• Issue

    Journal of Geophysical Research: Atmospheres: Volume 124, Issue 16

    8871-9770
    27 August 2019
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Issue Information

Free Access

Issue Information

  • Pages: 8871-8873
  • First Published: 03 October 2019

Research Articles

Climate and Dynamics

Free Access

Tracing Snowmelt Paths in an Integrated Hydrological Model for Understanding Seasonal Snowmelt Contribution at Basin Scale

Hongyi Li,  Xin Li,  Dawen Yang,  Jian Wang,  Bing Gao,  Xiaoduo Pan,  Yanlin Zhang,  Xiaohua Hao, 
  • Pages: 8874-8895
  • First Published: 15 July 2019
Key Points

  • Snowmelt contributions to hydrological processes are identified by tracing snowmelt pathways in an improved hydrological model
  • Seasonal difference of snowmelt contributions could be more reasonably identified by tracing snowmelt pathways in hydrological model
  • Snowmelt contributions are affected by weather and soil conditions not only in the snowmelt season but also year-round

Free Access

Impact of Atmospheric Rivers on Surface Hydrological Processes in Western U.S. Watersheds

Xiaodong Chen,  L. Ruby Leung,  Mark Wigmosta,  Marshall Richmond, 
  • Pages: 8896-8916
  • First Published: 05 August 2019
Key Points

  • AR events intensify snow ablation and nearly double the runoff magnitude response to precipitation compared to non-AR events
  • AR events modulate temperature and radiation and induce rain-on-snow, which contributes 25% of runoff volume when snowpack exists
  • ARs explain 30% to 60% of the interannual variance and sharpen the seasonality of water resources in the west coast mountain watersheds

Free Access

Respective and Combined Impacts of Regional SST Anomalies on Tropical Cyclogenesis in Different Sectors of the Western North Pacific

Renguang Wu,  Yiya Yang,  Xi Cao, 
  • Pages: 8917-8934
  • First Published: 09 August 2019
Key Points

  • Tropical cyclogenesis displays different features under various combinations of regional SST anomalies
  • Main environmental variables for tropical cyclogenesis change differ among different sectors
  • Environmental variable changes vary with the combination of regional SST anomalies

Free Access

The Summertime Precipitation Bias in E3SM Atmosphere Model Version 1 over the Central United States

X. Zheng,  J.-C. Golaz,  S. Xie,  Q. Tang,  W. Lin,  M. Zhang,  H.-Y. Ma,  E. L. Roesler, 
  • Pages: 8935-8952
  • First Published: 01 August 2019
Key Points

  • EAMv1 captures the diurnal cycle of the large-scale environment but misrepresents the diurnal cycle of precipitation over the Central United States
  • Hindcast simulations provide insights on the relationship between the precipitation bias and the large-scale environment over the Central United States
  • The coupling of the convection to the large-scale environment needs to be improved

Free Access

Ocean-Atmosphere Trajectories of Extended Drought in Southwestern North America

Luke A. Parsons,  Sloan Coats, 
  • Pages: 8953-8971
  • First Published: 06 August 2019
Key Points

  • We examine climate patterns associated with the life cycle of droughts in southwestern North America (SWNA) in observations and model data
  • Eastern Pacific ENSO events often precede droughts, cool Pacific anomalies maintain droughts, and central Pacific ENSO events end droughts
  • The state of the North Pacific and the type of El Niño event may modulate the likelihood of an El Niño event ending a drought

Free Access

Global Evaluation of Proxy System Models for Stable Water Isotopes With Realistic Atmospheric Forcing

Atsushi Okazaki,  Kei Yoshimura, 
  • Pages: 8972-8993
  • First Published: 08 July 2019
Key Points

  • Global evaluation of stable water isotope-based proxy system models (PSMs) shows reasonable performance for corals and tree-ring cellulose
  • PSM for ice cores is limited by the accuracy of input and may need to include additional processes (e.g., sublimation) to simulate interannual variability

Free Access

Intraseasonal Snow Cover Variations Over Western Siberia and Associated Atmospheric Processes

Lei Song,  Renguang Wu, 
  • Pages: 8994-9010
  • First Published: 08 August 2019
Key Points

  • The 9- to 30-day variation dominates total intraseasonal snow cover variations over western Siberia
  • The atmospheric circulation anomalies control the 9- to 30-day snow variation over western Siberia
  • The snowfall lags anomalous ascending motion, anomalous water vapor convergence, and water vapor increase in the atmosphere

