Selective absorption of solar radiation and upper ocean temperature in the equatorial western Pacific

Abstract

The solar radiation absorbed by seawater in the upper 0.45 m within the Tropical Ocean‐Global Atmosphere (TOGA) Coupled Ocean‐Atmosphere Response Experiment (COARE) domain is estimated from the observed surface heat fluxes and subsurface temperature during the TOGA COARE Intensive Observation Period. On the average, more than 39% of the net surface solar irradiance is estimated to be absorbed within the first 0.45 m. This value is higher than previous estimates. The observed absorption is applied to modify the parameterized transmittance profile representing the COARE domain, which is bordered by the optical water types IA, IB, and II [Jerlov, 1968]. The original and modified profiles of solar irradiance are prescribed in a one‐dimensional ocean model to test their effects on the model responses to the observed surface fluxes. The modified profiles for the three types of water all produce better simulation results than the corresponding original profiles in terms of the diurnal and intraseasonal sea surface temperature amplitudes. The model results support our estimate that the near‐surface absorption of solar radiation in the COARE region is stronger than that suggested by the water types IA, IB, and II.