Global Precipitation and ENSO

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:

image showing latest january rainfall anomalies image showing latest february rainfall anomalies
image showing latest march rainfall anomalies image showing latest April rainfall anomalies
image showing latest may rainfall anomalies image showing latest june rainfall anomalies
image showing latest july rainfall anomalies image showing latest august rainfall anomalies
image showing latest September rainfall anomalies image showing latest October rainfall anomalies
image showing latest November rainfall anomalies image showing latest December rainfall anomalies
(Figure 1)

image showing latest august rainfall anomalies 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.

image showing latest august rainfall anomalies Figure 2

Link to graph showing time series of ENSO
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).
Link to prediction index graph
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.

Link to Image showing El Niño minus La Niña Composites of Global Normalized Precipitation Anomalies

Figure 4 (click to enlarge)

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).

Link to image Showing rainfall anomalies and weather patterns from Ropelewski and Halpert (1987)
Figure 5 (click to enlarge)

Link to image Showing Global Precipitation Scenario for 2002-2003
Figure 6 (click to enlarge)

An example of our prediction and monitoring efforts presented for the 2002-03 El Niño is shown here. Fig. 6 represents the average response to El Niño in time and space.

REFERENCES

  • Curtis, S., and R. Adler, 2000: ENSO indices based on patterns of satellite-derived precipitation. J. Climate, 13, 2786-2793.

  • Curtis, S., G. J. Huffman, and R. F. Adler, 2002: Precipitation anomalies in the tropical Indian Ocean and their relation to the initiation of El Niño. Geophys. Res. Letters, 29(10), 1441, doi:10.1029/2001GL013399.

  • Curtis, S., R.F. Adler, G.J. Huffman, E. Nelkin, and D. Bolvin, 2001: Evolution of tropical and extratropical precipitation anomalies during the 1997 to 1999 ENSO cycle. Int. J. Climatol., 21, 961-971.

  • Ropelewski, C.F., and M.S. Halpert, 1987. Global and regional scale precipitation patterns associated with the El Niño / Southern Oscialltion. Mon. Wea. Rev., 115:1606-1626.

  • Link to local GPCP home page


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