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Newport News, VA, United States

Massie S.T.,U.S. National Center for Atmospheric Research | Hervig M.,GATS, Inc.
Journal of Quantitative Spectroscopy and Radiative Transfer | Year: 2013

The HITRAN 2012 compilation of the real and imaginary refractive indices of the materials in aerosols and cloud particles is reviewed. Additions to HITRAN 2012 focus upon materials that are absorptive (i.e. minerals, burning vegetation, brown carbon, desert dust, and volcanic ash). The HITRAN-RI program, created to facilitate usage of the indices, is discussed. The HITRAN-RI program inter-compares the indices of different data sets and calculates optical properties (i.e. extinction, scattering, absorption, single scattering albedo, backscattering, and asymmetry parameter) for user specified size distributions and particle types. The instructional component of HITRAN-RI introduces the user to Mie calculations for spheres and coated spheres, and applies various mixing rules by which one calculates the effective indices of a multi-component particle. © 2013 Elsevier Ltd. Source

Siskind D.E.,U.S. Navy | Stevens M.H.,U.S. Navy | Hervig M.E.,GATS, Inc. | Randall C.E.,University of Colorado at Boulder
Geophysical Research Letters | Year: 2013

Observations of polar mesospheric clouds by the Aeronomy of Ice in the Mesosphere Explorer show that for the Northern summers of 2007-2010, the cloud ice water content (IWC) and occurrence frequency varied with the meteorological forcing from the Southern winter stratosphere. With the increase in solar flux in the last two years, expectations were that the clouds would decrease due to reduced water vapor (H2O) and/or higher temperatures. Surprisingly, we observe more clouds in 2011 and 40% greater IWC in 2011 and 2012. The increase is particularly pronounced in the clouds with highest IWC. These high IWC clouds are associated with significant enhancements in total H2O (vapor and ice). We suggest this implies an additional source of H2O and that this is provided by space traffic exhaust. A preliminary estimate of the H2O released from summertime space traffic over the last six years is qualitatively consistent with this suggestion. © 2013 American Geophysical Union. All Rights Reserved. Source

Lieberman R.S.,GATS, Inc. | Akmaev R.A.,National Oceanic and Atmospheric Administration | Fuller-Rowell T.J.,University of Colorado at Boulder | Doornbos E.,Technical University of Delft
Geophysical Research Letters | Year: 2013

We present direct, global observations of longitudinally averaged CHAMP zonal winds gathered between 2003 and 2007. A diurnal variation dominates the global zonal wind. Westward flows are observed from the early morning through afternoon hours, while eastward flows peak in the evening. A semidiurnal harmonic is also present, with magnitudes that are approximately one third of the diurnal harmonic. The time mean wind indicates westward winds over much of the globe, with weak superrotation (+E, or eastward winds) that is symmetric about the equator during equinox, and confined to the winter hemisphere at solstice. Diurnal and time mean CHAMP winds agree fairly well with the Whole Atmosphere Model. Some differences are observed in the semidiurnal and higher-order tidal winds, that underscore the challenges of modeling the sources, sinks, and mean wind effects upon tides between the surface and 400 km. ©2013. American Geophysical Union. All Rights Reserved. Source

Krall J.,U.S. Navy | Huba J.D.,U.S. Navy | Fritts D.C.,GATS, Inc.
Geophysical Research Letters | Year: 2013

The Naval Research Laboratory three-dimensional simulation code SAMI3/ESF is used to study the response of the postsunset ionosphere to plane gravity waves. The effect of the vertical wind component of the wave is included as well as the effect of the background vertical wind, which can suppress equatorial spread F (ESF). It is shown that the strength of the coupling of the gravity wave to ESF increases with the vertical wavelength of the gravity wave. Long vertical wavelength modes (λ > 100 km) are more effective for seeding ESF. Key Points GW/ESF coupling increases with the vertical wavelength of the gravity wave The results are only partially consistent with the hypothesis of Tsunoda [2010] We demonstrate that an upward vertical background wind can suppress ESF ©2013. American Geophysical Union. All Rights Reserved. Source

Rong P.P.,Hampton University | Russell J.M.,Hampton University | Hervig M.E.,GATS, Inc. | Bailey S.M.,Virginia Polytechnic Institute and State University
Journal of Geophysical Research: Atmospheres | Year: 2012

Temperature, or alternatively, saturation vapor pressure (PSAT), dominantly controls the polar mesospheric cloud (PMC) seasonal onset and termination, characterized by a strong anticorrelated relationship between the Solar Occultation for Ice Experiment (SOFIE)-observed PMC frequency and P SAT on intraseasonal time scales. SOFIE is highly sensitive to weak clouds and can obtain a nearly full spectrum of PMCs. Both the SOFIE PMC frequency and PSAT indicate a rapid onset and termination of the season. Compared to PSAT, the water vapor partial pressure (P H2O) exhibits only a slight increase from before to after the start of the season. We are able to use the PSAT daily minimum and two averaged PH2O levels taken before and after the solstice, respectively, to estimate the start and end days of the PMC season within 1-2days uncertainty. SOFIE ice mass density and its relationship to P H2O and PSAT are examined on intraseasonal scales and for two extreme conditions, i.e., strong and weak cloud cases. In the strong cloud case, such as those bright clouds that occur during the core of the season, PH2O far exceeds PSAT and dominantly controls the ice mass density variation, while in the weak cloud case, such as those clouds that occur at the start and end of the season, PH2O and PSAT have comparable magnitudes, vary in concert, and have similar effects on the ice mass density variation. These results suggest that the long-term brightness trends reported by DeLand et al. (2007) are primarily driven by changes in water vapor (H2O), not temperature. Copyright © 2012 by the American Geophysical Union. Source

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