Ben P. Kirtman, J. Shukla and Zhengxin Zhu
Published in the Experimental Long-Lead Forecast Bulletin, June 1997
The El Niño forecasts are part of an ongoing research effort at COLA, and do not represent official forecasts. These forecasts should not be used as the basis of any commercial, policy, or other decisions. They are strictly research tools for advancing the understanding of the ocean-atmosphere system.
The NINO3 time series of the predicted SSTA for three forecasts initialized
on, March 1, 1997, April 1, 1997 and May 1, 1997, are shown below. Each
forecast is run for 18 months. The evolution of all three forecasts are
fairly consistent. The model predicts steady warming through boreal summer
and fall of 1997 with the strongest anomalies (approximately 1ºC)
occurring during the boreal winter of 1997-98. After the boreal winter
of 1997-98 the NINO3 anomaly in all three forecasts decay to near normal
conditions by the boreal summer of 1998.
| Time evolution of the NINO3 SSTA forecast. The solid red curve corresponds to the forecast initialized in March 1997, the dashed blue curve corresponds to the April 1997 forecast and the dotted green curve corresponds to the May 1997 forecast. |
The ensemble mean (average of all three forecasts) horizontal structure
of the predicted SSTA for the boreal summer of 1997, the boreal fall of
1997 and the boreal winter of 1997-98 are shown in the three panels below.
The ensemble mean forecast for summer 1997 calls for relatively warm SSTA
throughout much of the equatorial central and eastern Pacific. Typical
of this model there are two maxima; one in the central Pacific and one
in the eastern Pacific. Given the typical evolution of ENSO in this coupled
model, this current forecast for is quite warm. The SSTA continues to warm
through the boreal Fall with maxima will over 1ºC. By winter much
of the tropical Pacific is over 1ºC warmer than normal and there is
a sizable region in the central Pacific were the SSTA exceeds 1.5ºC.
| The ensemble mean anomalies in sea surface temperature (SSTA). The top panel shows the predicted ensemble mean averaged over June-July-August 1997. The middle panel shows the predicted ensemble mean SSTA averaged from September 1997 to November 1997. The bottom panel shows the ensemble mean averaged over December 1997 to February 1998. |
These latest forecasts are consistent with the forecast from the previous period, and indicate that peak El Niño conditions can be expected for the winter of 1997-98.