El Niño under close scrutinies

Image of the month - November 2002

Sea level height variations with respect to the mean, from altimeters onboard Jason-1, ERS-2 and GFO satellites, on September 15, October 9 and 23 (see updates in the El Niño bulletin). (Credits CLS/Cnes).
Sea Surface temperature anomalies on October 28, 2002 as seen by the ATSR instrument onboard ERS-2. (Credits Esa).


As all turbulents children, El Niño is under close monitoring. Several eyes are fixed on it: satellites and in-situ observation instruments are deployed to follow its every "move". Far from being redundants, each bring its own point of view to this monitoring, in order to have the best and earliest forecasting possible.
This year, after some forewarning signs in January and February, followed by a respite, El Niño really started at the end of May-beginning of June. Alert was given, and its amplitude estimated "weak to moderate" in July, more like "moderate" since September. Monitoring continues to keep this child under close scrutinies.

Wind vectors observed by the QuikScat scatterometer averaged over the 7-days centered on June 8, 2002 superimposed on sea level observed by Topex/Poseidon averaged over the same period of time. . The averages over the same 7-days in 2001, one year before, were subtracted from the wind vectors and sea levels to show the deviations from normal conditions. Wind are significantly different from one year to the other: this is the period when the phenomenon really started, after some forewarning signs in January-February. (Credits JPL/Nasa).
Tao array, decided after the major El Niño event of 1982-83 was gradually installed during the 1985-1994 period (Toga project), now consists of approximately 70 moorings in the Tropical Pacific Ocean, measuring surface and in-depth data, and telemetering them to shore in real-time via the Argos satellite system. (Credits Tao/Noaa).

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