Seminar Abstract
Andy Wood - June 10, 2003
with co-authors Alan Hamlet and Dennis Lettenmaier
Implementing Real-Time Seasonal Hydrologic Forecasting for the Western U.S.: Recent Progress
We are implementing an experimental end-to-end hydrologic forecasting
approach that uses ensemble climate forecasts to drive the Variable
Infiltration Capacity (VIC) macroscale hydrologic model for the
large river basins of the western U.S., producing streamflow forecasts
for lead times of six months to a year. Climate forecast ensembles
are derived from several climate models, and also formulated via the Extended Streamflow Prediction
(ESP) method; and the ESP forecasts are further composited to provide
ENSO and PDO conditioned ensembles. The forecasting project began
real-time (2-week) updates in the end of December, 2002, and ran
through April 2003, over a limited initial domain of the Pacific
Northwest. In that time, several improvements were pursued, including
the development of an assimilation of snow water equivalent observations
at the start of the forecast, and a modification of the surface
forcing estimation immediately prior to the forecast start. In
addition, a retrospective forecast skill analysis over the entire
western U.S. domain was undertaken to ascertain the value of the
climate model forecasts, relative to the ESP forecast baseline
and climatological forecasts. Results from the real-time and retrospective
forecast efforts will be discussed, along with the directions
anticipated for expanding the real time forecast system.