A Comparison of Winds Observed at Christmas Island using a Wind-Profiling Doppler Radar with NMC and ECMWF Analyses

Abstract

Wind profilers can provide useful wind data from remote regions of the globe, and incorporation of upper-level wind profiler data into analysis products can significantly improve the quality of analyses in data sparse regions. A wind-profiling Doppler radar was installed by the Acronomy Laboratory on Christmas Island during late 1985 as part of the Tropical Ocean Global Atmosphere (TOGA) Program. The Christmas Island profiler is self-contained and operates essentially unattended. Since April 1986, data from the Christmas Island profiler have been telemetered via GOES Satellite to provide hourly-averaged soundings of the wind four times daily keyed to the standard synoptic observing times and incorporated routinely onto the Global Telecommunication System (GTS) for world-wide distribution. In 1987 both NMC and ECMWF began using Christmas Island wind profiler observations in preparing their global analysis and forecast products. Detailed comparisons of NMC and ECMWF analyses with Christmas Island winds before and after profiler winds were introduced into the global analyses are presented. Results of statistical comparisons reveal a marked improvement in the analyses following the introduction of Christmas Island winds into the standard analysis products: before the Christmas Island winds were introduced into the analyses, monthly mean standard deviations between analyzed and observed winds were typically in the range 3?5 m · s?1 and monthly mean biases were typically in the range 1?3 m after the Christmas Island winds were introduced, the standard deviation was reduced to about 1?2 m . s?1 at most heights, while the bias values were reduced to less than 0.5 m · s?1 at most heights.