High‐Frequency Wind‐Related Seasonal Mean Latent Heat Flux Changes Over the Tropical Indo‐Western Pacific in El Niño and La Niña Years

Abstract

AbstractBy decomposing the variations of daily mean variables into synoptic, intraseasonal, and low‐frequency components, the present study compares seasonal mean latent heat flux (LHF) anomalies related to the three components over the tropical Indo‐Pacific region during El Niño and La Niña years. It is found that the high‐frequency (intraseasonal and synoptic) LHF has an important contribution to total seasonal mean LHF anomalies over the tropical eastern Indo‐western Pacific region. Large seasonal mean LHF anomalies related to high‐frequency wind variations are identified in weak low‐frequency seasonal mean wind regions where high‐frequency LHF may accumulate over a season as it increases in both westerly and easterly phases of high‐frequency wind variations. In those regions, the LHF anomalies related to high‐frequency wind variations cancel part of the low‐frequency LHF anomalies, reducing total seasonal mean LHF anomalies. As El Niño–Southern Oscillation (ENSO)‐induced lower‐level wind anomaly region moves with the stage of ENSO, large seasonal mean LHF anomalies related to high‐frequency wind variations displace with the season. The intensity of high‐frequency wind fluctuations is also a factor influencing the seasonal mean LHF related to high‐frequency wind variations. Thus, the ENSO affects the high‐frequency LHF variations through modulating both the location of weak low‐frequency wind region and intensity of high‐frequency wind fluctuations.