Breakout Summary Report

The Tracking Aerosol Convection Interactions Experiment (TRACER), conducted in 2021-2022 in the Houston area, focused on the complex interactions between aerosols, convection, and cloud processes. We propose a breakout session to bring together observational data from the TRACER campaign and cutting-edge modeling approaches to improve our understanding of convective clouds and how aerosols influence convection, cloud development, and precipitation.

The session will focus on discussing the observation data needs and metrics for evaluating and enhance model capabilities of simulating clouds and aerosol-cloud interactions, particularly to help the community modeling intercomparison project at cloud - resolving scale (TRACER-MIP): https://arm-synergy.github.io/tracer-mip/README.html. Discussing the TRACER-MIP roadmap and getting the observationalists and modelers working together on this project is one of the main goals.

The session focused on modeling and data needs for the TRACER model intercomparison project (MIP). Following an overview of the TRACER-MIP roadmap and the cases that have been selected (17 June, 07 August) by Jiwen Fan and Stephen Saleeby, a series of short presentations on available observational metrics from radar and satellite (Pavlos Kollias), other TRACER measurements (Virendra Ghate) and radar simulators (Mariko Oue) were presented. Discussion centered on the needs for TRACER-MIP model evaluation and analysis, the most appropriate and available observational datasets, and pathways to participation both through additional simulations and analysis efforts.

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The level of effort required (and associated funding) for the many suggested evaluation metrics was one of the largest issues. Prioritization and collaboration will be necessary to overcome these challenges. One issue was the use of CR-SIM with some of the models for which is has not preciously been used with.

Collection of simulation results has also been an ongoing issue. Disk space has been requested at NERSC to accommodate these data volumes.

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Several different observational targets for model evaluation were identified and discussed including: (1) precipitation, cloud- and echo-top height, radar reflectivity and other radar moments, vertical velocity for cloud properties and (2) sea-breeze properties, planetary boundary layer properties, surface fluxes and standard meteorological parameters. The use of tobac cell-tracking for model and observations datasets was identified as a tool to perform convective lifecycle comparisons. The radar simulator, CR-SIM was also identified as an important tool for comparing model output most directly to radar observables. The potential usefulness of complementary datasets was identified as a gap to investigate further including (but not limited to): (a) boundary layer thermodynamics from TRACER- Uncrewed Aerial Systems (UAS) for 17 June case, (b) surface met and fluxes from the NSF CUBE campaign, (c) GOES cloud property retrievals from NASA SatCORPS, (d) surface meteorology stations from the NWS and TCEQ, (e) precipitable water vapor from the Houston GPS network, and (f) Stereo-camera data for cloud development. 

The TRACER-MIP roadmap defines a general timeline for the delivery of simulations and plans for evaluation and analysis. https://arm-synergy.github.io/tracer-mip/Roadmap.html

Just as modeling groups have been solicited to provide simulations for the MIP, researchers who can provide or shepherd observational datasets for evaluation and analysis of the simulations are needed. An informal call, and collection of data will be undertaken shortly after the ASR/ARM meeting.