ALBERT

Beschreibung: 〈b〉A General Analytical Model for Head Response to Oscillatory Pumping in Unconfined Aquifers: Consider the Effects of Delayed Gravity Drainage and Initial Condition〈/b〉〈br〉 Ching-Sheng Huang, Ya-Hsin Tsai, Hund-Der Yeh, and Tao Yang〈br〉 Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2018-482,2018〈br〉 〈b〉Manuscript under review for HESS〈/b〉 (discussion: open, 2 comments)〈br〉 This study develops a new model describing head fluctuation induced by oscillatory pumping test (OPT) in unconfined aquifer with the effects of delayed gravity drainage (DGD) and initial condition regarding the hydraulic head prior to OPT. The DGD reduces to instantaneous gravity drainage when a dimensionless parameter exceeds 500. A pseudo-steady state model excluding initial condition causes a time shift from the actual transient model in predicting simple harmonic motion of head fluctuation.

Beschreibung: 〈b〉Direct or indirect recharge on groundwater in the middle-latitude desert of Otindag, China?〈/b〉〈br〉 Bing-Qi Zhu, Xiao-Zong Ren, and Patrick Rioual〈br〉 Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2018-395,2018〈br〉 〈b〉Manuscript under review for HESS〈/b〉 (discussion: open, 0 comments)〈br〉 Although rainfall is scarce in global deserts, the Otindag Desert is abundant of water resources (mainly groundwater). To understand the water origin in this desert, stable and radioactive isotopes and hydrochemistry of natural waters were investigated. The groundwaters in the desert were young but not of meteoric origin, i.e., out of control by the modern and palaeo- direct recharge. The tectonic control, but not the climate control, is essentially responsible for the water origin there.

Beschreibung: 〈b〉Inter-comparison of Atmospheric Trace Gas Dispersion Models: Barnett Shale Case Study〈/b〉〈br〉 Anna Karion, Thomas Lauvaux, Israel Lopez Coto, Colm Sweeney, Kimberly Mueller, Sharon Gourdji, Wayne Angevine, Zachary Barkley, Aijun Deng, Arlyn Andrews, Ariel Stein, and James Whetstone〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-736,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 In this study, we use atmospheric methane concentration observations collected during an airborne campaign to compare different model-based emissions estimates from the Barnett Shale oil and natural gas production basin in Texas, U.S.A. We find that the tracer dispersion model has a significant impact on the results, because the models differ in their simulation of vertical dispersion. Additional work is needed to evaluate and improve vertical mixing in the tracer dispersion models.

Beschreibung: 〈b〉Insights into the morphology of multicomponent organic/inorganic aerosols from molecular dynamics simulations〈/b〉〈br〉 Katerina S. Karadima, Vlasis G. Mavrantzas, and Spyros N. Pandis〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1098,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 We explore the morphologies of multicomponent nanoparticles through atomistic molecular dynamics simulations under atmospherically relevant conditions. Phase separation is predicted for almost all simulated nanoparticles either between organics and inorganics or between hydrophobic and hydrophilic constituents. Three main particle types were identified: organic islands at the surface, inorganic core-organic shell morphologies, and complex structures with hydrophobic and hydrophilic domains.

Beschreibung: 〈b〉Stochastic hydrogeology's biggest hurdles analyzed and its big blind spot〈/b〉〈br〉 Yoram Rubin, Ching-Fu Chang, Jiancong Chen, Karina Cucchi, Bradley Harken, Falk Heße, and Heather Savoy〈br〉 Hydrol. Earth Syst. Sci., 22, 5675-5695, https://doi.org/10.5194/hess-22-5675-2018, 2018〈br〉 This paper addresses questions related to the adoption of stochastic methods in hydrogeology, looking at factors such as environmental regulations, financial incentives, higher education, and the collective feedback loop involving these factors. We show that stochastic hydrogeology's blind spot is in focusing on risk while ignoring uncertainty, to the detriment of its potential clients. The imbalance between the treatments of risk and uncertainty is shown to be common to multiple disciplines.

Beschreibung: 〈b〉Monitoring Groundwater Storage Depletion Using Gravity Recovery and Climate Experiment (GRACE) Data in the Semi-Arid Catchments〈/b〉〈br〉 Nizar Abou Zaki, Ali Torabi Haghighi, Pekka M. Rossi, Mohammad J. Tourian, and Bjørn Klove〈br〉 Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2018-471,2018〈br〉 〈b〉Manuscript under review for HESS〈/b〉 (discussion: open, 0 comments)〈br〉 Groundwater is considered a main source of fresh water in semi-arid climatic zones, especially for agricultural usage. This study compares in-situ groundwater volume variation measurements with GRACE derived water mass data. The study concludes the possibility of using GRACE data to monitor groundwater depletion in catchments that lack measured data. GRACE data can here help in drawing general conclusions for integrated water resources management, and sustainable usage of this resources.

Beschreibung: 〈b〉Forcing mechanisms of the terdiurnal tide〈/b〉〈br〉 Friederike Lilienthal, Christoph Jacobi, and Christoph Geißler〈br〉 Atmos. Chem. Phys., 18, 15725-15742, https://doi.org/10.5194/acp-18-15725-2018, 2018〈br〉 The terdiurnal solar tide is an atmospheric wave, owing to the daily variation of solar heating with a period of 8 h. Here, we present model simulations of this tide and investigate the relative importance of possible forcing mechanisms because they are still under debate. These are, besides direct solar heating, nonlinear interactions between other tides and gravity wave–tide interactions. As a result, solar heating is most important and nonlinear effects partly counteract this forcing.

Beschreibung: 〈b〉Statistics on clouds and their relation to thermodynamic conditions at Ny-Ålesund using ground-based sensor synergy〈/b〉〈br〉 Tatiana Nomokonova, Kerstin Ebell, Ulrich Löhnert, Marion Maturilli, Christoph Ritter, and Ewan O'Connor〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1144,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 In this study, properties of clouds at the French–German Arctic Research station in Ny-Ålesund are related to in-cloud thermodynamic conditions. The used dataset was collected within the Arctic Amplification project with a set of active and passive remote instruments. The results are compared with a model output. A significant divergence in observations and modelling of single layer ice and mixed-phase clouds was found.

Beschreibung: 〈b〉Measurements of spectral irradiance during the solar eclipse of 21 August 2017: reassessment of the effect of solar limb darkening and of changes in total ozone〈/b〉〈br〉 Germar Bernhard and Boyan Petkov〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1048,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 Solar radiation at ultraviolet, visible, and infrared wavelengths was measured during the total solar eclipse of 21 August 2017. Data were used to study the wavelength-dependent changes of solar radiation at Earth's surface and to validate parameterizations of solar limb darkening (LD), which describes the change of the Sun's brightness between its center and its edge. The study highlights the importance of the LD effect when calculating total ozone and aerosol optical depth during an eclipse.

Beschreibung: 〈b〉Trends in air pollutants and health impacts in three Swedish cities over the past three decades〈/b〉〈br〉 Henrik Olstrup, Bertil Forsberg, Hans Orru, Mårten Spanne, Hung Nguyen, Peter Molnár, and Christer Johansson〈br〉 Atmos. Chem. Phys., 18, 15705-15723, https://doi.org/10.5194/acp-18-15705-2018, 2018〈br〉 This article analyzes the health effects caused by changes in air pollution concentrations during the period of 1990–2015 in Stockholm, Gothenburg, and Malmö: the three largest cities in Sweden. The air pollutants that have been measured and analyzed are NO〈sub〉〈i〉x〈/i〉〈/sub〉, NO〈sub〉2〈/sub〉, O〈sub〉3〈/sub〉, and PM〈sub〉10〈/sub〉. NO〈sub〉〈i〉x〈/i〉〈/sub〉 and NO〈sub〉2〈/sub〉 exhibit decreasing trends during this period, with beneficial effects on public health. An overall conclusion is that public health can largely benefit from reduced air pollution levels.

Beschreibung: 〈b〉Evaluation of soil moisture from CCAM-CABLE simulation, satellite based models estimates and satellite observations: Skukuza and Malopeni flux towers regional case study〈/b〉〈br〉 Floyd Vukosi Khosa, Mohau Jacob Mateyisi, Martina Reynita van Der Merwe, Gregor Timothy Feig, Francois Alwyn Engelbrecht, and Michael John Savage〈br〉 Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2018-546,2018〈br〉 〈b〉Manuscript under review for HESS〈/b〉 (discussion: open, 0 comments)〈br〉 The paper evaluates soil moisture outputs from three structurally distinct models against in situ data. Our goal is to find how site and region representative the model outputs are. This is a question of interest as some of the models have a specific regional focus on their inceptions. Much focus is placed on how the models capture the soil moisture signal. We find that there is agreement on seasonal patterns between the models and observations with a tolerable level of model uncertainty.

Beschreibung: 〈b〉Particle number size distribution and new particle formation under the influence of biomass burning at a high altitude background site at Mt. Yulong (3410 m), China〈/b〉〈br〉 Dongjie Shang, Min Hu, Jing Zheng, Yanhong Qin, Zhuofei Du, Mengren Li, Jingyao Fang, Jianfei Peng, Yusheng Wu, Sihua Lu, and Song Guo〈br〉 Atmos. Chem. Phys., 18, 15687-15703, https://doi.org/10.5194/acp-18-15687-2018, 2018〈br〉 Biomass burning (BB) activities have a great impact on the particle number size distribution in the upper troposphere of the Tibetan Plateau (TP), which could affect regional and global climate. We found that the cloud condensation nuclei concentration was 2–8 times higher during BB influenced periods than during clean periods on the TP. An unexpectedly low new particle formation frequency was found in clean atmosphere on the TP, due to low concentrations of anthropogenic precursors, i.e., SO〈sub〉2〈/sub〉.

Beschreibung: 〈b〉HESS Opinions: Incubating deep-learning-powered hydrologic science advances as a community〈/b〉〈br〉 Chaopeng Shen, Eric Laloy, Amin Elshorbagy, Adrian Albert, Jerad Bales, Fi-John Chang, Sangram Ganguly, Kuo-Lin Hsu, Daniel Kifer, Zheng Fang, Kuai Fang, Dongfeng Li, Xiaodong Li, and Wen-Ping Tsai〈br〉 Hydrol. Earth Syst. Sci., 22, 5639-5656, https://doi.org/10.5194/hess-22-5639-2018, 2018〈br〉 Recently, deep learning (DL) has emerged as a revolutionary tool for transforming industries and scientific disciplines. We argue that DL can offer a complementary avenue toward advancing hydrology. New methods are being developed to interpret the knowledge learned by deep networks. We argue that open competitions, integrating DL and process-based models, more data sharing, data collection from citizen scientists, and improved education will be needed to incubate advances in hydrology.

Beschreibung: 〈b〉Challenges to implementing bottom-up flood risk decision analysis frameworks: how strong are social networks of flooding professionals?〈/b〉〈br〉 James O. Knighton, Osamu Tsuda, Rebecca Elliott, and M. Todd Walter〈br〉 Hydrol. Earth Syst. Sci., 22, 5657-5673, https://doi.org/10.5194/hess-22-5657-2018, 2018〈br〉 Decision-making for flood risk management is often the collective effort of professionals within government, NGOs, private practice, and advocacy groups. Our research investigates differences among flood experts within Tompkins County, New York (USA). We explore how they differ in their perceptions of flooding risk, desired project outcomes, and knowledge. We observe substantial differences among experts, and recommend formally acknowledging these perceptions when engaging in flood management.

