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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
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
Piotr Kupiszewski, Marco Zanatta, Stephan Mertes, Paul Vochezer, Gary Lloyd, Johannes Schneider, Ludwig Schenk, Martin Schnaiter, Urs Baltensperger, Ernest Weingartner, Martin Gysel
Ice residual (IR) and total aerosol properties were measured in mixed-phase clouds (MPCs) at the high-alpine Jungfraujoch research station. Black carbon (BC) content and coating thickness of BC-containing particles were determined using single-particle soot photometers. The ice activated fraction (IAF), derived from a comparison of IR and total aerosol particle size distributions, showed an enrichment of large particles in the IR, with an increase in the IAF from values on the order of 10(-4) to 10(-3) for 100 nm (diameter) particles to 0...
October 27, 2016: Journal of Geophysical Research. Atmospheres: JGR
Wan-Ru Huang, Sheng-Hsiang Wang, Ming-Cheng Yen, Neng-Huei Lin, Parichart Promchote
During March and April, widespread burning occurs across farmlands in Indochina in preparation for planting at the monsoon onset. The resultant aerosols impact the air quality downwind. In this study, we investigate the climatic aspect of the interannual variation of springtime biomass burning in Indochina and its correlation with air quality at Mt. Lulin in Taiwan using long-term (2005-2015) satellite and global reanalysis data. Based on empirical orthogonal function (EOF) analysis, we find that the biomass burning activities vary with two geographical regions: northern Indochina (the primary EOF mode) and southern Indochina (the secondary EOF mode)...
September 16, 2016: Journal of Geophysical Research. Atmospheres: JGR
Deepti Singh, Daniel L Swain, Justin S Mankin, Daniel E Horton, Leif N Thomas, Bala Rajaratnam, Noah S Diffenbaugh
During the winters of 2013-2014 and 2014-2015, anomalously warm temperatures in western North America and anomalously cool temperatures in eastern North America resulted in substantial human and environmental impacts. Motivated by the impacts of these concurrent temperature extremes and the intrinsic atmospheric linkage between weather conditions in the western and eastern United States, we investigate the occurrence of concurrent "warm-West/cool-East" surface temperature anomalies, which we call the "North American winter temperature dipole...
September 16, 2016: Journal of Geophysical Research. Atmospheres: JGR
John Ware, Eric A Kort, Phil DeCola, Riley Duren
Atmospheric observations of greenhouse gases provide essential information on sources and sinks of these key atmospheric constituents. To quantify fluxes from atmospheric observations, representation of transport-especially vertical mixing-is a necessity and often a source of error. We report on remotely sensed profiles of vertical aerosol distribution taken over a 2 year period in Pasadena, California. Using an automated analysis system, we estimate daytime mixing layer depth, achieving high confidence in the afternoon maximum on 51% of days with profiles from a Sigma Space Mini Micropulse LiDAR (MiniMPL) and on 36% of days with a Vaisala CL51 ceilometer...
August 27, 2016: Journal of Geophysical Research. Atmospheres: JGR
A Battaglia, K Mroz, Tim Lang, F Tridon, S Tanelli, Lin Tian, Gerald M Heymsfield
Due to the large natural variability of its microphysical properties, the characterization of solid precipitation is a longstanding problem. Since in situ observations are unavailable in severe convective systems, innovative remote sensing retrievals are needed to extend our understanding of such systems. This study presents a novel technique able to retrieve the density, mass, and effective diameter of graupel and hail in severe convection through the combination of airborne microwave remote sensing instruments...
August 27, 2016: Journal of Geophysical Research. Atmospheres: JGR
Vanna C Chmielewski, Eric C Bruning
This study characterizes Lightning Mapping Array performance for networks that participated in the Deep Convective Clouds and Chemistry field program using new Monte Carlo and curvature matrix model simulations. These open-source simulation tools are readily adapted to real-time operations or detailed studies of performance. Each simulation accounted for receiver threshold and location, as well as a reference distribution of source powers and flash sizes based on thunderstorm observations and the mechanics of station triggering...