Free Access

Statistical Modeling of Tidal Weather in the Mesosphere and Lower Thermosphere

Ashan Vitharana,  Xuwen Zhu,  Jian Du,  Jens Oberheide,  William E. Ward, 
  • Pages: 9011-9027
  • First Published: 01 August 2019
Key Points

  • Quasi 23-day oscillation is observed in both eCMAM and SABER tidal weather
  • Tidal weather at one day can be predicted up to ~90% accuracy using a simple autoregression (AR) model

Free Access

Sensitivity of Coarse-Scale Snow-Free Land Surface Shortwave Albedo to Topography

Dalei Hao,  Jianguang Wen,  Qing Xiao,  Xingwen Lin,  Dongqin You,  Yong Tang,  Qiang Liu,  Sisi Zhang, 
  • Pages: 9028-9045
  • First Published: 05 August 2019
Key Points

  • We quantitatively investigated the sensitivities of coarse-scale snow-free albedo to topography using MODIS data and global sensitivity analysis method
  • MODIS land surface albedo over the Tibetan Plateau is highly sensitive to the topographic distribution
  • The mean slope and aspect anisotropic index account for about 16.7% and 14% of the total variance, respectively

Free Access

The Interannual Variability of Surface Winds in Antarctica and the Surrounding Oceans: A Climatological Analysis Using the ERA-Interim Reanalysis Data

Lejiang Yu,  Shiyuan Zhong, 
  • Pages: 9046-9061
  • First Published: 09 August 2019
Key Points

  • An analysis of season-dependent interannual variability of surface winds in Antarctica and the Southern Ocean has been done using ERA-Interim data
  • The leading modes of the variability are related, depending on seasons, to known modes of Southern Hemisphere large-scale circulation
  • The spatial patterns of the variability can be largely explained by anomalous surface pressure and wind relative to climatological patterns

Free Access

The Influence of Summer Deep Soil Temperature on Early Winter Snow Conditions in Eurasia in the NCEP CFSv2 Simulation

Ravi P. Shukla,  Bohua Huang,  Paul A. Dirmeyer,  James L. Kinter, 
  • Pages: 9062-9077
  • First Published: 09 August 2019
Key Points

  • Model overestimates SCF up to 60% in western Eurasia during October because LST reaches its freezing point there earlier than observed
  • The Model deep soil temperature has a noticeably smaller seasonal change than observed, resulting in a severe cold bias during summer
  • Cold deep soil temperature causes additional cooling in upper soil layer and helps to bring LST to freezing point early over there

Free Access

Modeling the Impacts of Urbanization and Open Water Surface on Heavy Convective Rainfall: A Case Study over the Emerging Xiong'an City, China

Yue Xing,  Guangheng Ni,  Long Yang,  Yan Yang,  Pei Xing,  Ting Sun, 
  • Pages: 9078-9098
  • First Published: 08 August 2019
Key Points

  • Open water surface and urbanization show contrasting impact on heavy rainfall under strong large-scale forcing
  • Changes in rainfall accumulation highlight strong dependence of urban-induced rainfall anomalies on urbanization stages
  • Interactions between open water and urban surface contribute to downwind rainfall enhancement through intensified moist convection

Free Access

Modeling Wildfire Smoke Feedback Mechanisms Using a Coupled Fire-Atmosphere Model With a Radiatively Active Aerosol Scheme

Adam K. Kochanski,  Derek V. Mallia,  Matthew G. Fearon,  Jan Mandel,  Amir H. Souri,  Tim Brown, 
  • Pages: 9099-9116
  • First Published: 12 July 2019
Key Points

  • Smoke significantly impacts meteorological conditions near wildland fires by radiatively driven near-surface cooling and warming aloft
  • Positive feedback is observed, where increasing smoke concentrations enhance atmospheric stability, reduce mixing, and increase near-surface PM2.5 concentrations
  • Radiative effects of wildfire some can be simulated in an integrated framework coupling atmospheric, fire, and chemical transport models

Free Access

Effects of Mosaic Land Use on Dynamically Downscaled WRF Simulations of the Contiguous United States

Megan S. Mallard,  Tanya L. Spero, 
  • Pages: 9117-9140
  • First Published: 16 July 2019
Key Points

