High frequency fluctuations in the heat content of an ocean generalcirculation model

[摘要] The transport and storage of heat by the ocean is of crucialimportance because of its effect on ocean dynamics and its impact on theatmosphere, climate and climate change. Unfortunately, limits to the amountof data that can be collected and stored mean that many experimental andmodelling studies of the heat budget have to make use of mean datasets wherethe effects of short term fluctuations are lost.

In this paper we investigate the magnitude of the resulting errors by making useof data from OCCAM, a high resolution global ocean model. The model carriesout a proper heat balance every time step so any imbalances that are found inthe analysis must result from the use of mean fields.

The study concentrates on two areas of the ocean affecting the El Nino. Thefirst is the region of tropical instability waves north of the Equator. Thesecond is in the upwelling region along the Equator.

It is shown that in both cases, processes with a period of less thanfive days can have a significant impact on the heat budget. Thus, analysesusing data averaged over five days or more are likely to have significanterrors. It is also shown that if a series of instantaneous valuesis available, reasonable estimates can be made of the size of theerrors. In model studies, such values are available in the form ofthe datasets used to restart the model. In experimental studies theymay be in the form of individual unaveraged observations.

[学科分类] 海洋学与技术