Evaluation of an interactive regional wind analysis procedure for the tropics

Abstract

An interactive tropical wind analysis technique is developed that combines the best features of the automated and subjective analyses over a limited region. An automated, large-scale analysis is used as a first-guess field. Composite observations over two 6-hour synoptic times and synthetic observations are added as increments to the first-guess field. Complete sets of synthetic observations are introduced to represent the upper- and lower-level structure of tropical cyclones, Tropical Upper Tropospheric Trough cells, upper-level anticyclonic cells, weak low- level cyclones, and point outflows from convective clusters. Point synthetic observations are inserted to represent satellite-observed features such as confluent asymptotes, or offset bad observations. A Multi-Quadric interpolation technique that draws closely to the wind observations effectively and efficiently provides an analysis on a 10 lat./long. grid. A sequence of 200 mb and 850 mb interactive analyses that includes Typhoon Robyn and Tropical Storm Steve is used to demonstrate changes from the first-guess and especially the vertical wind shear when synthetic observations are added.