  • WRF's Noah LSM is used in a dynamical downscaling application to compare the effects of mosaic land use against using the dominant category
  • Within the United States, mosaic increases urban area and reduces forest and cultivated land, leading to warmer temperatures and less precipitation
  • Within large cities, the opposite trend occurs, as greenspace within cities increases and 2-m temperatures are reduced

Free Access

An Overview of Low-Level Jet Winds and Corresponding Mixed Layer Depths During PECAN

Brian J. Carroll,  Belay B. Demoz,  Ruben Delgado, 
  • Pages: 9141-9160
  • First Published: 09 August 2019
Key Points

  • Doppler lidar wind profile analysis at three fixed observation sites for 30 southerly low-level jets, plus 11 cold-frontal northerly jets
  • Stronger low-level jets are preceded by deeper convective mixed layers and stronger boundary layer wind speeds
  • Stronger southerly jets are associated with a larger number of pristine convection initiation events per night

Open Access

Determining Factors of Monthly to Decadal Variability in Surface Solar Radiation in China: Evidences From Current Reanalyses

Fei Feng,  Kaicun Wang, 
  • Pages: 9161-9182
  • First Published: 07 August 2019
Key Points

  • All reanalyses overestimate the multiyear mean all-sky Rs over China, which is primarily due to their underestimation of cloud fraction
  • 73–12% of the trend biases in all-sky Rs can be explained by trend bias in cloud fraction
  • The trend bias in clear-sky-surface solar radiation (a proxy for aerosols) explains 43–30% of the trend bias in Rs

Free Access

Sensitivity of Summer Precipitation Simulation to Microphysics Parameterization Over Eastern China: Convection-Permitting Regional Climate Simulation

Ziyue Guo,  Juan Fang,  Xuguang Sun,  Yi Yang,  Jianping Tang, 
  • Pages: 9183-9204
  • First Published: 08 August 2019
Key Points

  • Large-scale atmospheric circulations are insensitive to the microphysics parameterizations, which do not significantly reduce the systematic biases
  • Convection-permitting simulations can capture the major precipitation diurnal variations and transition characteristics
  • The vertical profiles of solid hydrometeors, especially the snow and graupel particles, play important roles in precipitation amount simulations

Open Access

Role of Eurasian Snow Cover in Linking Winter-Spring Eurasian Coldness to the Autumn Arctic Sea Ice Retreat

Ruonan Zhang,  Chenghu Sun,  Renhe Zhang,  Weijing Li,  Jinqing Zuo, 
  • Pages: 9205-9221
  • First Published: 09 August 2019
Key Points

  • An anomalous “north-south” dipole mode of the snow water equivalent over the Eurasian mid-to-high latitudes can persist from winter to spring
  • The dipole mode of snow water equivalent tends to link prolonged winter-springtime Eurasian midlatitude cooling to autumn time sea ice retreat

Free Access

The Asymmetric Atmospheric Response to the Midlatitude North Pacific SST Anomalies

Lingfeng Tao,  Xuguang Sun,  Xiu-Qun Yang, 
  • Pages: 9222-9240
  • First Published: 10 August 2019
Key Points

  • Midlatitude cold SST anomalies can generate significant atmospheric anomalies with an equivalent barotropic structure than their counterpart
  • Both diabatic heating and transient eddy forcing in the central North Pacific are the major sources of asymmetric atmospheric responses
  • Moisture and its related vertical distribution of condensation heating are essential for the nonlinear atmospheric responses

Free Access

Assessment of Storm Wind Speed Prediction Using Gridded Bayesian Regression Applied to Historical Events With NCAR's Real-Time Ensemble Forecast System

Jaemo Yang,  Marina Astitha,  Craig S. Schwartz, 
  • Pages: 9241-9261
  • First Published: 30 July 2019
Key Points

  • Use of gridded Bayesian regression to improve storm wind speed forecast
  • Bayesian regression is successfully applied to NCAR's dynamic ensemble forecast
  • The new technique improves gridded storm wind speed forecasts using past event-based data and has the potential to be implemented in real time

Open Access

Middle- and High-Latitude Mesosphere and Lower Thermosphere Mean Winds and Tides in Response to Strong Polar-Night Jet Oscillations

J. Federico Conte,  Jorge L. Chau,  Dieter H. W. Peters, 
  • Pages: 9262-9276
  • First Published: 10 August 2019
Key Points

