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Journal of Geophysical Research. Atmospheres: JGR

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https://www.readbyqxmd.com/read/29576994/gravity-wave-dynamics-in-a-mesospheric-inversion-layer-1-reflection-trapping-and-instability-dynamics
#1
David C Fritts, Brian Laughman, Ling Wang, Thomas S Lund, Richard L Collins
An anelastic numerical model is employed to explore the dynamics of gravity waves (GWs) encountering a mesosphere inversion layer (MIL) having a moderate static stability enhancement and a layer of weaker static stability above. Instabilities occur within the MIL when the GW amplitude approaches that required for GW breaking due to compression of the vertical wavelength accompanying the increasing static stability. Thus, MILs can cause large-amplitude GWs to yield instabilities and turbulence below the altitude where they would otherwise arise...
January 27, 2018: Journal of Geophysical Research. Atmospheres: JGR
https://www.readbyqxmd.com/read/29527427/using-long-term-satellite-observations-to-identify-sensitive-regimes-and-active-regions-of-aerosol-indirect-effects-for-liquid-clouds-over-global-oceans
#2
Xuepeng Zhao, Yangang Liu, Fangquan Yu, Andrew K Heidinger
Long-term (1981-2011) satellite climate data records of clouds and aerosols are used to investigate the aerosol-cloud interaction of marine water cloud from a climatology perspective. Our focus is on identifying the regimes and regions where the aerosol indirect effects (AIEs) are evident in long-term averages over the global oceans through analyzing the correlation features between aerosol loading and the key cloud variables including cloud droplet effective radius (CDER), cloud optical depth (COD), cloud water path (CWP), cloud top height (CTH), and cloud top temperature (CTT)...
January 16, 2018: Journal of Geophysical Research. Atmospheres: JGR
https://www.readbyqxmd.com/read/29527426/spectral-characteristics-of-vlf-sferics-associated-with-rhessi-tgfs
#3
Andrew Mezentsev, Nikolai Lehtinen, Nikolai Østgaard, F J Pérez-Invernón, Steven A Cummer
We compared the modeled energy spectral density of very low frequency (VLF) radio emissions from terrestrial gamma ray flashes (TGFs) with the energy spectral density of VLF radio sferics recorded by Duke VLF receiver simultaneously with those TGFs. In total, six events with world wide lightning location network (WWLLN) defined locations were analyzed to exhibit a good fit between the modeled and observed energy spectral densities. In VLF range the energy spectral density of the TGF source current moment is found to be dominated by the contribution of secondary low-energy electrons and independent of the relativistic electrons which play their role in low-frequency (LF) range...
January 16, 2018: Journal of Geophysical Research. Atmospheres: JGR
https://www.readbyqxmd.com/read/29527425/the-evolution-and-structure-of-extreme-optical-lightning-flashes
#4
Michael Peterson, Scott Rudlosky, Wiebke Deierling
This study documents the composition, morphology, and motion of extreme optical lightning flashes observed by the Lightning Imaging Sensor (LIS). The furthest separation of LIS events (groups) in any flash is 135 km (89 km), the flash with the largest footprint had an illuminated area of 10,604 km2 , and the most dendritic flash has 234 visible branches. The longest-duration convective LIS flash lasted 28 s and is overgrouped and not physical. The longest-duration convective-to-stratiform propagating flash lasted 7...
December 27, 2017: Journal of Geophysical Research. Atmospheres: JGR
https://www.readbyqxmd.com/read/29479506/multi-year-composite-view-of-ozone-enhancements-and-stratosphere-to-troposphere-transport-in-dry-intrusions-of-northern-hemisphere-extratropical-cyclones
#5
Lyatt Jaeglé, Robert Wood, Krzysztof Wargan
We examine the role of extratropical cyclones in stratosphere-to-troposphere (STT) exchange with cyclone-centric composites of O3 retrievals from the Microwave Limb Sounder (MLS) and the Tropospheric Emission Spectrometer (TES), contrasting them to composites obtained with the Modern-Era Retrospective-analysis for Research and Applications (MERRA and MERRA-2) reanalyses and the GEOS-Chem chemical transport model. We identify 15,978 extratropical cyclones in the northern hemisphere (NH) for 2005-2012. The lowermost stratosphere (261 hPa) and middle troposphere (424 hPa) composites feature a 1,000 km-wide O3 enhancement in the dry intrusion (DI) airstream to the southwest of the cyclone center, coinciding with a lowered tropopause, enhanced potential vorticity, and decreased H2 O...
