A Comparative Analysis of Rawinsonde and Nimbus 6 and Tiros N Satellite Profile Data.

This report addresses the question regarding the extent to which satellite sounding data can be used to determine atmospheric structure. Comparisons are made between rawinsonde and satellite profiles in seven areas for a wide range of surface and weather conditions. Variables considered consist of temperature, dewpoint temperature, thickness, precipitable water, lapse rate of temperature, stability, geopotential height, mixing ratio, wind direction, wind speed, and kinematic parameters, including vorticity and the advection of vorticity and temperature. In addition, comparisons are made in the form of cross sections and synoptic fields for selected variables. Sounding data from the NIMBUS-6 and TIROS-N satellites were used. The NIMBUS-6 data were linearly interpolated to obtain soundings coincident in time with the rawinsonde soundings. The TIROS-N data were obtained concurrently with the rawinsonde data, and no interpolation was performed. Results from the analysis of the discrepancies between satellite and rawinsonde data were similar for both types of satellite data. Biases were observed in both sets of satellite data as a function of altitude, and the discrepancies were approximately randomly distributed in the 1000-500, 500-300, and 300-100 mb layers. Geostrophic wind computed from smoothed geopotential heights provided large-scale flow patterns that agreed well with the rawinsonde wind fields. Surface wind patterns as well as magnitudes computed by use of the log law to extrapolate wind to a heighth of 10 m agreed well with observations. Author