The surface heat fluxes along the eastern Pacific coast from 10°N to 40°S

Abstract

An adequate understanding of the ocean–atmosphere interface is important for understanding climate variability on different time scales. Thus, this research focuses on surface heat fluxes over seasonal scales and their changes during El Niño and La Niña along the eastern Pacific coast (10ºN–40ºS), consistent with oceanographic and meteorological fields. We used a wide range of up-to-date databases, new mean monthly heat air–sea fluxes (NOCS Flux Dataset v2.0) and complementary global databases (SODA reanalysis, SeaWiFS). The results reported here show that of all the fluxes contributing to net heat flux (Qnet ) , net shortwave radiation (Qsw ) is the term that warms and is most dominant, and latent heat flux (Qlat ) is the term that most contributes to cooling. Considering seasonal variability, Qsw reduction due to cloud cover in the latter half of the year was associated with the presence of the Intertropical Convergence Zone and the stratus cloud deck at 10ºN–Eq and Eq–30ºS, respectively. The smaller seasonal amplitude south of 30ºS was associated with the southern coastal jet that develops along the eastern flank of the low-level circulation over the southeast anticyclonic Pacific. During El Niño and La Niña, the most significant change was observed for Qlat in the first half of the year, between the equator and the Peruvian coast. Qlat tended to cool (warm) during El Niño (La Niña), acting as a negative feedback. Specifically for Qlat , we found that the air–sea specific humidity difference (rather than the wind) played a prominent role in both El Niño – Southern Oscillation phases. The sum of Qnet and the shortwave radiation that penetrates through the base of the mixed layer was compared with the sea surface temperature tendency and was discussed.