December 27, 2017: Journal of Geophysical Research. Atmospheres: JGR
https://www.readbyqxmd.com/read/29497588/in-flight-observation-of-gamma-ray-glows-by-ildas
#6
Pavlo Kochkin, A P J van Deursen, M Marisaldi, A Ursi, A I de Boer, M Bardet, C Allasia, J-F Boissin, F Flourens, N Østgaard
An Airbus A340 aircraft flew over Northern Australia with the In-Flight Lightning Damage Assessment System (ILDAS) installed onboard. A long-duration gamma ray emission was detected. The most intense emission was observed at 12 km altitude and lasted for 20 s. Its intensity was 20 times the background counts, and it was abruptly terminated by a distant lightning flash. In this work we reconstruct the aircraft path and event timeline. The glow-terminating flash triggered a discharge from the aircraft wing that was recorded by a video camera operating onboard...
December 16, 2017: Journal of Geophysical Research. Atmospheres: JGR
https://www.readbyqxmd.com/read/29780677/the-2016-southeastern-us-drought-an-extreme-departure-from-centennial-wetting-and-cooling
#7
A Park Williams, Benjamin I Cook, Jason E Smerdon, Daniel A Bishop, Richard Seager, Justin S Mankin
The fall 2016 drought in the southeastern United States (SE US) appeared exceptional based on its widespread impacts, but the current monitoring framework that only extends from 1979-present does not readily facilitate evaluation of soil-moisture anomalies in a centennial context. A new method to extend monthly gridded soil-moisture estimates back to 1895 is developed, indicating that since 1895, October-November 2016 soil moisture (0-200 cm) in the SE US was likely the second lowest on record, behind 1954...
October 27, 2017: Journal of Geophysical Research. Atmospheres: JGR
https://www.readbyqxmd.com/read/29527424/formaldehyde-in-the-tropical-western-pacific-chemical-sources-and-sinks-convective-transport-and-representation-in-cam-chem-and-the-ccmi-models
#8
Daniel C Anderson, Julie M Nicely, Glenn M Wolfe, Thomas F Hanisco, Ross J Salawitch, Timothy P Canty, Russell R Dickerson, Eric C Apel, Sunil Baidar, Thomas J Bannan, Nicola J Blake, Dexian Chen, Barbara Dix, Rafael P Fernandez, Samuel R Hall, Rebecca S Hornbrook, L Gregory Huey, Beatrice Josse, Patrick Jöckel, Douglas E Kinnison, Theodore K Koenig, Michael LeBreton, Virginie Marécal, Olaf Morgenstern, Luke D Oman, Laura L Pan, Carl Percival, David Plummer, Laura E Revell, Eugene Rozanov, Alfonso Saiz-Lopez, Andrea Stenke, Kengo Sudo, Simone Tilmes, Kirk Ullmann, Rainer Volkamer, Andrew J Weinheimer, Guang Zeng
Formaldehyde (HCHO) directly affects the atmospheric oxidative capacity through its effects on HOx . In remote marine environments, such as the Tropical Western Pacific (TWP), it is particularly important to understand the processes controlling the abundance of HCHO because model output from these regions is used to correct satellite retrievals of HCHO. Here, we have used observations from the CONTRAST field campaign, conducted during January and February 2014, to evaluate our understanding of the processes controlling the distribution of HCHO in the TWP as well as its representation in chemical transport/climate models...
October 27, 2017: Journal of Geophysical Research. Atmospheres: JGR
https://www.readbyqxmd.com/read/29682438/evaluating-a-space-based-indicator-of-surface-ozone-no-x-voc-sensitivity-over-midlatitude-source-regions-and-application-to-decadal-trends
#9
Xiaomeng Jin, Arlene M Fiore, Lee T Murray, Lukas C Valin, Lok N Lamsal, Bryan Duncan, K Folkert Boersma, Isabelle De Smedt, Gonzalo Gonzalez Abad, Kelly Chance, Gail S Tonnesen
Determining effective strategies for mitigating surface ozone (O3 ) pollution requires knowledge of the relative ambient concentrations of its precursors, NO x , and VOCs. The space-based tropospheric column ratio of formaldehyde to NO2 (FNR) has been used as an indicator to identify NO x -limited versus NO x -saturated O3 formation regimes. Quantitative use of this indicator ratio is subject to three major uncertainties: (1) the split between NO x -limited and NO x -saturated conditions may shift in space and time, (2) the ratio of the vertically integrated column may not represent the near-surface environment, and (3) satellite products contain errors...
October 16, 2017: Journal of Geophysical Research. Atmospheres: JGR
https://www.readbyqxmd.com/read/29399430/radio-frequency-electromagnetic-radiation-from-streamer-collisions
#10
Alejandro Luque
We present a full electromagnetic model of streamer propagation where the Maxwell equations are solved self-consistently together with electron transport and reactions including photoionization. We apply this model to the collision of counter-propagating streamers in gaps tens of centimeters wide and with large potential differences of hundreds of kilovolts. Our results show that streamer collisions emit electromagnetic pulses that, at atmospheric pressure, dominate the radio frequency spectrum of an extended corona in the range from about 100 MHz to a few gigahertz...
