Assimilation of Surface Meteorological Observations in COAMPS NAVDAS

Conventional meteorological surface stations typically offer complete observations of temperature, dew point, winds, and pressure with high temporal frequency. The density of these stations continues to increase, especially in the United States, as government agencies, private businesses, and individuals continue to build and maintain these stations for various meteorological uses. While these stations can offer important information to numerical models by correcting errors in the lower boundary condition of the initial state, they can also be very difficult to assimilate, due to siting and representativeness, station maintenance and quality control, and instrumentation configuration issues.

This work assesses the impact of the assimilation of these surface mesonet stations on Coupled Ocean-Atmosphere Mesoscale Prediction System (COAMPSŪ) forecasts using the NRL Atmospheric Variational Data Assimilation System (NAVDAS). Innovations from these observations in the Western United States during a 15 day winter period show relatively no bias and a fairly Gaussian shape to the innovation distribution. Impacts on COAMPS forecast determined from data denial experiments, as well as impacts computed through the adjoints of COAMPS and NAVDAS, will be presented.