Air temperature at ocean surface derived from surface-level humidity

A new method deriving surface air temperature from specific humidity is proposed. Surface atmospheric pressure and relative humidity in addition to specific humidity are necessary in order to derive surface air temperature. Assuming effects of variation of atmospheric pressure and relative humidity are small, climatological values are used for those values. Derived surface air temperature is compared with in situ surface air temperature. A cross-correlation coefficient is high and the rms error is small. However, the agreement between them varies spatially. The errors are largest in the eastern equatorial region and high-latitudes. The former may be caused by a large sampling error and remarkable internannual variation related to ENSO phenomena. On the other hand, the latter may be related to sensitivity of saturated vapor curve to air temperature. Sensible heat fluxes are estimated by using derived surface air temperature and compared with that by in situ data. For the whole North Pacific, a cross-correlation coefficient, a mean error and an rms difference are 0.89 W m^–2, 0.58 W m^–2 and 8.03 W m^–2, respectively.