July 27, 2016: Journal of Geophysical Research. Atmospheres: JGR
Kyle F Itterly, Patrick C Taylor, Jason B Dodson, Ahmed B Tawfik
Climate and reanalysis models contain large water and energy budget errors over tropical land related to the misrepresentation of diurnally forced moist convection. Motivated by recent work suggesting that the water and energy budget is influenced by the sensitivity of the convective diurnal cycle to atmospheric state, this study investigates the relationship between convective intensity, the convective diurnal cycle, and atmospheric state in a region of frequent convection-the Amazon. Daily, 3-hourly satellite observations of top of atmosphere (TOA) fluxes from Clouds and the Earth's Radiant Energy System Ed3a SYN1DEG and precipitation from Tropical Rainfall Measuring Mission 3B42 data sets are collocated with twice daily Integrated Global Radiosonde Archive observations from 2002 to 2012 and hourly flux tower observations...
July 27, 2016: Journal of Geophysical Research. Atmospheres: JGR
Hirohiko Masunaga, Zhengzhao Johnny Luo
A new, satellite-based methodology is developed to evaluate convective mass flux and large-scale total mass flux. To derive the convective mass flux, candidate profiles of in-cloud vertical velocity are first constructed with a simple plume model under the constraint of ambient sounding and then narrowed down to the solution that matches satellite-derived cloud top buoyancy. Meanwhile, the large-scale total mass flux is provided separately from satellite soundings by a method developed previously. All satellite snapshots are sorted into a composite time series that delineates the evolution of a vigorous and organized convective system...
July 16, 2016: Journal of Geophysical Research. Atmospheres: JGR
Andrew Mezentsev, Nikolai Østgaard, Thomas Gjesteland, Kjetil Albrechtsen, Nikolai Lehtinen, Martino Marisaldi, David Smith, Steven Cummer
A detailed analysis of Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) terrestrial gamma ray flashes (TGFs) is performed in association with World Wide Lightning Location Network (WWLLN) sources and very low frequency (VLF) sferics recorded at Duke University. RHESSI clock offset is evaluated and found to experience changes on the 5 August 2005 and 21 October 2013, based on the analysis of TGF-WWLLN matches. The clock offsets were found for all three periods of observations with standard deviations less than 100 μs...
July 16, 2016: Journal of Geophysical Research. Atmospheres: JGR
Kevin J Coakley, John B Miller, Stephen A Montzka, Colm Sweeney, Ben R Miller
The measured (14)C:(12)C isotopic ratio of atmospheric CO2 (and its associated derived Δ(14)C value) is an ideal tracer for determination of the fossil fuel derived CO2 enhancement contributing to any atmospheric CO2 measurement (Cff ). Given enough such measurements, independent top-down estimation of US fossil fuel-CO2 emissions should be possible. However, the number of Δ(14)C measurements is presently constrained by cost, available sample volume, and availability of mass spectrometer measurement facilities...
June 27, 2016: Journal of Geophysical Research. Atmospheres: JGR
Pengfei Yu, Owen B Toon, Charles G Bardeen, Anthony Bucholtz, Karen H Rosenlof, Pablo E Saide, Arlindo Da Silva, Luke D Ziemba, Kenneth L Thornhill, Jose-Luis Jimenez, Pedro Campuzano-Jost, Joshua P Schwarz, Anne E Perring, Karl D Froyd, N L Wagner, Michael J Mills, Jeffrey S Reid
The Rim Fire of 2013, the third largest area burned by fire recorded in California history, is simulated by a climate model coupled with a size-resolved aerosol model. Modeled aerosol mass, number, and particle size distribution are within variability of data obtained from multiple-airborne in situ measurements. Simulations suggest that Rim Fire smoke may block 4-6% of sunlight energy reaching the surface, with a dimming efficiency around 120-150 W m(-2) per unit aerosol optical depth in the midvisible at 13:00-15:00 local time...
