A METHOD FOR OBJECTIVE ANALYSIS OF STRATOSPHERIC CONSTANT-PRESSURE CHARTS

Abstract

A method of numerical objective analysis has been developed for application to stratospheric constant-pressure data at the 100-, 50-, 30-, and 10-mb. levels (approximately 16, 20, 24, and 31 km., respectively). This system evolved from successive modifications of the programs employed for operational objective analysis of lower-level charts at the National Meteorological Center. For use with stratospheric data, the Automatic Data Processing portion of these programs was expanded to correct for the errors in high-level rawinsonde temperatures and heights caused by short and long-wave radiational effects on the temperature sensor. In addition, procedures for vertical extrapolation of rawinsonde reports and merging of off-time data were incorporated to compensate for the scarcity of reports at a given observation time. General degradation of stratospheric data with increasing height necessitated more stringent data rejection criteria within the entire system. It was also essential that increased emphasis be placed on wind observations as an analysis parameter. The resulting charts have shown that the objective system employed produces analyses of acceptable quality. Improvements are continually being developed and incorporated to increase the efficacy and objectivity of the procedures and the quality and usefulness of the product. The main purposes of the computerized system are to provide good quality stratospheric analyses for anticipated operational requirements and to satisfy the needs of research. Daily analysis of Northern Hemisphere charts is being performed during the IQSY and is expected to continue after the end of the period. These maps are recorded for distribution on microfilm and also on punched-card decks containing grid-point data.