A method for computing hourly, historical, terrain-corrected microclimate anywhere on earth

Microclimates are the thermal and hydric environments organisms actually experience, and estimates of them are increasingly needed in environmental research. The availability of global weather and terrain datasets, together with increasingly sophisticated microclimate modelling tools, makes the prospect of a global, web-based microclimate estimation procedure feasible. We have developed such an approach for the r programming environment which integrates existing r packages for obtaining terrain and sub-daily atmospheric forcing data (elevatr and rncep), and two complementary microclimate modelling packages (NicheMapR and microclima). The procedure can be used to generate NicheMapR's hourly time-series outputs of above- and below-ground conditions, including convective and radiative environments, soil temperature, soil moisture and snow cover, for a single point, using microclima to account for local topographic and vegetation effects. Alternatively, it can use microclima to produce high-resolution grids of near-surface temperatures, using NicheMapR to derive calibration coefficients normally obtained from experimental data. We validate this integrated approach against a series of microclimate observations used previously in the tests of the respective models and show equivalent performance. It is thus now feasible to produce realistic estimates of microclimate at fine (<30 m) spatial and temporal scales anywhere on earth, from 1957 to present.