Air-mass Transformation across the Sst Front in the Kuroshio Extension Region Retrieved by the Surface Flux Buoys and Advanced Microwave Scanning Radiometer for Earth Observation Satellite

Wintertime sea surface heat flux variability across the Kuroshio Extension (KE) front is analyzed using two surface flux buoys moored on the northern and the southern sides of the KE front as well as the observation by Advanced Microwave Scanning Radiometer for Earth Observation Satellite (AMSR-E). The combined use of the wind speed and the other AMSR-E products (the sea surface temperature and the integrated water vapor) provides the instantaneous latent heat flux at every observation cells. The coincident data used are from periods during two winters in 2007 and 2008, when the two surface buoys had a complete suite of meteorological data. In these two winter periods, we focus on three types of typical weather patterns referred to here as: the northerly wind condition, the monsoon wind condition, and the normal condition. The difference in the surface heat flux between these conditions is attributed to the different air mass transformation. We analyzed the spatial change of the boundary layer parameters and their influence on the surface heat flux between the two buoys. During the northerly wind condition, the satellite measurement captures the rapid increase of the surface water vapor content associated with the SST front because of the nonlinearity of the ClausiusClapeyron relation. It is found that the change is consistent with the large latent heat flux in spite of the weaker wind speed in the southern side of the SST front.