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Journal of Geophysical Research. Atmospheres: JGR

L A McMurdie, A K Rowe, R A Houze, S R Brodzik, J P Zagrodnik, T M Schuldt
Enhancement of precipitation processes aloft over complex terrain is documented using reflectivity data from an S-band scanning radar (NPOL) that was deployed on the west coast of Washington State during the Olympic Mountains Experiment (OLYMPEX). From November 2015 through mid-January 2016, NPOL obtained high-resolution data within sectors over the ocean and over the windward slopes of the Olympic Mountains. Contoured Frequency by Altitude Diagrams of radar reflectivity highlight a higher frequency of occurrence of larger reflectivities for all heights between 2 and 8 km over land compared to ocean, with the largest difference in the 4- to 6-km range indicating a robust signature of enhancement aloft over the windward slopes...
November 16, 2018: Journal of Geophysical Research. Atmospheres: JGR
Deepti Singh, Sonali P McDermid, Benjamin I Cook, Michael J Puma, Larissa Nazarenko, Maxwell Kelley
Anthropogenic land use and land cover change is primarily represented in climate model simulations through prescribed transitions from natural vegetation to cropland or pasture. However, recent studies have demonstrated that land management practices, especially irrigation, have distinct climate impacts. Here we disentangle the seasonal climate impacts of land cover change and irrigation across areas of high agricultural intensity using climate simulations with three different land surface scenarios: (1) natural vegetation cover/no irrigation, (2) year 2000 crop cover/no irrigation, and (3) year 2000 crop cover and irrigation rates...
November 16, 2018: Journal of Geophysical Research. Atmospheres: JGR
Joyce E Penner, Cheng Zhou, Anne Garnier, David L Mitchell
We have implemented a parameterization for forming ice in large-scale cirrus clouds that accounts for the changes in updrafts associated with a spectrum of waves acting within each time step in the model. This allows us to account for the frequency of homogeneous and heterogeneous freezing events that occur within each time step of the model and helps to determine more realistic ice number concentrations as well as changes to ice number concentrations. The model is able to fit observations of ice number at the lowest temperatures in the tropical tropopause but is still somewhat high in tropical latitudes with temperatures between 195°K and 215°K...
October 27, 2018: Journal of Geophysical Research. Atmospheres: JGR
Y-S Chen, J Verlinde, E E Clothiaux, A S Ackerman, A M Fridlind, M Chamecki, P Kollias, M P Kirkpatrick, B-C Chen, G Yu, A Avramov
Large-eddy simulations of an observed single-layer Arctic mixed-phase cloud are analyzed to study the value of forward modeling of profiling millimeter-wave cloud radar Doppler spectral width for model evaluation. Individual broadening terms and their uncertainties are quantified for the observed spectral width and compared to modeled broadening terms. Modeled turbulent broadening is narrower than the observed values when the turbulent kinetic energy dissipation rate from the subgrid-scale model is used in the forward model...
July 27, 2018: Journal of Geophysical Research. Atmospheres: JGR
Sylvia G Dee, Jesse Nusbaumer, Adriana Bailey, James M Russell, Jung-Eun Lee, Bronwen Konecky, Nikolaus H Buenning, David C Noone
General circulation models (GCMs) predict that the global hydrological cycle will change in response to anthropogenic warming. However, these predictions remain uncertain, in particular for precipitation [IPCC, 2013]. Held and Soden [2006] suggest that as lower-tropospheric water vapor concentration increases in a warming climate, the atmospheric circulation and convective mass fluxes will weaken. Unfortunately, this process is difficult to constrain, as convective mass fluxes are poorly observed and incompletely simulated in GCMs...
July 27, 2018: Journal of Geophysical Research. Atmospheres: JGR
Brody R Fuchs, Steven A Rutledge, Brenda Dolan, Lawrence D Carey, Christopher Schultz
Microphysical and kinematic characteristics of two storm populations, based on their macroscale charge structures, are investigated in an effort to increase our understanding of the processes that lead to anomalous (or inverted charge) structures. Nine normal polarity cases (mid-level negative charge) with dual-Doppler and polarimetric coverage that occurred in northern Alabama, and six anomalous polarity cases (mid-level positive charge) that occurred in northeastern Colorado are included in this study. The results show that even though anomalous polarity storms formed in environments with similar instability, they had significantly larger and stronger updrafts...
