Prediction of the Spring Transition and Related Sea-Surface Temperature Anomalies

摘要

A hypotheesis by Elsberry and Garwood (1978) for generation of upper ocean temperature anomalies during the spring transition period was tested. If the transition between the winter and summer regimes occurred earlier (later) than normal, the seasonal heating was expected to have been accumulated in a shallow (deep) layer, and would have tended to produce a positive (negative) sea-surface temperature anomaly. The Garwood (1977) one-dimensional, oceanic mixed-layer model was used to predict the thermal structure changes, from March 15 to July 15 during 1976 and 1977. The forcing fields from the atmospheric prediction model of Fleet Numerical Oceanography Center (FNOC) were interpolated to hourly intervals. The suitability of the FNOC heat flux calculations was examined through comparison with the observed upper ocean heat content changes derived from the TRANSPAC data. The recomputed mixed-layer depth and temperature responses from the adjusted heat flux fields were used, in lieu of the original calculations, because of the improvement in the behavior of the time series predictions. Weather maps and atmospheric forcing fields were used in describing the meteorological conditions associated with the transition period. The relationship between the transition dates and the generation and persistence of thermal structure anomalies during the following months was generally supported by the model predictions.