An assessment of phase relationships between heat fluxes and ground surface temperatures in a diurnal cycle based on monitoring studies at the Verkhnee Dubrovo meteorological station

Abstract

Research subject. The relationships between heat fluxes and ground surface temperatures in a diurnal cycle.Methods. Experimental studies, including actinometric observations and monitoring of surface temperatures and surface heat fluxes for a soil and an artificial layer, were performed at the Verkhnee Dubrovo meteorological station in 2020.Results. The surface heat flux varies synchronously both with the total solar radiation near the earth’s surface and insolation at the upper boundary of the atmosphere. Maximal values of these heat fluxes are observed at the solar noon. The temperature response lags behind them by the time interval determined by the soil’s thermal heterogeneity. In this study, we extend our model of the ground surface temperature response to external radiative forcing, which was developed earlier, to the case of a thermal inhomogeneous half-space. An analytical expression for the simplest case of inhomogeneity (the presence of an upper layer with thermal properties different from those of the underlying rocks) is given and investigated. If the upper layer demonstrates a reduced thermal conductivity, the phase shift between the heat flux and the temperature response decreases in comparison with the value for a homogeneous half-space (45°).Conclusion. The soil studies conducted at the “Verkhnee Dubrovo” meteorological station allowed us to construct a thermophysical section and to verify the previously developed model using experimental data. The errors of theoretical estimates, in general, do not exceed those of the phase estimate at a 10-minute sampling rate. The obtained results can be applied when conducting climatic (including palaeoclimatic) and environmental studies, as well as when investigating heat exchange processes on artificial urban surfaces and their role in the formation of urban heat islands.