Impacts of Merging Profiler and Rawinsonde Winds on TOGA COARE Analyses

Abstract

During the intensive observing period of the Tropical Ocean Global Atmosphere Coupled Ocean?Atmosphere Response Experiment, a large number of collocated rawinsonde and profiler wind observations were taken at six Integrated Sounding System (ISS) sites and Biak, Indonesia. To mitigate limitations in the rawinsonde dataset due to missing and bad wind observations, a procedure was developed to combine profiler and sonde winds to produce an integrated, high-quality, upper-air sounding dataset. In addition to improving the overall quality of the winds, this procedure eliminates several data gaps in the sonde dataset. For example, below 800 hPa the amount of bad and missing wind data is reduced from about 45% to 20% at the land-based ISS sites. This paper describes the procedure for combining sonde and profiler winds into a single, coherent merged dataset. Examining the impact of this merger upon various atmospheric analyses, the authors find that inclusion of profiler winds results in some substantial changes in the analyses, particularly on daily to weekly timescales. To assess whether these changes are an improvement, budget-derived rainfall estimates from analyses with and without profiler winds are compared to Special Sensor Microwave/Imager satellite-based estimates. Overall, this comparison shows that inclusion of profiler winds into the sonde dataset has a beneficial impact upon the analyses. Information for accessing the merged datasets for the seven sites considered in this paper via the Internet is described.