Beschreibung: 〈b〉Hess Opinions: Socio-economic and ecological trade-offs of flood management – benefits of a transdisciplinary approach〈/b〉〈br〉 Karl Auerswald, Peter Moyle, Simon Paul Seibert, and Juergen Geist〈br〉 Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2018-544,2018〈br〉 〈b〉Manuscript under review for HESS〈/b〉 (discussion: open, 0 comments)〈br〉 The demand for flood protection often results in the construction of more and bigger levees along rivers. We highlight that such technical solutions often result in undesired socioeconomic and ecological consequences such as increased downstream flooding risk, changes of groundwater levels and a loss of aquatic and terrestrial biodiversity. We propose a transdisciplinary approach of integrated flood management and green infrastructure instead of reliance on technical protection measures.

Beschreibung: 〈b〉Long-term measurements of ground-level ozone in Windsor, Canada – Part I. temporal variations and trends〈/b〉〈br〉 Xiaohong Xu, Tianchu Zhang, and Yushan Su〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-851,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 This study investigates temporal variations and long-term trends of O〈sub〉3〈/sub〉 (ozone) and its precursors in Windsor, Canada. During the 1996–2015 study period, NO〈sub〉x〈/sub〉 (nitric oxides) and non-methane hydrocarbon concentrations decreased by 58 % and 61 % respectively. Annual O〈sub〉3〈/sub〉 concentrations increased by 33 %, due to (1) decreased O〈sub〉3〈/sub〉 titration owing to declining NO〈sub〉x〈/sub〉 concentrations, (2) reduced local photochemical production of O〈sub〉3〈/sub〉 due to dwindling precursor emissions, (3) increased background O〈sub〉3〈/sub〉 level.

Beschreibung: 〈b〉Accounting for the effects of non-ideal minor structures on the optical properties of black carbon aerosols〈/b〉〈br〉 Shiwen Teng, Chao Liu, Martin Schnaiter, Rajan K. Chakrabarty, and Fengshan Liu〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1102,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 This study introduces a parameter 〈q〉volume variation〈/q〉 to quantify and unify five different minor structures of black carbon (BC) aerosol, and develops an empirical relation to account for their effects on BC optical properties. The generalized correction obtained can be easily used for modeling optical properties of aggregates with non-ideal structures from those of ideal ones, and to be valuable for interpretation of measurements and practical modeling that requires large amount of simulations.

Beschreibung: 〈b〉Quantification of seasonal variabilities in groundwater discharge in an extensive irrigation watershed using H, O, and Sr isotopes〈/b〉〈br〉 Takeo Yoshida, Takanori Nakano, Ki-cheol Shin, Takeo Tsuchihara, Hiroki Minakawa, Susumu Miyazu, and Tomijiro Kubota〈br〉 Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2018-551,2018〈br〉 〈b〉Manuscript under review for HESS〈/b〉 (discussion: open, 0 comments)〈br〉 Irrigation for rice paddy accounts a large part of water use in watersheds, especially in the Asian countries. Although irrigation water is lost through vaporization by plants, some portion of the irrigation water recharge local aquifers and return to the original streams through subsurface pathways. However, quantifying the amount of water returning to the stream is not an easy task. We quantified the amount of return flow using 〈q〉colors of water〈/q〉, or environmental tracers dissolved in water.

Beschreibung: 〈b〉An important mechanism of regional O〈sub〉3〈/sub〉 transport for summer smog over the Yangtze River Delta in eastern China〈/b〉〈br〉 Jun Hu, Yichen Li, Tianliang Zhao, Jane Liu, Xiao-Ming Hu, Duanyang Liu, Yongcheng Jiang, Jianming Xu, and Luyu Chang〈br〉 Atmos. Chem. Phys., 18, 16239-16251, https://doi.org/10.5194/acp-18-16239-2018, 2018〈br〉 Using observational and modeling studies, the importance of the mechanism driving regional O〈sub〉3〈/sub〉 transport in the residual layer (RL) with respect to summer smog over the Yangtze River Delta region in eastern China was revealed. This mechanism was also examined in association with diurnal change in the atmospheric boundary layer. Regional O〈sub〉3〈/sub〉 transport through the nocturnal RL is believed to have great implications for understanding urban and regional O〈sub〉3〈/sub〉 pollution in this area.

Beschreibung: 〈b〉Global IWV trends and variability in atmospheric reanalyses and GPS observations〈/b〉〈br〉 Ana C. Parracho, Olivier Bock, and Sophie Bastin〈br〉 Atmos. Chem. Phys., 18, 16213-16237, https://doi.org/10.5194/acp-18-16213-2018, 2018〈br〉 Integrated water vapour from GPS observations and two modern atmospheric reanalyses were compared for 1995–2010. Means, variability and trend signs were in general good agreement. Regions and GPS stations with poor agreement were investigated further. Representativeness issues, uncertainties in reanalyses, and inhomogeneities in GPS were evidenced. Reanalyses were compared for an extended period, and a focus on north Africa and Australia highlighted the impact of dynamics on water vapour trends.

Beschreibung: 〈b〉Submicron aerosol composition in the world's most polluted megacity: The Delhi Aerosol Supersite campaign〈/b〉〈br〉 Shahzad Gani, Sahil Bhandari, Sarah Seraj, Dongyu S. Wang, Kanan Patel, Prashant Soni, Zainab Arub, Gazala Habib, Lea Hildebrandt Ruiz, and Joshua Apte〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1066,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 Delhi experiences particulate matter concentrations that are among the highest in the world. We conducted a long-term campaign to make highly time-resolved measurements of submicron particle (PM1) chemical composition in Delhi. Our dataset illuminates key sources and atmospheric processes that impact Delhi's PM1 concentrations, with sharp differences among seasons and between day and night. In addition to local sources, Delhi's PM1 levels are amplified by regional pollution and meteorology.

Beschreibung: 〈b〉Climatology of the mesopause density using a global distribution of meteor radars〈/b〉〈br〉 Wen Yi, Xianghui Xue, Iain M. Reid, Damian J. Murphy, Chris M. Hall, Masaki Tsutsumi, Baiqi Ning, Guozhu Li, Robert A. Vincent, Jingsong Chen, Jianfei Wu, Tingdi Chen, and Xiankang Dou〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1040,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 The seasonal variations in the mesopause densities, especially with regard to its global structure are still unclear. In this study, we report the climatology of the mesopause density estimated using multiyear observations from nine meteor radars from Arctic to Antarctic latitudes. The results reveal an significant AO and SAO in mesopause density, an asymmetry between the two polar regions and evidence of intra-seasonal oscillations, perhaps associated with the ISOs of the troposphere.

Beschreibung: 〈b〉Evaluating Models' Response Of Tropical Low Clouds to SST Forcings Using CALIPSO Observations〈/b〉〈br〉 Gregory Cesana, Anthony D. Del Genio, Andrew S. Ackerman, Maxwell Kelley, Gregory Elsaesser, Ann M. Fridlind, Ye Cheng, and Mao-Sung Yao〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1008,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 The response of low-clouds to climate change (i.e., cloud feedbacks) is still pointed out as being the largest source of uncertainty in climate models. Here we use CALIPSO observations to discriminate climate models that reproduce observed interannual change of cloud fraction with SST forcings, referred to as a present-day cloud feedback. Modeling moist processes in the planetary boundary layer is crucial to produce large stratocumulus decks and realistic present-day cloud feedbacks.

Beschreibung: 〈b〉Exploring accumulation-mode-H〈sub〉2〈/sub〉SO〈sub〉4〈/sub〉 versus SO〈sub〉2〈/sub〉 stratospheric sulfate geoengineering in a sectional aerosol-chemistry-climate model〈/b〉〈br〉 Sandro Vattioni, Debra Weisenstein, David Keith, Aryeh Feinberg, Thomas Peter, and Andrea Stenke〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1070,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 This study is among the first modelling studies on stratospheric sulfate geoengineering which couple a size-resolved sectional aerosol module interactively to well-described stratospheric chemistry and radiation schemes in a global three-dimensional chemistry-climate model. We found that compared to SO〈sub〉2〈/sub〉 injection, the direct emission of aerosols results in more effective radiative forcing and that sensitivities to different injection strategies may vary for different forms of injected sulfur.

Beschreibung: 〈b〉Atmospheric radiocarbon measurements to quantify CO〈sub〉2〈/sub〉 emissions in the UK from 2014 to 2015〈/b〉〈br〉 Angelina Wenger, Katherine Pugsley, Simon O'Doherty, Matt Rigby, Alistair J. Manning, Mark Lunt, and Emily White〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1042,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 We present 〈sup〉14〈/sup〉CO〈sub〉2〈/sub〉 observations at a background site in Ireland and a tall-tower site in the UK. These data have been used to calculate the contribution of fossil fuel sources to atmospheric CO〈sub〉2〈/sub〉 mole fractions from the UK and Ireland. 〈sup〉14〈/sup〉CO〈sub〉2〈/sub〉 emissions from nuclear industry sites in the UK causes a higher uncertainty in the results compared to observations in other locations. The observed ffCO〈sub〉2〈/sub〉 at the site was not significantly different from simulated values based on the bottom-up inventory.

Beschreibung: 〈b〉Contrasting physical properties of black carbon in urban Beijing between winter and summer〈/b〉〈br〉 Dantong Liu, Rutambhara Joshi, Junfeng Wang, Chenjie Yu, James D. Allan, Hugh Coe, Michael J. Flynn, Conghui Xie, James Lee, Freya Squires, Simone Kotthaus, Sue Grimmond, Xinlei Ge, Yele Sun, and Pingqing Fu〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1142,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 This study provides source attribution and characterization of BC in the Beijing urban environment in both winter and summer. For the first time, the physically and chemically based source apportionments are compared to evaluate the primary source contribution and secondary processing of BC-containing particle. A method is proposed to isolate the BC from transportation sector and coal combustion sources.

Beschreibung: 〈b〉Diurnal variation of heavy rainfall over the Beijing-Tianjin-Hebei region: Role of aerosol cloud effect and its sensitivity to moisture〈/b〉〈br〉 Siyuan Zhou, Jing Yang, Chuanfeng Zhao, Wei-Chyung Wang, Daoyi Gong, and Peijun Shi〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1072,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 Aerosol-cloud-precipitation interaction is a challenging problem in regional climate. Our study contrasted the observed diurnal variation of heavy rainfall and associated clouds in the Beijing-Tianjin-Hebei region between polluted and clean days during 11 summers. We found the heavy rainfall under pollution has earlier starting time, earlier peak time and longer duration, and further found aerosol radiative effect and cloud effect play different roles on different stages of rainfall development.

Beschreibung: 〈b〉Climate change effects on the hydrology of the headwaters of the Tagus River: implications for the management of the Tagus–Segura transfer〈/b〉〈br〉 Francisco Pellicer-Martínez and José Miguel Martínez-Paz〈br〉 Hydrol. Earth Syst. Sci., 22, 6473-6491, https://doi.org/10.5194/hess-22-6473-2018, 2018〈br〉 Effects that climate change could have on the Tajo–Segura transfer are evaluated. To that, water resources that would be in the donor basin are estimated by hydrological modelling if the last climatic projections are accomplished. For these water resources, the exploitation of the transfer is simulated using a decision support system, providing volumes that could be transferred to the Segura basin according to its operating rule.

