The latent and sensible heat fluxes over the western tropical pacific and its relationship to ENSO

Abstract

In this paper the Bulk Aerodynamic Formulas are used to compute the latent and sensible heat fluxes over the area 8°S-20°N, 130°-180°E for each month from January 1950 through December 1979 by using the data set of COADS supplied by NOAA of USA. The annual and monthly geographical distributions and the seasonal cycle of heat fluxes are carried out and a seasonal change of heat fluxes for ENSO year is also obtained by compositing individual ENSO year including 1951, 1953, 1957, 1963, 1965, 1969, 1972 and 1976. It is found that during ENSO episodes positive anomalies of heat fluxes appeared during the period of March to July and negative anomalies from August to March of the following year. The time series of sum of heat fluxes for March, April, May, June and July in each year from 1950 through 1979 had a significant link to the eastern tropical Pacific SST index (Wright, 1983). The correlation coefficient was 0.56. As it is found that in the latter half of each ENSO year (August—December) the frequency of typhoon formation in the area studied is less than normal, we suggest that the negative anomalies of heat fluxes during the same period be a mechanism for the decreased frequency of typhoon formation.