Title: “Satellite active remote sensing for numerical weather prediction”


Remote sensing of the earth’s atmosphere from space has been available for weather forecasting for almost 40 years. Initially just imagery,(for cloud analysis) and later sounding (profiles of temeperature), these ‘traditional’ passive instruments measure in the visible and infra-red wavebands, though more recently, microwave imagers and sounders have been deployed. However, remote sounding using active (e.g. radar) techniques have been flown in space since the mid-1970s, though it was not until ERS-1 in 1991 that quasi-operational active data became available for use in numerical weather prediction (NWP). New active (non-radar) techniques, using the Global Positioning System (GPS), are now at the transisition stage from research/demonstration and quasi-operational status.

This seminar will outline the principles of some of these active instruments and their derived meteorological data, and will summarise the problems and benefits in using these data in a modern operational NWP data assimilation system. This will be illustrated by the examples of scatterometers (for ocean surface winds), ground-based GPS (vertically integrated water vapour) and GPS radio-occultation (profiles of temperature and humidity) and their use in the Met Office’s 3-D variational data assimilation system.