New satellite-derived latent and sensible heat fluxes are performed by using WindSat wind speed, WindSat sea surface temperature, the European Centre for Medium-range Weather Forecasting (ECMWF) air humidity, and ECMWF air temperature from 2004 to 2014. The 55 moored buoys are used to validate them by using the 30 min and 25 km collocation window. Furthermore, the objectively analyzed air-sea heat fluxes (OAFlux) products and the National Centers for Environmental Prediction-National Center for Atmospheric Research reanalysis 2 (NCEP2) products are also used for global comparisons. The mean biases of sensible and latent heat fluxes between WindSat flux results and buoy flux data are -0.39 and -8.09 W/m², respectively. In addition, the root-mean-square (RMS) errors of the sensible and latent heat fluxes between them are 5.53 and 24.69 W/m², respectively. The RMS errors of sensible and latent heat fluxes are observed to gradually increase with an increasing buoy wind speed. The difference shows different characteristics with an increasing sea surface temperature, air humidity, and air temperature. The zonal average latent fluxes have some high regions which are mainly located in the trade wind zones where strong winds carry dry air in January, and the maximum value centers are found in the eastern waters of Japan and on the US east coast. Overall, the seasonal variability is pronounced in the Indian Ocean, the Pacific Ocean, and the Atlantic Ocean. The three sensible and latent heat fluxes have similar latitudinal dependencies; however, some differences are found in some local regions.

Latent and sensible heat fluxes based on observations from a Black Pearl wave glider were estimated along the main stream of the Kuroshio Current from the East China Sea to the east coast of Japan, from December 2018 to January 2019. It is found that the data obtained by the wave glider were comparable to the sea surface temperature data from the Operational Sea Surface Temperature and Sea Ice Analysis and the wind field data from WindSat. The Coupled Ocean Atmosphere Response Experiment 3.0 (COARE 3.0) algorithm was used to calculate the change in air-sea turbulent heat flux along the Kuroshio. The averaged latent heat flux (LHF) and sensible heat flux (SHF) were 235 W/m² and 134 W/m², respectively, and the values in the Kuroshio were significant larger than those in the East China Sea. The LHF and SHF obtained from Objectively Analyzed Air-Sea Fluxes for the Global Oceans (OAFlux) were closer to those measured by the wave glider than those obtained from National Centers for Environmental Prediction (NCEP) reanalysis products. The maximum deviation occurred in the East China Sea and the recirculation zone of the Kuroshio (deviation of SHF >200 W/m²; deviation of LHF >400 W/m²). This indicates that the NCEP and OAFlux products have large biases in areas with complex circulation. The wave glider has great potential to observe air-sea heat fluxes with a complex circulation structure.

Using a net surface heat flux (Q_net) product obtained from the objectively analyzed air-sea fluxes (OAFlux) project and the international satellite cloud climatology project (ISCCP), and temperature from the simple ocean data assimilation (SODA), the seasonal variations of the air-sea heat fluxes in the northwestern Pacific marginal seas (NPMS) and their roles in sea surface temperature (SST) seasonality are studied. The seasonal variations of Q_net, which is generally determined by the seasonal cycle of latent heat flux (LH), are in response to the advection-induced changes of SST over the Kuroshio and its extension. Two dynamic regimes are identified in the NPMS: one is the area along the Kuroshio and its extension, and the other is the area outside the Kuroshio. The oceanic thermal advection dominates the variations of SST and hence the sea-air humidity plays a primary role and explains the maximum heat losing along the Kuroshio. The heat transported by the Kuroshio leads to a longer period of heat losing over the Kuroshio and its Extension. Positive anomaly of heat content corresponds with the maximum heat loss along the Kuroshio. The oceanic advection controls the variations of heat content and hence the surface heat flux. This study will help us understand the mechanism controlling variations of the coupled ocean-atmosphere system in the NPMS. In the Kuroshio region, the ocean current controls the ocean temperature along the main stream of the Kuroshio, and at the same time, forces the air-sea fluxes.