Steiner, E. J., and S. J. S. Khalsa, 1987: Sea surface temperature, low-level moisture, and convection in the tropical Pacific. J. Geophys. Res., 92, 14217-14224.


Sea surface temperature (SST), lower tropospheric moisture, and deep convection in the Tropical Pacific are described and compared for the period January 1982-December 1985. All the data used were wholly or partially satellite derived, enabling the examination of continuous fields over large areas. SST data were from the blended analysis produced by the Climate Analysis Center; low-level precipitable water (LLPW) in the 1000- to 700-mb layer was derived from the TIROS-N operational vertical sounder aboard the NOAA polar-orbiting satellites; and deep convection was estimated from the presence of highly reflective clouds (HRC) visible on NOAA satellite picture mosaics. Monthly means of LLPW and HRC were computed from daily data to correspond to the averaging period of SST. Maxima and minima of the three variables were found to be offset in both time and space, demonstrating that high SST does not always result in enhanced local convection. In the eastern equatorial Pacific, increases of SST and LLPW were found to precede rises of HRC by one or more months. Variability of all three parameters in the eastern Pacific was dominated by the 1982-1983 El Niño-Southern Oscillation and the seasonal cycle, whereas the seasonal cycle of all parameters in the western and central Pacific was weak. The strong signals in the eastern equatorial Pacific were in part responsible for the higher correlation coefficients between all pairs of variables there. Recent modelling studies are beginning to take into consideration the complexity of atmospheric response to surface heating.