• Issue

    Journal of Geophysical Research: Atmospheres: Volume 123, Issue 21

    11,805-12,488
    16 November 2018

Issue Information

Free Access

Issue Information

  • Pages: 11,805-11,807
  • First Published: 04 December 2018

Commentary

Climate and Dynamics

Free Access

How Important Is Humidity in Heat Stress?

  • Pages: 11,808-11,810
  • First Published: 23 October 2018
Key Points

  • It is important to distinguish similar-sounding variables for characterizing heat
  • Wet-bulb temperature is very humidity sensitive, WBGT less so, and apparent temperature the least
  • WBGT is a more appropriate measure of present-day heat stress, but wet bulb is relevant to tolerance of hotter climates

Research Articles

Climate and Dynamics

Free Access

Characteristics of Atmospheric Wave-Induced Laminae Observed by Ozonesondes at the Southern Tip of South America

  • Pages: 11,811-11,829
  • First Published: 15 October 2018
Key Points

  • Ozonesonde data obtained at southern Patagonia were used to quantify the contribution of gravity waves and Rossby waves to ozone laminae
  • Rossby waves played a dominant role in creating ozone laminae, but the role of gravity waves was not negligible
  • Rossby wave-induced ozone variability was greater inside the polar vortex than outside or near the edge

Free Access

How Do Weak Tropical Cyclones Produce Heavy Rainfall When Making Landfall Over China

  • Pages: 11,830-11,848
  • First Published: 22 October 2018
Key Points

  • Weak tropical cyclones (TCs) can also produce heavy rainfall within a limited region during landfall
  • Upper-level divergence and vertical wind shear may increase for a weak TC when located on the right side of the upper easterly jet entrance
  • Asymmetric heavy rainfall from weak TC is caused by strong updraft and upper-level divergence over the downshear side

Free Access

Simulations of Zonal Mean Gravity Wave Drag Short-Term Variability in the Southern Hemisphere Mesosphere

  • Pages: 11,849-11,860
  • First Published: 23 October 2018
Key Points

  • Short-term (<30-day) zonal mean gravity wave drag variability in the SH mesosphere is investigated
  • Short-term variability in SH is largest during austral winter-spring and is nearly as large as in the NH during boreal winter
  • Gravity wave drag variability leads to short-term variability in mesosphere circulation and chemistry

Free Access

Evaluating Climate Sensitivity to CO2 Across Earth's History

  • Pages: 11,861-11,874
  • First Published: 22 October 2018
Key Points

  • Climate sensitivity to CO2 varied significantly across Earth's history
  • The adjusted radiative forcing from CO2 increases at high concentrations
  • Cloud albedo feedback cause an abrupt transition in climate for warming atmospheres

Open Access

Improving the Reliability and Added Value of Dynamical Downscaling via Correction of Large-Scale Errors: A Norwegian Perspective

  • Pages: 11,875-11,888
  • First Published: 23 October 2018
Key Points

  • The tested bias correction method reduces the North Atlantic storm track bias inherited from the GCM
  • The main improvement in storm track arises with the 3-D atmospheric bias correction, not from the SST corrections
  • For western Norway the bias correction leads to wetter wet years and drier dry years

Free Access

Temporal Trends in Absolute and Relative Extreme Temperature Events Across North America

  • Pages: 11,889-11,898
  • First Published: 24 October 2018
Key Points

  • Extreme heat events are increasing and extreme cold events are decreasing across the United States and Canada
  • Extreme temperature events relative to the time of the year are also changing in frequency

Free Access

Polar Jet Associated Circulation Triggered a Saharan Cyclone and Derived the Poleward Transport of the African Dust Generated by the Cyclone

  • Pages: 11,899-11,917
  • First Published: 10 October 2018
Key Points

  • A meandering polar jet initiated cyclogenesis over North Africa which caused a big dust storm in April 2011
  • The meandering polar jet favored the transport of the uplifted dust toward the Arctic through cut-off low formation
  • Ice melt occurred over southeastern Greenland during this event

Free Access

A Numerical Study of Gravity Wave Propagation Characteristics in the Stratospheric Thermal Duct

