〈/i〉CO〈sub〉2〈/sub〉 in Prydz Bay derived from its main controlling factors. The RMSE of the SOM-derived 〈i〉p〈/i〉CO〈sub〉2〈/sub〉 was 22.14 µatm compared to SOCAT datasets. Our results showed that the monthly averaged uptake of atmospheric CO〈sub〉2〈/sub〉 for February 2015 was 23.57±6.36 TgC. Strong potential anthropogenic CO〈sub〉2〈/sub〉 uptake in the 〈q〉shelf region〈/q〉 will enhance ocean acidification (OA) in the deep water of Prydz Bay and subsequently affect deep OA.

Description: 〈b〉Multi-decadal Hydrologic Change and Variability in the Amazon River Basin: Understanding Terrestrial Water Storage Variations and Drought Characteristics〈/b〉〈br〉 Suyog Chaudhari, Yadu Pokhrel, Emilio Moran, and Gonzalo Miguez-Macho〈br〉 Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2019-57,2019〈br〉 〈b〉Manuscript under review for HESS〈/b〉 (discussion: open, 0 comments)〈br〉 〈p〉We investigate the interannual and interdecadal hydrological changes in the Amazon river basin and its sub-basins during 1980–2015 period, using GRACE satellite data and a physically-based, 2-km grid continental scale hydrological model (Leaf-Hydro-Flood) that incorporates a prognostic groundwater scheme and the effects of land use land cover change (LULC). The analyses focus on the dominant mechanisms that modulate terrestrial water storage (TWS) variations and droughts. Our results indicate that (1) the model simulates the basin-averaged TWS variations remarkably well, however, disagreements are observed in spatial patterns of temporal trends for post-2008 period, (2) the 2010s is the driest period since 1980, characterized by a major shift in decadal mean compared to 2000s due to the increased frequency of droughts, (3) long-term trends in TWS suggests that the Amazon as a whole is getting wetter (1.13 mm/y), but its southern and south-eastern sub-basins are facing significant negative TWS trends, caused primarily by intensified LULC changes, (4) increasing divergence between dry season total water deficit (TWD) and TWS release (TWS-R) suggest a strengthening dry season, especially in the southern and south-eastern sub-basins, and (5) the sub-surface storage regulates the propagation of meteorological droughts into hydrological droughts by strongly modulating TWS release with respect to its storage preceding the drought condition. Our simulations provide crucial insight on the importance of sub-surface storage in alleviating surface water deficit across Amazon and open pathways for improving prediction and mitigation of extreme droughts under changing climate and increasing hydrologic alterations due to human activities (e.g., LULC change).〈/p〉

Description: 〈b〉China's historical record when searching for tropical cyclones corresponding to Intertropical Convergence Zone (ITCZ) shifts over the past 2 kyr〈/b〉〈br〉 Huei-Fen Chen, Yen-Chu Liu, Chih-Wen Chiang, Xingqi Liu, Yu-Min Chou, and Hui-Juan Pan〈br〉 Clim. Past, 15, 279-289, https://doi.org/10.5194/cp-15-279-2019, 2019〈br〉 China’s historical typhoon data show that (1) the tracks of typhoons correspond to the north–southward migration of the Intertropical Convergence Zone and phase of the North Atlantic Oscillation, which show a nearly 30-year and a 60-year cycle during the Little Ice Age (LIA) and (2) paleotyphoons made landfall in mainland China 1 month earlier during the Medieval Warm Period than during the LIA.

Description: 〈b〉Estimating confidence intervals for gravel bed surface grain size distributions〈/b〉〈br〉 Brett C. Eaton, R. Dan Moore, and Lucy G. MacKenzie〈br〉 Earth Surf. Dynam. Discuss., https//doi.org/10.5194/esurf-2019-4,2019〈br〉 〈b〉Manuscript under review for ESurf〈/b〉 (discussion: open, 0 comments)〈br〉 Researchers studying gravel bedded rivers almost always require a sample of the bed surface grain size range. These samples are typically expressed as cumulative frequency distributions. We present a technique for generating confidence intervals for the various size percentiles. This gives other researchers the ability to estimate the uncertainty of their samples, and to refine their sampling methods to achieve the desired level of precision.

Description: 〈b〉Toward high-spatial resolution hydrological modeling for China: Calibrating the VIC model〈/b〉〈br〉 Bowen Zhu, Xianhong Xie, Chuiyu Lu, Shanshan Meng, Yi Yao, and Yibing Wang〈br〉 Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2019-72,2019〈br〉 〈b〉Manuscript under review for HESS〈/b〉 (discussion: open, 0 comments)〈br〉 The hydrological modeling of China have been limited to spatial resolutions of 10 km or greater, rendering it impossible to assess local conditions. In our study, we developed a hydrological modeling based on VIC model at a much finer spatial scale (~ 6 km). The simulated runoff, SM and ET were extensively evaluated using observations and remote sensing data. This high-resolution modeling is capable of capturing flood and drought events with respect to their timing, duration, and spatial extent.

Description: 〈b〉Landslides Data Assimilation Using TRIGRS Based on Particle Filtering〈/b〉〈br〉 Changhu Xue, Guigen Nie, Jie Dong, Shuguang Wu, Jing Wang, Xiuzhen Li, and Xiaogang Zhang〈br〉 Nat. Hazards Earth Syst. Sci. Discuss., https//doi.org/10.5194/nhess-2019-16,2019〈br〉 〈b〉Manuscript under review for NHESS〈/b〉 (discussion: open, 0 comments)〈br〉 This paper provides an approach to apply data assimilation method to stability analysis and parameter update and feedback in a landslide. The experiment is implemented by particle filter algorithm. The result FS sequence of TRIGRS output decreases continuously with time and the assimilation can effectively correct the FS of the model output. The RMSD of FS indicates the assimilation results can correct the estimation of TRIGRS output close to actual observations.

Description: 〈b〉Enhancing the spatiotemporal features of polar mesosphere summer echoes using coherent MIMO and radar imaging at MAARSY〈/b〉〈br〉 Juan Miguel Urco, Jorge Luis Chau, Tobias Weber, and Ralph Latteck〈br〉 Atmos. Meas. Tech., 12, 955-969, https://doi.org/10.5194/amt-12-955-2019, 2019〈br〉 For decades, radar observations have been used to study complicated atmospheric dynamics. Previous observations of the mesosphere, between 80 and 90 km altitude, over polar regions have been limited to a spatial resolution of a few kilometers. In this work, we present a technique which allows 3-D radar observations of the mesospheric dynamics, with an unprecedented spatial resolution of ~ 900 m. We combine the concept of MIMO and high-resolution algorithms to improve the spatial resolution.

Description: 〈b〉Propagation to the upper atmosphere of acoustic-gravity waves from atmospheric fronts in the Moscow region〈/b〉〈br〉 Yuliya Kurdyaeva, Sergey Kulichkov, Sergey Kshevetskii, Olga Borchevkina, and Elena Golikova〈br〉 Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2019-16,2019〈br〉 〈b〉Manuscript under review for ANGEO〈/b〉 (discussion: open, 0 comments)〈br〉 To simulate the vertical propagation of atmospheric waves, experimental data on pressure variations at the Earth’s surface are used. These data are associated with the meteorological source. The simulation results have allowed to the first time estimate the amplitudes of temperature wave disturbances in the upper atmosphere caused by waves from the atmospheric front. The simulations have been performed using the Lomonosov supercomputer.

