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Altimetry applications in videos: Seasonal forecasting
By integrating oceanographic and meteorological data in models, it is possible to describe major seasonal trends several months in advance.
See the video Seasonal forecasting: flash (9 Mo) or mpeg (38 Mo)
The European Centre for Medium-range Weather Forecasts (ECMWF) located in Reading, England, stored in memory of its computers all the climate history of the past 30 years. Every day, 300 million data are processed and archived. Including data provided by the european organisation Eumetsat from satellites and radar altimeters, oceanographic data play a key role. By integrating these data in a coupled model describing both the ocean and the atmosphere, it is possible by successive iterations to provide weather forecasts as those that the public knows well for 10 days to come. But the major seasonal trends can also be described by the models, several months in advance.
A first example is given with La Niña, which at the opposite of El Niño corresponds to colder waters than usual. La Niña was strong in November 2007. In March 2008, model outputs predicted a return to normal conditions in June 2008.
Another exemple is given at a global scale, during the last winter, 2007-2008. The mean temperature over the 3 winter months reveals an anomaly in the Pacific Ocean and in the northern hemisphere with excessive temperatures, particularly in Siberia. Forecasts made by the ECMWF and proceeded one month, two months and even three months before the beginning of winter have been very close to the real conditions by describing precisely these anomalies.
The accuracy will still improve with the aim of winning one month's forecast per decade. With the integration of new altimetric data with Jason-2, climate and seasonal forecast is on the right road.
Further information:
- Applications: Climate, <link internal-link>What will next season be like?
- Ocean indicators: <link internal-link>El Niño bulletin, to see what's happening now
- ECMWF: <link http: www.ecmwf.int products forecasts seasonal documentation ch1.html _blank external-link-new-window>The basis of seasonal forecasting
- Eumetsat
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