• Issue

    Journal of Geophysical Research: Atmospheres: Volume 123, Issue 18

    9977-10,230, 10231-10247, 10,248-10,811
    27 September 2018

Issue Information

Free Access

Issue Information

  • Pages: 9977-9979
  • First Published: 20 October 2018

Research Articles

Climate and Dynamics

Free Access

Momentum Flux Spectra of a Mountain Wave Event Over New Zealand

  • Pages: 9980-9991
  • First Published: 13 July 2018
Key Points

  • A multiscale spectrum of mountain waves was observed during a mesospheric mountain wave event over New Zealand
  • Temperatures of the mountain waves were derived using sodium density mixing ratios
  • Average momentum fluxes associated with observed mountain waves were large compared to zonal means

Open Access

Large-Amplitude Mountain Waves in the Mesosphere Accompanying Weak Cross-Mountain Flow During DEEPWAVE Research Flight RF22

  • Pages: 9992-10,022
  • First Published: 03 August 2018
Key Points

  • Weak orographic forcing and conducive propagation conditions at lower altitudes can yield large mountain wave amplitudes in the mesosphere
  • Mesospheric mountain waves can extend over 1,000 km around the source terrain and persist for many hours after forcing ceases
  • Mesospheric mountain waves having {lambda}h < 100 km can achieve very large momentum fluxes and exhibit strong overturning and instabilities

Free Access

A Large Eddy Model Study on the Effect of Overshooting Convection on Lower Stratospheric Water Vapor

  • Pages: 10,023-10,036
  • First Published: 06 August 2018
Key Points

  • Idealized simulations of overshooting tropical convection indicate net moistening of the lower stratosphere
  • Stratospheric moistening results from ice sublimation and gravity wave breaking near the tropopause
  • Effects of near-tropopause vertical wind shear are mainly through modulation of gravity wave breaking rather than turbulent mixing

Free Access

Using Isotopic and Geochemical Tracers to Determine the Contribution of Glacier-Snow Meltwater to Streamflow in a Partly Glacierized Alpine-Gorge Catchment in Northeastern Qinghai-Tibet Plateau

  • Pages: 10,037-10,056
  • First Published: 18 August 2018
Key Points

  • Glacier-snow meltwater and baseflow contribute 30% and 55% of warm-season streamflow in an alpine-gorge headwater with 3% glacial coverage
  • Dominance of glacier-overlying snow in meltwater sources may explain fluctuations of meltwater contribution with high peaks
  • Small glaciers and porous aquifers play a more important role than expected in hydrological regulation in alpine-gorge catchments

Free Access

Characteristics of Water-Heat Exchanges and Inconsistent Surface Temperature Changes at an Elevational Permafrost Site on the Qinghai-Tibet Plateau

  • Pages: 10,057-10,075
  • First Published: 27 August 2018
Key Points

  • Near-surface air and land surface temperatures increased significantly, but ground surface and soil temperatures increased insignificantly
  • Seasonal thawing layer deepened evidently by increasing of soil moisture content
  • Soil heat flux increased significantly as the trend of annual albedo decreased

Free Access

Impacts of Autumnal Eurasian Snow Cover on Predominant Modes of Boreal Winter Surface Air Temperature Over Eurasia

  • Pages: 10,076-10,091
  • First Published: 29 August 2018
Key Points

  • The midlatitude Eurasian zonal dipole pattern of November snow cover can exert an influence on the first mode of winter Eurasian surface air temperature
  • The second mode of winter Eurasian surface air temperature has a close relationship with the October snow cover to the east of the Ural Mountains
  • Snow cover-related wave activity plays a crucial role in the connection between the autumn snow cover and winter surface air temperature over the Eurasian Continent

Free Access

Interdecadal Change of the Impact of Eurasian Snow on Spring Precipitation Over Southern China

  • Pages: 10,092-10,108
  • First Published: 31 August 2018
Key Points

  • The spring precipitation over southern China shows a pronounced climate change at 1987
  • The spring precipitation over southern China is significantly correlated with spring SCE anomalies northwest of Lake Baikal
  • The SCE anomalies around Lake Baikal contributed to the spring precipitation in the form of EOF1 and EOF2 mode before and after 1987

