The Diurnal Cycle of Land–Atmosphere Interactions across Oklahoma’s Winter Wheat Belt

Abstract

This manuscript documents the impact of Oklahoma?s winter wheat belt (WWB) on the near-surface atmosphere by comparing the diurnal cycle of meteorological conditions within the WWB relative to conditions in adjacent counties before and after the wheat harvest. To isolate the impact of the winter wheat belt on the atmosphere, data from several meteorological parameters were averaged to create a diurnal cycle before and after the wheat harvest. Observations from 17 Oklahoma Mesonet sites within the WWB (during a period of 9 yr) were compared with observations from 22 Mesonet sites in adjacent counties outside the winter wheat belt. The average diurnal cycles of dewpoint, temperature, and surface pressure exhibited patterns that revealed a distinct mesoscale impact of the wheat fields. The diurnal patterns were consistent with the status of the wheat crop and the grassland in adjacent counties. The impact of the WWB was shown to be more significant during a month when soil moisture was abundant, and minimal during a month when soil moisture was limited. Statistically significant, hydrostatically consistent afternoon surface pressure anomalies suggest that there is a strong possibility of weak mesoscale circulations induced by the WWB.