University of California Water Resources Center

The research problem studied here is whether regional streamflows can be identified and potentially predicted based on the impact ofEl Nino, La Nina and the Southern Oscillation. The research focused on the following question: Can streamflow and drought in California be predicted by scientifically understanding ENSO and large scale circulation patterns? ENSO is defined as the EI Nino/Southern Oscillation climatic phenomenon. For decades, the prediction of streamflow and drought has intrigued hydrologists; our current research suggests that ENSO strongly affects streamflow and thus could be an important factor in making long range forecasts of streamflow.

Researchers have determined that ENSO events have significant worldwide impacts on such events as precipitation, temperature, floods, droughts and wildfires. ENSO is a warm event in the tropical Pacific Ocean and is considered a significant perturbation of the general atmospheric circulation. EI Nifio events have been observed and recorded since 1726. They occur approximately once every 4 years; however, the time interval between successive events varies from 2 to 10 years.

The research objective was to identify regions of land that appear to have a coherent and consistent ENSO-related signal. The identification of these regions and the predictions of the onset of an ENSO event could then lead to the prediction of climatic anomalies.