  • Pages: 11,918-11,937
  • First Published: 19 October 2018
Key Points

  • The primary parameters of the ducted modes in a given thermal duct are mainly determined by the horizontal wavelength of the initial wave
  • The dynamics of the standing wave in the duct region are related to the initial wave forcing
  • The decay rate of the total energy in the thermal duct is largely affected by the initial wave forcing

Free Access

Joint Dependence Between River Water Temperature, Air Temperature, and Discharge in the Yangtze River: The Role of the Three Gorges Dam

  • Pages: 11,938-11,951
  • First Published: 23 October 2018
Key Points

  • A probabilistic method to examine the dependence of water/air temperature and discharge is described
  • The dependence of water/air temperature and discharge at Yichang site are strongly affected by the dam
  • The method also enables the risk estimation for different water temperature events

Open Access

Modulation of the ENSO on Winter Aerosol Pollution in the Eastern Region of China

  • Pages: 11,952-11,969
  • First Published: 19 October 2018
Key Points

  • ENSO tends to cause anomalies of aerosol pollution and distribution by modulating East Asian winter monsoon
  • El Niño and La Niña events have the roughly opposite impact on winter aerosols in ERC, especially in northern China
  • Anomalies in dynamic and thermodynamic conditions associated with ENSO lead to uncertainties in its effect on aerosols over southern China

Free Access

Solar Effects on the Atmospheric Electric Field During 2010–2015 at Low Latitudes

  • Pages: 11,970-11,979
  • First Published: 23 October 2018
Key Points

  • Solar flare photons are unlikely to affect the global atmospheric electric circuit at low latitudes
  • Solar proton events enhance the conductivity above thunderstorms resulting in an atmospheric electric field increase in fair weather regions at low latitudes
  • Ground level enhancement that occurred on 17 May 2012 was capable to produce an atmospheric electric field decrease in fair weather conditions at low-latitude regions

Free Access

Comparison of the Fast and Slow Climate Response to Three Radiation Management Geoengineering Schemes

  • Pages: 11,980-12,001
  • First Published: 23 October 2018
Key Points

  • We use NCAR CESM to simulate the climate response to stratospheric aerosol increase, marine cloud brightening, and cirrus cloud thinning
  • To offset CO2-induced global mean warming, different geoengineering schemes need different amounts of radiative forcing
  • Different geoengineering schemes produce different precipitation changes that are mainly associated with different fast adjustments

Free Access

Seasonal Evolution of Stratosphere-Troposphere Coupling in the Southern Hemisphere and Implications for the Predictability of Surface Climate

  • Pages: 12,002-12,016
  • First Published: 22 October 2018
Key Points

  • The seasonal evolution of stratosphere-troposphere coupling in the Southern Hemisphere (SH) is explored and updated using height-time domain EOF analysis
  • Variability in the SH tropospheric annular mode in spring-summer is significantly linked to the extratropical vortex as high as the stratopause and as early as June

Open Access

Distinct Influences of Land Cover and Land Management on Seasonal Climate

  • Pages: 12,017-12,039
  • First Published: 23 October 2018
Key Points

  • Climate impacts of irrigation and land cover change are comparable in magnitude but opposite in sign over some regions, especially Asia
  • Contrasting or amplifying effects of irrigation relative to land cover change extend beyond the growing season and can vary by season
  • Local and remote impacts are linked to changes in moisture flux, surface and upper-level temperature gradients, and regional circulations

Free Access

Acoustical Measurement of Natural Lightning Flashes: Reconstructions and Statistical Analysis of Energy Spectra

  • Pages: 12,040-12,065
  • First Published: 30 October 2018
Key Points

  • 3-D acoustic reconstructions of thunder in the range of [0.1 - 180] Hz allow separation between return strokes and intraclouds
  • Spectral analysis of several return strokes shows the production of an intense infrasound content
  • Statistical study on return strokes spectra shows a link between acoustic energy and stroke distance as well as one electrical parameter

Free Access

Simple Parameterization of Aerodynamic Roughness Lengths and the Turbulent Heat Fluxes at the Top of Midlatitude August-One Glacier, Qilian Mountains, China

