Surface heat budget and heat balance in the oceanic mixed layer in the central equatorial Pacific ocean during the 1986–87 El Niño
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In January–February 1987, an urgent cruise “JENEX-87” was carried out in the central equatorial Pacific during the occurrence of the 1986–87 El Niño. This cruise, supported by the Japan Science and Technology Agency, supplied heat flux data through the sea surface, on the basis of direct measurements of short- and long-wave radiation fluxes.
In the time average, the heat gain due to the radiation flux (153 W m−2) was almost compensated by the heat loss due to latent heat flux (130 W m−2), and thus the net heat gain was small in magnitude (20 W m−2). On the other hand, day-to-day changes of the net heat flux ranged within ±130 W m−2, mainly reflecting the downward short-wave radiation variations.
The heat balance in the surface oceanic mixed layer was investigated in two quadrangle areas (160°E-180° and 180°-160°W between 2°N and 2°S), using the surface heat flux and estimating the advective heat fluxes due to the geostrophic and Ekman currents. In these two quadrangles, we respectively derived −187±88 W m−2 and +27±95 W m−2. The former value, which is equivalent to about 1°C month−1 drop of the mixed layer temperature, is evidence of the abnormal oceanic condition in the occurrence of the 1986–87 El Niño event.
KeywordsHeat Flux Latent Heat Flux Surface Heat Flux Heat Gain Oceanic Mixed Layer
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