June 27, 2018: Journal of Geophysical Research. Atmospheres: JGR
Jesse Nusbaumer, David Noone
Atmospheric rivers are one of the major causes of extreme precipitation and flooding in many regions around the world, and have been found to contribute substantially to global poleward moisture transport. However, the evaporative origin of the moisture in atmospheric rivers remains unclear, at least on climatological time-scales. Here we use the water tracer and water isotope-enabled CAM5 model to examine the moisture sources of atmospheric rivers that impact the West Coast of the United States. The climatological distribution of moisture sources is determined for both the modern-era and for 2100 under an RCP8...
June 27, 2018: Journal of Geophysical Research. Atmospheres: JGR
C Roulston, C Paton-Walsh, T E L Smith, É-A Guérette, S Evers, C M Yule, G Rein, G R Van der Werf
Southeast Asia experiences frequent fires in fuel-rich tropical peatlands, leading to extreme episodes of regional haze with high concentrations of fine particulate matter (PM2.5 ) impacting human health. In a study published recently, the first field measurements of PM2.5 emission factors for tropical peat fires showed larger emissions than from other fuel types. Here we report even higher PM2.5 emission factors, measured at newly ignited peat fires in Malaysia, suggesting that current estimates of fine particulate emissions from peat fires may be underestimated by a factor of 3 or more...
May 27, 2018: Journal of Geophysical Research. Atmospheres: JGR
James T Kelly, Caroline L Parworth, Qi Zhang, David J Miller, Kang Sun, Mark A Zondlo, Kirk R Baker, Armin Wisthaler, John B Nowak, Sally E Pusede, Ronald C Cohen, Andrew J Weinheimer, Andreas J Beyersdorf, Gail S Tonnesen, Jesse O Bash, Luke C Valin, James H Crawford, Alan Fried, James G Walega
The San Joaquin Valley (SJV) of California experiences high concentrations of particulate matter NH4 NO3 during episodes of meteorological stagnation in winter. A rich data set of observations related to NH4 NO3 formation was acquired during multiple periods of elevated NH4 NO3 during the Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) field campaign in SJV in January and February 2013. Here NH4 NO3 is simulated during the SJV DISCOVER-AQ study period with the Community Multiscale Air Quality (CMAQ) model, diagnostic model evaluation is performed using the DISCOVER-AQ data set, and integrated reaction rate analysis is used to quantify HNO3 production rates...
May 16, 2018: Journal of Geophysical Research. Atmospheres: JGR
Jesús Vergara-Temprado, Mark A Holden, Thomas R Orton, Daniel O'Sullivan, Nsikanabasi S Umo, Jo Browse, Carly Reddington, María Teresa Baeza-Romero, Jenny M Jones, Amanda Lea-Langton, Alan Williams, Ken S Carslaw, Benjamin J Murray
It has been hypothesized that black carbon (BC) influences mixed-phase clouds by acting as an ice-nucleating particle (INP). However, the literature data for ice nucleation by BC immersed in supercooled water are extremely varied, with some studies reporting that BC is very effective at nucleating ice, whereas others report no ice-nucleating ability. Here we present new experimental results for immersion mode ice nucleation by BC from two contrasting fuels (n-decane and eugenol). We observe no significant heterogeneous nucleation by either sample...
April 27, 2018: Journal of Geophysical Research. Atmospheres: JGR
Thomas J Greenwald, Ralf Bennartz, Matthew Lebsock, João Teixeira
The first extended comprehensive data set of the retrieval uncertainties in passive microwave observations of cloud liquid water path (CLWP) for warm oceanic clouds has been created for practical use in climate applications. Four major sources of systematic errors were considered over the 9-year record of the Advanced Microwave Scanning Radiometer-EOS (AMSR-E): clear-sky bias, cloud-rain partition (CRP) bias, cloud-fraction-dependent bias, and cloud temperature bias. Errors were estimated using a unique merged AMSR-E/Moderate resolution Imaging Spectroradiometer Level 2 data set as well as observations from the Cloud-Aerosol Lidar with Orthogonal Polarization and the CloudSat Cloud Profiling Radar...
