[AOS08-P02] Mid-latitude source of the ENSO-spread in SINTEX-F ensemble predictions
Keywords:ENSO, seasonal prediction, spread
500 hPa geopotential height suggests that stochastic atmospheric precursor (without oceanic signal) during winter causes El Nino-like spread through air-sea interaction. The oceanic response in the form of upper heat content (in the top 150m) appears as a result of equatorial wind forcing during boreal spring and summer. These results of seasonal precursor signals in SINTEX-F2 ENSO spread suggest that the seasonal footprinting mechanism (SFM) type air-sea coupling process is important for ENSO spread related to the “spring-barrier”. The state dependence of ENSO spread to background ensemble-mean state (particularly sensitivity of the SFM and California Nino in “post El Nino” phase) was also discussed.