Techniques to Assimilate SSM/I Observations of Marine Atmospheric Storms
Abstract
This report describes the feature calibration and alignment (FCA) methodology and the results of applying FCA to the Navy's COAMPS mesoscale weather forecast system. FCA quantifies different components of error by defining horizontal adjustment fields of displacements and amplifications to be applied to the forecast fields. The adjustment is determined by minimizing an objective function which constrains the distorted forecast field to closely fit the available observations, and ensures that the final adjustment produced by the minimization is relatively smooth and not too large. The methodology was applied to short-term (12-hour) COAMPS model forecasts, which were compared against SSM/I retrievals of integrated water vapor (IWV). The adjusted forecasts were then used as the first guess fields of the COAMPS optimal interpolation data analysis cycle. Results from three case studies of marine storms over the North Pacific indicate that the adjustments to the first guess led to an improvement of the IWV forecasts. They also indicate that the adjustments are diminished during the data analysis steps of the COAMPS data assimilation system and during the first 12 hours of the forecast, suggesting the need for more effective ways of initializing the COAMPS model with the adjusted fields.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 11, 1998
- Accession Number
- ADA357839
Entities
People
- John Henderson
- Ross Hoffman
- Thomas Nehrkorn
Organizations
- Atmospheric and Environmental Research, Inc