Description: 〈b〉Impacts of short-term mitigation measures on PM〈sub〉2.5〈/sub〉 and radiative effects: a case study at a regional background site near Beijing, China〈/b〉〈br〉 Qiyuan Wang, Suixin Liu, Nan Li, Wenting Dai, Yunfei Wu, Jie Tian, Yaqing Zhou, Meng Wang, Steven Sai Hang Ho, Yang Chen, Renjian Zhang, Shuyu Zhao, Chongshu Zhu, Yongming Han, Xuexi Tie, and Junji Cao〈br〉 Atmos. Chem. Phys., 19, 1881-1899, https://doi.org/10.5194/acp-19-1881-2019, 2019〈br〉 〈p〉Measurements at a background site near Beijing showed that pollution controls implemented during the 19th National Congress of the Communist Party of China (NCCPC) were effective in reducing PM〈span〉〈sub〉2.5〈/sub〉〈/span〉. Mass concentrations of PM〈span〉〈sub〉2.5〈/sub〉〈/span〉 and its major chemical components were 20.6 %–43.1 % lower during the NCCPC-control period compared with a non-control period, and differences were greater on days with stable meteorological conditions. A receptor model showed that PM〈span〉〈sub〉2.5〈/sub〉〈/span〉 from traffic-related emissions, biomass burning, industrial processes, and mineral dust was 38.5 %–77.8 % lower during the NCCPC-control versus non-control period, but differences in PM〈span〉〈sub〉2.5〈/sub〉〈/span〉 from coal burning were small, and secondary sources were higher during the NCCPC-control period. During one pollution episode in the non-control period, secondary sources dominated, and the WRF-Chem model showed that the Beijing–Tianjin–Hebei (BTH) region contributed 73.6 % of PM〈span〉〈sub〉2.5〈/sub〉〈/span〉 mass. A second pollution episode was linked to biomass burning, and BTH contributed 46.9 % of PM〈span〉〈sub〉2.5〈/sub〉〈/span〉 mass. Calculations based on Interagency Monitoring of Protected Visual Environments (IMPROVE) algorithms showed that organic matter was the largest contributor to light extinction during the non-control period whereas 〈span〉NH〈sub〉4〈/sub〉NO〈sub〉3〈/sub〉〈/span〉 was the main contributor during the NCCPC. The Tropospheric Ultraviolet and Visible radiation model showed that the average direct radiative forcing (DRF) values at the Earth's surface were 〈span〉−14.0〈/span〉 and 〈span〉−19.3〈/span〉 W m〈span〉〈sup〉−2〈/sup〉〈/span〉 during the NCCPC-control and non-control periods, respectively, and the DRF for the individual PM〈span〉〈sub〉2.5〈/sub〉〈/span〉 components were 22.7 %–46.7 % lower during the NCCPC. The information and dataset from this study will be useful for developing air pollution control strategies in the BTH region and for understanding associated aerosol radiative effects.〈/p〉

Description: 〈b〉Detection and classification of laminae in balloon-borne ozonesonde profiles: application to the long-term record from Boulder, Colorado〈/b〉〈br〉 Kenneth Minschwaner, Anthony T. Giljum, Gloria L. Manney, Irina Petropavlovskikh, Bryan J. Johnson, and Allen F. Jordan〈br〉 Atmos. Chem. Phys., 19, 1853-1865, https://doi.org/10.5194/acp-19-1853-2019, 2019〈br〉 We analyzed balloon measurements of ozone between the surface and 25 km altitude above Boulder, Colorado, and developed an algorithm to detect and classify layers of either unusually high or unusually low ozone. These layers range in vertical thickness from a few hundred meters to a few kilometers. We found that these laminae are an important contributor to the overall variability in ozone, especially in the transition region between the troposphere and stratosphere.

Description: 〈b〉Mediterranean ocean colour Level 3 operational multi-sensor processing〈/b〉〈br〉 Gianluca Volpe, Simone Colella, Vittorio E. Brando, Vega Forneris, Flavio La Padula, Annalisa Di Cicco, Michela Sammartino, Marco Bracaglia, Florinda Artuso, and Rosalia Santoleri〈br〉 Ocean Sci., 15, 127-146, https://doi.org/10.5194/os-15-127-2019, 2019〈br〉 This work fully describes all the technical steps that are currently put in place in the context of the European Copernicus Marine Environment and Monitoring Service to make ocean colour data freely available to the general public. These data are useful for mapping phytoplankton dynamics on a daily and basin scale. The multi-sensor output compares well to data collected during dedicated field cruises, proving that the operational product can be successfully used for environmental monitoring.

Description: 〈b〉Automatic high-frequency measurements of full soil greenhouse gas fluxes in a tropical forest〈/b〉〈br〉 Elodie Alice Courtois, Clément Stahl, Benoit Burban, Joke Van den Berge, Daniel Berveiller, Laëtitia Bréchet, Jennifer Larned Soong, Nicola Arriga, Josep Peñuelas, and Ivan August Janssens〈br〉 Biogeosciences, 16, 785-796, https://doi.org10.5194/bg-16-785-2019, 2019〈br〉 Measuring greenhouse gases (GHGs) from a natural ecosystem remains a contemporary challenge. We tested the use of appropriate technology for the estimation of soil fluxes of the three main GHGs in a tropical rainforest for 4 months. We showed that our design allowed the continuous high-frequency measurement of the three gases in a tropical biome and provide recommendations for its implementation. This study is a major step in the estimation of the global GHG budget of tropical forests.

Description: 〈b〉The land–sea coastal border: a quantitative definition by considering the wind and wave conditions in a wave-dominated, micro-tidal environment〈/b〉〈br〉 Agustín Sánchez-Arcilla, Jue Lin-Ye, Manuel García-León, Vicente Gràcia, and Elena Pallarès〈br〉 Ocean Sci., 15, 113-126, https://doi.org/10.5194/os-15-113-2019, 2019〈br〉 A quantitative definition for the coastal border isotropy of met-ocean processes is proposed. Wind velocity and significant wave height anisotropies are examined along four transects at the north-western Mediterranean coast. Both decrease offshore, determining a coastal fringe of width of 2–4 km. The joint probability structure reflects a decoupling near the coast and a stronger dependence in the bay-like part, where the wave field is being more actively generated by the overlaying wind.

Description: 〈b〉Automatic high-frequency measurements of full soil greenhouse gas fluxes in a tropical forest〈/b〉〈br〉 Elodie Alice Courtois, Clément Stahl, Benoit Burban, Joke Van den Berge, Daniel Berveiller, Laëtitia Bréchet, Jennifer Larned Soong, Nicola Arriga, Josep Peñuelas, and Ivan August Janssens〈br〉 Biogeosciences, 16, 785-796, https://doi.org/10.5194/bg-16-785-2019, 2019〈br〉 Measuring greenhouse gases (GHGs) from a natural ecosystem remains a contemporary challenge. We tested the use of appropriate technology for the estimation of soil fluxes of the three main GHGs in a tropical rainforest for 4 months. We showed that our design allowed the continuous high-frequency measurement of the three gases in a tropical biome and provide recommendations for its implementation. This study is a major step in the estimation of the global GHG budget of tropical forests.

