TERRAPUB Journal of Oceanography

Journal of Oceanography, Vol. 50 (No. 1), pp. 17-30, 1994

Measurement of the Sea Surface Emissivity

Masanori Konda1, Norihisa Imasato1, Katsuya Nishi1 and Takashi Toda2

1Department of Geophysics, Kyoto University, Kyoto 606, Japan
2Lake Biwa Museum Project Office, Shiga Prefecture Board of Education, Otsu 520, Japan

(Received 14 May 1993; in revised form 26 July 1993; accepted 28 July 1993)

Abstract: The sea surface emissivity in the infrared region is determined on the basis of data analyses. Net radiation, surface irradiance and other oceanographical and meteorological variables are measured throughout most of the year at the oceanographical observatory tower in Tanabe Bay, Japan. We have found that 0.984 ± 0.004 is a reliable emissivity value from the night time data. Surface emission radiates not from the subsurface water but from the sea surface. The thermal skin layer on the sea surface, however, is disturbed and disappears under high wind speed over 5 m/s through the analyses of the radiation observation using the emissivity value of 0.984. Under low wind speed, the sea surface can be cooler or warmer than the subsurface due to overlying thermal conditions, and the skin layer can be neutral as the transient process between them. By using an emissivity value of 0.984, the temperature difference between the sea surface temperature and the temperature determined from surface irradiance that has been reported in the satellite data analyses is found to be reduced by half.

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