TY - JOUR

T1 - Estimating air-sea heat fluxes in semienclosed basins

T2 - The case of the Gulf of Elat (Aqaba)

AU - Ben-Sasson, Moshe

AU - Brenner, Steve

AU - Paldor, Nathan

PY - 2009

Y1 - 2009

N2 - Meteorological and oceanographic data collected at the head of the Gulf of Elat were used to compute the air-sea heat flux components and the heat storage in the water column, which are in turn used to estimate the heat balance of this semienclosed basin. The solar radiation was measured directly, whereas the longwave (LW) cooling and the turbulent heat fluxes (latent, LH; sensible, SH) were computed from commonly used bulk formulas. Nine formulas for LW and four formulas for LH1SH were tested for a total of 36 possible combinations. Independent estimates for the bounds on the advective heat flux through the straits and results from a one-dimensional mixed layer model provided criteria to help identify the best choice of bulk formulas for the gulf. It was concluded that the LW formula of Bignami together with the turbulent flux formulas of Kondo provide the best estimate of the heat balance of the gulf. Based on this, the annual mean evaporation is 1.6-1.8 m yr-1, with a minimum of 1 m yr-1 in (the long) summer and a maximum of 3-4 m yr-1 in (the short) winter. The increase in evaporation rate during the winter results from the instability of the atmosphere at that time when the sea surface temperature exceeds the air temperature; in the summer, when the air temperature is much higher than the sea surface temperature, evaporation nearly stops due to the atmospheric stability. This estimated evaporation rate for the gulf, which is similar for all four of the LH formulas considered, is significantly smaller than values commonly quoted in the literature. Finally, in contrast to previous studies, it is found that the advective heat flux from the Straits of Tiran is large and significant in spring, reaching an estimated value of over 125 W m-2, but its annually averaged value is only about 35-40 W m-2.

AB - Meteorological and oceanographic data collected at the head of the Gulf of Elat were used to compute the air-sea heat flux components and the heat storage in the water column, which are in turn used to estimate the heat balance of this semienclosed basin. The solar radiation was measured directly, whereas the longwave (LW) cooling and the turbulent heat fluxes (latent, LH; sensible, SH) were computed from commonly used bulk formulas. Nine formulas for LW and four formulas for LH1SH were tested for a total of 36 possible combinations. Independent estimates for the bounds on the advective heat flux through the straits and results from a one-dimensional mixed layer model provided criteria to help identify the best choice of bulk formulas for the gulf. It was concluded that the LW formula of Bignami together with the turbulent flux formulas of Kondo provide the best estimate of the heat balance of the gulf. Based on this, the annual mean evaporation is 1.6-1.8 m yr-1, with a minimum of 1 m yr-1 in (the long) summer and a maximum of 3-4 m yr-1 in (the short) winter. The increase in evaporation rate during the winter results from the instability of the atmosphere at that time when the sea surface temperature exceeds the air temperature; in the summer, when the air temperature is much higher than the sea surface temperature, evaporation nearly stops due to the atmospheric stability. This estimated evaporation rate for the gulf, which is similar for all four of the LH formulas considered, is significantly smaller than values commonly quoted in the literature. Finally, in contrast to previous studies, it is found that the advective heat flux from the Straits of Tiran is large and significant in spring, reaching an estimated value of over 125 W m-2, but its annually averaged value is only about 35-40 W m-2.

UR - http://www.scopus.com/inward/record.url?scp=65549100536&partnerID=8YFLogxK

U2 - 10.1175/2008JPO3858.1

DO - 10.1175/2008JPO3858.1

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AN - SCOPUS:65549100536

SN - 0022-3670

VL - 39

SP - 185

EP - 202

JO - Journal of Physical Oceanography

JF - Journal of Physical Oceanography

IS - 1

ER -