  • Categorization into strong PJO or non-PJO better suited to identify changes in wintertime MLT dynamics
  • Overall good agreement between the Ext-CMAM30 and specular meteor radar measurements
  • Observed behavior of MLT mean winds during strong PJOs depends on the polar vortex structure at mesospheric heights

Free Access

The Evolution and Role of Midtropospheric Cyclonic Vortex in the Formation of Super Typhoon Nepartak (2016)

Shenglan Wu,  Juan Fang, 
  • Pages: 9277-9298
  • First Published: 13 August 2019
Key Points

  • The midlevel vortex is correlated with convection and low-level vortex and demonstrates diurnal variations during the pregenesis stage
  • The intensification of midlevel vortex usually corresponds to the weakening of low-level vortex except for the deep convection phase
  • Midlevel vortex favors convection by enhancing local baroclinity and acting as a pouch in early and late pregenesis stage, respectively

Free Access

A Three-Dimensional Array for the Study of Infrasound Propagation Through the Atmospheric Boundary Layer

Madelon M. E. Smink,  Jelle D. Assink,  Fred C. Bosveld,  Pieter S. M. Smets,  Läslo G. Evers, 
  • Pages: 9299-9313
  • First Published: 07 August 2019
Key Points

  • A three-dimensional infrasound array is set up for characterizing upgoing and downgoing wavefronts in the atmospheric boundary layer
  • The importance of atmospheric boundary layer conditions on infrasound propagation modeling is shown
  • The observed upgoing and downgoing wavefronts are not fully explained by ray propagation modeling

Free Access

MJO Propagation Processes and Mean Biases in the SubX and S2S Reforecasts

Hyemi Kim,  Matthew A. Janiga,  Kathy Pegion, 
  • Pages: 9314-9331
  • First Published: 08 August 2019
Key Points

  • SubX and S2S reforecasts show MJO prediction skill out to 4.5 weeks based on the RMM index
  • SubX and S2S models fail to predict the MJO convection, associated circulations, and moisture advection processes beyond 10 days
  • Models have mean biases across the Indo-Pacific: a drier low troposphere, excess of surface rainfall, frequent occurrence of light rainfall

Free Access

Modeling Blowing Snow Over the Tibetan Plateau With the Community Land Model: Method and Preliminary Evaluation

Zhipeng Xie,  Zeyong Hu,  Yaoming Ma,  Genhou Sun,  Lianglei Gu,  Shuang Liu,  Yidan Wang,  Huixuan Zheng,  Weiqiang Ma, 
  • Pages: 9332-9355
  • First Published: 14 August 2019
Key Points

  • The PIEKTUK blowing snow model was coupled to the Community Land Model to better estimate the snow dynamics over the Tibetan Plateau
  • Snow cover, snow depth, and surface albedo can be better represented by the coupled model with the inclusion of blowing snow effects
  • A remarkable decrease of bias in the nighttime land surface temperature is detected in the coupled model simulation

Free Access

Tropospheric and Stratospheric Causal Pathways Between the MJO and NAO

Elizabeth A. Barnes,  Savini M. Samarasinghe,  Imme Ebert-Uphoff,  Jason C. Furtado, 
  • Pages: 9356-9371
  • First Published: 16 August 2019
Key Points

  • Causality methods identify both a stratospheric and tropospheric pathway from the MJO to the NAO
  • The NAO is 20–30% more likely to be in a particular state following particular MJO phases
  • The stratosphere conditions the NAO to be conducive, or not, to MJO influence

Open Access

Numerical Simulations of High-Frequency Gravity Wave Propagation Through Fine Structures in the Mesosphere

Tyler Mixa,  David Fritts,  Thomas Lund,  Brian Laughman,  Ling Wang,  Lakshmi Kantha, 
  • Pages: 9372-9390
  • First Published: 05 August 2019
Key Points

  • Fine structures produce a diversity of impacts on gravity wave propagation and instability evolution having large-scale implications
  • Stability and shear effects produce distinctive vortical evolutions that determine the locations and time scales of wave energy dissipation
  • Large-scale consequences can be predicted and merit inclusion in broader modeling efforts

Free Access

Budget Analyses of a Record-Breaking Rainfall Event in the Coastal Metropolitan City of Guangzhou, China

Yongjie Huang,  Yubao Liu,  Yuewei Liu,  Jason C. Knievel, 
  • Pages: 9391-9406
  • First Published: 09 August 2019
Key Points

