HR: 0830h
AN: A41A-08    [Abstracts]
TI: Predictability of the Seasonal Climate Associated with ENSO in NCEP Climate Forecast System
AU: * Zhang, Q
EM: Qin.Zhang@noaa.gov
AF: RSIS/Climate Prediction Center, NCEP/NWS/NOAA, 5200 Auth Road, Camp Springs, MD 20746 United States
AB: The predictability of seasonal climate associated with ENSO is studied for NCEP Climate Forecast System (CFS) 23-year retrospective forecasts. Warm-minus-cold composites of the lead 1-6 month sea surface temperature (SST) anomalies show an ENSO-like horse-shoes pattern in the tropical Pacific, comparable with observation. There is a corresponding increased precipitation band along the equator near the dateline extending eastward to the South American coast, as well as the less precipitation over the Maritime Continents and off-equatorial western Pacific. Extended empirical orthogonal function (EEOF) analysis of the SST anomaly recovers ENSO -like dominant mode in the tropics for all seasons. Identification of patterns that optimize the signal-to-noise ratio is obtained by linear regression of the ensemble means on the principal component (PC) time series of SST. The optimized height patterns for boreal winter and spring are similar, although the winter response over the northern extratropics is somewhat weaker. Some subtle changes in amplitude are found in difference of leading initial conditions. The signal-to-noise ratio is significantly greater than unity in the Tropics (all seasons), the northern Pacific and continental North America subtropics (boreal winter and spring), and the southern Pacific subtropics (boreal fall).
DE: 1620 Climate dynamics (3309)
SC: Atmospheric Sciences [A]
MN: 2005 Joint Assembly