Beschreibung: 〈b〉Assessing the Added Value of the Intermediate Complexity Atmospheric Research Model (ICAR) for Precipitation in Complex Topography〈/b〉〈br〉 Johannes Horak, Marlis Hofer, Fabien Maussion, Ethan Gutmann, Alexander Gohm, and Mathias W. Rotach〈br〉 Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2018-612,2018〈br〉 〈b〉Manuscript under review for HESS〈/b〉 (discussion: open, 1 comment)〈br〉 This study presents the first in-depth evaluation of the Intermediate Complexity Atmospheric Research model (ICAR) for high resolution precipitation fields. The model is evaluated with data from weather stations located in the Southern Alps of New Zealand. While ICAR underestimates rainfall amounts, it clearly improves over a coarser global model and shows the potential to generate precipitation fields for long-term impact studies focused on the local impact of a changing global climate.

Beschreibung: 〈b〉Numerical study on the response of the largest lake in China to climate change〈/b〉〈br〉 Dongsheng Su, Xiuqing Hu, Lijuan Wen, Lin Zhao, Zhaoguo Li, Juan Du, and Georgiy Kirillin〈br〉 Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2018-583,2018〈br〉 〈b〉Manuscript under review for HESS〈/b〉 (discussion: open, 0 comments)〈br〉 In this study, Freshwater Lake Model simulation results, verified by satellite and buoy observation data, were used to quantify the recent climate change effects on the thermal regime of the largest lake in China. Results indicate that the FLake model can nicely reproduce the lake thermal pattern. The lake surface is warming while the lake bottom has no significant trend. The climate change also caused an earlier ice off and later ice on, lead to an obvious change on the energy balance of lake.

Beschreibung: 〈b〉Climate Impact of Finnish Air Pollutants and Greenhouse Gases using Multiple Emission Metrics〈/b〉〈br〉 Kaarle J. Kupiainen, Borgar Aamaas, Mikko Savolahti, Niko Karvosenoja, and Ville-Veikko Paunu〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1086,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 We estimate global and Arctic temperature impacts of air pollutant and greenhouse gas emissions from a Northern European country, Finland, using different climate metrics. This is an example of how the climate impact of emissions from small countries and sources can be evaluated, which is challenging with climate models. We find that the CO2 emissions have the most significant climate impact that increases with longer time horizons. In the short term, emissions of CH4 and BC are also important.

Beschreibung: 〈b〉Contributions to the explosive growth of PM〈sub〉2.5〈/sub〉 mass due to aerosol–radiation feedback and decrease in turbulent diffusion during a red alert heavy haze in Beijing–Tianjin–Hebei, China〈/b〉〈br〉 Hong Wang, Yue Peng, Xiaoye Zhang, Hongli Liu, Meng Zhang, Huizheng Che, Yanli Cheng, and Yu Zheng〈br〉 Atmos. Chem. Phys., 18, 17717-17733, https://doi.org/10.5194/acp-18-17717-2018, 2018〈br〉 The explosive growth (EG) of PM〈sub〉2.5〈/sub〉 resulted in a PM〈sub〉2.5〈/sub〉 maximum, which was generally underestimated by atmospheric chemical models due to the deficient description of the local 〈q〉turbulence intermittent〈/q〉. The aerosol–radiation feedback (AF) and decrease in turbulence diffusion (DTD) may reduce the underestimation of PM〈sub〉2.5〈/sub〉 EG by 20–25% and 14–20%, respectively. The modeled EG stage PM〈sub〉2.5〈/sub〉 error was decreased from −40 to −51% to −11 to 2% by the combined effects of AF and DTD in Jing–Jin–Ji.

Beschreibung: 〈b〉Compliance and port air quality features of ship fuel switching regulation: by a field observation SEISO-Bohai〈/b〉〈br〉 Yanni Zhang, Fanyuan Deng, Hanyang Man, Mingliang Fu, Zhaofeng Lv, Qian Xiao, Xinxin Jin, Shuai Liu, Kebin He, and Huan Liu〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1233,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 In order to evaluate the impacts of switching fuel in China, a measurement campaign was conducted before and after the implementation of regulation at port. We find that switching to low sulphur fuels results in a SO〈sub〉2〈/sub〉 reduction by 70 % in ambient air. Four ship plumes among sixteen measured ship plumes indicate the usage of high SF fuel. Vanadium in PM〈sub〉2.5〈/sub〉 decreases by 97.1 % from 309.9 ng m〈sup〉−3〈/sup〉 to 9.1 ng m〈sup〉−3〈/sup〉 after. We also present a method to indicate sulphur content of fuel by measuring ship plume.

Beschreibung: 〈b〉Angular scattering of the Sahara dust aerosol〈/b〉〈br〉 Helmuth Horvath, Lucas Alados Arboledas, and Francisco José Olmo Reyes〈br〉 Atmos. Chem. Phys., 18, 17735-17744, https://doi.org/10.5194/acp-18-17735-2018, 2018〈br〉 Scattering properties of the atmospheric aerosol were measured in the Sierra Nevada with a custom-built polar nephelometer; scattering coefficient, phase function, asymmetry parameter, and backscattered fraction have been derived. Phase function and asymmetry parameter of the Sahara aerosol differ significantly from the usual aerosol. The asymmetry parameter permits distinction between Sahara and non-Sahara aerosol. Gobi desert aerosol scattering is similar to that of the Sahara.

Beschreibung: 〈b〉A 17 year climatology of the macrophysical properties of convection in Darwin〈/b〉〈br〉 Robert C. Jackson, Scott M. Collis, Valentin Louf, Alain Protat, and Leon Majewski〈br〉 Atmos. Chem. Phys., 18, 17687-17704, https://doi.org/10.5194/acp-18-17687-2018, 2018〈br〉 This paper looks at a 17 year database of echo top heights of thunderstorms in Darwin retrieved by CPOL. We find that the echo top heights are generally bimodal, corresponding to cumulus congestus and deep convection, and show a greater bimodality during an inactive MJO. Furthermore, we find that convective cell areas are larger in break conditions compared to monsoon conditions, but only during MJO-inactive conditions.

Beschreibung: 〈b〉Large contrast in the vertical distribution of aerosol optical properties and radiative effects across the Indo-Gangetic Plain during the SWAAMI–RAWEX campaign〈/b〉〈br〉 Aditya Vaishya, Surendran Nair Suresh Babu, Venugopalan Jayachandran, Mukunda M. Gogoi, Naduparambil Bharathan Lakshmi, Krishnaswamy Krishna Moorthy, and Sreedharan Krishnakumari Satheesh〈br〉 Atmos. Chem. Phys., 18, 17669-17685, https://doi.org/10.5194/acp-18-17669-2018, 2018〈br〉 Aircraft-based measurements of vertical profiles of aerosol properties, across the Indo-Gangetic Plain (IGP), prior to onset of the Indian summer monsoon reveal a highly absorbing aerosol system over the IGP. Aerosols over the west IGP are mostly natural, larger in size and scatter light efficiently. Those over the central and eastern IGP are mostly anthropogenic in origin, smaller in size and absorb more light. Elevated absorbing aerosol layers may modulate regional precipitation patterns.

Beschreibung: 〈b〉Marine boundary layer aerosol in the eastern North Atlantic: seasonal variations and key controlling processes〈/b〉〈br〉 Guangjie Zheng, Yang Wang, Allison C. Aiken, Francesca Gallo, Michael P. Jensen, Pavlos Kollias, Chongai Kuang, Edward Luke, Stephen Springston, Janek Uin, Robert Wood, and Jian Wang〈br〉 Atmos. Chem. Phys., 18, 17615-17635, https://doi.org/10.5194/acp-18-17615-2018, 2018〈br〉 Here, we elucidate the key processes that drive marine boundary layer (MBL) aerosol size distribution in the eastern North Atlantic (ENA) using long-term measurements. The governing equations of particle concentration are established for different modes. Particles entrained from the free troposphere represent the major source of MBL cloud condensation nuclei (CCN), contributing both directly to CCN population and indirectly by supplying Aitken-mode particles that grow to CCN in the MBL.

Beschreibung: 〈b〉Vertical aerosol distribution in the Southern hemispheric Midlatitudes as observed with lidar at Punta Arenas, Chile (53.2° S and 70.9° W) during ALPACA〈/b〉〈br〉 Andreas Foth, Thomas Kanitz, Ronny Engelmann, Holger Baars, Martin Radenz, Patric Seifert, Boris Barja, Heike Kalesse, and Albert Ansmann〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1124,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 In this study, we present the vertical aerosol distribution in the pristine region of the southern tip of South America determined by ground-based and spaceborne lidar observation. Most aerosol load is contained within the planetary boundary layer up to about 1200 m. The free troposphere is characterized by a very low aerosol concentration but a frequent occurrence of clouds. Lofted aerosol layers were rarely observed and, when present, were characterized by very low optical thicknesses.

Beschreibung: 〈b〉Comparing ERA-Interim clouds with satellite observations using a simplified satellite simulator〈/b〉〈br〉 Martin Stengel, Cornelia Schlundt, Stefan Stapelberg, Oliver Sus, Salomon Eliasson, Ulrika Willén, and Jan Fokke Meirink〈br〉 Atmos. Chem. Phys., 18, 17601-17614, https://doi.org/10.5194/acp-18-17601-2018, 2018〈br〉 We present a new approach to evaluate ERA-Interim reanalysis clouds using satellite observations. A simplified satellite simulator was developed that uses reanalysis fields to emulate clouds as they would have been seen by those satellite sensors which were used to compose Cloud_cci observational cloud datasets. Our study facilitates an adequate evaluation of modelled ERA-Interim clouds using observational datasets, also taking into account systematic uncertainties in the observations.

Beschreibung: 〈b〉Estimating the saturation vapor pressures of isoprene oxidation products C〈sub〉5〈/sub〉H〈sub〉12〈/sub〉O〈sub〉6〈/sub〉 and C〈sub〉5〈/sub〉H〈sub〉10〈/sub〉O〈sub〉6〈/sub〉 using COSMO-RS〈/b〉〈br〉 Theo Kurtén, Noora Hyttinen, Emma Louise D'Ambro, Joel Thornton, and Nønne Lyng Prisle〈br〉 Atmos. Chem. Phys., 18, 17589-17600, https://doi.org/10.5194/acp-18-17589-2018, 2018〈br〉 We use COSMO-RS to compute saturation vapor pressures for two products of isoprene photo-oxidation and compare the results to measurements. COSMO-RS is an attractive option for calculating properties of molecules, as it is based on quantum mechanics and requires few fitting parameters. However, we show that the default implementation of this method suffers from errors related to both conformational sampling and intramolecular hydrogen bonding. We propose solutions to these problems.

Beschreibung: 〈b〉Unexpected vertical structure of the Saharan Air Layer and giant dust particles during AER-D〈/b〉〈br〉 Franco Marenco, Claire Ryder, Victor Estellés, Debbie O'Sullivan, Jennifer Brooke, Luke Orgill, Gary Lloyd, and Martin Gallagher〈br〉 Atmos. Chem. Phys., 18, 17655-17668, https://doi.org/10.5194/acp-18-17655-2018, 2018〈br〉 The AER-D airborne campaign characterised Saharan dust in the eastern Atlantic. We report an instance of unusual vertical structure of the Saharan Air Layer during an intense event, showing a large radiative impact and correlated with anomalous lightning activity. Moreover, we report a significant presence of giant dust particles. This is important because most models would miss the giant particles. Our findings may change the way we represent dust transport and deposition in the Atlantic.

Beschreibung: 〈b〉A numerical process study on the rapid transport of stratospheric air down to the surface over western North America and the Tibetan Plateau〈/b〉〈br〉 Bojan Škerlak, Stephan Pfahl, Michael Sprenger, and Heini Wernli〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1252,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 Upper-level fronts are often associated with the rapid transport of stratospheric air to the lower troposphere, there leading to significantly enhanced ozone concentrations. This paper considers the multi-scale nature that is needed to bring stratospheric air down to the surface. The final transport step to the surface can be related to frontal zones and the associated vertical winds, or to to near-horizontal tracer transport followed by entrainment into a growing planetary boundary layer.

