Singhai, P and Chakraborty, A and Jana, K and Rajendran, K and Surendran, S and Pegion, K (2024) The curious case of a strong relationship between ENSO and Indian summer monsoon in CFSv2 model. In: Dynamics of Atmospheres and Oceans, 108 .
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Abstract
An ensemble of forecasts is necessary to identify the uncertainty in predicting a non-linear system like climate. While ensemble averages are often used to represent the mean state and diagnose physical mechanisms, they can lead to information loss and inaccurate assessment of the model's characteristics. Here, we highlight an intriguing case in the seasonal hindcasts of the Climate Forecast System version 2 (CFSv2). While all ensemble members often agree on the sign of predicted El Niño Southern Oscillation (ENSO) for a particular season, non-ENSO climate forcings, although present in some of the individual members, are disparate. As a result, an ensemble mean retains ENSO anomalies while diminishing non-ENSO signals. This difference between ENSO and non-ENSO signals significantly influences moisture convergence and Indian summer monsoon rainfall (ISMR). This stronger influence of ENSO on seasonal predictions increases ENSO�ISMR correlation in ensemble mean seasonal hindcasts. Thus, this discrepancy in the ENSO�ISMR relationship is not present in the individual ensemble members, considered individually or together (without averaging) as independent realizations. Therefore, adequate care should be taken while evaluating physical mechanisms of teleconnection in ensemble mean predictions that can often be skewed due to constructive or destructive superposition of different impacts. © 2024
| Item Type: | Journal Article |
|---|---|
| Publication: | Dynamics of Atmospheres and Oceans |
| Publisher: | Elsevier Ltd |
| Additional Information: | The copyright for this article belongs to the author. |
| Keywords: | Atmospheric thermodynamics; Climate models; Climatology; Weather forecasting, Climate forecast system version 2; Climate forecasts; El Nino southern oscillation; Ensemble mean; Forecast systems; Indian summer monsoon; Indian summer monsoon rainfall; Physical mechanism; System version; Teleconnections, Linear systems, climate modeling; El Nino-Southern Oscillation; monsoon; prediction; seasonal variation; teleconnection; weather forecasting |
| Department/Centre: | Division of Mechanical Sciences > Divecha Centre for Climate Change Division of Mechanical Sciences > Centre for Atmospheric & Oceanic Sciences |
| Date Deposited: | 26 Nov 2024 10:28 |
| Last Modified: | 26 Nov 2024 10:28 |
| URI: | http://eprints.iisc.ac.in/id/eprint/86887 |
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