  • Pages: 12,066-12,080
  • First Published: 26 October 2018
Key Points

  • A parameterization method is proposed to easily estimate aerodynamic roughness lengths (z0m) at glacier surfaces, using the bulk and profile methods
  • Hourly z0m values in the transitional range affected slightly by snowdrift are determined with the analysis of the parameterizations for z0m on the August-one glacier
  • The discrepancy in turbulent heat fluxes for different periods is closely related to the variations in main meteorological variables

Free Access

Impacts of Synoptic and Local Factors on Heat Wave Events Over Southeastern Region of Korea in 2015

  • Pages: 12,081-12,096
  • First Published: 25 October 2018
Key Points

  • Heat wave events for 1980–2016 defined by spatiotemporal criteria are classified into three clusters
  • Surface air temperature increased over the lee side because the Foehn effect was induced by flow blocking and the drawdown of dry air
  • The depletion of initial soil moisture increased surface air temperature by reducing the latent heat flux over Ulsan

Free Access

A Numerical Study of Convective-Scale Structures in the Outer Cores of Sheared Tropical Cyclones: 1. Updraft Traits in Different Vertical Wind Shear Magnitudes

  • Pages: 12,097-12,116
  • First Published: 31 October 2018
Key Points

  • An increase in the shear value leads to more significant downshear-left nascence of outer-core updrafts
  • The height of stronger vertical velocity in convective bursts decreases with the increasing shear
  • No relationships between environmental ingredients and the likelihood of outer-core updraft strength are found

Aerosol and Clouds

Open Access

Post Cold Frontal Clouds at the ARM Eastern North Atlantic Site: An Examination of the Relationship Between Large-Scale Environment and Low-Level Cloud Properties

  • Pages: 12,117-12,132
  • First Published: 09 October 2018
Key Points

  • Post cold frontal clouds at the ARM Eastern North Atlantic site are on average thicker, higher, and colder than clouds in non-post cold front subsidence periods
  • Weaker inversions and stronger surface temperature contrast help explain post cold frontal cloud characteristics
  • Low-level cloud boundaries are strongly correlated with the cold air outbreak parameter M in all subsidence periods at the ENA

Free Access

Large Increases in Primary Trimethylaminium and Secondary Dimethylaminium in Atmospheric Particles Associated With Cyclonic Eddies in the Northwest Pacific Ocean

  • Pages: 12,133-12,146
  • First Published: 12 October 2018
Key Points

  • Unexpected increases in aminium ions in atmospheric particles are observed over the oligotrophic open ocean
  • The maximum concentrations of particulate aminium ions are observed close to the largest observed cyclonic eddy at high wind speeds
  • We construct a novel conceptual model to interpret the unexpected increases in particulate aminium ions related to cyclonic eddies

Open Access

Observations and Cloud-Resolving Modeling of Haboob Dust Storms Over the Arabian Peninsula

  • Pages: 12,147-12,179
  • First Published: 12 October 2018
Key Points

  • An online convective-permitting WRF-Chem model successfully captured a prolonged convective event and associated haboobs over the Arabian Peninsula
  • A 25 Tg of dust were emitted during the 10-day period of convective activity, 40% of which was removed by rainfall
  • When local dust production was high, the WRF-Chem model underestimated the PM10 mass concentration by a factor of 1.5-2

Free Access

Toward a Broadband Parameterization Scheme for Estimating Surface Solar Irradiance: Development and Preliminary Results on MODIS Products

  • Pages: 12,180-12,193
  • First Published: 12 October 2018
Key Points

  • A new broadband SSI parameterization scheme is developed
  • The parameterization scheme is efficient and easy to implement
  • Validation results show a comparable accuracy with other approaches

Open Access

Terrain-Enhanced Precipitation Processes Above the Melting Layer: Results From OLYMPEX

  • Pages: 12,194-12,209
  • First Published: 18 October 2018
Key Points

  • Enhancement of precipitation processes is found in radar reflectivity data above the melting level over complex terrain
  • Enhancement aloft is especially pronounced during periods of high vapor transport, onshore flow, and neutral low-level static stability
  • Satellite-borne radar detects this enhancement so that reliable estimates of precipitation over remote mountain regions are possible

