Exploring Brightness Temperatures and Atmospheric State Relationships in the Ensemble Mars Atmosphere Reanalysis System (EMARS)

Open Access
- Author:
- Mc Michael, Ryan
- Graduate Program:
- Meteorology and Atmospheric Science
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- October 24, 2022
- Committee Members:
- Steven J Greybush, Thesis Advisor/Co-Advisor
Eugene Edmund Clothiaux, Committee Member
Paul Markowski, Professor in Charge/Director of Graduate Studies
Christopher Blaszczak-Boxe, Committee Member - Keywords:
- Mars
Brightness temperature
Data assimilation
EMARS
Radiative transfer - Abstract:
- Brightness temperatures can be used to quantify synoptic-scale variability on the surface of Mars. Eddies in the brightness temperature field are the result of transient surface temperature and dust patterns. Transient eddies, observed in Mars’ wintertime hemisphere, contribute to the generation of global dust storms that impact the planetary energy budget from dust radiative forcing, adjust the physical and chemical structure of the atmosphere, and disrupt spacecraft operations. Better prediction of dust storm genesis requires improved transient eddy modeling in the lowest atmosphere scale height. Assimilating radiances into global climate models better constrains eddy behavior, but before direct assimilation is performed, relationships between modeled brightness temperatures and other physical predictors are assessed. To do this, we utilize data from the Ensemble Mars Atmosphere Reanalysis System. First, brightness temperature time series are built using a multiple linear regression model. The surface temperature, atmospheric dust and water ice, and surface water and CO2 ices constrain much of the observed patterns in brightness temperature variability, and their regression parameters define the spatiotemporal patterns of radiative forcing. The combined behaviors observed in the model regression coefficients and model evaluation correlations correspond to the understanding that physical forcing on brightness temperature is nonlinear. Maps of ensemble perturbation correlations, quantities directly responsible for updating the atmospheric state in reanalysis, are plotted to show spatial variability across various latitudes. Vertical profiles of temperature and aerosol distribution demonstrates how the coupling between the atmospheric dust, water ice, and surface temperatures modulate incoming and outgoing longwave radiation, ultimately adjusting modeled brightness temperatures.