SEARCH Projects

NOAA SEARCH Element 4: Correction of Systematic Errors in TOVS Radiances

PI: Jennifer Francis, Rutgers University PI: Tony Reale PI: Axel Schweiger, U of Washington

Abstract

The TIROS Operational Vertical Sounder (TOVS) instrument has flown on NOAA polar-orbiting satellites since 1979 and has collected one of the longest and most complete satellite data records in existence. It was originally designed to serve the weather forecasting community by providing temperature and moisture profiles in regions of the Earth that have few conventional meteorological stations. The TOVS data can also be used to retrieve cloud properties (coverage, cloud-top height, optical depth, and phase) and surface properties (skin temperature, surface type, drag coefficient). While this instrument was intended for operational applications, many researchers have demonstrated its tremendous potential for studying a wide range of climate applications as well, particularly in regions with poor coverage of conventional measurements, such as the Arctic Ocean and adjacent seas.

A problem arises in using TOVS data for climate applications, however, as the radiances were not adequately calibrated for long-term accuracy. Consequently, substantial systematic errors from various sources greatly reduce the potential value of TOVS observations for monitoring and understanding climate change. The proposed work will attempt to identify, quantify, and mitigate these errors with the ultimate goal of producing a 20-year (or more) record of TOVS radiances and retrieved products that are as error-free as practicable, given available resources. Many of the known errors should be regionally and seasonally independent, but we suspect that some may be peculiar to or exacerbated in Arctic conditions. Thus, while our efforts will be global, our focus will be primarily Arctic. The expected product of this investigation will be a data set of tremendous value both for geophysical retrievals with sufficient accuracy to identify changes since 1979, as well as for direct assimilation by numerical atmospheric models.