Ground-Based Radar Retrievals of Convective Detrainment Heights

Deep moist convection is able to rapidly transport mass and chemical constituents from the boundary layer to the upper troposphere and lower stratosphere (UTLS). The transported boundary layer air has a strong impact on the radiative and climatic balance as the air contains a vastly different chemical composition than the UTLS air. Whether the polluted air is ejected into the free troposphere or lower stratosphere has important implications on the redistribution of greenhouses gases, particularly on the production and/or destruction of ozone. While aircraft and multi-Doppler observations have been commonly used to identify the detrainment altitudes for convection in the mid-latitudes via in-situ chemical measurements and vertical divergence observations, respectively, both datasets are typically limited to field campaigns which occur infrequently and are limited spatially. To better understand where convection detrains mass and to constrain model simulations, more frequent observations are needed. Here, a methodology that uses the convectively-generated anvil as proxy for mass detrainment is built upon and coupled with high-resolution ground-based radar observations to determine convective mass detrainment altitudes. By combining this methodology with the NEXRAD network, mass detrainment altitudes for deep convection across the central and eastern CONUS are retrieved across seven years for the months of May and July as these periods contain different convective-forcing dynamics. It is found that, while the majority of mass detrainment occurs below the tropopause, convection is able to transport mass above the unperturbed tropopause via the convectively-generated anvil. Morphological effects on the mass detrainment heights are also investigated.