Using ASCAT Wind and Other Data in Marine Forecasting

1.0 Introduction » 1.1 About Scatterometer and Altimeter Observations

Real-time oceanographic observations are available from weather buoys and ships carrying weather monitoring equipment. The coverage of this data is, however, very limited, particularly over the Southern Ocean. As a result, forecasters rely almost exclusively on numerical weather prediction (NWP) to forecast weather systems, such as cold fronts, and their impact on the weather and sea state. The lack of observational data also means that there are few ways to verify the accuracy of the NWP weather and marine forecasts.

Satellite-based technologies have been changing this. For example, scatterometers, such as the Advanced Scatterometer or ASCAT on the Metop satellite series, and altimeters, such as the Jason series and Saral/Altika, are providing much needed wind and wave information over the world’s marine areas, both coastal and deep ocean. This information can be integrated with ship and buoy observations and satellite imagery to better assess current ocean conditions and evaluate the accuracy of NWP model analyses and forecasts.

Plot showing significant wave height data over the North Pacific Ocean as measured by Jason-2, Cryosat-2, and Altika polar-orbiting altimeters on October 18, 2013.

If you’re not familiar with scatterometers and altimeters, they are satellite-based microwave radars that emit microwave energy towards the surface of the earth and measure the returned signal. The signals are processed to produce various geophysical parameters used in marine forecasting and other disciplines. Among the marine parameters are sea surface height, significant wave height, and wind speed from altimeters; and wind speed and direction from scatterometers.