Beschreibung: 〈b〉Anthropogenic and natural drivers of a strong winter urban heat island in a typical Arctic city〈/b〉〈br〉 Mikhail Varentsov, Pavel Konstantinov, Alexander Baklanov, Igor Esau, Victoria Miles, and Richard Davy〈br〉 Atmos. Chem. Phys., 18, 17573-17587, https://doi.org/10.5194/acp-18-17573-2018, 2018〈br〉 This study reports on the urban heat island (UHI) in a typical Arctic city in winter. Using in situ observations, remote sensing data and modeling, we show that the urban temperature anomaly reaches up to 11  K with a mean value of 1.9 K. At least 50 % of this anomaly is caused by the UHI effect, driven mostly by heating. The rest is created by natural microclimatic variability over the hilly terrain. This is a strong argument in support of energy efficiency measures in the Arctic cities.

Beschreibung: 〈b〉Comprehensive organic emission profiles for gasoline, diesel, and gas-turbine engines including intermediate and semi-volatile organic compound emissions〈/b〉〈br〉 Quanyang Lu, Yunliang Zhao, and Allen L. Robinson〈br〉 Atmos. Chem. Phys., 18, 17637-17654, https://doi.org/10.5194/acp-18-17637-2018, 2018〈br〉 This work combines previously published data to illustrate the mechanics of emission from internal combustion engine sources. Engine exhaust can be decomposed into combustion "by-product", "unburned fuel" and "oil" modes. Intermediate and semi-volatile organic compounds are included to create comprehensive model-ready organic emission profiles. Gasoline and gas-turbine engine emissions are enriched in intermediate volatile organic compounds relative to unburned fuel.

Beschreibung: 〈b〉Mechanism of ozone loss under enhanced water vapour conditions in the mid-latitude lower stratosphere in summer〈/b〉〈br〉 Sabine Robrecht, Bärbel Vogel, Jens-Uwe Grooß, Karen Rosenlof, Troy Thornberry, Andrew Rollins, Martina Krämer, Lance Christensen, and Rolf Müller〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1193,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 The potential destruction of stratospheric ozone in the mid-latitudes has been discussed recently. We analysed this ozone loss mechanism and its sensitivities. In a certain temperature range, we found a threshold in water vapour, which has to be exceeded for ozone loss to occur. We show the dependence of this water vapour threshold on temperature, sulphate content and air composition. This study provides a basis to estimate the impact of potential sulphate geoengineering on stratospheric ozone.

Beschreibung: 〈b〉Quantifying uncertainty from aerosol and atmospheric parameters and their impact on climate sensitivity〈/b〉〈br〉 Christopher G. Fletcher, Ben Kravitz, and Bakr Badawy〈br〉 Atmos. Chem. Phys., 18, 17529-17543, https://doi.org/10.5194/acp-18-17529-2018, 2018〈br〉 The most important number for future climate projections is Earth's climate sensitivity (CS), or how much warming will result from increased carbon dioxide. We cannot know the true CS, and estimates of CS from climate models have a wide range. This study identifies the major factors that control this range, and we show that the choice of methods used in creating a climate model are three times more important than fine-tuning the details of the model after it is created.

Beschreibung: 〈b〉Seasonal differences in formation processes of oxidized organic aerosol near Houston, TX〈/b〉〈br〉 Qili Dai, Benjamin C. Schulze, Xiaohui Bi, Alexander A. T. Bui, Fangzhou Guo, Henry W. Wallance, Nancy P. Sanchez, James H. Flynn, Barry L. Lefer, Yinchang Feng, and Robert J. Griffin〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1269,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 The formation processes of secondary organic aerosol remain to be fully understood. We reported the measurement data from two field campaigns within Houston, TX to investigate the effects of aqueous-phase chemistry and photochemistry in processing oxygenated organic aerosol (OOA) in winter and summer. Both photochemistry and aqueous-phase processing appear to facilitate more oxidized OOA formation. The processing mechanism of less oxidized OOA apparently depended on relative humidity.

Beschreibung: 〈b〉The impact of mineral dust on cloud formation during the Saharan dust event in April 2014 over Europe〈/b〉〈br〉 Michael Weger, Bernd Heinold, Christa Engler, Ulrich Schumann, Axel Seifert, Romy Fößig, Christiane Voigt, Holger Baars, Ulrich Blahak, Stephan Borrmann, Corinna Hoose, Stefan Kaufmann, Martina Krämer, Patric Seifert, Fabian Senf, Johannes Schneider, and Ina Tegen〈br〉 Atmos. Chem. Phys., 18, 17545-17572, https://doi.org/10.5194/acp-18-17545-2018, 2018〈br〉 The impact of desert dust on cloud formation is investigated for a major Saharan dust event over Europe by interactive regional dust modeling. Dust particles are very efficient ice-nucleating particles promoting the formation of ice crystals in clouds. The simulations show that the observed extensive cirrus development was likely related to the above-average dust load. The interactive dust–cloud feedback in the model significantly improves the agreement with aircraft and satellite observations.

Beschreibung: 〈b〉Measurements of I/SVOCs in biomass-burning smoke using solid-phase extraction disks and two-dimensional gas chromatography〈/b〉〈br〉 Lindsay E. Hatch, Albert Rivas-Ubach, Coty N. Jen, Mary Lipton, Allen H. Goldstein, and Kelley C. Barsanti〈br〉 Atmos. Chem. Phys., 18, 17801-17817, https://doi.org/10.5194/acp-18-17801-2018, 2018〈br〉 We demonstrate the use of solid-phase extraction (SPE) disks for the untargeted analysis of gas-phase intermediate volatility and semi-volatile organic compounds emitted from biomass burning. SPE and Teflon filter samples collected from laboratory fires were analyzed by two-dimensional gas chromatography, with distinct differences in the observed chromatographic profiles as a function of fuel type. Fuel-dependent emissions and volatility differences among benzenediol isomers were captured.

Beschreibung: 〈b〉Evaluating the performance of two surface layer schemes for the momentum and heat exchange processes during severe haze pollution in Jing-Jin-Ji in eastern China〈/b〉〈br〉 Yue Peng, Hong Wang, Yubin Li, Changwei Liu, Tianliang Zhao, Xiaoye Zhang, Zhiqiu Gao, Tong Jiang, Huizheng Che, and Meng Zhang〈br〉 Atmos. Chem. Phys., 18, 17421-17435, https://doi.org/10.5194/acp-18-17421-2018, 2018〈br〉 Two surface layer schemes are evaluated in eastern China based on observational flux data. The results indicate that the Li scheme better describes regional atmosphere stratification compared with the MM5 scheme, especially for the transition stage from unstable to stable atmosphere conditions, corresponding to PM〈sub〉2.5〈/sub〉 accumulation. Our research suggests the potential improved possibilities for severe haze prediction in eastern China by coupling Li online into atmosphere chemical models.

Beschreibung: 〈b〉Experimental and model assessment of PM〈sub〉2.5〈/sub〉 and BC emissions and concentrations in a Brazilian city – the Curitiba case study〈/b〉〈br〉 Lars Gidhagen, Patricia Krecl, Admir Créso Targino, Gabriela Polezer, Ricardo H. M. Godoi, Francisco Castelhano, Erika Felix, Yago Alonso Cipoli, Francisco Malucelli, Alyson Wolf, Marcelo Alonso, David Segersson, Jorge Humberto Amorim, and Francisco Mendonça〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1094,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 Exposure to atmospheric fine particles constitutes a threat to health for urban citizens. Data on airborne fine particle emissions and concentrations in cities are valuable to traffic and air quality managers, urban planners, health practitioners, as well as to legislators and decision makers, however this type of data are lacking in most Brazilian cities. The integrated and comparatively rapid methodology described can be applied to other cities requiring a diagnostic air pollution assessment.

Beschreibung: 〈b〉Photooxidants from Brown Carbon and Other Chromophores in Illuminated Particle Extracts〈/b〉〈br〉 Richie Kaur, Jacqueline R. Labins, Scarlett S. Helbock, Wenqing Jiang, Keith Bein, Qi Zhang, and Cort Anastasio〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1258,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 We measured hydroxyl radical (〈sup〉•〈/sup〉OH), singlet oxygen (〈sup〉1〈/sup〉O〈sub〉2〈/sub〉*) and organic triplets (〈sup〉3〈/sup〉C*) in illuminated aqueous particle extracts. After measuring the impact of dilution on oxidant concentrations, we extrapolated our results to predict them in ambient particles – 〈sup〉1〈/sup〉O〈sub〉2〈/sub〉* and 〈sup〉3〈/sup〉C* concentrations appear to be greatly enhanced, while 〈sup〉•〈/sup〉OH appears largely unchanged. Two of these oxidants (〈sup〉1〈/sup〉O〈sub〉2〈/sub〉*, 〈sup〉3〈/sup〉C*) are not yet included in atmospheric models, and our results make it possible to include them in the future.

Beschreibung: 〈b〉H〈sub〉2〈/sub〉SO〈sub〉4〈/sub〉–H〈sub〉2〈/sub〉O–NH〈sub〉3〈/sub〉 ternary ion-mediated nucleation (TIMN): kinetic-based model and comparison with CLOUD measurements〈/b〉〈br〉 Fangqun Yu, Alexey B. Nadykto, Jason Herb, Gan Luo, Kirill M. Nazarenko, and Lyudmila A. Uvarova〈br〉 Atmos. Chem. Phys., 18, 17451-17474, https://doi.org/10.5194/acp-18-17451-2018, 2018〈br〉 Aerosol nucleation exerts important influences on the climate, hydrological cycle, and air quality. We have developed an advanced physical–chemical model that describes ion-induced and neutral nucleation involving ammonia, sulfuric acid, and water vapors. The model is shown to reproduce laboratory measurements taken under a wide range of conditions, offers physiochemical insights into the ternary nucleation process, and provides an accurate approach to calculate ternary rate in the atmosphere.

Beschreibung: 〈b〉Caffeine vs. carbamazepine as indicators of wastewater pollution in a karst aquifer〈/b〉〈br〉 Noam Zach Dvory, Yakov Livshitz, Michael Kuznetsov, Eilon Adar, Guy Gasser, Irena Pankratov, Ovadia Lev, and Alexander Yakirevich〈br〉 Hydrol. Earth Syst. Sci., 22, 6371-6381, https://doi.org/10.5194/hess-22-6371-2018, 2018〈br〉 This research is paramount given the significance of karst aquifers as essential drinking water sources. While CBZ is considered conservative, CAF is subject to sorption and degradation, and therefore each of these two pollutants can be considered effective tracers for specific assessment of aquifer contamination. The model presented in this paper shows how each of the mentioned contaminants could serve as a better tool for aquifer contamination characterization and its treatment.

Beschreibung: 〈b〉Large-scale ERT surveys for investigating shallow regolith properties and architecture〈/b〉〈br〉 Laurent Gourdol, Rémi Clément, Jérôme Juilleret, Laurent Pfister, and Christophe Hissler〈br〉 Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2018-519,2018〈br〉 〈b〉Manuscript under review for HESS〈/b〉 (discussion: open, 0 comments)〈br〉 Electrical Resistivity Tomography (ERT) is a remarkable tool for characterizing the geometry and properties of the regolith. However, its use for large horizontal surveys remains cumbersome to characterize shallow subsurface structures due to the requirement of small electrode spacing increments. Here we propose a new approach to overcome this limitation. We demonstrate that our protocol significantly improves the accuracy of ERT profiles when using large electrode spacing increments.

