A univariate optimum interpolation analysis scheme has been developed for operational and research use over tropical latitudes. Features of the scheme include its three dimensional aspect, the choice of sigma (normalised pressure) as the vertical coordinate and the use of frictionally-corrected surface wind observations to delineate near-equatorial systems and the Australian summer heat low. The analysis procedure is illustrated using a situation that occurred during the Winter Monsoon Experiment (WMONEX). Assessment by operational forecasters, and by comparison with available subjective analyses, indicates that the numerical product is comparable in skill to manual analyses and suitable for operational use. Moreover, given an observing network comparable to that of WMONEX, meaningful synoptic-scale divergence fields can be obtained from the analysed winds, suggesting that the analysis method is assimilating the observations in a physically realistic manner.
Davidson et al. (Tue,) studied this question.