Daily dynamics of radiation surface temperature of different land cover types in a temperate cultural landscape: Consequences for the local climate

摘要

Surface temperature (Ts) is directly related to the capacity of every ecosystem to direct energy to different heat fluxes. Vegetation with a sufficient supply of water is able to cool down the surface by enhancing the latent heat flux via evapotranspiration. We chose seven types of land covers common in a temperate agricultural landscape and used a combined method of airship thermal scanning of T_s and ground measuring of thermodynamic T_a to show their T_s and T_a (air temperature) characteristics under high solar irradiance and their consequences for local climate; simultaneously we showed that this temperature difference increases with water content A combined method of airship thermal scanning of T_s and ground measuring of thermodynamic T_a was used. The localities differed markedly in both the values and the dynamics of T_s and T_s - T_a. In the early afternoon the difference in T_s between the different land covers reached almost 20 °C. Ecosystems with non-functional or no vegetation largely resembled the asphalt surface, whereas the ecosystems covered with dense, bushy or tree vegetation showed relatively well balanced daily temperature dynamics with low temperature extremes and a slow temperature morning increase or afternoon decrease. T_s - T_a at the peaking solar irradiance ranged between -1 °C at the forest and 14-17 °C at the dry harvested meadow and the asphalt surface respectively. We highlight the importance of T_s as a measurable indicator of ecosystem and landscape functioning and outline the importance of functional vegetation for climate. Those feedbacks between vegetation, surface temperature, water and climate are crucial in the landscape management, climate change discussions and therefore for decision makers and landscape developers.