Variational Retrieval of Eastern Pacific Atmospheric Boundary Layer Parameters Using ATOVS with the COAMPS Mesoscale Forecast System

A one-dimensional variational (1DVAR) retrieval scheme is used to investigate the ability of the Advanced TIROS Operational Vertical Sounder (ATOVS) to contribute information to a mesoscale NWP system within tbe summertime Eastern Pacific (EPAC) environment. Tbis system is the Coupled Ocean - Atmospbere Mesoscale Prediction System (COAMPS) and the Naval Research Laboratory (NRL) Atmospberic Variational Data Assimilation System (NAVDAS). Analyses of information content and retrieval performance sbow that, when treated optimally, significant humidity and temperature information can be derived from ATOVS retrievals within the clear and cloudy sky summertime EPAC environment. A study of retrieval error sensitivity to representative background slate 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 sbort-term forecasts and a synoptically relevant background error covariance matrix. The time period of interest coincides with the DYCOMS Phase II field study. The 1DVAR retrieval results indicate that ATOVS observations can provide information that, when used in concert with a COAMPS background field, reduce the retrieval error and adjust the retrieval within the shallow boundary layer toward the designawd "true" profile.Naval Postgraduate School Monterey CA is the author of 'Variational Retrieval of Eastern Pacific Atmospheric Boundary Layer Parameters Using ATOVS with the COAMPS Mesoscale Forecast System', published 2002 under ISBN 9781423507802 and ISBN 1423507800.