An investigation of the seasonal thermal response of the upper North Pacific Ocean using satellite data and in situ data.

摘要

The thermal structure and response of the upper North Pacific Ocean is studied using satellite sea level data, satellite surface temperature data, surface fluxes, and in situ measurements. To set the background for more quantitative studies in later chapters, I first present a qualitative picture of the upper layer thermal structure in the North Pacific Ocean. From an analysis of expendable bathythermograph data obtained from volunteer observing ships during the period 1976-1989, I find that the seasonal cycle in temperature is clearly identifiable in the upper 100m and suppressed at lower depths. The temperature and stratification at the thermocline, and the thermocline depth, are related to the surface temperature. Thus, I find that warm surface temperatures are correlated with shallower and more stratified thermoclines.;Then, the seasonal heat budget in the upper North Pacific Ocean is investigated using an assortment of data sets. First, I use data from expendable bathythermographs to show that the heat storage rate (the oceanic response) and the surface forcing (net surface heat flux) balance very well. The heat storage rate is computed to fixed depths and to fixed isotherms. I find that the heat storage rate computed to fixed isotherms is more stable. The heat storage rate is sensitive to the choice of spatial scale and isotherm depth. The Ekman heat advection and the entrainment flux are estimated and shown to be not significant.;Later, the response of TOPEX/POSEIDON sea level deviations to surface thermal forcing is investigated for 5;Finally, satellite surface temperatures and satellite sea level heights are used in a seasonal heat budget of the upper North Pacific Ocean. The depth of the heat trapping layer is computed and shown to have a seasonal variation. Also, the heat storage rate computed from satellite data balances the net heat flux quite well, demonstrating one-dimensional balance between the local oceanic response and the surface forcing.