The OSU global coupled atmosphere/ocean general circulation
model (A/O GCM) has been used to simulate the present (lxCO₂)
climate and to investigate a CO₂-induced (2xCO₂) climate change.
Previous analysis of the lxCO₂ simulation showed distinct errors in
the simulated sea surface temperature (SST) and sea ice which were
attributed primarily to the atmospheric GM (AGCM). Analysis of
the 2xCO₂ simulation showed that the CO₂-induced warming penetrated
into the ocean; this caused a delay in the equilibration of the
climate system with an estimated e-folding time of 50-75 years.
The present study has two objectives. The principal objective is
to answer the question: By what pathways and through which physical
processes does the simulated ocean general circulation produce
the penetration of the CO₂-induced warming into the ocean? The
secondary objective is to evaluate the performance of the oceanic
GCM (OGCM) in the lxCO₂ simulation.
The comparison of the simulated lxCO₂ internal oceanic fields
with the corresponding observations shows that although they are
basically similar, there are distinct errors. Further analysis
shows that these errors were generated by the OGCM during its spin-up
integration prior to its coupling with the AGCM. This study
thus shows that it is not sufficient to compare the simulated SST
with the observed SST to evaluate the performance of the OGCM. It
is also necessary to compare the simulated internal oceanic quantities
with the corresponding observed quantities.
The global mean analysis of the CO₂-induced climate changes
shows that the ocean gains heat at a rate of 3 W/m² due to the CO₂
doubling. This heat penetrates downward into the ocean predominantly
through the reduction in the convective overturning. The
zonal mean analysis shows that the surface warming increased from
the tropics toward the mid-latitudes of both hemispheres and penetrated
gradually to the deeper ocean. The oceanic warming penetrated
to a greater depth in the subtropics and mid-latitudes than
in the equatorial region. A zonal mean heat budget analysis shows
that the CO₂-induced warming of the ocean occurs predominantly
through the downward transport of heat, with the meridional heat
flux being only of secondary importance. In the tropics the penetration
of the CO₂-induced heating is minimized by the upwelling of
cold water. In the subtropics the heating is transported downward
more readily by the downwelling existing there. In the high latitudes
the suppressed convection plays the dominant role in the
downward penetration of the CO₂-induced heating. / Graduation date: 1987
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/29322 |
| Date | 25 November 1986 |
| Creators | Jiang, Xingjian |
| Contributors | Schlesinger, Michael E. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
Page generated in 0.0018 seconds