GIS ANALYSIS OF POSITION ERRORS IN CURRENT HYDROMETEOROLOGICAL PRACTICE

A Commercial-Off-The-Shelf (COTS) Geographic Information System (GIS) is used to analyze the consequences of various position assumptions commonly employed in current hydrometeorological practice. The common assumption that rawinsonde horizontal displacement is insignificant is shown to lead to errors ~ 5 m s-1 in wind speed in an objective analysis, with additioinal impacts to wind direction and temperature in regions of strong vertical wind shear. The same procedure is applied to ACARS to demonstrate similar potential errors in vertical profiles constructed from aircraft ascents/descents. This level of wind speed error has been claimed to be a fundamental limitation in rawinsonde measurements, but may actually be a result of data analysis procedures. This paper includes a status (and directory) of efforts to provide hydrometeorological data in GIS-Ready formats, as well as progress toward the incorporation of COTS GIS into weather services operations.