Beschreibung: 〈b〉The impact of multi-species surface chemical observation assimilation on air quality forecasts in China〈/b〉〈br〉 Zhen Peng, Lili Lei, Zhiquan Liu, Jianning Sun, Aijun Ding, Junmei Ban, Dan Chen, Xingxia Kou, and Kekuan Chu〈br〉 Atmos. Chem. Phys., 18, 17387-17404, https://doi.org/10.5194/acp-18-17387-2018, 2018〈br〉 An EnKF system was developed to simultaneously assimilate multiple surface measurements, including PM〈sub〉10〈/sub〉, PM〈sub〉2.5〈/sub〉, SO〈sub〉2〈/sub〉, NO〈sub〉2〈/sub〉, O〈sub〉3〈/sub〉, and CO, via the joint adjustment of ICs and source emissions. Large improvements were achieved in the first 24 h forecast for PM〈sub〉2.5〈/sub〉, PM〈sub〉10〈/sub〉, SO〈sub〉2〈/sub〉, and CO during an extreme haze episode that occurred in early October 2014 over the North China Plain, but no improvements were achieved for NO〈sub〉2〈/sub〉 and O〈sub〉3〈/sub〉.

Beschreibung: 〈b〉Arctic ice clouds over northern Sweden: microphysical properties studied with the Balloon-borne Ice Cloud particle Imager B-ICI〈/b〉〈br〉 Veronika Wolf, Thomas Kuhn, Mathias Milz, Peter Voelger, Martina Krämer, and Christian Rolf〈br〉 Atmos. Chem. Phys., 18, 17371-17386, https://doi.org/10.5194/acp-18-17371-2018, 2018〈br〉 Balloon-borne measurements of microphysical properties of Arctic ice clouds have been performed with an in situ particle imager and been analyzed for the first time with respect to how the ice particles have formed. Ice particle size, shape and number show large variations from cloud to cloud, which cannot be explained with local conditions only, and rather depend on conditions at cloud formation. Taking this into account when parametrizing ice cloud properties may improve retrievals and models.

Beschreibung: 〈b〉Computation and analysis of atmospheric carbon dioxide annual mean growth rates from satellite observations during 2003–2016〈/b〉〈br〉 Michael Buchwitz, Maximilian Reuter, Oliver Schneising, Stefan Noël, Bettina Gier, Heinrich Bovensmann, John P. Burrows, Hartmut Boesch, Jasdeep Anand, Robert J. Parker, Peter Somkuti, Rob G. Detmers, Otto P. Hasekamp, Ilse Aben, André Butz, Akihiko Kuze, Hiroshi Suto, Yukio Yoshida, David Crisp, and Christopher O'Dell〈br〉 Atmos. Chem. Phys., 18, 17355-17370, https://doi.org/10.5194/acp-18-17355-2018, 2018〈br〉 We present a new satellite data set of column-averaged mixing ratios of carbon dioxide (CO〈sub〉2〈/sub〉), which covers the time period 2003 to 2016. We used this data set to compute annual mean atmospheric CO〈sub〉2〈/sub〉 growth rates. We show that the growth rate is highest during 2015 and 2016 despite nearly constant CO〈sub〉2〈/sub〉 emissions from fossil fuel burning in recent years. The high growth rates are attributed to year 2015-2016 El Nino episodes. We present correlations with fossil fuel emissions and ENSO indices.

Beschreibung: 〈b〉Attributing differences in the fate of lateral boundary ozone in AQMEII3 models to physical process representations〈/b〉〈br〉 Peng Liu, Christian Hogrefe, Ulas Im, Jesper H. Christensen, Johannes Bieser, Uarporn Nopmongcol, Greg Yarwood, Rohit Mathur, Shawn Roselle, and Tanya Spero〈br〉 Atmos. Chem. Phys., 18, 17157-17175, https://doi.org/10.5194/acp-18-17157-2018, 2018〈br〉 This study represents an intercomparison of four regional-scale air quality simulations in order to understand the model similarities and differences in estimating the impact of ozone imported from outside of the US on the surface ozone within the US at process level. Vertical turbulent mixing stands out as a primary contributor to the model differences in inert tracers.

Beschreibung: 〈b〉From ERA-Interim to ERA5: considerable impact of ECMWF's next-generation reanalysis on Lagrangian transport simulations〈/b〉〈br〉 Lars Hoffmann, Gebhard Günther, Dan Li, Olaf Stein, Xue Wu, Sabine Griessbach, Yi Heng, Paul Konopka, Rolf Müller, Bärbel Vogel, and Jonathon S. Wright〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1199,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 ECMWF's new reanalysis ERA5 provides better resolution and improved representations of meso- and synoptic scale features of the atmosphere. Here, we assessed the impact of this challenging new data set on Lagrangian trajectory calculations for the free troposphere and stratosphere. Key findings are significant transport deviations between ERA5 and ERA-Interim products as well as significantly improved conservation of potential temperature in the stratosphere for ERA5.

Beschreibung: 〈b〉Trends in Global Tropospheric Ozone Inferred from a Composite Record of TOMS/OMI/MLS/OMPS Satellite Measurements and the MERRA-2 GMI Simulation〈/b〉〈br〉 Jerry R. Ziemke, Luke D. Oman, Sarah A. Strode, Anne R. Douglass, Mark A. Olsen, Richard D. McPeters, Pawan K. Bhartia, Lucien Froidevaux, Gordon J. Labow, Jacquie C. Witte, Anne M. Thompson, David P. Haffner, Natalya A. Kramarova, Stacey M. Frith, Liang-Kang Huang, Glen R. Jaross, Colin J. Seftor, Mathew T. Deland, and Steven L. Taylor〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-716,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 Both a 38-year merged satellite record of tropospheric ozone from TOMS/OMI/MLS/OMPS and a MERRA-2 GMI model simulation show large increases of 6–7 Dobson Units from the Near East to India/East Asia and eastward over the Pacific. These increases in tropospheric ozone are attributed to increases in pollution over the region over the last several decades. Secondary 38-year increases of 4–5 Dobson Units with both GMI model and satellite measurements occur over central Africa/tropical Atlantic.

Beschreibung: 〈b〉In situ measurements of cloud microphysical and aerosol properties during the break-up of stratocumulus cloud layers in cold air outbreaks over the North Atlantic〈/b〉〈br〉 Gary Lloyd, Thomas W. Choularton, Keith N. Bower, Martin W. Gallagher, Jonathan Crosier, Sebastian O'Shea, Steven J. Abel, Stuart Fox, Richard Cotton, and Ian A. Boutle〈br〉 Atmos. Chem. Phys., 18, 17191-17206, https://doi.org/10.5194/acp-18-17191-2018, 2018〈br〉 The work deals with cold weather outbreaks at high latitudes that often bring severe weather such as heavy snow, lightning and high winds but are poorly forecast by weather models. Here we made measurements of these events and the clouds associated with them using a research aircraft. We found that the properties of these clouds were often very different to what the models predicted, and these results can potentially be used to bring significant improvement to the forecasting of these events.

Beschreibung: 〈b〉Two years of online measurement of fine particulate nitrate in the western Yangtze River Delta: influences of thermodynamics and N〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 hydrolysis〈/b〉〈br〉 Peng Sun, Wei Nie, Xuguang Chi, Yuning Xie, Xin Huang, Zheng Xu, Ximeng Qi, Zhengning Xu, Lei Wang, Tianyi Wang, Qi Zhang, and Aijun Ding〈br〉 Atmos. Chem. Phys., 18, 17177-17190, https://doi.org/10.5194/acp-18-17177-2018, 2018〈br〉 A total of 2 years of online measurement of particulate nitrate was conducted at the SORPES station in the western Yangtze River Delta, eastern China. Nitrate was found to be the major driver of haze pollution and behaved differently in different seasons. In summer, thermodynamic equilibrium and photochemical processes controlled nitrate formation. In winter, N〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 hydrolysis was demonstrated to be a major contributor to the nitrate episodes.

Beschreibung: 〈b〉High Time Resolution Source Apportionment of PM〈sub〉2.5〈/sub〉 in Beijing with Multiple Models〈/b〉〈br〉 Yue Liu, Mei Zheng, Mingyuan Yu, Xuhui Cai, Huiyun Du, Jie Li, Tian Zhou, Caiqing Yan, Xuesong Wang, Zongbo Shi, Roy M. Harrison, Qiang Zhang, and Kebin He〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1234,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 This study is part of the UK-China APHH campaign. To identify both source types and source regions at the same time, this study developed a combined method including receptor model, footprint model, and air quality model for the first time to investigate sources of PM〈sub〉2.5〈/sub〉 during haze episodes in Beijing. It is an expansion of the application of receptor model and is helpful for formulating effective control strategies to improve air quality in this region.

Beschreibung: 〈b〉The influence of spatiality on shipping emissions, air quality and potential human exposure in Yangtze River Delta/Shanghai, China〈/b〉〈br〉 Junlan Feng, Yan Zhang, Shanshan Li, Jingbo Mao, Allison P. Patton, Yuyan Zhou, Weichun Ma, Cong Liu, Haidong Kan, Cheng Huang, Jingyu An, Li Li, Yin Shen, Qingyan Fu, Xinning Wang, Juan Liu, Shuxiao Wang, Dian Ding, Jie Cheng, Wangqi Ge, Hong Zhu, and Katherine Walker〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1163,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 This study aims to estimate the emissions, air quality, and population exposure impacts of shipping in 2015 prior to the implementation of the DECAs. It showed that ship emissions within 12 nautical miles (NM) could account for over 55 % of the ships' impact on air pollution in the YRD in summer season. Ships entering the Yangtze River and other inland waterways of Shanghai contribute 40–80 % of the ship related air pollution and population exposure，which have an important implications for policy.

Beschreibung: 〈b〉Characterization of urban amine-containing particles in Southwestern China: seasonal variation, source, and processing〈/b〉〈br〉 Yang Chen, Mi Tian, Rujin Huang, Guangming Shi, Huanbo Wang, Chao Peng, Junji Cao, Qiyuan Wang, Shumin Zhang, Dongmei Guo, Leiming Zhang, and Fumo Yang〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1119,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 Amine-containing particles were characterized in an urban area of Chongqing during both summer and winter using a single particle aerosol mass spectrometer (SPAMS). Amines were observed to internally mix with elemental carbon (EC), organic carbon (OC), sulfate, and nitrate. Diethylamine (DEA) was the most abundant in both number and peak area among amine-containing particles. vegetation and traffic were the primary sources of particulate amines.

Beschreibung: 〈b〉Direct radiative effect of dust-pollution interactions〈/b〉〈br〉 Klaus Klingmüller, Jos Lelieveld, Vlassis A. Karydis, and Georgiy L. Stenchikov〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1104,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 Within the atmosphere desert dust and anthropogenic pollution are mixed and interact which affects the abundance and optical properties of the particulate matter. This results in an anthropogenic climate forcing associated with mineral dust notwithstanding the natural origin of most aeolian dust. With a global chemistry-climate model we estimate this forcing to represent a considerable fraction of the total dust forcing.

Beschreibung: 〈b〉The relative impact of cloud condensation nuclei and ice nucleating particle concentrations on phase partitioning in Arctic mixed-phase stratocumulus clouds〈/b〉〈br〉 Amy Solomon, Gijs de Boer, Jessie M. Creamean, Allison McComiskey, Matthew D. Shupe, Maximilian Maahn, and Christopher Cox〈br〉 Atmos. Chem. Phys., 18, 17047-17059, https://doi.org/10.5194/acp-18-17047-2018, 2018〈br〉 The results of this study indicate that perturbations in ice nucleating particles (INPs) dominate over cloud condensation nuclei (CCN) perturbations in Arctic mixed-phase stratocumulus; i.e., an equivalent fractional decrease in CCN and INPs results in an increase in the cloud-top longwave cooling rate, even though the droplet effective radius increases and the cloud emissivity decreases. In addition, cloud-processing causes layering of aerosols with increased concentrations of CCN at cloud top.

