Analyses of information content and theoretical retrieval performance show that, when treated optimally, significant humidity and temperature information can be derived from ATOVS infrared and microwave retrievals within the clear and cloudy sky summertime EPAC environment. A study of theoretical retrieval error sensitivity to representative EPAC background state vector elements and associated errors was also conducted to establish the a priori elements critical for successful 1DVAR retrievals.
1DVAR profile temperature and humidity retrievals were generated using both simulated and actual ATOVS observations constrained by the COAMPS 6-hr forecasts and a synoptically relevant background error covariance matrix. The time period of interest coincides with the Dynamics and Chemistry of Marine Stratocumulus (DYCOMS) Phase II field study. The 1DVAR results are consistent with the theoretical information content study and indicate that these satellite observations can provide information that, when used in concert with a reasonable first-guess background (i.e., from COAMPS), reduce the retrieval error and adjust the retrieval within the shallow boundary layer toward the designated "true" profile.
The generally good agreement between theoretical retrieval errors and the error statistics calculated using non-linear Newtonian iteration demonstrates consistency and reliability of the NRL 1DVAR retrieval scheme.
COAMPS is a trademark of Naval Research Laboratory.