Description: 〈b〉Brief communication: Evaluation and inter-comparisons of Qinghai–Tibet Plateau permafrost maps based on a new inventory of field evidence〈/b〉〈br〉 Bin Cao, Tingjun Zhang, Qingbai Wu, Yu Sheng, Lin Zhao, and Defu Zou〈br〉 The Cryosphere, 13, 511-519, https://doi.org/10.5194/tc-13-511-2019, 2019〈br〉 Many maps have been produced to estimate permafrost distribution over the Qinghai–Tibet Plateau. However the evaluation and inter-comparisons of them are poorly understood due to limited in situ measurements. We provided an in situ inventory of evidence of permafrost presence or absence, with 1475 sites over the Qinghai–Tibet Plateau. Based on the in situ measurements, our evaluation results showed a wide range of map performance, and the estimated permafrost region and area are extremely large.

Description: 〈b〉Multivariate stochastic bias corrections with optimal transport〈/b〉〈br〉 Yoann Robin, Mathieu Vrac, Philippe Naveau, and Pascal Yiou〈br〉 Hydrol. Earth Syst. Sci., 23, 773-786, https://doi.org/10.5194/hess-23-773-2019, 2019〈br〉 Bias correction methods are used to calibrate climate model outputs with respect to observations. In this article, a non-stationary, multivariate and stochastic bias correction method is developed based on optimal transport, accounting for inter-site and inter-variable correlations. Optimal transport allows us to construct a joint distribution that minimizes energy spent in bias correction. Our methodology is tested on precipitation and temperatures over 12 locations in southern France.

Description: 〈b〉Isotopic and chromatographic fingerprinting of the sources of dissolved organic carbon in a shallow coastal aquifer〈/b〉〈br〉 Karina T. Meredith, Andy Baker, Martin S. Andersen, Denis M. O'Carroll, Helen Rutlidge, Liza K. McDonough, Phetdala Oudone, Eliza Bryan, and Nur Syahiza Zainuddin〈br〉 Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2018-627,2019〈br〉 〈b〉Manuscript under review for HESS〈/b〉 (discussion: open, 0 comments)〈br〉 Dissolved organic carbon within groundwater and processes controlling it, remain largely unknown. Groundwater is lower compared to surface waters. The average groundwater concentration at this coastal site was five times higher than the global median, doubling with depth, but with no change in chromatographic character. The lack of oxygen limited the rate of organic matter processing leading to enhanced preservation. Changes in coastal hydrology could lead to the flux of unreacted organic carbon.

Description: 〈b〉El Niño–Southern Oscillation (〈i〉ENSO〈/i〉) event reduces CO〈sub〉2〈/sub〉 uptake of an Indonesian oil palm plantation〈/b〉〈br〉 Christian Stiegler, Ana Meijide, Yuanchao Fan, Ashehad Ashween Ali, Tania June, and Alexander Knohl〈br〉 Biogeosciences Discuss., https//doi.org/10.5194/bg-2019-49,2019〈br〉 〈b〉Manuscript under review for BG〈/b〉 (discussion: open, 0 comments)〈br〉 We show the response of a commercial oil palm plantation in Indonesia to the extreme El Niño–Southern Oscillation (ENSO) event in 2015. Our measurements and model suggest that without human-induced forest fires and related smoke emission, the observed negative impact on oil palm carbon dioxide greenhouse gas fluxes, carbon accumulation and yield due to ENSO-related drought would have been less pronounced. With respect to climate change we highlight the importance of fire prevention in the area.

Description: 〈b〉Improving quality of empirical Greens functions, obtained by cross-correlation of high-frequency ambient seismic noise〈/b〉〈br〉 Nikita Afonin, Elena Kozlovskaya, Jouni Nevalainen, and Janne Narkilahti〈br〉 Solid Earth Discuss., https//doi.org/10.5194/se-2019-29,2019〈br〉 〈b〉Manuscript under review for SE〈/b〉 (discussion: open, 0 comments)〈br〉 〈p〉Studying the uppermost structure of the subsurface is a necessary part for solving many practical problems (exploration of minerals, groundwater studies, geoengineering, etc.). Practical application of active seismic methods is not always possible because of different reasons, such as logistical difficulties, high cost of work, high level of seismic and acoustic noise, etc. That is why developing and improving of passive seismic methods for these purposes is one of the important problems in applied geophysics. In our study, we describe the way of improving quality of Empirical Green’s Functions (EGFs), evaluated from high-frequency ambient seismic noise, by using of advanced technique of cross-correlation functions stacking in the time domain (in this paper we use term “high-frequency” for the frequencies higher than 1 Hz). In compare to existing techniques, based on weight-stacking, our proposed technique makes it possible to more significantly increase the signal-to-noise ratio and, therefore quality of the EGF. The technique is based on both iterative and global optimization algorithms, where the optimized parameter is a signal-to-noise ratio of an EGF, retrieved for each iteration. The technique has been tested with the field data acquired in an area with high level of industrial noise (Pyhäsalmi Mine, Finland) and in an area with low level of anthropogenic noise (Kuusamo Greenstone Belt, Finland). The results show that the our proposed technique can be used for extraction of EGFs from high-frequency seismic noise in practical problems of mapping of the shallow subsurface in areas with high and low level of high-frequency seismic noise.〈/p〉

Description: 〈b〉Development of a general calibration model and long-term performance evaluation of low-cost sensors for air pollutant gas monitoring〈/b〉〈br〉 Carl Malings, Rebecca Tanzer, Aliaksei Hauryliuk, Sriniwasa P. N. Kumar, Naomi Zimmerman, Levent B. Kara, Albert A. Presto, and R. Subramanian〈br〉 Atmos. Meas. Tech., 12, 903-920, https://doi.org/10.5194/amt-12-903-2019, 2019〈br〉 This paper compares several methods for calibrating data from low-cost air quality monitors to reflect the concentrations of various gaseous pollutants in the atmosphere, identifying the best-performing approaches. With these calibration methods, such monitors can be used to gather information on air quality at a higher spatial resolution than is possible using traditional technologies and can be deployed to areas (e.g. developing countries) where there are no existing monitor networks.

Description: 〈b〉Incorporating Wind Sheltering and Sediment Heat Flux into 1-D Models of Small Boreal Lakes: A Case Study with the Canadian Small Lake Model V2.0〈/b〉〈br〉 Murray D. MacKay〈br〉 Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2018-258,2019〈br〉 〈b〉Manuscript under review for GMD〈/b〉 (discussion: open, 0 comments)〈br〉 Lakes interact with their surroundings through flux exchange at their bottom sediments and with the atmosphere at the surface, and these linkages must be represented in climate and weather prediction models in order to completely elucidate the role of lakes in the climate system. Here schemes for the inclusion of wind sheltering and sediment heat flux simple enough to be included in any one dimensional lake model are presented, along with example simulations of the Canadian Small Lake Model.

Description: 〈b〉Faulting patterns in the Lower Yarmouk Gorge potentially influence groundwater flow paths〈/b〉〈br〉 Nimrod Inbar, Eliahu Rosenthal, Fabien Magri, Marwan Alraggad, Peter Möller, Akiva Flexer, Joseph Guttman, and Christian Siebert〈br〉 Hydrol. Earth Syst. Sci., 23, 763-771, https://doi.org/10.5194/hess-23-763-2019, 2019〈br〉 In areas of enigmatic hydrology, water scarcity, and transboundary water resources, management strategies should rely on comprehensive modeling which must be based on realistic geometry, including all relevant structural features. Based on available geophysical and geological data, a new faulting pattern in the Lower Yarmouk Gorge is suggested as a basis for hydrogeological modeling. Furthermore, unexpected pull-apart basin rim fault evolution is discussed in the context of tectonic collision.