Beschreibung: 〈b〉Soil-atmosphere exchange of carbonyl sulfide in Mediterranean citrus orchard〈/b〉〈br〉 Fulin Yang, Rafat Qubaja, Fyodor Tatarinov, Rafael Stern, and Dan Yakir〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1206,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 The contribution of soil carbonyl sulfate (COS) flux is probably the major limitation to the application of COS as a novel tracer of canopy scale CO〈sub〉2〈/sub〉 uptake. We provide new, field-based high-resolution results on the spatial and temporal variations of soil COS flux, its relationships to CO〈sub〉2〈/sub〉 exchange, and the key factors influencing it. We furthermore provide the only study, to our knowledge, that validate the increasingly used surface dynamic chamber approach with soil concentration profiles.

Beschreibung: 〈b〉Application of a hygroscopicity tandem differential mobility analyzer for characterizing PM emissions in exhaust plumes from an aircraft engine burning conventional and alternative fuels〈/b〉〈br〉 Max B. Trueblood, Prem Lobo, Donald E. Hagen, Steven C. Achterberg, Wenyan Liu, and Philip D. Whitefield〈br〉 Atmos. Chem. Phys., 18, 17029-17045, https://doi.org/10.5194/acp-18-17029-2018, 2018〈br〉 We report detailed lab-based performance evaluation of a robust hygroscopic tandem differential mobility analyzer (HTDMA), in terms of hygroscopic properties such as growth factor (GF) and the hygroscopicity parameter (κ). The HTDMA was deployed during a field campaign to measure the hygroscopic properties of aircraft engine PM emissions in the exhaust plumes from a CFM56-2C1 engine burning regular jet fuel, alternative fuels, and blends.

Beschreibung: 〈b〉Elucidating real-world vehicle emission factors from mobile measurements over a large metropolitan region: a focus on isocyanic acid, hydrogen cyanide, and black carbon〈/b〉〈br〉 Sumi N. Wren, John Liggio, Yuemei Han, Katherine Hayden, Gang Lu, Cris M. Mihele, Richard L. Mittermeier, Craig Stroud, Jeremy J. B. Wentzell, and Jeffrey R. Brook〈br〉 Atmos. Chem. Phys., 18, 16979-17001, https://doi.org/10.5194/acp-18-16979-2018, 2018〈br〉 We made measurements from a mobile laboratory across a large urban area and determined fleet-average vehicle emission factors (EFs) for a suite of traffic-related air pollutants. We present the first real-world EFs for isocyanic acid (HNCO) and hydrogen cyanide (HCN) and insight into their on-road variability. We find that vehicles may represent an important source of these air toxics at an urban scale. This work has implications for understanding population exposure to these species.

Beschreibung: 〈b〉Surface–atmosphere exchange of inorganic water-soluble gases and associated ions in bulk aerosol above agricultural grassland pre- and postfertilisation〈/b〉〈br〉 Robbie Ramsay, Chiara F. Di Marco, Mathew R. Heal, Marsailidh M. Twigg, Nicholas Cowan, Matthew R. Jones, Sarah R. Leeson, William J. Bloss, Louisa J. Kramer, Leigh Crilley, Matthias Sörgel, Meinrat Andreae, and Eiko Nemitz〈br〉 Atmos. Chem. Phys., 18, 16953-16978, https://doi.org/10.5194/acp-18-16953-2018, 2018〈br〉 Understanding the impact of agricultural activities on the atmosphere requires more measurements of inorganic trace gases and associated aerosol counterparts. This research presents 1 month of measurements above agricultural grassland during a period of fertiliser application. It was found that emissions of the important trace gases ammonia and nitrous acid peaked after fertiliser use and that the velocity at which the measured aerosols were deposited was dependent upon their size.

Beschreibung: 〈b〉A propensity index for surface runoff on a karst plateau〈/b〉〈br〉 Christian Reszler, Jürgen Komma, Hermann Stadler, Elmar Strobl, and Günter Blöschl〈br〉 Hydrol. Earth Syst. Sci., 22, 6147-6161, https://doi.org/10.5194/hess-22-6147-2018, 2018〈br〉 Karst aquifers are vulnerable to pollution due to the typically short particle travel times. As the rainwater runs off on the surface it may collect contamination before infiltrating. This paper proposes a new field-mapping method for the ability of the landscape to produce and convey surface runoff. The method is based on local data collection in the field, and a visual assessment of surface runoff traces from a distance, which makes it suitable for larger areas than traditional field mapping.

Beschreibung: 〈b〉Analysis of combined and isolated effects of land-use and land-cover changes and climate change on the upper Blue Nile River basin's streamflow〈/b〉〈br〉 Dagnenet Fenta Mekonnen, Zheng Duan, Tom Rientjes, and Markus Disse〈br〉 Hydrol. Earth Syst. Sci., 22, 6187-6207, https://doi.org/10.5194/hess-22-6187-2018, 2018〈br〉 Understanding responses by changes in land use and land cover (LULC) and climate over the past decades on streamflow in the upper Blue Nile River basin is important for water management and water resource planning. Streamflow in the UBNRB has shown an increasing trend over the last 40 years, while rainfall has shown no trend change. LULC change detection findings indicate increases in cultivated land and decreases in forest coverage prior to 1995.

Beschreibung: 〈b〉Controls of fluorescent tracer retention by soils and sediments〈/b〉〈br〉 Marcus Bork, Jens Lange, Markus Graf-Rosenfellner, and Friederike Lang〈br〉 Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2018-549,2018〈br〉 〈b〉Manuscript under review for HESS〈/b〉 (discussion: open, 0 comments)〈br〉 Fluorescent tracers such as uranine and sulforhodamine B are useful tools to gain knowledge about water and solute fluxes in aquatic and terrestrial ecosystems. In batch experiments, we investigated systematically the influence of pH, organic carbon and texture on tracer adsorption on soils and sediments and quantified their impact and possible interactions. Overall, the investigated controls determine if the respective tracer shows more conservative or more non-conservative transport behaviour.

Beschreibung: 〈b〉Toward a conceptual framework of hyporheic exchange across spatial scales〈/b〉〈br〉 Chiara Magliozzi, Robert C. Grabowski, Aaron I. Packman, and Stefan Krause〈br〉 Hydrol. Earth Syst. Sci., 22, 6163-6185, https://doi.org/10.5194/hess-22-6163-2018, 2018〈br〉 The hyporheic zone is the area below riverbeds where surfacewater and groundwater mix. Hyporheic flow is linked to river processes and functions, but research to date has not sufficiently addressed how factors operating at different scales in time and space drive hyporheic flow variations at reach and larger scales. This review presents the scale-specific processes and interactions that control hyporheic flow, and a case study showing how valley factors affect its expression at the reach scale.

Beschreibung: 〈b〉Interrelations between surface, boundary layer, and columnar aerosol properties over a continental urban site〈/b〉〈br〉 Dongxiang Wang, Dominika Szczepanik, and Iwona S. Stachlewska〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1219,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 〈p〉PollyXT Raman Polarization Lidar observations were performed at the Remote Sensing laboratory in Warsaw (52.2109° N, 20.9826° E), Poland, in the framework of the European Aerosol Research Lidar Network (EARLINET) and the Aerosols, Clouds and Trace gases Research Infrastructure (ACTRIS). Data collected in July, August and September of 2013, 2015 and 2016 were analysed using the classical Raman approach. In total 202 sets of profiles of the particle extinction and backscatter coefficient, and linear particle depolarization ratio at 355 nm and 532 nm were derived for statistical investigations (EARLINET/ACTRIS Data Base). The main analysis was focused on intensive optical properties obtained within aerosol boundary layer (ABL). The interrelationships of different optical properties inside ABL are discussed for different periods: entire day, nocturnal time and sunrise/sunset time. In addition, the lidar derived boundary layer optical properties were compared with the columnar daytime aerosol properties derived from radiometer (MFR-7, PolandAOD-NET) and photometer (C318, AERONET). Relationships of these and surface in-situ measurements of particulate matter with an aerodynamic diameter 10) and 2.5) (WIOŚ Network) are investigated. Within boundary layer, the lidar derived optical properties (entire day, 202 sets) revealed the mean aerosol optical depth (AOD〈sub〉ABL〈/sub〉) of 0.27 ± 0.17 at 355 nm and 0.15 ± 0.10 at 532 nm; the mean Ångström exponent (ÅE〈sub〉ABL〈/sub〉) of 1.65 ± 0.45; the mean lidar ratio (LR〈sub〉ABL〈/sub〉) of 49 ± 16 sr at 355 nm and 41 ± 15 sr at 532 nm; the mean linear particle depolarization ratio (PLDR〈sub〉ABL〈/sub〉) of 0.02 ± 0.01 at 355 nm and 0.05 ± 0.02 at 532 nm, the mean water vapor mixing ratio (WVMR〈sub〉ABL〈/sub〉) of 8.16 ± 2.40 g/kg. Aerosol composition within ABL was assessed based on the derived properties interpreted with respect to values reported in literature and backward trajectories; it consisted either of pure urban anthropogenic pollution aerosols (~ 60 %), its mixtures with biomass burning aerosols (ABL exhibit positive correlation (~ 0.6), attributed in majority cases to local anthropogenic pollution. LR〈sub〉ABL〈/sub〉 and surface fine to coarse mass ratio (FCMR) presents weak positive-correlation (~ 0.4) at nocturnal time, due to the higher(lower) occurrence of fine(coarse) particles at night. On the contrary, weak negative-correlation (~ −0.3) of LR〈sub〉ABL〈/sub〉 and FCMR are present in sunrise/sunset time, for inverse occurrence of fine and coarse particles. A negative-correlation of PLDR〈sub〉ABL〈/sub〉 and FCMR (~ −0.4 at 355 nm, −0.6 to −0.7 at 532 nm) for all time period and no relation between PLDR〈sub〉ABL〈/sub〉 and ÅE〈sub〉ABL〈/sub〉 (~ 0.05) was found. Relation of AOD〈sub〉ABL〈/sub〉 and PM〈sub〉10〈/sub〉 reveals positive correlation (0.4 355; 0.5 532) for sunrise/sunset time, but no significant correlations found for AOD〈sub〉ABL〈/sub〉 and PM〈sub〉2.5〈/sub〉 (0.26 at 355; 0.16 at 532 nm). In general, a positive correlation of AOD〈sub〉ABL〈/sub〉 and LR〈sub〉ABL〈/sub〉 (stronger pronounced at 355 nm) and a negative correlation ÅE〈sub〉ABL〈/sub〉 and LR〈sub〉ABL〈/sub〉 (stronger pronounced at 532 nm) is observed. The ÅECL values stay roughly between 1.0 and 2.0, while the ÅE〈sub〉ABL〈/sub〉 values range from 0.1 to 2.5, indicating a variety of particle sizes occurring inside ABL during summer and early-autumn period in Warsaw.〈/p〉

Beschreibung: 〈b〉Effect of sea-salt aerosol on tropospheric bromine chemistry〈/b〉〈br〉 Lei Zhu, Daniel J. Jacob, Sebastian D. Eastham, Melissa P. Sulprizio, Xuan Wang, Tomás Sherwen, Mat J. Evans, Qianjie Chen, Becky Alexander, Theodore K. Koenig, Rainer Volkamer, L. Gregory Huey, Michael Le Breton, Thomas J. Bannan, and Carl J. Percival〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1239,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 We quantify the effect of sea-salt aerosol on tropospheric bromine chemistry with a new mechanistic description of the halogen chemistry in a global atmospheric chemistry model. For the first time, we are able to reproduce the observed levels of bromide activation from the sea-salt aerosol in a manner consistent with bromine oxide radical measured from various platforms. Sea-salt aerosol plays a far more complex role in global tropospheric chemistry than previously recognized.

