Mean monthly diurnal cycles observed with PRE-STORM surface data

Data from 84 surface mesonetwork stations deployed across Oklahoma and Kansas are used to calculate monthly mean diurnal cycles at each mesonetwork site during May and June of 1985 during the Preliminary Regional Experiment for Stormscale Operational and Research Meteorology (PRE-STORM). The horizontal variations in mean monthly temperatures and specific humidities are large, even though this experimental domain covers only a portion of each state. Landscape differences cause much of this variation, with the harvesting of winter wheat over a large region of Oklahoma in late May being one of the more clear factors influencing the surface layer cycles. A subjective classification of the mean monthly diurnal cycles shows that the type of diurnal cycle changes as the vegetation changes. However, this relationship is strongly modified by the effects of convection. Results suggest that the mean diurnal cycles include the effects of convective downdrafts, indicating that the interaction of convection with the atmospheric surface layer is an important process even on monthly timescales. This is important to consider for those trying to evaluate regional climate simulations.