April 16, 2018: Journal of Geophysical Research. Atmospheres: JGR
H Moon, L Gudmundsson, S I Seneviratne
The persistence of drought events largely determines the severity of socioeconomic and ecological impacts, but the capability of current global climate models (GCMs) to simulate such events is subject to large uncertainties. In this study, the representation of drought persistence in GCMs is assessed by comparing state-of-the-art GCM model simulations to observation-based data sets. For doing so, we consider dry-to-dry transition probabilities at monthly and annual scales as estimates for drought persistence, where a dry status is defined as negative precipitation anomaly...
April 16, 2018: Journal of Geophysical Research. Atmospheres: JGR
B M Hare, O Scholten, A Bonardi, S Buitink, A Corstanje, U Ebert, H Falcke, J R Hörandel, H Leijnse, P Mitra, K Mulrey, A Nelles, J P Rachen, L Rossetto, C Rutjes, P Schellart, S Thoudam, T N G Trinh, S Ter Veen, T Winchen
Lightning mapping technology has proven instrumental in understanding lightning. In this work we present a pipeline that can use lightning observed by the LOw-Frequency ARray (LOFAR) radio telescope to construct a 3-D map of the flash. We show that LOFAR has unparalleled precision, on the order of meters, even for lightning flashes that are over 20 km outside the area enclosed by LOFAR antennas (∼3,200 km2 ), and can potentially locate over 10,000 sources per lightning flash. We also show that LOFAR is the first lightning mapping system that is sensitive to the spatial structure of the electrical current during individual lightning leader steps...
March 16, 2018: Journal of Geophysical Research. Atmospheres: JGR
Christopher J Schultz, Timothy J Lang, Eric C Bruning, Kristin M Calhoun, Sebastian Harkema, Nathan Curtis
This study examined 34 lightning flashes within four separate thundersnow events derived from lightning mapping arrays (LMAs) in northern Alabama, central Oklahoma, and Washington DC. The goals were to characterize the in-cloud component of each lightning flash, as well as the correspondence between the LMA observations and lightning data taken from national lightning networks like the National Lightning Detection Network (NLDN). Individual flashes were examined in detail to highlight several observations within the dataset...
February 27, 2018: Journal of Geophysical Research. Atmospheres: JGR
A I Gevaert, D G Miralles, R A M de Jeu, J Schellekens, A J Dolman
The land surface controls the partitioning of water and energy fluxes and therefore plays a crucial role in the climate system. The coupling between soil moisture and air temperature, in particular, has been shown to affect the severity and occurrence of temperature extremes and heat waves. Here we study soil moisture-temperature coupling in five land surface models, focusing on the terrestrial segment of the coupling in the warm season. All models are run off-line over a common period with identical atmospheric forcing data, in order to allow differences in the results to be attributed to the models' partitioning of energy and water fluxes...
February 16, 2018: Journal of Geophysical Research. Atmospheres: JGR
F Carbone, A G Bruno, A Naccarato, F De Simone, C N Gencarelli, F Sprovieri, I M Hedgecock, M S Landis, H Skov, K A Pfaffhuber, K A Read, L Martin, H Angot, A Dommergue, O Magand, N Pirrone
The probability density function (PDF) of the time intervals between subsequent extreme events in atmospheric Hg0 concentration data series from different latitudes has been investigated. The Hg0 dynamic possesses a long-term memory autocorrelation function. Above a fixed threshold Q in the data, the PDFs of the interoccurrence time of the Hg0 data are well described by a Tsallis q-Exponential function. This PDF behavior has been explained in the framework of superstatistics, where the competition between multiple mesoscopic processes affects the macroscopic dynamics...
January 27, 2018: Journal of Geophysical Research. Atmospheres: JGR
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
A M Sayer, N C Hsu, J Lee, C Bettenhausen, W V Kim, A Smirnov
The Suomi National Polar-Orbiting Partnership (S-NPP) satellite, launched in late 2011, carries the Visible Infrared Imaging Radiometer Suite (VIIRS) and several other instruments. VIIRS has similar characteristics to prior satellite sensors used for aerosol optical depth (AOD) retrieval, allowing the continuation of space-based aerosol data records. The Deep Blue algorithm has previously been applied to retrieve AOD from Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and Moderate Resolution Imaging Spectro-radiometer (MODIS) measurements over land...
January 16, 2018: 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
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