The Relationship between the Time of the Maximum Surface Temperature and the Time of Inversion of the Energy Fluxes

In this work, we present a preliminary analysis to a new method of estimation of surface energy fluxes and growth rate of the height of the Convective Boundary Layer (CBL) on a monthly scale. In the model, it is assumed that the temporal evolution of temperature and specific humidity is governed by the surface fluxes of energy and its convergence in the CBL on a monthly scale. The inverse estimation method allows estimating the surface energy fluxes from the time series of temperature and specific humidity series and CBL height at 0900 LST and 1600 LST. Thus the evaluation of the model can be performed from the deviations between the observed and estimated series of temperature and specific humidity. However, after the time at which maximum temperature occurs, model performance decreases, and it no longer reproduces the drop in temperature. To investigate the relationship between such temperature drop and surface energy fluxes, 170 sites from the AmeriFLUX network with heterogeneous surfaces and distinct data periods were evaluated. The observed drop in temperature for the analyzed sites occurs on average about 3.2 h before the inversion of the sensible heat flux and around 3.6 h before the inversion of the net radiation, whereas the latent heat flux becomes dominant after the inversion of the sensible heat flux; this latent heat flux dominance is believed to be causing the decrease in temperature. As this study continues, we will further investigate the relationship between the time at which the maximum temperature occurs and the energy fluxes.