Sea surface temperature signatures of oceanic internal waves in low winds

Publication Type  Journal Article
Year of Publication  2007
Authors  Farrar, J. T.; Zappa, C. J.; Weller, R. A.; Jessup, A. T.
Journal Title  Journal of Geophysical Research-Oceans
Volume  112
Issue  C6
Pages  -
Journal Date  Jun 20
ISBN Number  0148-0227
Accession Number  ISI:000247536200004
Key Words  atmosphere response experiment; bulk parameterization; tropical pacific; skin temperature; infrared imagery; cool-skin; breaking; models; layer; interface
Abstract  

[1] In aerial surveys conducted during the Tropical Ocean - Global Atmosphere Coupled Ocean-Atmosphere Response Experiment and the low-wind component of the Coupled Boundary Layer Air-Sea Transfer (CBLAST-Low) oceanographic field programs, sea surface temperature (SST) variability at relatively short spatial scales (O(50 m) to O( 1 km)) was observed to increase with decreasing wind speed. A unique set of coincident surface and subsurface oceanic temperature measurements from CBLAST-Low is used to investigate the subsurface expression of this spatially organized SST variability, and the SST variability is linked to internal waves. The data are used to test two previously hypothesized mechanisms for SST signatures of oceanic internal waves: a modulation of the cool-skin effect and a modulation of vertical mixing within the diurnal warm layer. Under conditions of weak winds and strong insolation ( which favor formation of a diurnal warm layer), the data reveal a link between the spatially periodic SST fluctuations and subsurface temperature and velocity fluctuations associated with oceanic internal waves, suggesting that some mechanism involving the diurnal warm layer is responsible for the observed signal. Internal-wave signals in skin temperature very closely resemble temperature signals measured at a depth of about 20 cm, indicating that the observed internal-wave SST signal is not a result of modulation of the cool-skin effect. Numerical experiments using a one-dimensional upper ocean model support the notion that internal-wave heaving of the warm-layer base can produce alternating bands of relatively warm and cool SST through the combined effects of surface heating and modulation of wind-driven vertical shear.

Notes  

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URL  <Go to ISI>://000247536200004
DOI  Doi 10.1029/2006jc003947