Interannual Variation in Surface Net Heat Flux in the Barents Sea

The Barents Sea is one of the Arctic regions with a large heat loss to the atmosphere. The changes in heat loss affect the Arctic and mid-latitude climates. Previous studies have shown that surface net heat flux is correlated with sea ice, ocean heat content, or atmospheric variation. However, the dominant factor for the interannual variation in surface net heat flux in the Barents Sea remains unclear. This study investigates the controlling factor for the interannual variations in the surface net heat flux in the Barents Sea using ECMWF ERA5 data from 1979 to 2018. To understand the sea ice effect, we decompose regional mean surface net heat flux into ice-free and ice-covered surface net heat flux. The results show that regional mean surface net heat flux is highly correlated with ice-free surface net heat flux. The variation in ice-free surface net heat flux includes the effect of sea ice change and ice-free surface net heat flux itself. Decomposition of these effects indicates that ice-free surface net heat flux itself plays a dominant role. In addition, we divide ice-free surface net heat flux into shortwave radiative flux, longwave radiative flux, sensible heat flux, and latent heat flux. It is shown that ice-free surface net heat flux is well explained by sensible and latent heat flux. Moreover, we assessed the controlling factors for sensible and latent heat flux. The results indicate that the sensible and latent heat flux changes are mainly related to air temperature and humidity. Since air temperature and humidity depend on wind direction, it is inferred that changes in the atmospheric circulation pattern explain the interannual variation in surface net heat flux in the Barents Sea.