Free Access

Heterogeneous Ice Nucleation in the Tropical Tropopause Layer

  • Pages: 12,210-12,227
  • First Published: 21 September 2018
Key Points

  • Effective heterogeneous ice nuclei can alter TTL cirrus microphysical properties and occurrence frequencies
  • Using abundant effective IN (e.g., dust or sugar/acid organics) in TTL cirrus simulations results in disagreement with observations
  • Ice nuclei can increase or decrease TTL cirrus occurrence frequency

Free Access

Thermal and Microphysical Effects of Ice Clouds on Torrential Rainfall Over Northern China

  • Pages: 12,228-12,235
  • First Published: 24 October 2018
Key Points

  • The inclusion of the thermal effects of ice clouds weakens daytime rainfall mainly by the inclusion of latent-heat effects of ice clouds
  • The inclusion of the thermal effects of ice clouds increases nighttime rainfall mainly by the inclusion of radiative effects of ice clouds
  • The inclusion of microphysical effects of ice clouds increases rainfall directly by the inclusion of deposition

Open Access

A Modeling Study on the Sensitivities of Atmospheric Charge Separation According to the Relative Diffusional Growth Rate Theory to Nonspherical Hydrometeors and Cloud Microphysics

  • Pages: 12,236-12,252
  • First Published: 22 September 2018
Key Points

  • Nonspherical hydrometeors and anisotropic diffusional growth can influence collisional charge separation
  • The importance of local diffusional graupel growth can be masked by ice multiplication
  • Interpretation and application of traditional RDGR plots are complicated by strong hydrometeor size and shape sensitivities

Free Access

Improving Cloud Optical Property Retrievals for Partly Cloudy Pixels Using Coincident Higher-Resolution Single Band Measurements: A Feasibility Study Using ASTER Observations

  • Pages: 12,253-12,276
  • First Published: 09 October 2018
Key Points

  • Cloud property retrievals for partially cloudy pixels can be significantly biased
  • Based on simple assumptions, the average of the overcast subpixel reflectance can be estimated for MBL cloud scenes
  • The estimations yield retrievals, which are unbiased by the clear-sky component of the pixels

Open Access

Direct Measurements of Dry and Wet Deposition of Black Carbon Over a Grassland

  • Pages: 12,277-12,290
  • First Published: 21 October 2018
Key Points

  • First direct measurements of black carbon by SP2 and eddy covariance over grassland suggest a dry deposition velocity of 0.3 ± 0.2 mm/s
  • Wet deposition is the dominant process of black carbon loss, but dry deposition can significantly impact black carbon lifetime
  • Measurements suggest that current atmospheric model parameterizations capture the atmospheric lifetime of black carbon reasonably well

Free Access

An Improved High-Spatial-Resolution Aerosol Retrieval Algorithm for MODIS Images Over Land

  • Pages: 12,291-12,307
  • First Published: 22 October 2018
Key Points

  • An I-HARLS AOD retrieval algorithm (1 km) for MODIS images is proposed over land
  • I-HARLS AOD retrievals agree well with AERONET AOD measurements over land
  • I-HARLS AOD retrievals are overall better and less biased than MOD04_3K AOD products

Free Access

Stratospheric Aerosols, Polar Stratospheric Clouds, and Polar Ozone Depletion After the Mount Calbuco Eruption in 2015

  • Pages: 12,308-12,331
  • First Published: 27 October 2018
Key Points

  • The simulated sulfate aerosol are generally consistent with balloon and satellite data, but simulated PSCs over-denitrify the Antarctic
  • The simulated volcanic sulfate aerosol from the Mount Calbuco eruption penetrated into the Antarctic vortex in May 2015 and thereafter
  • Volcanic sulfate aerosol from Mount Calbuco and previous eruptions causes the ozone hole to develop earlier in the year and has a larger area

Free Access

The Great Slave Lake PyroCb of 5 August 2014: Observations, Simulations, Comparisons With Regular Convection, and Impact on UTLS Water Vapor

  • Pages: 12,332-12,352
  • First Published: 23 October 2018
Key Points

  • Observations and simulations of a pyroCb show a distinct convective lifecycle from meteorological Cb
  • A-Train observations show ice sublimation in the aging plume over five days and enhanced localized water vapor in the stratosphere
  • Model tests show pyroCb dynamics is dominated by surface heat flux, with lesser dependence on aerosol loading and midlevel instability.