Description: 〈b〉Water exchange between the Sea of Azov and the Black Sea through the Kerch Strait〈/b〉〈br〉 Ivan Zavialov and Alexander Osadchiev〈br〉 Ocean Sci. Discuss., https//doi.org/10.5194/os-2019-2,2019〈br〉 〈b〉Manuscript under review for OS〈/b〉 (discussion: open, 0 comments)〈br〉 This study is focused on water exchange between the Sea of Azov and the Black Sea. The Sea of Azov is a small and freshened sea that receives a large freshwater discharge and, therefore, can be regarded as a large river estuary connected by narrow Kerch Strait with the Black Sea. In this work we show that water transport through the Kerch Strait is governed by wind forcing and do not show dependence on river discharge rate to the Sea of Azov on intra-annual time scale.

Description: 〈b〉Faulting patterns in the Lower Yarmouk Gorge potentially influence groundwater flow paths〈/b〉〈br〉 Nimrod Inbar, Eliahu Rosenthal, Fabien Magri, Marwan Alraggad, Peter Möller, Akiva Flexer, Joseph Guttman, and Christian Siebert〈br〉 Hydrol. Earth Syst. Sci., 23, 763-771, https://doi.org/10.5194/hess-23-763-2019, 2019〈br〉 In areas of enigmatic hydrology, water scarcity, and transboundary water resources, management strategies should rely on comprehensive modeling which must be based on realistic geometry, including all relevant structural features. Based on available geophysical and geological data, a new faulting pattern in the Lower Yarmouk Gorge is suggested as a basis for hydrogeological modeling. Furthermore, unexpected pull-apart basin rim fault evolution is discussed in the context of tectonic collision.

Description: 〈b〉How large are temporal representativeness errors in paleoclimatology?〈/b〉〈br〉 Daniel E. Amrhein〈br〉 Clim. Past Discuss., https//doi.org/10.5194/cp-2019-10,2019〈br〉 〈b〉Manuscript under review for CP〈/b〉 (discussion: open, 0 comments)〈br〉 〈p〉Ongoing work in paleoclimate reconstruction prioritizes understanding the origins and magnitudes of errors that arise when comparing models and data. One class of such errors arises from assumptions of proxy temporal representativeness – broadly, the time scales over which paleoclimate proxy measurements are associated with climate variables. In the case of estimating time mean values over an interval, errors can arise when the time interval over which data are averaged and the interval that is being studied have different lengths, or if those intervals are offset from one another in time. Because it is challenging to tailor proxy measurements to precise time intervals, such errors are expected to be common in model-data and data-data comparisons, but how large and prevalent they are is unclear. The goal of this work is to provide a framework for first-order quantification of temporal representativity errors and to study the interacting effects of sampling error, archive smoothing (e.g. by bioturbation in sediment cores), chronological offsets and errors (e.g. arising from radiocarbon dating), and the spectral character of the climate process being sampled.〈/p〉 〈p〉 In some cases, particularly for small values of target intervals 〈i〉τ〈/i〉〈sub〉〈i〉x〈/i〉〈/sub〉 relative to sample intervals 〈i〉τ〈/i〉〈sub〉〈i〉y〈/i〉〈/sub〉, errors can be large relative to signals of interest. Errors from mismatches in 〈i〉τ〈/i〉〈sub〉〈i〉x〈/i〉〈/sub〉 and 〈i〉τ〈/i〉〈sub〉〈i〉y〈/i〉〈/sub〉 can have magnitudes comparable to those from chronological uncertainty. Archive smoothing can reduce sampling errors by acting as an anti-aliasing filter, but destroys high-frequency climate information. An extension of the approach to paleoclimate time series, which are sequences of time-average values, shows that measurement intervals shorter than the spacing between samples lead to errors, absent compensating effects from archive smoothing. Including these sources of uncertainty will improve accuracy in model-data comparisons and data comparisions and syntheses. Moreover, because sampling procedures emerge as important parameters in uncertainty quantification, reporting salient information about how records are processed and assessments of archive smoothing and chronological uncertainties alongside published data is important to be able to use records to their maximum potential in paleoclimate reconstruction and data assimilation.〈/p〉

Description: 〈b〉MICS-Asia III: Multi-model comparison and evaluation of aerosol over East Asia〈/b〉〈br〉 Lei Chen, Yi Gao, Meigen Zhang, Joshua S. Fu, Jia Zhu, Hong Liao, Jialin Li, Kan Huang, Baozhu Ge, Xuemei Wang, Yun Fat LAM, Chuan Yao Lin, Syuichi Itahashi, Tatsuya Nagashima, Mizuo Kajino, Kazuyo Yamaji, Zifa Wang, and Jun-ichi Kurokawa〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1346,2019〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 Simulated aerosol concentrations from 14 CTMs within the framework of MICS–Asia III are detailedly evaluated with an extensive set of measurements in East Asia. Similarities and differences among model performances are also analyzed. Although more considerable capacities for reproducing the aerosol concentrations and their variations are shown in current CTMs than those in MICS–Asia II, more efforts are needed to reduce diversities of simulated aerosol concentrations among air quality models.

Description: 〈b〉Multi-year effect of wetting on CH〈sub〉4〈/sub〉 flux at taiga–tundra boundary in northeastern Siberia deduced from stable isotope ratios of CH〈sub〉4〈/sub〉〈/b〉〈br〉 Ryo Shingubara, Atsuko Sugimoto, Jun Murase, Go Iwahana, Shunsuke Tei, Maochang Liang, Shinya Takano, Tomoki Morozumi, and Trofim C. Maximov〈br〉 Biogeosciences, 16, 755-768, https://doi.org10.5194/bg-16-755-2019, 2019〈br〉 (1) Wetting event with extreme precipitation increased methane emission from wetland, especially two summers later, despite the decline in water level after the wetting. (2) Isotopic compositions of methane in soil pore water suggested enhancement of production and less significance of oxidation in the following two summers after the wetting event. (3) Duration of water saturation in the active layer may be important for predicting methane emission after a wetting event in permafrost ecosystems.

Description: 〈b〉Could the two anticyclonic eddies during winter 2003/2004 be reproduced and predicted in the northern South China Sea?〈/b〉〈br〉 Dazhi Xu, Wei Zhuang, and Youfang Yan〈br〉 Ocean Sci., 15, 97-111, https://doi.org/10.5194/os-15-97-2019, 2019〈br〉 The reproductivity and predictability of mesoscale eddies in the northern South China Sea are investigated with a focus on two anticyclonic eddies based on an assimilated system. The results show that generation, evolution, and propagation paths of these two eddies can be well reproduced and forecasted when the observed amplitude 〉8 cm. However, when their amplitudes are

Description: 〈b〉The impact of topography on seismic amplification during the 2005 Kashmir Earthquake〈/b〉〈br〉 Saad Khan, Mark van der Meijde, Harald van der Werff, and Muhammad Shafique〈br〉 Nat. Hazards Earth Syst. Sci. Discuss., https//doi.org/10.5194/nhess-2019-13,2019〈br〉 〈b〉Manuscript under review for NHESS〈/b〉 (discussion: open, 0 comments)〈br〉 In 2005, northern Pakistan was hit by a 7.6 magnitude earthquake. The epicenter was located near capital of the Pakistani territory of Azad Kashmir and also affected Pakistan's Khyber Pakhtunkhwa province and Indian-administered Jammu and Kashmir region. It was believed that the local topography might have significant role in direct and indirect damage in the region. This study shows that the local topography played significant role in the earthquake induced damage in the region.

