Introduction

by Mary Forsythe — last modified Jan 31, 2012 05:21 AM

Although no satellite instrument can measure the wind field directly there are a number of techniques that can be used to derive wind observations.  In the 1960s and 70s, Ted Fujita pioneered the work on remote sensing of atmospheric motion by tracking clouds in satellite image sequences from TIROS-1 and ATS-1 (see Menzel 2000 BAMS 82 p33-47). The winds derived using this approach are known as atmospheric moATS1 imagetion vectors (AMVs); they have been assimilated operationally in NWP models since the 1980s.  Over recent decades the quality and quantity of AMV data has increased due to improvements in the satellite imager instruments and the AMV derivation method.  AMVs can also be produced using multi-angle radiometers on polar orbiters (e.g. MISR).  A key advantage is the capability for stereo-based height assignment, however, a large constellation of satellites would be required to provide good spatial and temporal coverage.

Satellite data can be used to derive surface winds over the oceans; these have proved particularly useful for tropical cyclone forecasts.  Two instrument types carried on polar orbiting satellites are commonly used: (1) active radar scatterometers (e.g. SeaWinds and ASCAT) and (2) passive microwave radiometers (e.g. SSM/I and WindSat).  The wind derivation in both cases is based on the effect of near-surface winds on ocean surface roughness.

A noticeable gap in the wind observing network is information on the vertical structure of the wind field.  Future missions including Doppler Wind Lidar on ADM-Aeolus and winds derived from tracking single level moisture fields derived from geostationary hyperspectral sounders (e.g. MTG-IRS) may help to fill this gap.