The Western Pacific Warm Pool Sea - Air Interface Heat Flux Exchange Intraseasonal Oscillation

The distribution characteristics of sea surface heat fluxes and their 30-60-day oscillations (MJO) over the western Pacific warm pool from 1995 to 2004 are studied firstly, using the daily averaged data from NOAA Climate Diagnostics Center. Each sea surface heat flux shows obvious differences in different seasons, especially in summer. The standard deviations and their seasonal differences of Qlat (Latent Heat Net Flux) and Qsw (Net Shortwave Radiation Flux) are greater than that of Qlw (Net Longwave Radiation Flux) and Qsen (Sensible Heat Net Flux), which indicates Qlat and Qsw may act as the leading roles in the exchange process of sea surface heat fluxes. The evolutions of MJO Qlat and 10m wind field display a unique feature in that a well-developed MJO anticyclone (cyclone) is almost anchored over the same region at the peak suppressed (enhanced) MJO Qlat phase over the western Pacific warm pool. And in one rounded MJO cycle, Qlat put up better relativity with Qnet than the other heat fluxes either in corresponding region or numerical value.Excluding synoptic variations, the seasonal evolution of one heat flux variable may be divided into two components: annual cycle, and intraseasonal oscillation, and we found that the latter contributes more for every heat flux. From 1979 to 2004(26 years), following the wintertime warm, cold ENSO events, the evolution of heat fluxes over the western Pacific warm pool show significant differences during April-August, and it is mainly caused by Qlat and Qsw. On the whole, the MJO is stronger in cold ENSO events, especially in June and July; but in warm ENSO events, the stronger MJO take place in April, May and August, so that there is out-of-phase feature of summertime MJO for heat fluxes between the warm and cold ENSO cases.The cases of strong and weak convection are selected based on the interannual variation of OLR (outgoing longwave radiation). The different evolution characteristics of Qnet in this two cases also mostly owe to Qlat and Qsw. And Qnet should have some relation with OLR, because of their coherent variety that the increaser (decreasing) heat flux from the ocean to atmosphere relates to the enhanced (suppressed) convection. For the importance of Qlat during the air-sea heat flux exchange, it seems to connect well with OLR too.