Latent Heat Fluxes Trend and their Response to El Niño Southern Oscillation at the Global Scale

This study employed the Japanese Ocean flux data sets with use of remote sensing observations version 2 (JOFURO2) to examine global-scale seasonal variations and trends in Latent heat flux (LHF) over a 19-year period. Furthermore, additional analysis has been conducted to determine the response of LHF to the El Niño Southern Oscillation (ENSO) phenomenon. To assess variability, trends, and strength of relationships with ENSO, statistical score analysis was employed using seasonal means, standard deviations, linear trends, and linear correlations, respectively. In this study, the seasons were classified as December-January-February (DJF), March-April-May (MAM), June-July-August (JJA), and September-October-November (SON). The result of the study revealed that the highest LHF values tracked the annual movement of the sun. In the Northern Hemisphere, the highest spatial trends occurred during DJF, while JJA exhibited the peak values in the Southern Hemisphere. This spatial pattern aligns with the seasonal means of LHF, where the highest and lowest standard deviations and trends coincide with the corresponding regions of high and low LHF. This finding suggests that the standard deviation patterns support the observed variability in seasonal LHF means. The strongest spatial correlations between LHF and ENSO were observed over the Indian Ocean during the SON season. In contrast, the correlations between LHF and ENSO in the Atlantic Ocean exhibited spatial heterogeneity, with a significant correlation only during the DJF season. In general, the seasonal spatio-temporal patterns suggest a dynamic link between LHF and ENSO, potentially linked to large-scale monsoon system changes, the specific locations and distributions of positive/negative trends and standard deviations in LHF reveal a spatial response that appears independent of the ENSO phenomenon.