Research Scientist
NorthWest Research Associates, Inc., CoRA Division, Boulder, CO
Specialized professional competence:
* Theoretical work
* Computer modeling
Representative recent research:
* Estimated the thermospheric spectra from a deep convective plume, and found that the GW horizontal and vertical wavelengths increase significantly with altitude. Also, the horizontal phase speed spectra increases significantly with altitude
* Calculated the dissipation altitudes, maximum vertical wavelengths, horizontal distances traveled, and time take to travel these distances for a wide range of GWs in a variety of thermospheric temperatures and from launch altitudes in the lower atmosphere and thermosphere
* Studied the propagation of gravity waves from convection into the thermosphere using our 3D ray-trace code
* Studied the dissipation of gravity waves from convection in the thermosphere, and found that they create large-scale horizontal body forces. These body forces may be an efficient source of large-scale secondary gravity waves and horizontal neutral winds that are variable in space and time
* Derived an anelastic dispersion relation which includes the correct thermospheric dissipation needed to ray trace gravity waves in the thermosphere
* Derived the gravity wave and mean responses to intermittent body forces and heatings
* Studied the radiation of secondary waves from gravity wave breaking
* Studied the radiation of gravity waves from mesoscale convective complexes
* Studied the radiation of waves from multiple and intermittent horizontal and vertical body forcings
* Studying the source of waves from up-gully flows from CASES
Other professional experience:
* Postdoc at LASP with Dr. D. Fritts at the University of Colorado, Boulder, Oct. 1995 - Jan. 1997;
* President's Postdoctoral Fellow, Center for Particle Astrophysics, University of California, Berkeley, Sept. 1993 - Sept. 1995;
* Guest Scientist in Numerical Cosmology, Theoretical Astrophysics, Fermi National Accelerator Lab, Jan. - Aug. 1993.
Academic Background:
* B.A. in physics and chemistry (1987), University of Rochester;
* M.A. in physics (1990), University of Chicago;
* Ph.D. in physics (1993), University of Chicago.
Publications:
* Sharon L. Vadas and Dave C. Fritts, 2008: "Reconstruction of the gravity wave field excited by convective plumes via ray tracing in real space", Annals. Geophys, submitted Apr. 15, 2008. Pdf version of this paper
* Sharon L. Vadas, M.J. Taylor, D. Pautet, P. Stamus, D.C. Fritts, F. Sao Sabbas, and V. Thiago, 2008: "Convection: the likely source of the medium-scale gravity waves observed in the OH airglow layer", Ann. Geophys, submitted Apr. 2, 2008. Pdf version of this paper
* Sharon L. Vadas and Mike Nicolls, 2008: "Temporal Evolution of Neutral, Thermospheric Winds and Plasma Response using PFISR Measurements of Gravity Waves" submitted to JASTP Mar 25, 2008. Pdf version of this paper
* Sharon L. Vadas and Mike Nicolls, 2008: "Using PFISR Measurements and Gravity Wave Dissipative Theory to Determine the Neutral, Background Thermospheric Winds" Geoph. Res. Letters, 35, {L02105, doi:10.1029/2007GL031522}
* Sharon L. Vadas, 2007: "Horizontal and vertical propagation, and dissipation of gravity waves in the thermosphere from lower atmospheric and thermospheric sources", J. Geoph. Res., {112}'{A06305, doi:10.1029/2006JA011845}.
* Sharon L. Vadas and David C. Fritts, 2006: "The influence of solar variability on gravity wave structure and dissipation in the thermosphere from tropospheric convection", J. Geoph. Res., {111, A10S12}'{doi:10.1029/2005JA011510}.
* Sharon L. Vadas and David C. Fritts, 2005: "Thermospheric responses to gravity waves: Influences of increasing viscosity and thermal diffusivity", J. Geoph. Res.,{110, D15103}'{doi:10.1029/2004JD005574}.
* Fritts, D. C., S. L. Vadas, K. Wan, and J. A. Werne, 2005: Mean and variable forcing of the middle atmosphere by gravity waves", J. Atmos. Solar-Terres. Phys., 68, 247-265.
* Sharon L. Vadas and David C. Fritts, 2004: "Thermospheric responses to gravity waves arising from mesoscale convective complexes", J. Atmos. Terr. Sci., 66, 781-804.
* Sharon L. Vadas, David C. Fritts, and M. Joan Alexander, 2003: "Mechanism for the generation of secondary waves in wave breaking regions", Jour. Atmos. Sci., 60, 194--214.
* Sharon L. Vadas and David C. Fritts, 2002: "The Importance of spatial variability in the generation of secondary gravity waves from local body forces," Geophys. Res. Lett., 29(20) 10.1029/2002GL015574
* David C. Fritts, Sharon L. Vadas, and Y. Yamada, 2002: "An estimate of strong local body forcing and gravity wave radiation based on OH airglow and meteor radar observations", Geophy. Res. Lett, 29(10) 10.1029/2001GL013753
* Ben Balsley, David C. Fritts, R. Frehlich, M. Jones, S.L. Vadas, R. Coulter, 2002: "Up-gully flow in the great plains region: a mechanism for perturbing the nightime lower atmosphere", Geophys. Res. Lett., 29(19) 10.1029/2002GL015435
* Sharon L. Vadas and David C. Fritts, 2001: "Gravity wave radiation and mean responses to local body forces in the atmosphere,"Jour. Atmos. Sci., 58, 2249--2279.
* David C. Fritts, Sharon L. Vadas and Oyvind Andreassen, 1998: "Gravity wave excitation and momentum transport in the solar interior: Implications for a residual circulation and lithium depletion," Astronomy & Astrophysics, 333, 343-361
click here for NSF studies . .