Reintroducing radiometric surface temperature into the <scp>P</scp>enman‐<scp>M</scp>onteith formulation

Abstract

Abstract Here we demonstrate a novel method to physically integrate radiometric surface temperature ( T R ) into the Penman‐Monteith (PM) formulation for estimating the terrestrial sensible and latent heat fluxes ( H and λE ) in the framework of a modified Surface Temperature Initiated Closure (STIC). It combines T R data with standard energy balance closure models for deriving a hybrid scheme that does not require parameterization of the surface (or stomatal) and aerodynamic conductances ( g S and g B ). STIC is formed by the simultaneous solution of four state equations and it uses T R as an additional data source for retrieving the “near surface” moisture availability ( M ) and the Priestley‐Taylor coefficient (α). The performance of STIC is tested using high‐temporal resolution T R observations collected from different international surface energy flux experiments in conjunction with corresponding net radiation ( R N ), ground heat flux ( G ), air temperature ( T A ), and relative humidity ( R H ) measurements. A comparison of the STIC outputs with the eddy covariance measurements of λE and H revealed RMSDs of 7–16% and 40–74% in half‐hourly λE and H estimates. These statistics were 5–13% and 10–44% in daily λE and H . The errors and uncertainties in both surface fluxes are comparable to the models that typically use land surface parameterizations for determining the unobserved components ( g S and g B ) of the surface energy balance models. However, the scheme is simpler, has the capabilities for generating spatially explicit surface energy fluxes and independent of submodels for boundary layer developments.