Scientists associated with the Mesoscale Atmospheric Processes Branch not only produce global precipitation data sets, but also use these data to monitor global climate anomalies. One major component of this activity is to characterize the ENSO phenomenon. We begin by monitoring the precipitation anomalies in the Indian Ocean / Maritime Continent / Pacific Ocean:
Taking the largest precipitation anomalies within the Maritime Continent
and Pacific Boxes in indices of the strength of the Walker Circulation are computed
(Curtis and Adler 2000).
A detailed summary of the methodology can be found here.
A table of the these values can be found here
The time series of ENSO in terms of gradient of precipitation anomalies is shown on the right.
|Precipitation anomalies in the eastern Indian Ocean have been linked to MJO propagation and the initiation of El Niños. An empirical scheme has been developed to determine when precipitation anomalies in the eastern Indian Ocean may be important for the development of El Niño. Detailed information about this technique can be found in (Curtis et al. 2002).||
Figure 3 (click to enlarge)
From this work a prediction index was developed and is shown with ESPI (Figure 3). Note that for the five strongest El Niños the index is high about 12-16 months before the middle of the events.
Precipitation anomalies over the globe are quantified during El Niño and La Niña events. Figure 4 gives the average El Niño minus La Niña conditions for the 31 year period from 1979 through 2010.
Figure 5 is a reproduction of
Plate 4 in Curtis et al. (2001) showing the rainfall anomalies for the 1997-98 El Niño in relation to the
canonical El Niño-related weather patterns from Ropelewski and Halpert (1987).
An example of our prediction and monitoring efforts presented for the
2002-03 El Niño is shown here.
represents the average response to El Niño in time and space.