  • Budgets of moisture, momentum, and heat were computed to study the mechanism for the record-breaking rainfall in Guangzhou, China
  • The persistent onshore warm and moist mesoscale flow from the south and east in the lower troposphere provided the main fuel
  • Buoyancy and dynamic acceleration and the shallow weak cool pools jointly supported the sustained and strong slantwise updrafts

Free Access

Observed Atmospheric and Surface Variability on Heterogeneous Terrain at the Hectometer Scale and Related Advective Transports

Gemma Simó,  Joan Cuxart,  Maria A. Jiménez,  Daniel Martínez-Villagrasa,  Rodrigo Picos,  Alvaro López-Grifol,  Belén Martí, 
  • Pages: 9407-9422
  • First Published: 19 August 2019
Key Points

  • The observed atmospheric variability over semiarid terrain at the hectometer scale is significant
  • Thermal advection is quantitatively close to the turbulent heat fluxes in clear nights with weak winds
  • In dry conditions, local advection of moisture can be of the same order of evapotranspiration

Free Access

Does ERA-5 Outperform Other Reanalysis Products for Hydrologic Applications in India?

Shanti Shwarup Mahto,  Vimal Mishra, 
  • Pages: 9423-9441
  • First Published: 09 August 2019
Key Points

  • Five new-era reanalysis products were evaluated for the hydrological applications in India during 1980–2018
  • ERA-5 performs better than other reanalysis products for ET and soil moisture in India

Aerosol and Clouds

Free Access

The Plasma Nature of Lightning Channels and the Resulting Nonlinear Resistance

C. L. da Silva,  R. G. Sonnenfeld,  H. E. Edens,  P. R. Krehbiel,  M. G. Quick,  W. J. Koshak, 
  • Pages: 9442-9463
  • First Published: 05 August 2019
Key Points

  • A novel physics-based yet computationally efficient model of the lightning channel nonlinear resistance is introduced
  • The model reproduces the finite time scale of streamer-to-leader transition and the steady-state negative differential resistance
  • The model captures the experimentally inferred direct relationship between electrical and optical properties of rocket-triggered lightning

Free Access

Superposition of Gobi Dust and Southeast Asian Biomass Burning: The Effect of Multisource Long-Range Transport on Aerosol Optical Properties and Regional Meteorology Modification

Kan Huang,  Joshua S. Fu,  Neng-Huei Lin,  Sheng-Hsiang Wang,  Xinyi Dong,  Guochen Wang, 
  • Pages: 9464-9483
  • First Published: 05 August 2019
Key Points

  • One long-range transport event with concurring dust and biomass burning aerosol layers was observed over the West Pacific region
  • Strong warming near the surface and at higher tropospheric altitudes was ascribed to the massive aerosol inputs from the transported plumes
  • A “double dome” mechanism effect was proposed that dust and biomass burning plumes at high altitudes could effectively warm the atmosphere

Free Access

Effects of Sea Spray on Microphysics and Intensity of Deep Convective Clouds Under Strong Winds

J. Shpund,  A. Khain,  D. Rosenfeld, 
  • Pages: 9484-9509
  • First Published: 08 July 2019
Key Points

  • Deep convective clouds typical of eyewall of TCs are simulated
  • Sea spray particles, production, and transport at strong winds are simulated using Eulerian-Lagrangian model and are transported to clouds
  • Sea spray particles produce a new type of clouds having both continental and maritime properties; SSPs lead to convection invigoration

Free Access

Satellite Limb Observations of Unprecedented Forest Fire Aerosol in the Stratosphere

Adam E. Bourassa,  Landon A. Rieger,  Daniel J. Zawada,  Sergey Khaykin,  L. W. Thomason,  Doug A. Degenstein, 
  • Pages: 9510-9519
  • First Published: 08 August 2019
Key Points

  • Satellite limb measurements show that forest fires in August 2017 created a layer of persistent high-altitude aerosol in the stratosphere
  • The magnitude and extent of the aerosol has not been observed before in the satellite limb sounding era from a forest fire event
  • Agreement between limb scatter and occultation measurements is generally within 20% despite potential bias due to modified aerosol shape and composition

Free Access

Melting Layer Attenuation at Ka- and W-Bands as Derived From Multifrequency Radar Doppler Spectra Observations

Haoran Li,  Dmitri Moisseev, 
  • Pages: 9520-9533
  • First Published: 07 August 2019
Key Points