October 16, 2017: Journal of Geophysical Research. Atmospheres: JGR
https://www.readbyqxmd.com/read/29333358/investigating-the-seasonal-and-diurnal-cycles-of-ocean-vector-winds-near-the-philippines-using-rapidscat-and-ccmp
#11
Timothy J Lang
The seasonal and diurnal cycles of ocean vector winds in the domain of the South China Sea are characterized and compared using RapidScat and the Cross-Calibrated Multi-Platform (CCMP) data sets. Broad agreement in seasonal flow patterns exists between these data sets during the year 2015. Both observe the dramatic reversal from wintertime trade winds (November-April) to westerly flow associated with the summer monsoon (May-October). These seasonal changes have strong but not equivalent effects on mean wind divergence patterns in both data sets...
September 27, 2017: Journal of Geophysical Research. Atmospheres: JGR
https://www.readbyqxmd.com/read/29576993/new-insights-about-cloud-vertical-structure-from-cloudsat-and-calipso-observations
#12
Lazaros Oreopoulos, Nayeong Cho, Dongmin Lee
Active cloud observations from A-Train's CloudSat and CALIPSO satellites offer new opportunities to examine the vertical structure of hydrometeor layers. We use the 2B-CLDCLASS-LIDAR merged CloudSat-CALIPSO product to examine global aspects of hydrometeor vertical stratification. We group the data into major Cloud Vertical Structure (CVS) classes based on our interpretation of how clouds in three standard atmospheric layers overlap, and provide their global frequency of occurrence. The two most frequent CVS classes are single-layer (per our definition) low and high clouds which represent ~53% of cloudy skies, followed by high clouds overlying low clouds, and vertically extensive clouds that occupy near-contiguously a large portion of the troposphere...
September 16, 2017: Journal of Geophysical Research. Atmospheres: JGR
https://www.readbyqxmd.com/read/29308343/urban-emissions-of-water-vapor-in-winter
#13
Olivia E Salmon, Paul B Shepson, Xinrong Ren, Allison B Marquardt Collow, Mark A Miller, Annmarie G Carlton, Maria O L Cambaliza, Alexie Heimburger, Kristan L Morgan, Jose D Fuentes, Brian H Stirm, Robert Grundman, Russell R Dickerson
Elevated water vapor (H2 Ov ) mole fractions were occassionally observed downwind of Indianapolis, IN, and the Washington, D.C.-Baltimore, MD, area during airborne mass balance experiments conducted during winter months between 2012 and 2015. On days when an urban H2 Ov excess signal was observed, H2 Ov emissions estimates range between 1.6 × 104 and 1.7 × 105 kg s-1 , and account for up to 8.4% of the total (background + urban excess) advected flow of atmospheric boundary layer H2 Ov from the urban study sites...
September 16, 2017: Journal of Geophysical Research. Atmospheres: JGR
https://www.readbyqxmd.com/read/28955601/analysis-of-aerosol-composition-data-for-western-united-states-wildfires-between-2005-and-2015-dust-emissions-chloride-depletion-and-most-enhanced-aerosol-constituents
#14
Joseph S Schlosser, Rachel A Braun, Trevor Bradley, Hossein Dadashazar, Alexander B MacDonald, Abdulmonam A Aldhaif, Mojtaba Azadi Aghdam, Ali Hossein Mardi, Peng Xian, Armin Sorooshian
This study examines major wildfires in the western United States between 2005 and 2015 to determine which species exhibit the highest percent change in mass concentration on day of peak fire influence relative to preceding nonfire days. Forty-one fires were examined using the Environmental Protection Agency (EPA) Interagency Monitoring of Protected Visual Environments (IMPROVE) data set. Organic carbon (OC) and elemental carbon (EC) constituents exhibited the highest percent change increase. The sharpest enhancements were for the volatile (OC1) and semivolatile (OC2) OC fractions, suggestive of secondary organic aerosol formation during plume transport...
August 27, 2017: Journal of Geophysical Research. Atmospheres: JGR
https://www.readbyqxmd.com/read/28955600/analysis-of-remotely-sensed-and-surface-data-of-aerosols-and-meteorology-for-the-mexico-megalopolis-area-between-2003-and-2015
#15
Marco Mora, Rachel A Braun, Taylor Shingler, Armin Sorooshian
This paper presents an aerosol characterization study from 2003 to 2015 for the Mexico City Metropolitan Area using remotely sensed aerosol data, ground-based measurements, air mass trajectory modeling, aerosol chemical composition modeling, and reanalysis data for the broader Megalopolis of Central Mexico region. The most extensive biomass burning emissions occur between March and May concurrent with the highest aerosol optical depth, ultraviolet aerosol index, and surface particulate matter (PM) mass concentration values...