Description: 〈b〉Systematic comparison of five machine-learning methods in classification and interpolation of soil particle size fractions using different transformed data〈/b〉〈br〉 Mo Zhang and Wenjiao Shi〈br〉 Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2018-584,2019〈br〉 〈b〉Manuscript under review for HESS〈/b〉 (discussion: open, 1 comment)〈br〉 We systematically analyzed both direct (or indirect) soil texture classification and soil particle size fractions (psf) interpolation using five machine learning methods combined with untransformed and log ratio transformed data. The results showed that random forest had notable consequences for soil psf interpolation and soil texture classification (indirect performed better). Our systematic comparison helps to elucidate the processing and selection of compositional data in spatial simulation.

Description: 〈b〉The impact of topography on seismic amplification during the 2005 Kashmir Earthquake〈/b〉〈br〉 Saad Khan, Mark van der Meijde, Harald van der Werff, and Muhammad Shafique〈br〉 Nat. Hazards Earth Syst. Sci. Discuss., https//doi.org/10.5194/nhess-2019-13,2019〈br〉 〈b〉Manuscript under review for NHESS〈/b〉 (discussion: open, 0 comments)〈br〉 In 2005, northern Pakistan was hit by a 7.6 magnitude earthquake. The epicenter was located near capital of the Pakistani territory of Azad Kashmir and also affected Pakistan's Khyber Pakhtunkhwa province and Indian-administered Jammu and Kashmir region. It was believed that the local topography might have significant role in direct and indirect damage in the region. This study shows that the local topography played significant role in the earthquake induced damage in the region.

Description: 〈b〉Systematic comparison of five machine-learning methods in classification and interpolation of soil particle size fractions using different transformed data〈/b〉〈br〉 Mo Zhang and Wenjiao Shi〈br〉 Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2018-584,2019〈br〉 〈b〉Manuscript under review for HESS〈/b〉 (discussion: open, 1 comment)〈br〉 We systematically analyzed both direct (or indirect) soil texture classification and soil particle size fractions (psf) interpolation using five machine learning methods combined with untransformed and log ratio transformed data. The results showed that random forest had notable consequences for soil psf interpolation and soil texture classification (indirect performed better). Our systematic comparison helps to elucidate the processing and selection of compositional data in spatial simulation.

Description: 〈b〉Contributions of different anthropogenic volatile organic compound sources to ozone formation at a receptor site in the Pearl River Delta region and its policy implications〈/b〉〈br〉 Zhuoran He, Xuemei Wang, Zhenhao Ling, Jun Zhao, Hai Guo, Min Shao, and Zhe Wang〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1293,2019〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 In this study, source apportionment of volatile organic compounds (VOCs) and their contributions to photochemical O〈sub〉3〈/sub〉 formation was analyzed by the Positive Matrix Factorization model and an observation-based model for data collected at a receptor site in the Pearl River Delta (PRD) region. Furthermore, the policies for controlling VOC were brief reviewed. The findings could provide quantitative information on devising appropriate measures on the VOCs, NOx, and O〈sub〉3〈/sub〉 pollution in PRD.

Description: 〈b〉A near-surface sea temperature time series from Trieste, north Adriatic Sea (1899–2015)〈/b〉〈br〉 Fabio Raicich and Renato R. Colucci〈br〉 Earth Syst. Sci. Data Discuss., https//doi.org/10.5194/essd-2019-15,2019〈br〉 〈b〉Manuscript under review for ESSD〈/b〉 (discussion: open, 0 comments)〈br〉 Thanks to near-surface sea temperatures measured at Trieste, north Adriatic Sea, from 1899 to 2015, we estimated mean daily temperatures at 2-m depth and built a quasi-homogeneous 117-year-long time series. We described the instruments used and the sites of measurements, that are all within Trieste harbour. The data set represents a valuable tool to study sea-temperature variability on different time scale. A mean temperature rise rate of 1.1 ± 0.3 °C per century was estimated.

Description: 〈b〉Apparent discrepancy of Tibetan ice core δ〈sup〉18〈/sup〉O records may be attributed to misinterpretation of chronology〈/b〉〈br〉 Shugui Hou, Wangbin Zhang, Hongxi Pang, Shuangye Wu, Theo M. Jenk, and Margit Schwikowski〈br〉 The Cryosphere Discuss., https//doi.org/10.5194/tc-2018-295,2019〈br〉 〈b〉Manuscript under review for TC〈/b〉 (discussion: open, 0 comments)〈br〉 The apparent discrepancy between the Holocene δ〈sup〉18〈/sup〉O records of the Guliya and the Chongce ice cores may be attributed to a possible misinterpretation of the Guliya ice core chronology.

Description: 〈b〉A near-surface sea temperature time series from Trieste, north Adriatic Sea (1899–2015)〈/b〉〈br〉 Fabio Raicich and Renato R. Colucci〈br〉 Earth Syst. Sci. Data Discuss., https//doi.org/10.5194/essd-2019-15,2019〈br〉 〈b〉Manuscript under review for ESSD〈/b〉 (discussion: open, 0 comments)〈br〉 Thanks to near-surface sea temperatures measured at Trieste, north Adriatic Sea, from 1899 to 2015, we estimated mean daily temperatures at 2-m depth and built a quasi-homogeneous 117-year-long time series. We described the instruments used and the sites of measurements, that are all within Trieste harbour. The data set represents a valuable tool to study sea-temperature variability on different time scale. A mean temperature rise rate of 1.1 ± 0.3 °C per century was estimated.

Description: 〈b〉Event couple spectral ratio 〈i〉Q〈/i〉 method for earthquake clusters: application to northwest Bohemia〈/b〉〈br〉 Marius Kriegerowski, Simone Cesca, Matthias Ohrnberger, Torsten Dahm, and Frank Krüger〈br〉 Solid Earth, 10, 317-328, https://doi.org/10.5194/se-10-317-2019, 2019〈br〉 We developed a method that allows to estimate the acoustic attenuation of seismic waves within regions with high earthquake source densities. Attenuation is of high interest as it allows to draw conclusions on the origin of seismic activity. We apply our method to north-west Bohemia, which is regularly affected by earthquake swarms during which thousands of earthquakes are registered within a few days. We find reduced attenuation within the active volume, which may indicate high fluid content.

Description: 〈b〉Event couple spectral ratio 〈i〉Q〈/i〉 method for earthquake clusters: application to northwest Bohemia〈/b〉〈br〉 Marius Kriegerowski, Simone Cesca, Matthias Ohrnberger, Torsten Dahm, and Frank Krüger〈br〉 Solid Earth, 10, 317-328, https://doi.org/10.5194/se-10-317-2019, 2019〈br〉 We developed a method that allows to estimate the acoustic attenuation of seismic waves within regions with high earthquake source densities. Attenuation is of high interest as it allows to draw conclusions on the origin of seismic activity. We apply our method to north-west Bohemia, which is regularly affected by earthquake swarms during which thousands of earthquakes are registered within a few days. We find reduced attenuation within the active volume, which may indicate high fluid content.

