Monday, 10 February 2003
A Super-Ob for the WSR-88D Radar Radial Winds for use in The NCEP Operational Assimilation System
Redundant observations impose a burden on an operational assimilation system since each datum is processed with repetitive interpolations from the analysis grid to its location and back again. This effort is carried out for each datum regardless of the information that can be attributed to it in the overall assimilation. The time and storage expended on mutually redundant data could be better spent on improving other aspects of an assimilation. Therefore, it is desirable to effect whatever data compression the ensemble of fresh observations allow, subject to the resulting degradation of the otherwise "optimal" analysis being negligible. The term for a surrogate datum which replaces several partially redundant actual data is a "super observation" or "super-ob". These have been applied to operational analysis at NCEP for subsets of the WSR-88D radar Radial Wind National Industrial Data System (NIDS) observations. However, the precision and information content of the radial wind can be improved if data at each radar site is directly utilized at the resolution and precision of the WSR-88D radar. We report a new product for the Open RPG software system called the Radar Super-ob which takes the result of radar scans and averages data points within a prescribed 3-dimensional volume before transmission and central collection of base data. In addition, with data compression, the total volume of data is reduced allowing quality control information to be included.
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