Research Projects

The primary aim of this work is to determine the distribution of atomic hydrogen from thermospheric altitudes, into the exosphere on the nightside of the earth. The approach is the coupled analysis of ground-based atomic hydrogen Balmer-alpha and Balmer-beta intensities and line profiles by forward radiative transport (RT) modeling.

Existing and new data of unprecedented precision from our Fabry-Perot instruments will be used for this purpose. This multi-line analysis technique utilizes the differing transport properties of hydrogen Lyman- beta (primarily responsible for Balmer-alpha), and Lyman-gamma (primarily responsible for Balmer-beta) in the terrestrial atmosphere. By forward-model/data comparisons of the variation of the observed emissions with solar depression angle and viewing geometry we will retrieve hydrogen density profiles and other signatures of exospheric physics. Overall, the investigation aims to (1) determine the distribution of atomic hydrogen in the thermosphere and exosphere, (2) quantify how that distribution responds to changes in solar/geophysical conditions, (3) obtain high resolution Balmer-alpha and Balmer-beta line profiles to fully characterize cascade and multiple scattering contributions to the profile in the search for signatures of the exospheric satellite, ballistic and escaping particle populations, and (4) field- test and apply an innovative new class of interference spectrometer to geocoronal studies.