  • Ka-/W-band melting layer attenuation is derived
  • The melting layer attenuation is derived by analyzing X-, Ka-, and W-band radar Doppler spectra
  • Presented results are in good agreement with previously reported melting layer modeling results for rain rates smaller than 3 mm/hr

Free Access

Laboratory Experiments of Volcanic Ash Resuspension by Wind

V. Etyemezian,  J. A. Gillies,  L. G. Mastin,  A. Crawford,  R. Hasson,  A. R. Van Eaton,  G. Nikolich, 
  • Pages: 9534-9560
  • First Published: 07 August 2019
Key Points

  • Laboratory experiments show that volcanic ash deposits are highly wind erodible, with resuspension comparable to the most erodible soils
  • Humidity and the addition of liquid water impact ash resuspension in complex ways
  • Resuspendable particles are emitted at a rate proportional to the shear velocity raised to a power of 2.9–5.3

Free Access

Numerical Simulation of the Formation of a Large Lower Positive Charge Center in a Tibetan Plateau Thunderstorm

Fei Wang,  Xiaohua Deng,  Yijun Zhang,  Yajun Li,  Guangshu Zhang,  Liangtao Xu,  Dong Zheng, 
  • Pages: 9561-9593
  • First Published: 07 August 2019
Key Points

  • Low freezing level and weak convection in the Tibetan Plateau appear to be the root cause of the formation of the large LPCC
  • Inductive charging is an important complement to the lower dipole of the tripole charge structure; its impact is assessed quantitatively
  • Weak updraft is the key to produce the similar characteristics between Tibetan Plateau thunderstorms and Japanese winter storms

Free Access

Effect of Aerosols on the Ice Cloud Properties Over the Tibetan Plateau

Yuzhi Liu,  Shan Hua,  Rui Jia,  Jianping Huang, 
  • Pages: 9594-9608
  • First Published: 07 August 2019
Key Points

  • The inconsistent effects of aerosols on ice cloud properties between daytime and nighttime over the Tibetan Plateau are investigated
  • A potential relationship may exist between the aerosol index and ice cloud properties
  • Aerosols show dominant influence on daytime ICDR and nocturnal IWP and ICOD

Free Access

Characteristics of Heavy Particulate Matter Pollution Events Over Hong Kong and Their Relationships With Vertical Wind Profiles Using High-Time-Resolution Doppler Lidar Measurements

Yuanjian Yang,  Steve H.L. Yim,  Jim Haywood,  Martin Osborne,  Jazz C.S. Chan,  Zhaoliang Zeng,  Jack C.H. Cheng, 
  • Pages: 9609-9623
  • First Published: 29 July 2019
Key Points

  • Transboundary particulate matter pollution episodes (EP) were mainly caused by surface high pressure, cold front, dust storm, or typhoons
  • Vertical wind profiles show the different relationships between wind speed at various altitudes and surface particulate matter
  • The maximum transport height extended from surface to about 2.0 km or even higher in superregional and regional transboundary EPs

Free Access

Evaluation of Shallow-Cumulus Entrainment Rate Retrievals Using Large-Eddy Simulation

S. Drueke,  D. J. Kirshbaum,  P. Kollias, 
  • Pages: 9624-9643
  • First Published: 08 August 2019
Key Points

  • A new cumulus entrainment retrieval based on a turbulent kinetic energy similarity theory is presented
  • The first numerical verification of shallow-cumulus entrainment-retrieval methods, using large-eddy simulations as OSSEs, is provided
  • For the three retrievals under consideration, the mean absolute error ranged from around 20% to around 50%

Free Access

Formation of Arctic Stratocumuli Through Atmospheric Radiative Cooling

Lucien F. Simpfendoerfer,  Johannes Verlinde,  Jerry Y. Harrington,  Matthew D. Shupe,  Yao-Sheng Chen,  Eugene E. Clothiaux,  Jean-Christophe Golaz, 
  • Pages: 9644-9664
  • First Published: 16 July 2019
Key Points

  • Radiative transfer calculations suggest that Arctic stratocumuli can form naturally through clear-sky radiative cooling during all seasons
  • Properties of Arctic stratocumuli that form by radiative cooling are sensitive to the characteristics of the environment in which they form
  • These sensitivities might have important implications for the Arctic climate

