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Journal of Geophysical Research. Atmospheres: JGR

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
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
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
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
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
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
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
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
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 (H2Ov) 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 H2Ov excess signal was observed, H2Ov 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 H2Ov from the urban study sites...
September 16, 2017: Journal of Geophysical Research. Atmospheres: JGR
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
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
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
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
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
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
Barbara Scherllin-Pirscher, Andrea K Steiner, Gottfried Kirchengast, Marc Schwärz, Stephen S Leroy
High-resolution measurements from Global Navigation Satellite System (GNSS) radio occultation (RO) provide atmospheric profiles with independent information on altitude and pressure. This unique property is of crucial advantage when analyzing atmospheric characteristics that require joint knowledge of altitude and pressure or other thermodynamic atmospheric variables. Here we introduce and demonstrate the utility of this independent information from RO and discuss the computation, uncertainty, and use of RO atmospheric profiles on isohypsic coordinates-mean sea level altitude and geopotential height-as well as on thermodynamic coordinates (pressure and potential temperature)...
February 16, 2017: Journal of Geophysical Research. Atmospheres: JGR
Christoph Köhn, Gabriel Diniz, Muhsin N Harakeh
It has been discussed that lightning flashes emit high-energy electrons, positrons, photons, and neutrons with single energies of several tens of MeV. In the first part of this paper we study the absorption of neutron beams in the atmosphere. We initiate neutron beams of initial energies of 350 keV, 10 MeV, and 20 MeV at source altitudes of 4 km and 16 km upward and downward and see that in all these cases neutrons reach ground altitudes and that the cross-section areas extend to several km(2). We estimate that for terrestrial gamma-ray flashes approximately between 10 and 2000 neutrons per ms and m(2) are possibly detectable at ground, at 6 km, or at 500 km altitude...
January 27, 2017: Journal of Geophysical Research. Atmospheres: JGR
I Pisso, C Lund Myhre, S M Platt, S Eckhardt, O Hermansen, N Schmidbauer, J Mienert, S Vadakkepuliyambatta, S Bauguitte, J Pitt, G Allen, K N Bower, S O'Shea, M W Gallagher, C J Percival, J Pyle, M Cain, A Stohl
Methane stored in seabed reservoirs such as methane hydrates can reach the atmosphere in the form of bubbles or dissolved in water. Hydrates could destabilize with rising temperature further increasing greenhouse gas emissions in a warming climate. To assess the impact of oceanic emissions from the area west of Svalbard, where methane hydrates are abundant, we used measurements collected with a research aircraft (Facility for Airborne Atmospheric Measurements) and a ship (Helmer Hansen) during the Summer 2014 and for Zeppelin Observatory for the full year...
December 16, 2016: Journal of Geophysical Research. Atmospheres: JGR
Xiang Ni, Chuntao Liu, Qinghong Zhang, Daniel J Cecil
A 16-yr record of hail reports over the south U.S. and from weather stations in China are collocated with Precipitation Features (PF) derived from the Tropical Rainfall Measuring Mission (TRMM) radar and passive microwave observations. Differences in the way hail is reported in the two nations make it difficult to draw meaningful conclusions about storm frequency. But taking the two together yields a wide spectrum of hail sizes, suitable for comparing with remote sensing measurements. While U.S. hail reports are dominated by cases with hail size greater than 19 mm, hail reports in China mostly include diameters of 1-10 mm and mostly occur over the Tibetan Plateau...
October 27, 2016: Journal of Geophysical Research. Atmospheres: JGR
Sebastian Ehrhart, Luisa Ickes, Joao Almeida, Antonio Amorim, Peter Barmet, Federico Bianchi, Josef Dommen, Eimear M Dunne, Jonathan Duplissy, Alessandro Franchin, Juha Kangasluoma, Jasper Kirkby, Andreas Kürten, Agnieszka Kupc, Katrianne Lehtipalo, Tuomo Nieminen, Francesco Riccobono, Linda Rondo, Siegfried Schobesberger, Gerhard Steiner, António Tomé, Daniela Wimmer, Urs Baltensperger, Paul E Wagner, Joachim Curtius
Binary nucleation of sulphuric acid-water particles is expected to be an important process in the free troposphere at low temperatures. SAWNUC (Sulphuric Acid Water Nucleation) is a model of binary nucleation that is based on laboratory measurements of the binding energies of sulphuric acid and water in charged and neutral clusters. Predictions of SAWNUC are compared for the first time comprehensively with experimental binary nucleation data from the CLOUD chamber at European Organization for Nuclear Research...
October 27, 2016: Journal of Geophysical Research. Atmospheres: JGR
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