Relative Contributions of Surface Parcel and Atmospheric Environment to Convective Potential during Interstorm Periods

Abstract Convective instability is affected by both surface heat fluxes into near-surface air parcels and the atmospheric profile encountered as these air parcels are lifted aloft. In this study, we investigate the evolution of buoyancy experienced by surface-based parcels, taking interstorm soil moisture drydowns as fundamental time periods. We use profile observations of atmospheric temperature and humidity from ground-based passive remote sensing and in situ observations available at the U.S. Department of Energy Atmospheric Radiation Measurement Southern Great Plains site in Oklahoma, United States, and examine drydown events during the warm seasons from 2017 to 2022. Results reveal new insights on the emergence and growth of convective available potential energy (CAPE) during drydowns. We observe that the peak convective potential appears in the afternoon and grows in the midtroposphere (68% of 66 drydown events), with the largest CAPE values toward the end of the drydown event. We also find that the near-surface parcel contributes more to the evolution of CAPE than the atmospheric environment (86% of drydown events). These findings highlight the importance of surface heat fluxes and moisture availability from surface-based parcels in modulating the evolution of atmospheric conditions favorable for convection, underscoring the interplay between surface processes and atmospheric dynamics in driving convective instability. Significance Statement Land–atmosphere interactions, particularly feedbacks between soil moisture and precipitation, are pivotal in shaping convective processes, yet their influence on weather and climate remains poorly characterized. This study leverages high-resolution thermodynamic profiles of the atmosphere at a research site in Oklahoma, United States, to investigate the evolution of buoyancy and CAPE during drydown interstorm periods. By linking surface processes, boundary layer dynamics, and parcel ascent, our findings provide critical insights into the mechanisms driving convection. These results enhance the understanding of land–atmosphere coupling, improving forecasts of moist convection and its preconditions across diverse environmental conditions.