Description: 〈b〉Tropospheric water vapor profiles obtained with FTIR: comparison with balloon-borne frost point hygrometers and influence on trace gas retrievals〈/b〉〈br〉 Ivan Ortega, Rebecca R. Buchholz, Emrys G. Hall, Dale F. Hurst, Allen F. Jordan, and James W. Hannigan〈br〉 Atmos. Meas. Tech., 12, 873-890, https://doi.org/10.5194/amt-12-873-2019, 2019〈br〉 In this work we evaluate the accuracy of water vapor ground-based FTIR retrievals in the lower and upper troposphere using coincident high-quality vertically resolved balloon-borne NOAA FPH measurements. Our results suggest that highly structured water vapor vertical gradients are captured with the FTIR and found a negligible bias in the immediate layer above the instrument altitude accounting for a water vapor time variability of less than 2 %.

Description: 〈b〉Measurements of hydroperoxy radicals (HO〈sub〉2〈/sub〉) at atmospheric concentrations using bromide chemical ionisation mass spectrometry〈/b〉〈br〉 Sascha R. Albrecht, Anna Novelli, Andreas Hofzumahaus, Sungah Kang, Yare Baker, Thomas Mentel, Andreas Wahner, and Hendrik Fuchs〈br〉 Atmos. Meas. Tech., 12, 891-902, https://doi.org/10.5194/amt-12-891-2019, 2019〈br〉 Within this study we demonstrate reliable measurement of hydroperoxy (HO〈sub〉2〈/sub〉) radicals via chemical ionisation mass spectrometry. HO〈sub〉2〈/sub〉 is detected as an ion cluster with bromide ions, which allows a selective detection. This direct and sensitive measurement provides reliable data of HO〈sub〉2〈/sub〉 radical concentrations in the atmosphere as demonstrated in the first application in simulation chamber experiments.

Description: 〈b〉Tropospheric water vapor profiles obtained with FTIR: comparison with balloon-borne frost point hygrometers and influence on trace gas retrievals〈/b〉〈br〉 Ivan Ortega, Rebecca R. Buchholz, Emrys G. Hall, Dale F. Hurst, Allen F. Jordan, and James W. Hannigan〈br〉 Atmos. Meas. Tech., 12, 873-890, https://doi.org/10.5194/amt-12-873-2019, 2019〈br〉 In this work we evaluate the accuracy of water vapor ground-based FTIR retrievals in the lower and upper troposphere using coincident high-quality vertically resolved balloon-borne NOAA FPH measurements. Our results suggest that highly structured water vapor vertical gradients are captured with the FTIR and found a negligible bias in the immediate layer above the instrument altitude accounting for a water vapor time variability of less than 2 %.

Description: 〈b〉Measurements of hydroperoxy radicals (HO〈sub〉2〈/sub〉) at atmospheric concentrations using bromide chemical ionisation mass spectrometry〈/b〉〈br〉 Sascha R. Albrecht, Anna Novelli, Andreas Hofzumahaus, Sungah Kang, Yare Baker, Thomas Mentel, Andreas Wahner, and Hendrik Fuchs〈br〉 Atmos. Meas. Tech., 12, 891-902, https://doi.org/10.5194/amt-12-891-2019, 2019〈br〉 Within this study we demonstrate reliable measurement of hydroperoxy (HO〈sub〉2〈/sub〉) radicals via chemical ionisation mass spectrometry. HO〈sub〉2〈/sub〉 is detected as an ion cluster with bromide ions, which allows a selective detection. This direct and sensitive measurement provides reliable data of HO〈sub〉2〈/sub〉 radical concentrations in the atmosphere as demonstrated in the first application in simulation chamber experiments.

Description: 〈b〉Kinetic mass-transfer calculation of water isotope fractionation due to cloud microphysics in a regional meteorological model〈/b〉〈br〉 I-Chun Tsai, Wan-Yu Chen, Jen-Ping Chen, and Mao-Chang Liang〈br〉 Atmos. Chem. Phys., 19, 1753-1766, https://doi.org/10.5194/acp-19-1753-2019, 2019〈br〉 In conventional models, isotope exchange between liquid and gas phases is usually assumed to be in equilibrium, and the highly kinetic phase transformation processes inferred in clouds are yet to be fully investigated. We show that different factors controlling isotopic composition, including water vapor sources, atmospheric transport, phase transition pathways of water in clouds, and kinetic-versus-equilibrium mass transfer, contributed significantly to the variations in isotope composition.

Description: 〈b〉Characterisation and source identification of biofluorescent aerosol emissions over winter and summer periods in the United Kingdom〈/b〉〈br〉 Elizabeth Forde, Martin Gallagher, Virginia Foot, Roland Sarda-Esteve, Ian Crawford, Paul Kaye, Warren Stanley, and David Topping〈br〉 Atmos. Chem. Phys., 19, 1665-1684, https://doi.org/10.5194/acp-19-1665-2019, 2019〈br〉 The abundance and diversity of airborne biological particles in different environments remains poorly constrained. Measurements of such particles were conducted at four sites in the United Kingdom, using real-time fluorescence instrumentation. Using local land cover types, sources of suspected particle types were identified and compared. Most sites exhibited a wet-discharged fungal spore dominance, with the exception of one site, which was inferred to be influenced by a local dairy farm.

Description: 〈b〉Turbulent enhancement of radar reflectivity factor for polydisperse cloud droplets〈/b〉〈br〉 Keigo Matsuda and Ryo Onishi〈br〉 Atmos. Chem. Phys., 19, 1785-1799, https://doi.org/10.5194/acp-19-1785-2019, 2019〈br〉 This paper presents a parameterization to predict the influence of microscale turbulent clustering of cloud droplets on the radar reflectivity factor, based on a direct numerical simulation (DNS) of turbulence. The proposed parameterization takes account of the turbulent clustering structure of droplets with arbitrary size distributions. This paper also discusses quantitative influences on realistic radar observations, applying the parameterization to high-resolution cloud-simulation data.

Description: 〈b〉Retrieving the age of air spectrum from tracers: principle and method〈/b〉〈br〉 Aurélien Podglajen and Felix Ploeger〈br〉 Atmos. Chem. Phys., 19, 1767-1783, https://doi.org/10.5194/acp-19-1767-2019, 2019〈br〉 The age spectrum (distribution of transit times) provides a compact description of transport from the surface to a given point in the atmosphere. It also determines the surface-emitted tracer content of an air parcel. We propose a method to invert this relation in order to retrieve age spectra from tracer concentrations and demonstrate its feasibility in idealized and model setups. Applied to observations, the approach might help to better constrain atmospheric transport timescales.

Description: 〈b〉Evidence for a major missing source in the global chloromethane budget from stable carbon isotopes〈/b〉〈br〉 Enno Bahlmann, Frank Keppler, Julian Wittmer, Markus Greule, Heinz Friedrich Schöler, Richard Seifert, and Cornelius Zetzsch〈br〉 Atmos. Chem. Phys., 19, 1703-1719, https://doi.org/10.5194/acp-19-1703-2019, 2019〈br〉 Chloromethane is the most important natural carrier of chlorine to the stratosphere. From a newly determined carbon isotope effect of −11.2 ‰ for the tropospheric loss of CH〈sub〉3〈/sub〉Cl we derive a tropical rainforest CH〈sub〉3〈/sub〉Cl source of 670 ± 200 Gg a〈sup〉−1〈/sup〉, 60 % smaller than previous estimates. A revision of previous bottom-up estimates using above-ground biomass instead of rainforest area strongly supports this lower estimate. Our results suggest a large unknown tropical value of 1530 ± 200 Gg a〈sup〉−1〈/sup〉.