Free Access

Falling Snow Radiative Effects Enhance the Global Warming Response of the Tropical Pacific Atmosphere

  • Pages: 10,109-10,124
  • First Published: 31 August 2018
Key Points

  • Radiative effect associated with precipitating ice (snow) is not considered in most GCMs
  • The impacts of snow radiative effects under global warming are investigated in a 1pctCO2 simulation
  • Changes in tropical Pacific climate are enhanced when the snow radiative effect is considered

Free Access

Sudden Stratospheric Warming Formation in an Idealized General Circulation Model Using Three Types of Tropospheric Forcing

  • Pages: 10,125-10,139
  • First Published: 31 August 2018
Key Points

  • Wave 1 and wave 2 tropospheric heating perturbations cause large numbers of both split and displacement SSWs
  • SSWs are produced both as a result of anomalous tropospheric wave activity and due to internal stratospheric processes
  • Surface signatures of splits and displacements are found to be different when the model is forced by wave 1 heating but not wave 2

Free Access

Diurnal Cycle of Precipitation and Cloud Clusters in the MJO and ITCZ Over the Indian Ocean

  • Pages: 10,140-10,161
  • First Published: 27 August 2018
Key Points

  • Satellite and radar data show a nighttime rain max with noticeable differences between the MJO and ITCZ over the equatorial Indian Ocean
  • The nighttime precipitation max in the ITCZ is more pronounced than in the MJO, which is associated with large long-lasting cloud clusters
  • Radar data show a secondary afternoon rain max in the equatorial region when diurnal cycle of SST is > 0.5 °C and wind speed is <5 m/s

Open Access

The Influences of the Arctic Troposphere on the Midlatitude Climate Variability and the Recent Eurasian Cooling

  • Pages: 10,162-10,184
  • First Published: 30 August 2018
Key Points

  • The Arctic troposphere impacts the large-scale atmospheric circulation and climate variability at midlatitudes
  • The modulation of Siberian High by Arctic troposphere impacts the climate variability in south Siberia and East Asia
  • The Arctic troposphere is closely associated with the recent cooling trends over Northern Eurasia

Free Access

Precipitation Partitioning in Multiscale Atmospheric Simulations: Impacts of Stability Restoration Methods

  • Pages: 10,185-10,201
  • First Published: 31 August 2018
Key Points

  • Precipitation partitioning is found to be biased toward subgrid-scale precipitation in a seasonal simulation using 12-km grids
  • As compared to default method, a new convective adjustment time scale method is found to partition total precipitation more realistically
  • The new method yielded better precipitation estimates across various spatial scales demonstrating its scale awareness

Free Access

Potential Impacts of Climate Variation on Potato Field Evapotranspiration: Field Experiment and Numerical Simulation of Potato Water Use in an Arid Site

  • Pages: 10,202-10,214
  • First Published: 31 August 2018
Key Points

  • Annual temperature and ET0 have significant increasing trends during the last 60 years
  • A HYDRUS-1D model for potato water use was successfully calibrated and validated with field measurements
  • Increase of atmospheric temperature in future would lead to the increase of actual potato ET and increase of water use for potato growth

Free Access

Extreme Climate Event Changes in China in the 1.5 and 2 °C Warmer Climates: Results From Statistical and Dynamical Downscaling

  • Pages: 10,215-10,230
  • First Published: 30 August 2018
Key Points

  • Statistical and dynamical downscaling methods are used to analyze extreme climate event changes in China in the 1.5 and 2 °C warmer climates
  • Bias correction methods aimed at correcting the climatology of temperatures and precipitation are applied to both models
  • Changing patterns of temperature indices are similar between the two models in the two warmer climates

Free Access

Comparison of Subseasonal-to-Seasonal Model Forecasts for Major Stratospheric Sudden Warmings

