Influences of snow event on energy balance over temperate meadow in dormant season based on eddy covariance measurements

Abstract

Based on the eddy flux and meteorological measurements, we analyzed variation of the components of energy balance before, during and after the snow coverage in dormant season over temperate meadow. The results showed that the energy balance ratio EBR was 0.76, lowest in the fresh snow phase and positively correlated with friction velocity u∗. Furthermore, the energy balance closure error had a diurnal cycle. The radiation partition and energy balance changed in the presence of the snow cover. The surface albedo was high during snow coverage (maximum in the fresh snow phase) and low in the snow-free period (including pre-snow and snow-melted phases). The ratio of net radiation Rn to solar radiation Q was higher in the snow-melted phase, and lower in the fresh snow phase, so did the peaks in diurnal courses of the energy fluxes (Rn, latent heat flux LE, sensible heat flux H, and soil and storage heat flux G + S). The daily-integrated value of H increased followed by Rn in the snow-melting phase, LE and G + S increased quickly followed by Rn in the snow-melted phase. Daily average Bowen ratio β was large in the snow-melting phase and low in the snow-melted phase, indicating that more energy partitioning of Rn into H in the snow-melting phase but LE in the snow-melted phase.