Free Access

Seasonal Variations in High Arctic Free Tropospheric Aerosols Over Ny-Ålesund, Svalbard, Observed by Ground-Based Lidar

  • Pages: 12,353-12,367
  • First Published: 26 October 2018
Key Points

  • The aerosol concentration in the free troposphere was highest in late spring and summer and lowest in late summer and fall
  • The aerosol particle depolarization ratio in the free troposphere was largest in winter and spring and smallest in summer
  • The values of the particle depolarization ratio are consistent with a previously found mixture of liquid phase sulfate and soot particles

Composition and Chemistry

Free Access

Nitrogen Oxides Emissions, Chemistry, Deposition, and Export Over the Northeast United States During the WINTER Aircraft Campaign

  • Pages: 12,368-12,393
  • First Published: 09 October 2018
Key Points

  • Existing anthropogenic NOx inventory is consistent with aircraft and ground-based observations over Northeast United States during winter
  • NOx has a 22 hr lifetime, with half of NOy present as NOx, 37% as HNO3 and pNO3, and remaining 13% mostly as PAN
  • Model reproduces NOy partitioning and predicts a 42% NOx export efficiency in winter, with a 55–45% split between wet and dry deposition

Free Access

Molecular Characterization and Seasonal Variation in Primary and Secondary Organic Aerosols in Beijing, China

  • Pages: 12,394-12,412
  • First Published: 12 October 2018
Key Points

  • Biomass burning was the dominant contributor during the year, especially in the harvest and domestic heating seasons
  • The maximum trehalose content occurred during a dust storm (27–29 April 2012) in Beijing
  • Isoprene and α/β-pinene SOA tracers peaked in summer, while the β-caryophyllene SOA tracer increased in winter due to biomass burning

Free Access

First Assessment of Inorganic Nitrogen Deposition Budget Following the Impoundment of a Subtropical Hydroelectric Reservoir (Nam Theun 2, Lao PDR)

  • Pages: 12,413-12,428
  • First Published: 15 October 2018
Key Points

  • Dry and wet inorganic nitrogen deposition fluxes have been estimated for the Nam Theun 2 Reservoir and the vegetated area present before impoundment
  • Wet deposition was the major source of the atmospheric nitrogen input to the Nam Theun 2 Reservoir, contributing to 80% of the total deposition
  • The total inorganic N deposition over the studied area has been reduced by 26% after impoundment

Free Access

Methyl, Ethyl, and Propyl Nitrates: Global Distribution and Impacts on Reactive Nitrogen in Remote Marine Environments

  • Pages: 12,429-12,451
  • First Published: 18 September 2018
Key Points

  • Model including air-sea exchange reproduces observed alkyl nitrates from 20 years of airborne data
  • Methyl nitrate is the dominant form of reactive nitrogen in the tropical Pacific and Southern Ocean
  • Alkyl nitrates serve as a small but growing source of nitrogen oxides to the remote troposphere

Free Access

Assimilation of IASI Ozone-Sensitive Channels in Preparation for an Enhanced Coupling Between Numerical Weather Prediction and Chemistry Transport Models

  • Pages: 12,452-12,473
  • First Published: 25 October 2018
Key Points

  • IASI ozone-sensitive channels are also sensitive to temperature and humidity
  • Using a realistic ozone information input of the RTTOV RTM allows to better simulate IASI ozone-sensitive channels radiances
  • A simplified framework such as the 1D-Var data assimilation is used to prepare for an enhanced coupling between NWP and CTM

Free Access

Retrieval of Atmospheric Fine Particulate Density Based on Merging Particle Size Distribution Measurements: Multi-instrument Observation and Quality Control at Shouxian

  • Pages: 12,474-12,488
  • First Published: 03 September 2018
Key Points

  • The merging algorithm to achieve the real-time retrieval of fine mode aerosol density and number size distribution is improved
  • A method for estimating the uncertainties of retrieved densities and merged number size distributions from the fit residuals is proposed
  • A scheme of multi-instrument observation and quality control is proposed