Statistical Assessment Of Noaa-10 Co-located Soundings Using A Physical Retrieval System

Abstract

We examinedthetemperature differences between NOAA-10 and radiosonde temperature soundings for co-located 18,000 cases during April-May, 1989 where the satellite and radiosonde were close in space and time. The means of the differences were close to 0. The standard deviations of the differences were in the 2 - 4 degree OC range and were computed as a function of longitude, latitude, and 14 standard pressure layers. The standard deviations varied most in the vertical, and least with longitude. INTRODUCTION As part of our effort to examine the ,spatial correlation of observational errors in satellite temperature retrievals, we also studied the differences in co-located .satellite and radiosonde temperature profiles. The NOAA-10 polar-orbiting satellite looks at every point on earth twice daily, at approximately 1930 and 0730 local time. Radiosondes are also launched twice each day around the world, at 0000 and 1200 GMT. This means that each day, for certain sectors of the earth, the satellite and radiosonde collect temperature data from essentially the same atmosphere. These temperature soundings, close in both space and time, are called Ilmatchupll soundings. We examined nearly 18,000 of these matchups from a three-week period in April and May of 1989 for two