STANFORD UNIVERSITY
EE 350 RADIOSCIENCE SEMINAR
Professor Len Tyler

Fall 2000-2001

Date: Wednesday, November 15, 2000
Time: 4:15-5:30 PM; Refreshments at 4:00 PM
Location: 380-380Y


General Circulation and Modeling of Mars' Atmosphere

Dr. Jeffery L. Hollingsworth
NASA Ames Research Center

Abstract

Over the past two decades, furthering our understanding of the global atmospheric circulation on Mars has been a focus of research in the Planetary Systems Branch at NASA Ames. As in Earth's atmosphere, Mars' atmospheric circulation exhibits variability over a vast range of spatial and temporal scales, some of which is driven by similar physical processes (e.g., Hadley circulation cells; global-scale thermal tidal modes; planetary waves forced via flow over large-scale orographic complexes like Earth's Himalayan plateau; and developing, traveling and decaying extratropical weather cyclones associated with pole-to-equator thermal contrasts). Other sources of variability arise from distinctly martian physical mechanisms (e.g., condensation (sublimation) during the winter (summer) season of the atmosphere's primary chemical constituent (predominantly CO2), and regional- and global-scale dust storms). Ultimately, these investigations aspire to improve our knowledge of the dynamics of the planet's present environment and past climates, and from a comparative planetology perspective, to better understand similar processes that governthe dynamics of the Earth's climate.

In this seminar, an overview of various components of Mars' atmospheric circulation and its climate will be presented. Simulation results using the NASA Ames Mars general circulation model (MGCM) -- a time-dependent, 3D numerical model of the atmosphere's hydrodynamic state as determined by self-consistent algorithms for radiative (e.g., solar and infrared absorption, emission and scattering in the planet's tenuous and frequently dustladen atmosphere) and near-surface processes (e.g., boundary-layer dissipation associated with atmospheric turbulence) -- will be discussed. In parallel efforts, spacecraft data from the recent Mars Pathfinder mission and the ongoing Mars Global Surveyor (MGS) mission are utilized to validate the climate simulation results, while at the same time, both mechanistic and full-up simulations provide a global context for the remotely sensed data. Both the data analysis and modeling efforts can significantly enhance the assessment of Mars' present climate, and thereby will provide a more comprehensive climate database for future missions scheduled during NASA's Mars Surveyor program.