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.
Awards:
* CEDAR Prize Lecturer (2008): "The coupling of the lower atmosphere to the thermosphere via gravity wave excitation, propagation and dissipation"
Publications:
* Sharon L. Vadas, Jia Yue, Joe She, Pete Stamus, and Alan Liu, 2008: "A model study of the effects of winds on concentric rings of gravity waves from a convective plume near Fort Collins on 11 May 2004", Jour. Geoph. Res, in press. Pdf version of this paper
* Yue, J., S.L. Vadas, C.-Y. She, T. Nakamura, S. Reising, D. Krueger, H.-Li Liu, P. Stamus, D. Thorsen, W. Lyons, T. Li, 2008: "A study of OH imager observed concentric gravity waves near Fort Collins on 11 May 2004", Jour. Geoph. Res, in press.
* 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., in press. Pdf version of this paper
* Sharon L. Vadas, M.J. Taylor, D. Pautet, P. Stamus, D.C. Fritts, F.T. Sao Sabbas, and V.T. Rampinelli, P. Batista, and H. Takahashi, 2008: "Convection: the likely source of the medium-scale gravity waves observed in the OH airglow layer near Brasilia, Brazil, during the SpreadFEx campaign", Ann. Geophys, in press. 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" JASTP, under review. Pdf version of this paper
* Dave C. Fritts and Sharon L. Vadas, 2008: "Gravity wave penetration into the thermosphere: Sensitivity to solar cycle variations and mean winds", Annals. Geophys, 26, 3841-3861. pdf version of this paper
* Taylor, M.J., P.-D. Pautet, A.F. Medeiros, R.A. Buriti, J. Fechine, D.C. Fritts, S.L. Vadas, H. Takahashi, and F.T. Sao Sabbas, 2008: "Characteristics of mesospheric gravity waves near the magnetic equator, Brazil during the SpreadFEx campaign", Ann. Geophys., in press.
* Fritts, D. C., Abdu, M. A., Batista, B. R., Batista, I. S., Batista, P. P., Buriti, R., Clemesha, B. R., Comberiate, J., Dautermann, T., de Paula, E., Fechine, B. J., Fejer, B., D.Gobbi, Haase, J., Kamalabadi, F., Laughman, B., Lima, P. P., Liu, H., Medeiros, A., Pautet, D., ao Sabbas, F. S., Sobral, J. H. A., Stamus, P., Takahashi, H., Taylor, M. J., Vadas, S. L., and Wrasse, C., 2007: "The Spread F Experiment (SpreadFEx): Program overview and first results", Earth, Planets and Space, in press.
* Fritts, D.C., M. A. Abdu, B. R. Batista, I. S. Batista, P. P. Batista, R. Buriti, B. R. Clemesha, T. Dautermann, E. de Paula, B. J. Fechine, B. Fejer, D. Gobbi, J. Haase, F. Kamalabadi, E. R. Kherani, B. Laughman, P. P. Lima, H.-L. Liu, A. Medeiros, D. Pautet, D. M. Riggin, F. S. Rodrigues, F.T. Sao Sabbas, J. H. A. Sobral, P. Stamus, H. Takahashi, M. J. Taylor, S. L. Vadas, F. Vargas, C. Wrasse, 2008a: "Overview and Summary of the Spread F Experiment (SpreadFEx)", Annals Geoph., in press.
* Fritts, D.C., S.L. Vadas, D.M. Riggin, M.A. Abdu, I.S. Batista, H. Takahashi, A. Medeiros, F. Kamalabadi, H.-L. Liu, B. J. Fejer,and M.J. Taylor, 2008: "Gravity wave and tidal influences on equatorial spread F based on observations during the spread F experiment (SpreadFEx)", Annals Geoph., 26, 3235-3252.
* Takahashi, H., M. J. Taylor, P.-D. Pautet, A. F. Medeiros, D. Gobbi, C. M. Wrasse, J. Fechine, M. A. Abdu, I. S. Batista, E. Paula, J.H.A. Sobral, D. Arruda, S. L. Vadas, F. S. Sabbas and D. C. Fritts, 2008: "Simultaneous observation of ionospheric plasma bubbles and mesospheric gravity waves during the SpreadFEx Campaign", Annals Geoph., under review.
* Sao Sabbas, F.T., V. T. Rampinelli, J. Santiago, P. Stamus, S.L. Vadas, G. Dolif Neto, 2008: "Characterization of convective gravity wave sources in satellite IR imagery", Annals Geoph., under review.
* 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} Pdf version of this paper
* Earle, G.D., A. Mwene-Musumba, and S.L. Vadas, 2008: "Satellite-Based measurements of gravity wave-induced Mid-latitude plasma density perturbations" J. Geoph. Res, 113, A03303, doi:10.1029/2007JA012766. Pdf version of this paper
* 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}. Pdf version of this paper
* 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}. Pdf version of this paper
* 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. Pdf version of this paper
* 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