Description: 〈b〉A top-down assessment using OMI NO〈sub〉2〈/sub〉 suggests an underestimate in the NO〈sub〉〈i〉x〈/i〉〈/sub〉 emissions inventory in Seoul, South Korea, during KORUS-AQ〈/b〉〈br〉 Daniel L. Goldberg, Pablo E. Saide, Lok N. Lamsal, Benjamin de Foy, Zifeng Lu, Jung-Hun Woo, Younha Kim, Jinseok Kim, Meng Gao, Gregory Carmichael, and David G. Streets〈br〉 Atmos. Chem. Phys., 19, 1801-1818, https://doi.org/10.5194/acp-19-1801-2019, 2019〈br〉 Using satellite data, we are able to estimate the emissions of NO〈sub〉x〈/sub〉 (NO〈sub〉x〈/sub〉=NO+NO〈sub〉2〈/sub〉), a toxic group of air pollutants, in the Seoul metropolitan area. We first develop an enhanced satellite product that better observes NO〈sub〉2〈/sub〉 in urban regions. Using this new product, we derive NO〈sub〉x〈/sub〉 emissions to be twice as large as the emissions reported by the South Korean government. The implication is that the measures taken to reduce NO〈sub〉x〈/sub〉 emissions in South Korea have not been as effective as regulators have thought.

Description: 〈b〉Frontogenesis of the Angola–Benguela Frontal Zone〈/b〉〈br〉 Shunya Koseki, Hervé Giordani, and Katerina Goubanova〈br〉 Ocean Sci., 15, 83-96, https://doi.org/10.5194/os-15-83-2019, 2019〈br〉 With an ocean frontogenetic function, the frontogenesis of the Angola–Benguela Frontal Zone (ABFZ) is investigated. On an annual-mean timescale, the meridional confluence of Angola and Benguela currents and tilting effect due to the upwelling are the main sources to generate the ABFZ. The annual cycle of the ABFZ is also mainly driven by these two effects.

Description: 〈b〉Impact of assimilating sea ice concentration, sea ice thickness and snow depth in a coupled ocean–sea ice modelling system〈/b〉〈br〉 Sindre Fritzner, Rune Graversen, Kai H. Christensen, Philip Rostosky, and Keguang Wang〈br〉 The Cryosphere, 13, 491-509, https://doi.org/10.5194/tc-13-491-2019, 2019〈br〉 In this work, a coupled ocean and sea-ice ensemble-based assimilation system is used to assess the impact of different observations on the assimilation system. The focus of this study is on sea-ice observations, including the use of satellite observations of sea-ice concentration, sea-ice thickness and snow depth for assimilation. The study showed that assimilation of sea-ice thickness in addition to sea-ice concentration has a large positive impact on the coupled model.

Description: 〈b〉Hydrologic Diversity in Glacier Bay Alaska: Spatial Patterns and Temporal Change〈/b〉〈br〉 Ryan L. Crumley, David F. Hill, Jordan P. Beamer, and Elizabeth Holzenthal〈br〉 The Cryosphere Discuss., https//doi.org/10.5194/tc-2019-1,2019〈br〉 〈b〉Manuscript under review for TC〈/b〉 (discussion: open, 0 comments)〈br〉 In this study we investigate the historical (1980–2015) and forecast (2070–2099) components of freshwater runoff to Glacier Bay, Alaska using a modeling approach. We find that many of the historically snow-dominated watersheds in Glacier Bay National Park and Preserve may transition towards rainfall-dominated hydrographs in a future scenario in which CO〈sub〉2〈/sub〉 emissions are not mitigated. The changes in timing and volume of freshwater entering Glacier Bay will affect bay ecology and hydrochemistry.

Description: 〈b〉Characterisation and source identification of biofluorescent aerosol emissions over winter and summer periods in the United Kingdom〈/b〉〈br〉 Elizabeth Forde, Martin Gallagher, Virginia Foot, Roland Sarda-Esteve, Ian Crawford, Paul Kaye, Warren Stanley, and David Topping〈br〉 Atmos. Chem. Phys., 19, 1665-1684, https://doi.org/10.5194/acp-19-1665-2019, 2019〈br〉 The abundance and diversity of airborne biological particles in different environments remains poorly constrained. Measurements of such particles were conducted at four sites in the United Kingdom, using real-time fluorescence instrumentation. Using local land cover types, sources of suspected particle types were identified and compared. Most sites exhibited a wet-discharged fungal spore dominance, with the exception of one site, which was inferred to be influenced by a local dairy farm.

Description: 〈b〉Evidence for a major missing source in the global chloromethane budget from stable carbon isotopes〈/b〉〈br〉 Enno Bahlmann, Frank Keppler, Julian Wittmer, Markus Greule, Heinz Friedrich Schöler, Richard Seifert, and Cornelius Zetzsch〈br〉 Atmos. Chem. Phys., 19, 1703-1719, https://doi.org/10.5194/acp-19-1703-2019, 2019〈br〉 Chloromethane is the most important natural carrier of chlorine to the stratosphere. From a newly determined carbon isotope effect of −11.2 ‰ for the tropospheric loss of CH〈sub〉3〈/sub〉Cl we derive a tropical rainforest CH〈sub〉3〈/sub〉Cl source of 670 ± 200 Gg a〈sup〉−1〈/sup〉, 60 % smaller than previous estimates. A revision of previous bottom-up estimates using above-ground biomass instead of rainforest area strongly supports this lower estimate. Our results suggest a large unknown tropical value of 1530 ± 200 Gg a〈sup〉−1〈/sup〉.

Description: 〈b〉Impact of assimilating sea ice concentration, sea ice thickness and snow depth in a coupled ocean–sea ice modelling system〈/b〉〈br〉 Sindre Fritzner, Rune Graversen, Kai H. Christensen, Philip Rostosky, and Keguang Wang〈br〉 The Cryosphere, 13, 491-509, https://doi.org/10.5194/tc-13-491-2019, 2019〈br〉 In this work, a coupled ocean and sea-ice ensemble-based assimilation system is used to assess the impact of different observations on the assimilation system. The focus of this study is on sea-ice observations, including the use of satellite observations of sea-ice concentration, sea-ice thickness and snow depth for assimilation. The study showed that assimilation of sea-ice thickness in addition to sea-ice concentration has a large positive impact on the coupled model.

Description: 〈b〉New particle formation in the active volcanic plume of the Piton de la Fournaise: specific features from a long-term dataset〈/b〉〈br〉 Clémence Rose, Brice Foucart, David Picard, Aurélie Colomb, Jean-Marc Metzger, Pierre Tulet, and Karine Sellegri〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2019-100,2019〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 New particle formation (NPF) is a significant climate-relevant source of aerosols in the atmosphere. We show that during the eruptive period of the Piton de la Fournaise in 2015, NPF was favoured compared to regular days. Using the largest data set ever reported in volcanic plume conditions, we quantify the emission rates of particles over a broad size range and provide a new statistically robust parameterization to take into account this important source of atmospheric particles in models.