  • Pages: 10231-10247
  • First Published: 30 August 2018
Key Points

  • Some of the S2S models of interest forecast the five target MSSWs better than others
  • The vortex split MSSWs are more difficult to forecast than the vortex displacement MSSWs
  • The forecasts vary with lead times and models in stratospheric polar vortex and tropospheric planetary waves

Free Access

Precipitation Redistribution Method for Regional Simulations of Radioactive Material Transport During the Fukushima Daiichi Nuclear Power Plant Accident

  • Pages: 10,248-10,259
  • First Published: 31 August 2018
Key Points

  • Wet deposition of 137Cs simulated by the regional isotope tracer model is redistributed in correspondence with observed precipitation
  • To reproduce wet deposition, both high-resolution boundary condition in the model and highly accurate simulated precipitation are necessary
  • In our results, validation is evaluated differently depending on the time boundary of the measurement of 137Cs fallouts

Free Access

A Modeling Study of Narrow Electric Field Signatures Produced by Lightning Strikes to Tall Towers

  • Pages: 10,260-10,277
  • First Published: 15 August 2018
Key Points

  • Electric field signatures of lightning strikes to tall towers tend to exhibit earlier zero crossing compared to strikes to shorter objects
  • Such signatures cannot be reproduced by traditional models and require a narrower input current waveform or its faster decay with height
  • For towers with height >100 m, contribution to the total electric field peak from the tower is greater than that from the lightning channel

Free Access

Evaluation of Freshwater Flow From Rivers to the Sea in CMIP5 Simulations: Insights From the Congo River Basin

  • Pages: 10,278-10,300
  • First Published: 31 August 2018
Key Points

  • Evaluations of river discharge into oceans from CMIP5 experiment are lacking, and a novel approach is here applied for the Congo River
  • Most CMIP5 models overestimate the discharge of the Congo River, while the best performing models fail to capture the seasonal timing
  • Using indicators of abnormal low-flow periods' attributes, the simulated discharge provides biased representation of hydrological droughts

Free Access

Toward a Satellite-Derived Climatology of Blowing Snow Over Antarctica

  • Pages: 10,301-10,313
  • First Published: 03 September 2018
Key Points

  • A first satellite-derived climatology of blowing snow over Antarctica is presented
  • Blowing snow frequency exceeds 70% over large regions of East Antarctica
  • Some areas of East Antarctic show a statistically significant increasing trend in blowing snow frequency

Free Access

Did Smoke From City Fires in World War II Cause Global Cooling?

  • Pages: 10,314-10,325
  • First Published: 31 August 2018
Key Points

  • Between 3 February and 9 August 1945, an area of 461 km2 in 69 Japanese cities, including Hiroshima and Nagasaki, was burned during the U.S. B-29 Superfortress air raids, producing massive amounts of smoke
  • Because of multiple uncertainties in smoke injected to the stratosphere, solar radiation observations, and surface temperature observations, it is not possible to formally detect a cooling signal from World War II smoke
  • These results do not invalidate nuclear winter theory that much more massive smoke emissions from nuclear war would cause large climate change and impacts on agriculture

Free Access

Broadband RF Interferometric Mapping and Polarization (BIMAP) Observations of Lightning Discharges: Revealing New Physics Insights Into Breakdown Processes

  • Pages: 10,326-10,340
  • First Published: 06 September 2018
Key Points

  • A new broadband radio frequency interferometry and polarization system for lightning study is introduced
  • Impulsive pulses are observed often linearly polarized while occasional pulses elliptically polarized, related to conventional/relativistic breakdowns
  • Lightning is initiated with fast positive streamers that show no evidence of relativistic process

Free Access

Combining ASCAT and NEXRAD Retrieval Analysis to Explore Wind Features of Mesoscale Oceanic Systems

  • Pages: 10,341-10,360
  • First Published: 06 September 2018
Key Points

  • ASCAT is able to identify surface features that are of key importance for the evolution of the mesoscale systems
  • The complementarity of ASCAT and radar wind retrievals provide additional information to assess the low-level conditions within the precipitating system
  • Only small amounts of vertically integrated ice and liquid water were found for unflagged ASCAT winds, as expected