Beschreibung: 〈b〉How does initial soil moisture influence the hydrological response? A case study from southern France〈/b〉〈br〉 Magdalena Uber, Jean-Pierre Vandervaere, Isabella Zin, Isabelle Braud, Maik Heistermann, Cédric Legoût, Gilles Molinié, and Guillaume Nord〈br〉 Hydrol. Earth Syst. Sci., 22, 6127-6146, https://doi.org/10.5194/hess-22-6127-2018, 2018〈br〉 We investigate how rivers in a flash-flood-prone region in southern France respond to rainfall depending on initial soil moisture. Therefore, high-resolution data of rainfall, river discharge and soil moisture were used. We find that during dry initial conditions, the rivers hardly respond even for heavy rain events, but for wet initial conditions, the response remains unpredictable: for some rain events almost all rainfall is transformed to discharge, whereas this is not the case for others.

Beschreibung: 〈b〉The influence of photochemical aging on light absorption of atmospheric black carbon and aerosol single-scattering albedo〈/b〉〈br〉 Xuezhe Xu, Weixiong Zhao, Xiaodong Qian, Shuo Wang, Bo Fang, Qilei Zhang, Weijun Zhang, Dean S. Venables, Weidong Chen, Yong Huang, Xueliang Deng, Biwen Wu, Xinfeng Lin, Sen Zhao, and Yingxiang Tong〈br〉 Atmos. Chem. Phys., 18, 16829-16844, https://doi.org/10.5194/acp-18-16829-2018, 2018〈br〉 We report the direct field measurement of size-resolved mixing state, E〈sub〉abs〈/sub〉, and aerosol single-scattering albedo (SSA) at λ = 532 nm at a rural site in east China in summer. Parameterization of E〈sub〉abs〈/sub〉 and SSA captures much of the influence of black carbon (BC) coating and particle absorption. The results show that absorption amplification depends on the coating thickness and the absorption of coating materials, and photochemistry plays role in modifying the absorption of BC-containing particles.

Beschreibung: 〈b〉Validating the water vapour content from a reanalysis product and a regional climate model over Europe based on GNSS observations〈/b〉〈br〉 Julie Berckmans, Roeland Van Malderen, Eric Pottiaux, Rosa Pacione, and Rafiq Hamdi〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1097,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 The use of ground-based observations is suitable for the assessment of atmospheric water vapour in climate models. We used water vapour observations from 100 European sites to evaluate two models: a reanalysis product and a regional climate model. The results reveal patterns in the water vapour distribution both in time and space that are relevant as water vapour plays a key role in the feedback process of a changing climate.

Beschreibung: 〈b〉A proxy for atmospheric daytime gaseous sulfuric acid concentration in urban Beijing〈/b〉〈br〉 Yiqun Lu, Chao Yan, Yueyun Fu, Yan Chen, Yiliang Liu, Gan Yang, Yuwei Wang, Federico Bianchi, Biwu Chu, Ying Zhou, Rujing Yin, Rima Baalbaki, Olga Garmash, Chenjuan Deng, Weigang Wang, Yongchun Liu, Tuukka Petäjä, Veli-Matti Kerminen, Jingkun Jiang, Markku Kulmala, and Lin Wang〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1132,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 Gaseous sulfuric acid is one of the key precursors for atmospheric new particle formation processes, but its measurement remains a major challenge. This work develops an estimation method for gaseous sulfuric acid concentration in an urban environment in China using multiple atmospheric variables that are easier to measure. Consideration of heterogeneous formation of HONO and subsequent photo-production of OH radicals improves the performance of the estimation method.

Beschreibung: 〈b〉Effects of brown coatings on the absorption enhancement of black carbon: a numerical investigation〈/b〉〈br〉 Jie Luo, Yongming Zhang, Feng Wang, and Qixing Zhang〈br〉 Atmos. Chem. Phys., 18, 16897-16914, https://doi.org/10.5194/acp-18-16897-2018, 2018〈br〉 The absorption enhancement of black carbon with brown coatings is investigated. In addition, the ratio of the absorption of BC coated by brown carbon (BrC) to an external mixture of BrC and BC (〈i〉E〈/i〉〈sub〉abs_internal〈/sub〉) is also investigated. The lensing effect and sunglasses effect are clearly defined. The applicability of the core–shell sphere model was investigated. The effects of the size distribution, fractal dimension, and wavelength dependency are also explored.

Beschreibung: 〈b〉Microphysical characteristics of frozen droplet aggregates from deep convective clouds〈/b〉〈br〉 Junshik Um, Greg M. McFarquhar, Jeffrey L. Stith, Chang Hoon Jung, Seoung Soo Lee, Ji Yi Lee, Younghwan Shin, Yun Gon Lee, Yiseok Isaac Yang, Seong Soo Yum, Byung-Gon Kim, Joo Wan Cha, and A-Reum Ko〈br〉 Atmos. Chem. Phys., 18, 16915-16930, https://doi.org/10.5194/acp-18-16915-2018, 2018〈br〉 During the 2012 Deep Convective Clouds and Chemistry experiment upper anvils of two storms were sampled. The occurrence of well-defined pristine crystals was low in the anvils, while single frozen droplets and frozen droplet aggregates (FDAs) were the dominant habits. A new algorithm was developed to automatically identify the number, size, and relative position of element frozen droplets within FDAs. The morphological characteristics of FDAs were compared with those of black carbon aggregates.

Beschreibung: 〈b〉Impacts of physical parameterization on prediction of ethane concentrations for oil and gas emissions in WRF-Chem〈/b〉〈br〉 Maryam Abdi-Oskouei, Gabriele Pfister, Frank Flocke, Negin Sobhani, Pablo Saide, Alan Fried, Dirk Richter, Petter Weibring, James Walega, and Gregory Carmichael〈br〉 Atmos. Chem. Phys., 18, 16863-16883, https://doi.org/10.5194/acp-18-16863-2018, 2018〈br〉 This study presents a quantification of model uncertainties due to configurations and errors in the emission inventories. The analysis includes performing simulations with different configurations and comparisons with airborne and ground-based observations with a focus on capturing transport and emissions from the oil and gas sector. The presented results reflect the challenges that one may face when attempting to improve emission inventories by contrasting measured with modeled concentrations.

Beschreibung: 〈b〉Dynamic responses of DOC and DIC transport to different flow regimes in a subtropical small mountainous river〈/b〉〈br〉 Yu-Ting Shih, Pei-Hao Chen, Li-Chin Lee, Chien-Sen Liao, Shih-Hao Jien, Fuh-Kwo Shiah, Tsung-Yu Lee, Thomas Hein, Franz Zehetner, Chung-Te Chang, and Jr-Chuan Huang〈br〉 Hydrol. Earth Syst. Sci., 22, 6579-6590, https://doi.org/10.5194/hess-22-6579-2018, 2018〈br〉 DOC and DIC export in Taiwan shows that the annual DOC and DIC fluxes were 2.7–4.8 and 48.4–54.3 ton C km〈sup〉2〈/sup〉 yr〈sup〉1〈/sup〉, respectively, which were approximately 2 and 20 times higher than the global means of 1.4 and 2.6 ton C km〈sup〉2〈/sup〉 yr〈sup〉1〈/sup〉, respectively.

Beschreibung: 〈b〉Modeling experiments on seasonal lake ice mass and energy balance in Qinghai-Tibet Plateau: A case study〈/b〉〈br〉 Wenfeng Huang, Bin Cheng, Jinrong Zhang, Zheng Zhang, Timo Vihma, Zhijun Li, and Fujun Niu〈br〉 Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2018-616,2018〈br〉 〈b〉Manuscript under review for HESS〈/b〉 (discussion: open, 0 comments)〈br〉 Up to now, little is known on ice thermodynamics and lake-atmosphere interaction over Tibetan Plateau during ice-covered seasons due to a lack of field data. In this study, model experiments on ice thermodynamics were conducted in a shallow lake using HIGHTSI. Water-ice heat flux was a major source of uncertainty for lake ice thickness. Heat and mass budgets were estimated within the vertical air-ice-water system. Strong ice sublimation occurred and was responsible for water loss during winter.

Beschreibung: 〈b〉Evaluation of drought representation and propagation in Regional Climate Model simulations over Spain〈/b〉〈br〉 Anaïs Barella-Ortiz and Pere Quintana-Seguí〈br〉 Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2018-603,2018〈br〉 〈b〉Manuscript under review for HESS〈/b〉 (discussion: open, 0 comments)〈br〉 Drought is an important climatic risk. Its representation and propagation by regional climate models from Med-CORDEX simulations is analysed using standardized indices. Results show that these models improve meteorological drought representation, but large uncertainties are identified in its propagation and the way soil moisture and hydrological droughts are characterised. These are mainly due to model formulation, making necessary further improvements in land surface modelling.

Beschreibung: 〈b〉Elevated atmospheric mercury concentrations at the Russian polar station Amderma during Icelandic volcanoes' eruptions〈/b〉〈br〉 Fidel Pankratov, Alexander Mahura, Tuukka Petäjä, Valentin Popov, and Vladimir Masloboev〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1228,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 1 comment)〈br〉 Analysis of long-term observations for atmospheric mercury in the Russian Arctic, considering inter-annual, seasonal and monthly variabilities is in focus. Linkage of elevated concentrations with volcanic eruptions in Iceland is explored. Results showed that active volcanoes can play a role of sources for increased mercury levels in the Northern Hemisphere due to long-range atmospheric transport of volcanic clouds towards the Arctic.

Beschreibung: 〈b〉On the uncertainty of initial condition and initialization approaches in variably saturated flow modeling〈/b〉〈br〉 Danyang Yu, Jinzhong Yang, Liangsheng Shi, Qiuru Zhang, Kai Huang, Yuanhao Fang, and Yuanyuan Zha〈br〉 Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2018-557,2018〈br〉 〈b〉Manuscript under review for HESS〈/b〉 (discussion: open, 0 comments)〈br〉 Soil water movement is quite important due to its direct effects on environment, agriculture and hydrology. Simulation of soil water movement requires accurate determination of model parameters as well as initial and boundary conditions. However, it is difficult to obtain the accurate initial soil moisture/matric potential profile at the beginning of simulation time, making it necessary to run the simulation model from arbitrary initial condition until the uncertainty of initial condition (UIC) is diminished. The behavior of this process is usually defined as “warming up”. In this paper, two common methods in quantifying the UIC (one is based on running a single simulation recursively across multiple hydrological years, and the other is based on Monte-Carlo simulations with various initial condition) are compared and the required “warm-up” time twu (minimum time required for model to warm up to eliminate the UIC) is identified with different soil textures, meteorological conditions, and soil profile lengths. Then we analyze the effects of different initial conditions on parameter estimation within two data assimilation frameworks (i.e, ensemble Kalman filter and iterative ensemble smoother), and assess several existing model initializing methods to obtain initial condition based on the availability of data related to the retrieval of initial soil moisture profile. Results reveal that Monte-Carlo simulations and the recursive simulation over many years can both demonstrate the temporal behavior of UIC and a common threshold is recommended to determine the warm-up time for both methods. Besides, the relationship between warm-up time for variably saturated flow modeling and the model settings (soil textures, meteorological conditions and soil profile length) are quantitatively identified. In addition, we propose a “warm-up” period before assimilating data in order to obtain a better performance of parameter and state estimation.

