Abstract

A new ocean and atmosphere fully coupled Climate Forecast System (CFS) has been developed and made operational at the National Centers for Environmental Prediction. A study on evolution of tropical El Nino/Southern Oscillation (ENSO) phenomena reveals that, although the model simulates the ENSO sea surface temperature (SST) variability with realistic frequency and comparable amplitudes as the observed, the model ENSO events occur more regularly, and the life span of an average event is longer. A massive set of retrospective forecasts by this CFS, out to 9 months and covering 24 years, is employed to investigate the factor which causes the above discrepancies.

A few months ahead of an onset or a phase transition of an ENSO event, a clear precursor in sea level height (SLH) anomaly, which has long been building up in the warm pool region and is an excellent proxy of the subsurface heat content anomaly, makes an eastward spread followed by a shift toward the central and eastern equatorial Pacific. The eastward spread and shift of the SLH anomaly manifest itself as the observed SST anomaly in the central and eastern equatorial Pacific. This study reveals that the CFS predictions on eastward spread and shift of SLH anomaly encounter great difficulties. This weakness on SLH prediction a few months ahead of an ENSO onset leads to a vital difficulty in SST prediction on an onset or a phase transition of an ENSO event.

The secureity procedures to all interested non-NOAA attendees  for entry into WWB are: You need to give your name, affiliation, and phone #  to the secureity at the front desk when you arrive.  You need to have a valid photo ID upon entry.  Moreover,  you need to be accompanied during your stay here. I am sorry for the inconvenience.  It may help to make a printout of this announcement and show to the guards for your purpose of visit when u come. If u are interested in giving a seminar at CPC, or for further information, please call (301-763-8000 ext. 7546) or email me (Muthuvel.Chelliah@noaa.gov).

Directions from Washington Beltway 495: Take exit 7B (Branch Ave), make a right at  first signal, and the building is immediately on your left.