Description: 〈b〉Turbulent enhancement of radar reflectivity factor for polydisperse cloud droplets〈/b〉〈br〉 Keigo Matsuda and Ryo Onishi〈br〉 Atmos. Chem. Phys., 19, 1785-1799, https://doi.org/10.5194/acp-19-1785-2019, 2019〈br〉 This paper presents a parameterization to predict the influence of microscale turbulent clustering of cloud droplets on the radar reflectivity factor, based on a direct numerical simulation (DNS) of turbulence. The proposed parameterization takes account of the turbulent clustering structure of droplets with arbitrary size distributions. This paper also discusses quantitative influences on realistic radar observations, applying the parameterization to high-resolution cloud-simulation data.

Description: 〈b〉Biomass-burning smoke heights over the Amazon observed from space〈/b〉〈br〉 Laura Gonzalez-Alonso, Maria Val Martin, and Ralph A. Kahn〈br〉 Atmos. Chem. Phys., 19, 1685-1702, https://doi.org/10.5194/acp-19-1685-2019, 2019〈br〉 The vertical distribution of fire smoke and factors that control its rise had not yet been quantified across the Amazon. We developed a satellite-based long record of smoke plume heights. We find that smoke heights are driven by many factors: vegetation, seasonality, time of day, fire intensity, and atmospheric and drought conditions. Also, drought increases fire pollution, with implications for air quality. Policies to control fires may be crucial in the future as more droughts are projected.

Description: 〈b〉Impact of a nitrogen emission control area (NECA) on the future air quality and nitrogen deposition to seawater in the Baltic Sea region〈/b〉〈br〉 Matthias Karl, Johannes Bieser, Beate Geyer, Volker Matthias, Jukka-Pekka Jalkanen, Lasse Johansson, and Erik Fridell〈br〉 Atmos. Chem. Phys., 19, 1721-1752, https://doi.org/10.5194/acp-19-1721-2019, 2019〈br〉 Air emissions of nitrogen oxides from ship traffic in the Baltic Sea are a health concern in coastal areas of the Baltic Sea region. We find that the introduction of the nitrogen emission control area (NECA) is critical for reducing ship emissions of nitrogen oxides to levels that are low enough to sustainably dampen ozone production. The decline of the ship-related nitrogen deposition to the Baltic Sea between 2012 and 2040 varies between 46 % and 78 % in different regulation scenarios.

Description: 〈b〉Frontogenesis of the Angola–Benguela Frontal Zone〈/b〉〈br〉 Shunya Koseki, Hervé Giordani, and Katerina Goubanova〈br〉 Ocean Sci., 15, 83-96, https://doi.org/10.5194/os-15-83-2019, 2019〈br〉 With an ocean frontogenetic function, the frontogenesis of the Angola–Benguela Frontal Zone (ABFZ) is investigated. On an annual-mean timescale, the meridional confluence of Angola and Benguela currents and tilting effect due to the upwelling are the main sources to generate the ABFZ. The annual cycle of the ABFZ is also mainly driven by these two effects.

Description: 〈b〉Parameter-state ensemble thinning for short-term hydrological prediction〈/b〉〈br〉 Bruce Davison, Vincent Fortin, Alain Pietroniro, Man K. Yau, and Robert Leconte〈br〉 Hydrol. Earth Syst. Sci., 23, 741-762, https://doi.org/10.5194/hess-23-741-2019, 2019〈br〉 This paper explores a new method of predicting streamflow using a complex model. It makes use of streamflow observations to reduce an existing ensemble of model runs for predictive purposes. The study illustrated that the method could work given the proper constraints, which were only possible if there was enough knowledge about how the river responded to precipitation in the previous months. Ideas were discussed to allow the method to be used in a way to predict future streamflow.

Description: 〈b〉Robust uncertainty assessment of the spatio-temporal transferability of glacier mass and energy balance models〈/b〉〈br〉 Tobias Zolles, Fabien Maussion, Stephan Peter Galos, Wolfgang Gurgiser, and Lindsey Nicholson〈br〉 The Cryosphere, 13, 469-489, https://doi.org/10.5194/tc-13-469-2019, 2019〈br〉 A mass and energy balance model was subjected to sensitivity and uncertainty analysis on two different Alpine glaciers. The global sensitivity analysis allowed for a mass balance measurement independent assessment of the model sensitivity and functioned as a reduction of the model free parameter space. A novel approach of a multi-objective optimization estimates the uncertainty of the simulated mass balance and the energy fluxes. The final model uncertainty is up to 1300 kg m〈sup〉−3〈/sup〉 per year.

Description: 〈b〉The influence of wind and land evapotranspiration on the variability of moisture sources and precipitation of the Yangtze River Valley〈/b〉〈br〉 Astrid Fremme and Harald Sodemann〈br〉 Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2018-629,2019〈br〉 〈b〉Manuscript under review for HESS〈/b〉 (discussion: open, 0 comments)〈br〉 This study examines the evaporation sources of precipitation falling over the Yangtze River Valley on China's East coast. The summer monsoon rainfall causes large seasonal and interannual variations which affect a large population. We found that evaporation from surrounding land regions is important, supplying more than half of the summertime precipitation. Extreme dry and wet summers are connected to contributions from specific land and ocean regions.

Description: 〈b〉Hydrologic Diversity in Glacier Bay Alaska: Spatial Patterns and Temporal Change〈/b〉〈br〉 Ryan L. Crumley, David F. Hill, Jordan P. Beamer, and Elizabeth Holzenthal〈br〉 The Cryosphere Discuss., https//doi.org/10.5194/tc-2019-1,2019〈br〉 〈b〉Manuscript under review for TC〈/b〉 (discussion: open, 0 comments)〈br〉 In this study we investigate the historical (1980–2015) and forecast (2070–2099) components of freshwater runoff to Glacier Bay, Alaska using a modeling approach. We find that many of the historically snow-dominated watersheds in Glacier Bay National Park and Preserve may transition towards rainfall-dominated hydrographs in a future scenario in which CO〈sub〉2〈/sub〉 emissions are not mitigated. The changes in timing and volume of freshwater entering Glacier Bay will affect bay ecology and hydrochemistry.

Description: 〈b〉Kinetic mass-transfer calculation of water isotope fractionation due to cloud microphysics in a regional meteorological model〈/b〉〈br〉 I-Chun Tsai, Wan-Yu Chen, Jen-Ping Chen, and Mao-Chang Liang〈br〉 Atmos. Chem. Phys., 19, 1753-1766, https://doi.org/10.5194/acp-19-1753-2019, 2019〈br〉 In conventional models, isotope exchange between liquid and gas phases is usually assumed to be in equilibrium, and the highly kinetic phase transformation processes inferred in clouds are yet to be fully investigated. We show that different factors controlling isotopic composition, including water vapor sources, atmospheric transport, phase transition pathways of water in clouds, and kinetic-versus-equilibrium mass transfer, contributed significantly to the variations in isotope composition.

Description: 〈b〉Robust uncertainty assessment of the spatio-temporal transferability of glacier mass and energy balance models〈/b〉〈br〉 Tobias Zolles, Fabien Maussion, Stephan Peter Galos, Wolfgang Gurgiser, and Lindsey Nicholson〈br〉 The Cryosphere, 13, 469-489, https://doi.org/10.5194/tc-13-469-2019, 2019〈br〉 A mass and energy balance model was subjected to sensitivity and uncertainty analysis on two different Alpine glaciers. The global sensitivity analysis allowed for a mass balance measurement independent assessment of the model sensitivity and functioned as a reduction of the model free parameter space. A novel approach of a multi-objective optimization estimates the uncertainty of the simulated mass balance and the energy fluxes. The final model uncertainty is up to 1300 kg m〈sup〉−3〈/sup〉 per year.