June 27, 2016: Journal of Geophysical Research. Atmospheres: JGR
T Delahaye, S E Maxwell, Z D Reed, H Lin, J T Hodges, K Sung, V M Devi, T Warneke, P Spietz, H Tran
In this article we describe a high-precision laboratory measurement targeting the R(6) manifold of the 2ν 3 band of (12)CH4. Accurate physical models of this absorption spectrum will be required by the Franco-German, Methane Remote Sensing LIDAR (MERLIN) space mission for retrievals of atmospheric methane. The analysis uses the Hartmann-Tran profile for modeling line shape and also includes line-mixing effects. To this end, six high-resolution and high signal-to-noise absorption spectra of air-broadened methane were recorded using a frequency-stabilized cavity ring-down spectroscopy apparatus...
June 27, 2016: Journal of Geophysical Research. Atmospheres: JGR
Marco Möller, Friedrich Obleitner, Carleen H Reijmer, Veijo A Pohjola, Piotr Głowacki, Jack Kohler
Large-scale modeling of glacier mass balance relies often on the output from regional climate models (RCMs). However, the limited accuracy and spatial resolution of RCM output pose limitations on mass balance simulations at subregional or local scales. Moreover, RCM output is still rarely available over larger regions or for longer time periods. This study evaluates the extent to which it is possible to derive reliable region-wide glacier mass balance estimates, using coarse resolution (10 km) RCM output for model forcing...
May 27, 2016: Journal of Geophysical Research. Atmospheres: JGR
J Brant Dodson, Patrick C Taylor
Amazonian deep convection experiences a strong diurnal cycle driven by the cycle in surface sensible heat flux, which contributes to a significant diurnal cycle in the top of the atmosphere (TOA) radiative flux. Even when accounting for seasonal variability, the TOA flux diurnal cycle varies significantly on the monthly timescale. Previous work shows evidence supporting a connection between variability in the convective and radiative cycles, likely modulated by variability in monthly atmospheric state (e.g...
May 16, 2016: Journal of Geophysical Research. Atmospheres: JGR
Chathurika M Rathnayake, Nervana Metwali, Zach Baker, Thilina Jayarathne, Pamela A Kostle, Peter S Thorne, Patrick T O'Shaughnessy, Elizabeth A Stone
Bioaerosols are well-known immune-active particles that exacerbate respiratory diseases. Human exposures to bioaerosols and their resultant health impacts depend on their ambient concentrations, seasonal and spatial variation, and co-pollutants, which are not yet widely characterized. In this study, chemical and biological tracers of bioaerosols were quantified in respirable particulate matter (PM10) collected at three urban and three background sites in the Midwestern United States across four seasons in 2012...
May 16, 2016: Journal of Geophysical Research. Atmospheres: JGR
John M C Plane, Juan Carlos Gómez-Martín, Wuhu Feng, Diego Janches
Silicon is one of the most abundant elements in cosmic dust, and meteoric ablation injects a significant amount of Si into the atmosphere above 80 km. In this study, a new model for silicon chemistry in the mesosphere/lower thermosphere is described, based on recent laboratory kinetic studies of Si, SiO, SiO2, and Si(+). Electronic structure calculations and statistical rate theory are used to show that the likely fate of SiO2 is a two-step hydration to silicic acid (Si(OH)4), which then polymerizes with metal oxides and hydroxides to form meteoric smoke particles...
April 16, 2016: Journal of Geophysical Research. Atmospheres: JGR
N Østgaard, B E Carlson, R S Nisi, T Gjesteland, Ø Grøndahl, A Skeltved, N G Lehtinen, A Mezentsev, M Marisaldi, P Kochkin
Discharge experiments were carried out at the Eindhoven University of Technology in 2013. The experimental setup was designed to search for electrons produced in meter-scale sparks using a 1 MV Marx generator. Negative voltage was applied to the high voltage (HV) electrode. Five thin (1 mm) plastic detectors (5 cm(2) each) were distributed in various configurations close to the spark gap. Earlier studies have shown (for HV negative) that X-rays are produced when a cloud of streamers is developed 30-60 cm from the negative electrode...
March 27, 2016: Journal of Geophysical Research. Atmospheres: JGR
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