Annual and interannual variability of the North Pacific ocean‐to‐atmosphere total heat transfer

Abstract

Using the sum of latent and sensible heat fluxes and back radiation between the ocean and the atmosphere to express the total heat transfer, Q_T , the annual and interannual variations of Q_T over the North Pacific were calculated and analysed. The total heat transfer is positive (atmosphere gains heat from the ocean) for all seasons and all regions of the North Pacific and there is a close relationship with the main ocean currents. The area of maximum heat transfer is the Kuroshio area with an annual variation mainly determined by the Asian monsoon circulation. The maximum heat transfer is in January and the minimum, in June. Conversely, the maximum total heat transfer to the air over the Gulf of Alaska occurs in October. This follows from the interaction of the annual cycle of the oceanic thermal content (which is a maximum in late summer) and the occurrence of stormy conditions in the late fall. The Q_T over the California Current area is about 70% of that over the Kuroshio at the same latitude on the other side of the basin. The spectrum of the anomalies from the 30‐year mean annual cycle show low frequency variations of period about 5 years in the Kuroshio area and about 2 years in the Alaska and California areas. After filtering out the monthly fluctuations, it was found that the Kuroshio area heat transfer was correlated with variations across the central North Pacific to about 170°W. The remainder of the basin, including the area of the North Equatorial Current, was correlated with heating variations in both the California and Alaska Current regions.