Free Access

Objective Quantification of Convective Clustering Observed During the AMIE/DYNAMO Two-Day Rain Episodes

  • Pages: 10,361-10,378
  • First Published: 30 August 2018
Key Points

  • Objective scalar metrics designed to quantify degrees of clustering are applied to the AMIE/DYNAMO ground-based radar observations
  • The AMIE/DYNAMO two-day rain events feature two distinct phases of convective clustering
  • The metric based on nearest-neighbor distance of convective entities is skillful in capturing both phases of convective clustering

Free Access

Effect of Air-Sea Environmental Conditions and Interfacial Processes on Extremely Intense Typhoon Haiyan (2013)

  • Pages: 10,379-10,405
  • First Published: 11 September 2018
Key Points

  • It was the atmospheric conditions that determined the small size and fast translation speed of simulated Haiyan
  • Faster translation speed and less sea surface cooling beneath the frictional convergence area led to Haiyan's extraordinary intensity
  • Understanding of the effect of ocean and air-sea processes on TCs serves as a guideline for improvement of the coupled model

Free Access

What Controls ENSO Teleconnection to East Asia? Role of Western North Pacific Precipitation in ENSO Teleconnection to East Asia

  • Pages: 10,406-10,422
  • First Published: 13 September 2018
Key Points

  • The ENSO impacts over East Asia can be largely explained by a combination of WNP and equatorial CP precipitation forcing
  • The WNP precipitation is a key contributor to the ENSO's impacts on the East Asian climate
  • The diverse regional impacts among different ENSO events can be explained by the relative roles of the WNP and equatorial CP precipitation

Open Access

Validating the Integrated Multisatellite Retrievals for Global Precipitation Measurement in Terms of Diurnal Variability With Hourly Gauge Observations Collected at 50,000 Stations in China

  • Pages: 10,423-10,442
  • First Published: 11 September 2018
Key Points

  • IMERG precipitation has a low probability of detection (POD≈50%) and a high false alarm ratio (FAR≈50%)
  • Inverse correlation between diurnal cycles of frequency and intensity are found, making an offset to the better estimate of amount
  • Inhomogeneity of merged data sources in IMERG results in the systematic biases in its diurnal cycle

Free Access

Interannual Variability of Atmospheric Conditions and Surface Melt in Greenland in 2000–2014

  • Pages: 10,443-10,463
  • First Published: 13 September 2018
Key Points

  • Four melt variables: number of melt days, cumulative and maximum melt extent, and the amount of melt have different interannual variations
  • Vertically integrated column water is correlated with the number of melt days, cumulative melt extent, and modeled melt amount
  • The only forcing variable found correlating (negatively) with the maximum melt extent was the occurrence of northeasterly air-mass origin

Aerosol and Clouds

Free Access

Cloud Top Phase Distributions of Simulated Deep Convective Clouds

  • Pages: 10,464-10,476
  • First Published: 29 August 2018
Key Points

  • Cloud top phase distributions of deep convective clouds differ systematically from in-cloud phase distributions
  • The phase distributions contain fingerprints of primary and secondary ice formation processes
  • Coarse graining and covariation of the cloud dynamics diminish these fingerprints of microphysical processes

Free Access

Cloud Microphysical Factors Affecting Simulations of Deep Convection During the Presummer Rainy Season in Southern China

  • Pages: 10,477-10,505
  • First Published: 18 July 2018
Key Points

  • Biases in model clouds and rain arise from the partitioning of water between hydrometeor species
  • A small subset of parameterization changes can reproduce the variations between microphysics schemes
  • The number of prognostic variables has less effect than the choice of subgrid-scale closures

Open Access

Background Free-Tropospheric Ice Nucleating Particle Concentrations at Mixed-Phase Cloud Conditions

  • Pages: 10,506-10,525
  • First Published: 21 August 2018
Key Points

  • Background free-tropospheric INP concentrations at 242 K in the immersion mode measured at the High Altitude Research Station Jungfraujoch reach a maximum interquartile range of 10 INP/stdL
  • Agreement with INP concentrations under similar measurement conditions but in different locations in the free troposphere also suggests ~10 INP/stdL regardless of location
  • No seasonal variability in INP concentrations in the background free troposphere is observed at the High Altitude Research Station Jungfraujoch

