Abstract: The analysis of the variation characteristics of water and heat fluxes and climatological footprints in desertification areas is of great significance for understanding climate changes and water cycle in arid and semi-arid regions. Taking the Horqin cascade ecological zone as the study area, this paper analyzed the dynamic changes of water and heat fluxes and flux footprint in different temporal scales of the cascade ecosystem by using the large aperture scintillometer and automatic meteorological station data from March to December 2017. The results showed that:The diurnal variation of water and heat fluxes is obvious, the energy proportions of each branch are different. The near-surface energy fluxes curves show a significant unimodal trend in sunny days and there was no significant regular changes in on cloudy days; The seasonal variation of water and heat fluxes is significant.The sensible heat flux in summer is smaller than that in spring, autumn and winter, and the latent heat flux is the largest in summer, followed by spring and autumn, and the smallest in winter. The source area varies greatly on the hourly scale and daily scale; On the seasonal scale, the source area is spring > autumn > summer, and the differences of flux footprint between seasonal scales is lower than that of the hourly scale and daily scale.According to the types of underlying surface, the maize land in the middle of the light path was the largest proportion of the source area, followed by sand dune and meadow underlying surface, the small lake accounted for a smallest proportion of the source area. The source area at different temporal scales had different contribution sources.

Key words: water and heat fluxes, large aperture scintillometer, Horqin sandy land, complex underlying surface, footprint climatology