dlh37@cornell.edu telephone (607) 255-0630 facsimile (607) 254-4780 Mailing address: Department of Earth and Atmospheric Sciences Cornell University Ithaca, NY 14853

David L. Hysell joined the department of Earth and Atmospheric Sciences as an associate professor in the spring of 2002. Hysell had been a graduate student in ECE at Cornell, where he received his Ph.D. degree in 1992 and worked as a post-doctoral researcher with the Space Plasma Physics group until 1994. Prior to returning to Ithaca, he was an associate professor in the Physics department at Clemson University. His research interests are in the area of upper atmospheric physics, space plasmas, and radar remote sensing. Upper atmospheric physics overlaps broadly with other disciplines in Earth and Atmospheric Sciences, particularly in the areas of atmospheric science, ground penetrating and synthetic aperture radar, geodesy, geomagnetism, and theoretical and computational fluid dynamics.

Hysell's research focuses on theoretical and experimental investigations of space plasmas in the Earth's ionosphere between 80 and 1500 km altitude. Much of his experimental research is carried out at two radar observatories supported by Cornell: the Jicamarca Radio Observatory near Lima, Peru, and the Arecibo telescope in Puerto Rico. The density, temperature, composition, and dynamics of the ionosphere and upper atmosphere can be studied from these observatories through a process known as incoherent scatter. Incoherent radar scatter is very weak and can only be observed with very large, powerful radars like Jicamarca and Arecibo. The upper atmosphere is a sensitive telltale of the effects of space weather and long-term global change, and radar measurements have important consequences for essential human activities.

At times, however, the ionosphere becomes unstable and produces spontaneously a spectrum of intense plasma waves and irregularities. These irregularities interfere with terrestrial and satellite communication links upon which humanity is becoming increasingly dependent. The irregularities can also be seen with radars through a process known as coherent scatter. Coherent radar scatter is quite strong and can be observed even with relatively modest radar systems. Hysell has designed and built a number of small, portable coherent scatter radars for studying plasma instabilities and irregularities in the Earth's ionosphere at low, middle, and high latitudes. Using radar interferometry and imaging techniques similar to those applied in radio astronomy and medicine, Hysell uses the radars to observe the growth, propagation, and decay of ionospheric plasma irregularities in three spatial dimensions and in time. The imaging techniques were developed working at Jicamarca and at the Middle and Upper (MU) atmospheric radar in Shigaraki, Japan. In the near future, new imaging radars will be deployed in St. Croix, USVI, and Homer, Alaska.

Recent Publications

Hysell, D., R. Miceli, J. Munk, D. Hampton, C. Heinselman, M. Nicolls, S. Powell, K. Lynch, and M. Lessard (2012), Comparing VHF coherent scatter from the radar aurora with incoherent scatter and all-sky auroral imagery, J. Geophys. Res., 117, A10313, doi:10.1029/2012JA018010.

Hysell, D. L., E. Nossa, M. F. Larsen, J. Munro, S. Smith, M. P. Sulzer, and S. A. González (2012), Dynamic instability in the lower thermosphere inferred from irregular sporadic E layers, J. Geophys. Res., 117, A08305, doi:10.1029/2012JA017910.

Aveiro, H. C., and D. L. Hysell (2012), Implications of the equipotential field line approximation for equatorial spread F analysis, Geophys. Res. Lett., 39, L11106, doi:10.1029/2012GL051971.

Aveiro, H. C., D. L. Hysell, R. G. Caton, K. M. Groves, J. Klenzing, R. F. Pfaff, R. Stoneback, and R. A. Heelis (2012), Three-dimensional numerical simulations of equatorial spread F: Results and observations in the Pacific sector, J. Geophys. Res., 117, A03325, doi:10.1029/2011JA017077.

Hysell, D. L., R. H. Varney, M. N. Vlasov, E. Nossa, B. Watkins, T. Pedersen, and J. D. Huba (2012), Estimating the electron energy distribution during ionospheric modification from spectrographic airglow measurements, J. Geophys. Res., 117, A02317, doi:10.1029/2011JA017187.

Aveiro, H. C., D. L. Hysell, J. Park, and H. Lühr (2011), Equatorial spread F-related currents: Three-dimensional simulations and observations, Geophys. Res. Lett., 38, L21103, doi:10.1029/2011GL049586.

Hysell, D. L., R. B. Hedden, W. E. Swartz, D. T. Farley, J. L. Chau, and M. A. Milla (2011), Magnetic aspect sensitivity of 3-m F-region field-aligned plasma density irregularities over Jicamarca, J. Geophys. Res., 116, A10302, doi:10.1029/2011JA016856.