Free Access

Larger Submicron Particles for Emissions With Residential Burning in Wintertime San Joaquin Valley (Fresno) than for Vehicle Combustion in Summertime South Coast Air Basin (Fontana)

  • Pages: 10,526-10,545
  • First Published: 30 July 2018
Key Points

  • In Fresno, residential wood burning contributions resulted in larger mass (300-460 nm) and number (70-150 nm) mode diameters
  • In Fontana, vehicle emissions and secondary aerosol components produced smaller mass (120-310 nm) and number (30-50 nm) mode diameters
  • Surface-limited processes in Fontana and volume-limited aqueous reactions in Fresno contributed to secondary organic mass

Free Access

Parameterization of In-Cloud Aerosol Scavenging Due to Atmospheric Ionization: Part 3. Effects of Varying Droplet Radius

  • Pages: 10,546-10,567
  • First Published: 21 August 2018
Key Points

  • Our new and simplified parameterization provides accurate representation of our new and comprehensive simulations of in-cloud scavenging
  • Our modified analytic solution varies the effective droplet collision radius to represent the short-range image force, intercept, and flow around the particle
  • We have extended the range of parameterization to particle radius up to 10 μm, particle density 2,000 kg/m3, and droplet radius 15 μm

Free Access

High Summertime Aerosol Loadings Over the Arabian Sea and Their Transport Pathways

  • Pages: 10,568-10,590
  • First Published: 03 September 2018
Key Points

  • Mineral dust aerosols dominate (38–54%) the extremely high aerosol loadings over the Arabian Sea in summer
  • These dust aerosols are transported from the Middle East and the Thar Desert by cyclonic (at altitude of 500 m) and anticyclonic (5000 m) flows
  • Dust aerosols show a strong interdecadal variability over the Arabian Sea and the Middle East during 2000–2016

Free Access

Characteristics of Optically Thin Coastal Florida Cumuli Derived From Surface-Based Lidar Measurements

  • Pages: 10,591-10,605
  • First Published: 06 September 2018
Key Points

  • Optical depth and sizes of small shallow cumuli are characterized by a micropulse lidar during a 10-week period
  • Thirteen percent of sampled clouds have optical depths <1. These clouds typically reside below 1 km and are <60 m thick and <100 m wide
  • These radiatively important clouds are too small for robust characterization from space

Aerosol and Clouds

Free Access

Method to Estimate Water Vapor Supersaturation in the Ambient Activation Process Using Aerosol and Droplet Measurement Data

  • Pages: 10,606-10,619
  • First Published: 05 August 2018
Key Points

  • Ambient water vapor supersaturation can be calculated using aerosol and cloud measurements
  • Low supersaturations less than 0.05% were found for a dense radiation fog in the North China Plain
  • Significant contribution of unactivated haze particles to the total fog droplets was found in the heavily polluted fog episode

Composition and Chemistry

Free Access

Regional Similarities and NOx-Related Increases in Biogenic Secondary Organic Aerosol in Summertime Southeastern United States

  • Pages: 10,620-10,636
  • First Published: 04 August 2018
Key Points

  • Aerosol concentration and composition are largely similar at two different forested sites during summertime in the southeastern United States
  • FTIR of ambient biogenic SOA factors are similar to isoprene and monoterpene chamber experiment, supporting NOx-related oxidation pathways
  • NOx increases biogenic SOA by 0.5 ± 0.1 μg/m3 for CTR-LO-OOA and 1.0 ± 0.3 μg/m3 for CTR-BOA for each ppb NOx above 1 ppb at Centreville but not at Look Rock (where NOx was usually below 1 ppb)

Free Access

Vertical Profiles of Tropospheric Ozone From MAX-DOAS Measurements During the CINDI-2 Campaign: Part 1—Development of a New Retrieval Algorithm