Beschreibung: 〈b〉Observation operators for assimilation of satellite observations in fluvial inundation forecasting〈/b〉〈br〉 Elizabeth S. Cooper, Sarah L. Dance, Javier García-Pintado, Nancy K. Nichols, and Polly Smith〈br〉 Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2018-589,2018〈br〉 〈b〉Manuscript under review for HESS〈/b〉 (discussion: open, 0 comments)〈br〉 Flooding from rivers is a huge and costly problem worldwide. Computer simulations can help to warn people if and when they are likely to be affected by river flood water, but such predictions are not always accurate or reliable. Information about flood extent from satellites can help keep these forecasts on track. Here we investigate different ways of using information from satellite images, and look at the effect on computer predictions. This will help to develop flood warning systems.

Beschreibung: 〈b〉Modeling the impact of heterogeneous reactions of chlorine on summertime nitrate formation in Beijing, China〈/b〉〈br〉 Xionghui Qiu, Qi Ying, Shuxiao Wang, Lei Duan, Jian Zhao, Jia Xing, Dian Ding, Yele Sun, Baoxian Liu, Aijun Shi, Xiao Yan, Qingcheng Xu, and Jiming Hao〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1270,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 Current chemical transport models can’t capture the diurnal and nocturnal variation of atmospheric nitrate, which may be relative to the missing of atmospheric chlorine chemistry. In this work, the Community Multiscale Air Quality (CMAQ) model with an improved chlorine heterogeneous chemistry is applied to simulate the impact of chlorine chemistry on summer nitrate concentration in Beijing. The results of this work can improve our understandings on nitrate formation.

Beschreibung: 〈b〉Investigation of CATS aerosol products and application toward global diurnal variation of aerosols〈/b〉〈br〉 Logan Lee, Jianglong Zhang, Jeffrey S. Reid, and John E. Yorks〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1298,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 〈p〉We present a comparison of 1064 nm aerosol optical depth (AOD) and aerosol extinction profiles from the Cloud-Aerosol Transport System (CATS) Level 2 aerosol product with collocated Aerosol Robotic Network (AERONET) AOD, Aqua and Terra Moderate Imaging Spectroradiometer (MODIS) Dark Target (AOD) and Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) AOD and extinction data for the period of Feb. 2015–Oct. 2017. Upon quality assurance checks of CATS data, reasonable agreements are found between aerosol data from CATS and other sensors. Using quality assured CATS aerosol data, for the first time, variations in AODs and aerosol extinction profiles are evaluated at 00, 06, 12, and 18 UTC (and/or 0:00 am, 6:00 am, 12:00 pm and 6:00 pm local solar times) on both regional and global scales. This study suggests that marginal variations are found in AOD from a global mean perspective, with the maximum and minimum aerosol vertical profiles found at local noon and 6:00 pm local time respectively, for both the June–November and December–May seasons. Strong diurnal variations are found over North Africa and India for the December–May season, and over North Africa, Middle East, and India for the June–November season. In particular, over North Africa, during the June-November season, a diurnal peak in aerosol extinction profile of 20 % larger than daily mean is found at 6:00 am (early morning local time), which may possibly be associated with dust generation through the breaking down of low level jet during morning hours.〈/p〉

Beschreibung: 〈b〉Estimating radar precipitation in cold climates: the role of air temperature within a non-parametric framework〈/b〉〈br〉 Kuganesan Sivasubramaniam, Ashish Sharma, and Knut Alfredsen〈br〉 Hydrol. Earth Syst. Sci., 22, 6533-6546, https://doi.org/10.5194/hess-22-6533-2018, 2018〈br〉 This study investigates the use of gauge precipitation and air temperature observations to ascertain radar precipitation in cold climates. The use of air temperature as an additional variable in a non-parametric model improved the estimation of radar precipitation significantly. Further, it was found that the temperature effects became insignificant when air temperature was above 10 °C. The findings from this study could be important for using radar precipitation for hydrological applications.

Beschreibung: 〈b〉Modelling the high-resolution dynamic exposure to flood in city-region〈/b〉〈br〉 Xuehong Zhu, Qiang Dai, Dawei Han, Lu Zhuo, Shaonan Zhu, and Shuliang Zhang〈br〉 Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2018-590,2018〈br〉 〈b〉Manuscript under review for HESS〈/b〉 (discussion: open, 0 comments)〈br〉 Urban flooding exposure is generally investigated with the assumption of stationary disasters and disaster-bearing bodies within an event, and thus cannot satisfy the increasingly elaborative modelling and management of urban flood. In this study, a comprehensive method was developed to simulate dynamic exposure to urban flooding considering residents’ travel behavior. Several scenarios, including diverse flooding types and various responses of residents to flooding, were considered.

Beschreibung: 〈b〉Rapid SO〈sub〉2〈/sub〉 emission reductions significantly increase tropospheric ammonia concentrations over the North China Plain〈/b〉〈br〉 Mingxu Liu, Xin Huang, Yu Song, Tingting Xu, Shuxiao Wang, Zhijun Wu, Min Hu, Lin Zhang, Qiang Zhang, Yuepeng Pan, Xuejun Liu, and Tong Zhu〈br〉 Atmos. Chem. Phys., 18, 17933-17943, https://doi.org/10.5194/acp-18-17933-2018, 2018〈br〉 〈p〉The North China Plain has been identified as a significant hotspot of ammonia (〈span〉NH〈sub〉3〈/sub〉〈/span〉) due to extensive agricultural activities. Satellite observations suggest a significant increase of about 30 % in tropospheric gas-phase 〈span〉NH〈sub〉3〈/sub〉〈/span〉 concentrations in this area during 2008–2016. However, the estimated 〈span〉NH〈sub〉3〈/sub〉〈/span〉 emissions decreased slightly by 7 % because of changes in Chinese agricultural practices, i.e., the transition in fertilizer types from ammonium carbonate fertilizer to urea, and in the livestock rearing system from free-range to intensive farming. We note that the emissions of sulfur dioxide (〈span〉SO〈sub〉2〈/sub〉〈/span〉) have rapidly declined by about 60 % over the recent few years. By integrating measurements from ground and satellite, a long-term anthropogenic 〈span〉NH〈sub〉3〈/sub〉〈/span〉 emission inventory, and chemical transport model simulations, we find that this large 〈span〉SO〈sub〉2〈/sub〉〈/span〉 emission reduction is responsible for the 〈span〉NH〈sub〉3〈/sub〉〈/span〉 increase over the North China Plain. The simulations for the period 2008–2016 demonstrate that the annual average sulfate concentrations decreased by about 50 %, which significantly weakens the formation of ammonium sulfate and increases the average proportions of gas-phase 〈span〉NH〈sub〉3〈/sub〉〈/span〉 within the total 〈span〉NH〈sub〉3〈/sub〉〈/span〉 column concentrations from 26 % (2008) to 37 % (2016). By fixing 〈span〉SO〈sub〉2〈/sub〉〈/span〉 emissions of 2008 in those multi-year simulations, the increasing trend of the tropospheric 〈span〉NH〈sub〉3〈/sub〉〈/span〉 concentrations is not observed. Both the decreases in sulfate and increases in 〈span〉NH〈sub〉3〈/sub〉〈/span〉 concentrations show highest values in summer, possibly because the formation of sulfate aerosols is more sensitive to 〈span〉SO〈sub〉2〈/sub〉〈/span〉 emission reductions in summer than in other seasons. Besides, the changes in 〈span〉NO〈sub〉〈i〉x〈/i〉〈/sub〉〈/span〉 emissions and meteorological conditions both decreased the 〈span〉NH〈sub〉3〈/sub〉〈/span〉 column concentrations by about 3 % in the study period. Our simulations suggest that the moderate reduction in 〈span〉NO〈sub〉〈i〉x〈/i〉〈/sub〉〈/span〉 emissions (16 %) favors the formation of particulate nitrate by elevating ozone concentrations in the lower troposphere.〈/p〉

Beschreibung: 〈b〉Photochemical box modelling of volcanic SO〈sub〉2〈/sub〉 oxidation: isotopic constraints〈/b〉〈br〉 Tommaso Galeazzo, Slimane Bekki, Erwan Martin, Joël Savarino, and Stephen R. Arnold〈br〉 Atmos. Chem. Phys., 18, 17909-17931, https://doi.org/10.5194/acp-18-17909-2018, 2018〈br〉 Volcanic sulfur can have climatic impacts for the planet via sulfate aerosol formation, leading also to pollution events. We provide model constraints on tropospheric volcanic sulfate formation, with implications for its lifetime and impacts on regional air quality. Oxygen isotope investigations from our model suggest that in the poor tropospheric plumes of halogens, the O2/TMI sulfur oxidation pathway might significantly control sulfate production. The produced sulfate has no isotopic anomaly.

Beschreibung: 〈b〉Estimates of sub-national methane emissions from inversion modelling〈/b〉〈br〉 Sarah Connors, Alistair J. Manning, Andrew D. Robinson, Stuart N. Riddick, Grant L. Forster, Anita Ganesan, Aoife Grant, Stephen Humphrey, Simon O'Doherty, Dave E. Oram, Paul I. Palmer, Robert L. Skelton, Kieran Stanley, Ann Stavert, Dickon Young, and Neil R. P. Harris〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1187,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 Methane is an important greenhouse gas & reducing its emissions is a vital part of climate change mitigation to limit global temperature increase to 1.5 °C or 2.0 °C. This paper explains a way to estimate emitted methane over a sub-national area by combining measurements & computer dispersion modelling in a so-called 〈q〉inversion〈/q〉 technique. Compared with the current national inventory, our results show lower emissions for Cambridgeshire, possibly due to waste sector emission differences.

Beschreibung: 〈b〉Characteristics of the tropical tropopause inversion layer using high-resolution temperature profiles retrieved from COSMIC GNSS Radio Occultation〈/b〉〈br〉 Noersomadi Noersomadi, Toshitaka Tsuda, and Masatomo Fujiwara〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1182,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 Characteristics of static stability (N2) in the tropical tropopause are analyzed using 0.1 km vertical resolution temperature profiles retrieved from COSMIC GNSS-RO. We define the tropopause inversion layer (TIL) by the sharp increase in N2 across the cold point tropopause (CPT) and the thickness of the enhanced peak in N2 just above CPT. We investigated the TIL at the intra-seasonal to inter annual time scales above the Maritime Continent and Pacific Ocean with different land-sea distribution.

Beschreibung: 〈b〉Antarctic clouds, supercooled liquid water and mixed-phase investigated with DARDAR: geographical and seasonal variations〈/b〉〈br〉 Constantino Listowski, Julien Delanoë, Amélie Kirchgaessner, Tom Lachlan-Cope, and John King〈br〉 Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-1222,2018〈br〉 〈b〉Manuscript under review for ACP〈/b〉 (discussion: open, 0 comments)〈br〉 Using satellite cloud products we investigate the distribution and variation of cloud occurrences in the Antarctic (60 °S–90 °S), and more particularly of the supercooled liquid water (SLW). In distinguishing between pure SLW and SLW mixed with ice we pin down unreported variations of low-level mixed-phase clouds so far, which point to the role of biological emissions, in addition to the atmospheric temperature and the sea ice fraction, as driver of the seasonal cycle of mixed-phase clouds.