Using ENSO indicators and sea surface temperatures for long-range streamflow forecasting
In the past decade, there has been an increased awareness of the relationship between the El Nino-Southern Oscillation (ENSO) and streamflow in various regions of the world. The research presented here focuses on two regions that are strongly influenced by ENSO activities - the Pacific Northwest U.S. and Eastern Australia. At present in the Pacific Northwest, long range streamflow forecasts are not offered. Yet, a significant lag relationship exists between ENSO and streamflow. Using this lag relationship, this study proposes to extend the prediction of spring-summer runoff in the Pacific Northwest from the current one- to three-month lead time to a three- to seven-month lead time. This study looks at the Columbia River Basin, where testing is being conducted on a long range seasonal streamflow forecasting model that uses, as predictors, Persistence in streamflow along with two ENSO indicators: the Southern Oscillation Index (SOI) and the Wright Sea Surface Temperatures (SSTw). It was found that, at some stations, a three- to seven-month lead time forecast of spring-summer runoff had better skill than Climatology. Results are presented for the 1998 spring-summer runoff forecast. In Australia, there has been recent research at the Australian Bureau of Meteorology Research Centre (BMRC) that has focused on predicting seasonal rainfall from Pacific Ocean sea surface temperatures (SSTs). The work presented here for Eastern Australia is a seasonal streamflow forecast methodology that uses the SST series in conjunction with a ENSO indicator and the serial correlation of streamflow. These forecast take the form of a continuous probability of exceedance of streamflow at varying levels. The use of a continuous probability of exceedance forecast gives water authorities a wider range of options for using the forecast based on their assumed risk level. This seasonal streamflow forecast model is tested on five stations in Eastern Australia for the time period 1950-1996. Preliminary results suggest that forecasting of austral winter and spring streamflow are best accomplished with the previous season streamflow (i.e., serial correlation of streamflow).
Eastern Australia; El Nino-Southern Oscillation (ENSO); Hydroclimatology; Long range streamflow forecast models; Pacific northwest; Precipitation models; Water supply
Environmental Sciences | Fresh Water Studies | Meteorology
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Dracup, J. A.,
Piechota, T. C.
Using ENSO indicators and sea surface temperatures for long-range streamflow forecasting.
Available at: http://digitalscholarship.unlv.edu/presentations/12