AAS 97-637
NEUTRAL DENSITY SPECIFICATION USING FIRST PRINCIPLE MODELS: SEMI-ANNUAL VARIATIONS AND STORMS
T.J. Fuller-Rowell, M.V. Codrescu, J.M. Forbes - CIRES University of Colorado and NOAA Space Environment Center
Abstract
The goal of the present work is to use first-principle models to improve neutral density specification and forecasting. If we can understand the cause of density variations then we have the potential to make improvements. For example, a mechanism has been proposed for the semi-annual density > variation that suggests it is a natural process in the thermosphere, and does not require an external driver. Physical models indicate that the global scale, interhemispheric circulation at solstice acts like a huge turbulent eddy and drives a semi-annual density anomaly. Having simulated the effect the dependence on altitude and solar cycle can be examined. Another example is the response to magnetospheric sources. During a geomagnetic storm the neutral density changes drastically, and has distinct patterns dependent on the magnitude and temporal variation of the magnetospheric source. Joule heating causes most of the initial thermal expansion and increase of neutral gas density. The h
Dr. Louis G. Walters - Aegis Research Corporation
Mission Area Planning
Dr. Paul W. Schumacher, Jr. - U.S. Naval Space Command
Applications of Advanced Filter Technologies