Open Access

A 14-Year Climatology of Saharan Dust Emission Mechanisms Inferred From Automatically Tracked Plumes

Thomas Caton Harrison,  Richard Washington,  Sebastian Engelstaedter, 
  • Pages: 9665-9690
  • First Published: 08 August 2019
Key Points

  • A novel method is developed to identify emission mechanisms from automatically tracked dust plumes in the central and western Sahara
  • Dust plumes across 14 summers are tracked individually and classified probabilistically as low-level jet or cold pool outflow events
  • Eighty-two percent of dust pixels are associated with cold pool outflow events, but low-level jets dominate in the highly active Tidihelt Depression

Free Access

Atmospheric Instability Dominates the Long-Term Variation of Cloud Vertical Overlap Over the Southern Great Plains Site

Jiming Li,  Bida Jian,  Chuanfeng Zhao,  Yuxin Zhao,  Jing Wang,  Jianping Huang, 
  • Pages: 9691-9701
  • First Published: 16 August 2019
Key Points

  • Cloud overlap parameterization used to calculate the total cloud fraction (TCF) in climate models has still received far less attention
  • Dynamical factors are proven able to develop overlap parameterization and reduce the TCF bias over SGP site compared with previous one
  • Contribution calculation verifies that atmospheric instability contributes 70% of long-term variation of cloud overlap over SGP site

Composition and Chemistry

Free Access

Deposition of Organic and Black Carbon: Direct Measurements at Three Remote Stations in the Himalayas and Tibetan Plateau

Fangping Yan,  Cenlin He,  Shichang Kang,  Pengfei Chen,  Zhaofu Hu,  Xiaowen Han,  Sangita Gautam,  Caiqing Yan,  Mei Zheng,  Mika Sillanpää,  Peter A. Raymond,  Chaoliu Li, 
  • Pages: 9702-9715
  • First Published: 07 August 2019
Key Points

  • Large spatial variations in WIOC and BC deposition rates were found among three study stations due to complex local factors
  • In situ BC dry/wet deposition rates at study station were much higher than those from the CAM5 model due to the influence of mineral dust
  • Dry deposition rates of WIOC and BC were comparable or even higher than their wet deposition rates at the study stations

Open Access

Spatial Distributions and Seasonal Changes of Current-Use Pesticides from the North Pacific to the Arctic Oceans

Yuan Gao,  Hongyuan Zheng,  Yinyue Xia,  Min Chen,  Xiang-Zhou Meng,  Minghong Cai, 
  • Pages: 9716-9729
  • First Published: 08 August 2019
Key Points

  • 8 CUPs are reported firstly from the north Pacific to Arctic Ocean
  • Weak air-sea exchange is firstly proposed for 8 CUPs
  • Fluxes in the ocean are firstly estimated showing dramatic seasonal variations

Free Access

Aerosol pH Dynamics During Haze Periods in an Urban Environment in China: Use of Detailed, Hourly, Speciated Observations to Study the Role of Ammonia Availability and Secondary Aerosol Formation and Urban Environment

Guoliang Shi,  Jiao Xu,  Xurong Shi,  Baoshuang Liu,  Xiaohui Bi,  Zhimei Xiao,  Kui Chen,  Jie Wen,  Shihao Dong,  Yingze Tian,  Yinchang Feng,  Haofei Yu,  Shaojie Song,  Qianyu Zhao,  Jie Gao,  Armistead G. Russell, 
  • Pages: 9730-9742
  • First Published: 08 July 2019
Key Points

  • NH4+/NH3 and pH had a more nonlinear relationship during highly polluted periods, compared to less polluted periods
  • NH4+/NH3 (g) was important for stabilizing pH during the heavily polluted periods
  • SOR was higher than NOR under conditions with high acidity, light pollution, and low water content in the winter

Open Access

Modeling the Effect of Potential Nitric Acid Removal During Convective Injection of Water Vapor Over the Central United States on the Chemical Composition of the Lower Stratosphere

C. E. Clapp,  J. G. Anderson, 
  • Pages: 9743-9770
  • First Published: 07 August 2019
Key Points

  • Photochemical box model defines the vertically resolved response of the stratosphere chemical composition to convective perturbation
  • Effect of nitric acid removal on column ozone loss is dependent on favorability of initial conditions to heterogeneous chlorine activation
  • Nitric acid removal has the most impact on column ozone loss under conditions of mild favorability to chlorine activation