August 27, 2017: Journal of Geophysical Research. Atmospheres: JGR
https://www.readbyqxmd.com/read/28989832/constraints-to-do-realistic-modeling-of-the-electric-field-ahead-of-the-tip-of-a-lightning-leader
#16
Alexander Broberg Skeltved, Nikolai Østgaard, Andrew Mezentsev, Nikolai Lehtinen, Brant Carlson
Several computer models exist to explain the observation of terrestrial gamma-ray flashes (TGFs). Some of these models estimate the electric field ahead of lightning leaders and its effects on electron acceleration and multiplication. In this paper, we derive a new set of constraints to do more realistic modeling. We determine initial conditions based on in situ measurements of electric field and vertical separation between the main charge layers of thunderclouds. A maximum electric field strength of 50 kV/cm at sea level is introduced as the upper constraint for the leader electric field...
August 16, 2017: Journal of Geophysical Research. Atmospheres: JGR
https://www.readbyqxmd.com/read/28804697/evaluation-of-satellite-and-reanalysis-based-global-net-surface-energy-flux-and-uncertainty-estimates
#17
Chunlei Liu, Richard P Allan, Michael Mayer, Patrick Hyder, Norman G Loeb, Chris D Roberts, Maria Valdivieso, John M Edwards, Pier-Luigi Vidale
The net surface energy flux is central to the climate system yet observational limitations lead to substantial uncertainty. A combination of satellite-derived radiative fluxes at the top of atmosphere adjusted using the latest estimation of the net heat uptake of the Earth system, and the atmospheric energy tendencies and transports from the ERA-Interim reanalysis are used to estimate surface energy flux globally. To consider snowmelt and improve regional realism, land surface fluxes are adjusted through a simple energy balance approach at each grid point...
June 27, 2017: Journal of Geophysical Research. Atmospheres: JGR
https://www.readbyqxmd.com/read/29651373/using-modis-cloud-regimes-to-sort-diagnostic-signals-of-aerosol-cloud-precipitation-interactions
#18
Lazaros Oreopoulos, Nayeong Cho, Dongmin Lee
Coincident multi-year measurements of aerosol, cloud, precipitation and radiation at near-global scales are analyzed to diagnose their apparent relationships as suggestive of interactions previously proposed based on theoretical, observational, and model constructs. Specifically, we examine whether differences in aerosol loading in separate observations go along with consistently different precipitation, cloud properties, and cloud radiative effects. Our analysis uses a cloud regime (CR) framework to dissect and sort the results...
May 27, 2017: Journal of Geophysical Research. Atmospheres: JGR
https://www.readbyqxmd.com/read/28603681/methane-emissions-from-the-marcellus-shale-in-southwestern-pennsylvania-and-northern-west-virginia-based-on-airborne-measurements
#19
Xinrong Ren, Dolly L Hall, Timothy Vinciguerra, Sarah E Benish, Phillip R Stratton, Doyeon Ahn, Jonathan R Hansford, Mark D Cohen, Sayantan Sahu, Hao He, Courtney Grimes, Ross J Salawitch, Sheryl H Ehrman, Russell R Dickerson
Natural gas production in the U.S. has increased rapidly over the past decade, along with concerns about methane (CH4) leakage (total fugitive emissions), and climate impacts. Quantification of CH4 emissions from oil and natural gas (O&NG) operations is important for establishing scientifically sound, cost-effective policies for mitigating greenhouse gases. We use aircraft measurements and a mass balance approach for three flight experiments in August and September 2015 to estimate CH4 emissions from O&NG operations in the southwestern Marcellus Shale region...
April 27, 2017: Journal of Geophysical Research. Atmospheres: JGR
https://www.readbyqxmd.com/read/29082119/relationships-between-radiation-clouds-and-convection-during-dynamo
#20
Paul E Ciesielski, Richard H Johnson, Xianan Jiang, Yunyan Zhang, Shaocheng Xie
The relationships between radiation, clouds, and convection on an intraseasonal time scale are examined with data taken during the Dynamics of the Madden-Julian Oscillation (MJO) field campaign. Specifically, column-net, as well as vertical profiles of radiative heating rates, computed over Gan Island in the central Indian Ocean (IO) are used along with an objective analysis of large-scale fields to examine three MJO events that occurred during the 3 month period (October to December 2011) over this region...
March 16, 2017: Journal of Geophysical Research. Atmospheres: JGR
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