The atmospheric response to the oceanic forcing in the eastern Pacific along
the northern equatorial sea surface temperature (SST) front is investigated in
terms of sensible and latent heat flux during the 6-month period 28 July 1999
through 27 January 2000. Of particular interest is the atmospheric boundary
layer (ABL) response to oceanic Tropical Instability Waves (TIWs) that distort
the SST front during May through January in normal years. In previous studies,
time series of boundary layer properties clearly show the influence of TIWs but
the relationship to spatial patterns of SST and wind stress has been inferred only
from sparse in situ data.
In this study, satellite observations are used to composite in situ data from
moorings to compensate for the lack of a spatially dense mooring array. The variability
in the position of the SST front caused by propagating TIWs enables fixed
mooring locations to measure the atmospheric boundary layer (ABL) response
from a large range of locations relative to the front. The satellite data enable
determination of the precise location of the mooring relative to the front. The
advantage of this strategy is the recurring measurement of the ABL response to
the SST front over the six month period considered here.
The results indicate that the TIW-induced perturbations of sensible and latent
heat flux are spatially shifted in phase towards the east relative to the perturbations
of SST. The maximum fluxes are not centered directly over the warmest
water, but are shifted towards the portion of the frontal region where a disequilibrium
boundary layer is expected due to the advection of colder air from the
equatorial region. The changes of sensible and latent heat fluxes across the SST
front have magnitudes of about 11 Wm⁻² and 126 Wm⁻², respectively.
The sensible and latent heat flux patterns are interpreted in two complementary
ways: (1) as an atmospheric response to the change of oceanic forcing as
air flows across the SST front; and (2) as the atmospheric response to westward
propagating TIWs along the SST front. / Graduation date: 2001
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/28703 |
| Date | 22 February 2001 |
| Creators | Thum, Nicolai |
| Contributors | Esbensen, Steven K. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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