  • Pages: 10,637-10,670
  • First Published: 21 August 2018
Key Points

  • Problems of MAX-DOAS retrievals of tropospheric O3 are clarified and mostly solved
  • New MAX-DOAS retrieval methods of vertical profiles of tropospheric O3 are developed
  • The feasibility of the new methods is proven and deficiencies are described for future research

Free Access

Application of an LAI Inversion Algorithm Based on the Unified Model of Canopy Bidirectional Reflectance Distribution Function to the Heihe River Basin

  • Pages: 10,671-10,687
  • First Published: 30 August 2018
Key Points

  • LAI retrieval algorithms based on a unified model can be applied to various vegetation conditions
  • The ratio of the sky scattering and the clumping index are of great importance for LAI retrieval
  • Leaf reflectance holds the biggest impact on the reflectance ascertained from satellite images, which need to be determined accurately

Free Access

Simultaneous Rayleigh-Scatter and Sodium Resonance Lidar Temperature Comparisons in the Mesosphere-Lower Thermosphere

  • Pages: 10,688-10,706
  • First Published: 30 August 2018
Key Points

  • First simultaneous temperature comparisons from collocated Rayleigh and Na lidars were made over one annual cycle
  • Good agreement was found in the two lidars' temperatures from 85 to 95 km
  • Significant temperature differences were found above 95 km and below 85 km

Free Access

Organic Aerosol Particle Chemical Properties Associated With Residential Burning and Fog in Wintertime San Joaquin Valley (Fresno) and With Vehicle and Firework Emissions in Summertime South Coast Air Basin (Fontana)

  • Pages: 10,707-10,731
  • First Published: 30 July 2018
Key Points

  • Oxidized organic and amine fragment concentrations were higher on high-fog days than on low-fog days at Fresno
  • Uncommon trace organic fragments (m/z 27 and m/z 63), nitrate, sulfate, and single-particle types associated with fireworks persisted at high concentrations at Fontana for 5 days after emission
  • Nitrate-related and other organic aerosol mass factors were largely on different particle types at Fresno but were mixed at Fontana

Free Access

Modeling Regional Pollution Transport Events During KORUS-AQ: Progress and Challenges in Improving Representation of Land-Atmosphere Feedbacks

  • Pages: 10,732-10,756
  • First Published: 27 August 2018
Key Points

  • SMAP assimilation most strongly modifies short-term regional atmospheric modeling skill in East Asia transitional climate zones
  • SMAP assimilation improves water vapor and carbon monoxide transport from northern central China to South Korea
  • SMAP assimilation impact on air quality modeling skill in part relies on the quality of model chemical IC/LBC and various emission inputs

Open Access

Changes in the Isotopic Signature of Atmospheric Nitrous Oxide and Its Global Average Source During the Last Three Millennia

  • Pages: 10,757-10,773
  • First Published: 31 August 2018
Key Points

  • The isotopic composition of nitrous oxide in the preindustrial period was determined with high precision
  • The isotopic composition of nitrous oxide changed during the transition to the industrial period
  • The temporal evolution of δ15Nav is different from that of δ18O implying a decoupling of sources over the industrial period

Free Access

Changes in Global Tropospheric OH Expected as a Result of Climate Change Over the Last Several Decades

  • Pages: 10,774-10,795
  • First Published: 05 September 2018
Key Points

  • Trends in OH between 1980 and 2015 were modeled using observed ozone column, water vapor, methane, model-simulated NOx, and Hadley cell width
  • Most (94%) of the expected, CH4-induced decline in OH was offset by increases due to H2O, NOx, overhead O3, and tropical widening (in order of impact)
  • Trends depend on time frame examined; NOx and overhead O3 drive most of OH increase between 1980 and 2005

Free Access

Decadal Trends in Wet Sulfur Deposition in China Estimated From OMI SO2 Columns

  • Pages: 10,796-10,811
  • First Published: 11 September 2018
Key Points

  • Wet SO42− deposition is estimated from OMI PBL SO2 columns in China
  • The average wet SO42− deposition is 10.4 kg S · ha−1 · year−1 across China
  • Wet SO42− deposition significantly decreased in the NC, CC, and SC regions from 2005 to 2016