Estimation of kilometer-scale heat fluxes over a hilly area in Northern China using an optical-microwave scintillometer

Abstract

Both sensible and latent heat fluxes are important components in the land surface energy budget, and accurately estimating them on kilometer-scale are important for understanding and modeling local hydro meteorological process. Scintillometry could provide kilometer-scale averaged turbulent heat fluxes, and has been used as ground-based remote sensing for estimating surface energy and water budget. This research compared heat fluxes obtained using an optical-microwave scintillometer (OMS) and an eddy covariance system (EC) over a typical temperate deciduous forest in hilly area, northern China. The observation period mainly represents growing season, from April to October 2018. We estimated the sensible and latent heat fluxes using both the two-wavelength method and the bichromatic correlation method, and the EC measurements were used as a benchmark. The results show the sensible heat fluxes from OMS showed 2% higher than EC, whilst the latent heat fluxes from OMS showed around 10% higher than EC. Changes in hydrological conditions or footprints have no significant effects on the measured turbulent fluxes from OMS. We also founded that there are slightly differences between fluxes derived by the two-wavelength method and the bichromatic correlation method due to assumed rTq value. Based on these results, we conclude that OMS can be a reliable approach to measure kilometer-scale surface turbulent heat fluxes over the hilly area, and its ability to estimate kilometer-area sensible and latent heat fluxes looks promising.