The TRACER Field Campaign: Measurement and Modeling Activities for the Study of Aerosol-Convection Interactions

The TRacking Aerosol Convection interactions Experiment (TRACER) took place in the southeast Texas region near Houston, TX from 01 October 2021 through 30 September 2022 with an intensive operational period (IOP) during June through September 2022. The major foci of the campaign were the study of convective lifecycle, aerosol lifecycle and aerosol-convection interactions. The coastal urban environment of southeastern Texas was selected for the TRACER deployment due to the high frequency of isolated convective cells, often occurring along the sea breeze front and the diversity of aerosol sources, including both anthropogenic and natural sources. During TRACER the first ARM Mobile Facility, a comprehensive suite of ground-based instrumentation for observing cloud, aerosol, meteorological, radiation and precipitation properties, was deployed at La Porte, TX, a region that experiences significant aerosol loading from industrial and urban sources. During the IOP, the C-band ARM Scanning Precipitation Radar (C-SAPR) operated in state-of-the-science automated cell-tracking mode providing high-resolution observations of the evolution of convective cells. An ancillary site was also deployed during the IOP, in Guy, TX, collecting aerosol and meteorological measurements in a rural environment meant to represent the environmental background state. Many guest and inter-agency instrumentation was also deployed during the IOP to fill measurement gaps and to quantify the regional variability of the convective environment.

In this presentation, we highlight the ongoing and planned measurement and modeling activities aimed at improving our understanding of convective lifecycle and aerosol-convection interactions. In particular, these activities include the characterization of the convective environment, the analysis of unique radar datasets, and the developing plans for a model intercomparison project. The characterization of the convective environment has focused on quantifying the regional and temporal variability of thermodynamic and aerosol properties, along with the characterization of the sea- and bay-breeze circulations and the associated air mass boundaries. The unique radar cell-tracking observations are being combined with operational weather and vertically pointing observations to quantify the lifecycle of convective cells and the evolution of precipitation microphysical properties within the convective updraft. Following on the success of the recent Aerosol, Cloud, Precipitation and Climate (ACPC) model intercomparison project (MIP), a new second MIP, TRACER-MIP, will focus on leveraging the high-resolution measurements collected during TRACER to evaluate a suite of state-of-the-art cloud-resolving model simulations with varying physics representations and complexity. These simulations will be used to examine the atmospheric processes leading to model biases and inter-model spread towards reducing uncertainty in aerosol-cloud interactions.