The observed relationship of cloud to surface longwave radiation and air temperature at Ny-Ålesund, Svalbard

Ten-year (2004–2013) observations of cloud and surface shortwave (SW) and longwave (LW) fluxes at Ny-Ålesund were analysed to investigate monthly variations in cloudiness and their impacts on the surface LW radiation budget and near-surface temperature (Ts). The cloud fraction (CF) showed distinct monthly variations, high in summer (0.90) and lower in winter (0.79). The downward SW flux increased from March and showed a peak (~200 W m−2) in June. In contrast, the downward LW (LWD) flux increased from ~200 W m−2 in February to ~300 W m−2 in July. Both LWD and upward LW (LWU) fluxes and their difference increased during winter as lowest cloud base height (LCBH) decreased and CF increased. Ts difference and both LW fluxes difference (ΔLWD and ΔLWU), calculated as the difference in monthly mean Ts and LW between all-sky and cloud-free conditions, were highly correlated (R2 = 0.68 for LWD and…