Breakout Summary Report

ARM/ASR User and PI Meeting

Breakout Description

The Large-Eddy Simulation (LES) Atmospheric Radiation Measurement (ARM) Symbiotic Simulation and Observation (LASSO) activity has developed two scenarios—for shallow and deep convection—and is in the process of developing a third for maritime clouds. A recent virtual session sought information on how to best design this new scenario that focuses on maritime clouds at ARM’s East North Atlantic observatory. We will review the insights from this session and seek additional viewpoints from the broader community of interested researchers. We will also give an update on the LASSO-CACTI release, of which the 2 PB of data is now available for a combination of mesoscale ensembles and targeted LES simulations. In preparation for a workshop anticipated in September, we will begin a discussion about what the future of LASSO should look like and how we can best balance ARM’s available resources with the needs of the community when designing libraries of simulations.

Main Discussion

Note for attendence count: 95 in person, 35 virtual sessions

This session focused on theLarge-Eddy Simulation (LES) Atmospheric Radiation Measurement (ARM) Symbiotic Simulation and Observation (LASSO) (https://www.arm.gov/capabilities/modeling/lasso) activity. The session had three primary goals, with the agenda organized around three blocks of time, respectively:

• Promote the availability and contents of the LASSO-CACTI scenario


• Disseminate information from the LASSO-ENA Planning Workshop (https://discourse.arm.gov/t/lasso-ena-planning-workshop-27-jul-2023/150) and gather further community input for planning the LASSO-ENA scenario


• Alert the ARM and ASR community to the upcoming Future of LASSO Workshop and associated call for white papers to inform the workshop’s discussions

For LASSO-CACTI, information was provided about the types of simulations and diagnostics provided with this scenario, which focuses on deep convection during the Cloud, Aerosol and Complex Terrain Interactions (CACTI) campaign. Examples of early research using LASSO-CACTI were highlighted by Zhe Feng, Enoch Jo, and James Marquis. Cloud tracking technology was shown to provide detailed information about cloud life cycles and motion within the LES output. This was then coupled with detailed entrainment and detrainment calculations of individual cloud surfaces, which will be used to increase understanding of mixing within clouds and inform improved parameterizations of convection in climate and weather models. Additional analyses of horizontal flow convergence zones were combined with cloud tracking to better understand interactions between mesoscale and cloud-scale processes during deep convection initiation.

A summary of the current thinking for how to design the LASSO-ENA scenario was presented next. This focused on the perceived priorities of the research community and how ARM can provide simulations that would address the related modeling needs. Possible model configurations were discussed along with input from the LASSO-ENA Planning Workshop, which was held the week prior to the PI Meeting. A sampling of potential applications of a LASSO-ENA scenario was summarized by Virendra Ghate for multiple researchers, which highlighted mesoscale variability, cumulus-coupled stratocumulus, virga impact on the sub-cloud environment, cold pools, turbulence impacts on precipitation, subgrid variability of the cloud field, and cloud susceptibility to cloud droplet number. As demonstrated by this range of applications, there is a pull between research requiring model domains that are 100 km or larger that will have lower spatial resolution versus cloud-scale details that would need higher resolution and thus only be possible for smaller domains. Available observations were noted along with the need to select case dates with minimal impact of the island on the meteorology.

The third major topic was the upcoming Future of LASSO Workshop to be held November 2–3, 2023. The workshop motivations were presented along with the plan to use community-submitted white papers to inform the workshop agenda and content. Attendees were encouraged to collaborate and provide white papers that will inform what LASSO will become in the future. Those interested in attending the workshop should contact Gustafson at lasso@arm.gov.

Key Findings

Users showed excitement for the LASSO-CACTI simulations and had questions about accessing them. The LASSO team will be working over the next several months to finalize the data set and publicize it.

There are competing needs for the LASSO-ENA scenario that complicate designing a modeling approach that meets everyone's needs. The general thinking leans toward providing cheaper, easier to produce simulations that would become the foundation for modelers to work with, upon which they would then do their own simulations for the more computationally costly details. ARM should consider doing detailed but computationally intensive simulations for a subset of cases combined with the computationally cheaper simulations for a larger number of days. Many modelers also seemed enthusiastic about using a Lagrangian modeling approach to better capture the developing cloud conditions. In addition, for understanding cloud transitions and aerosol effects on clouds, simulations need to be made in a Lagrangian framework as compared to the traditionally used Eulerian framework. The lack of availability of ARM observations away from the observatory location will complicate the handling of comparing the model to observations.

Issues

 N/A

Needs

LASSO depends on the continued support of the research community to inform future development and use the LASSO products. The development team appreciates the ongoing support of the ARM infrastructure to produce these data sets.

Decisions

 N/A

Future Plans

Input for the LASSO-ENA scenario will be compiled and used to inform the case selection, design the modeling approach, and develop model evaluation methodologies using the ARM observations. Initial pilot simulations have been performed, which will be modified and iterated upon based on the feedback. A virtual listening session is planned for early 2024 to vet the arrived-at configuration and approach, similar to what was done for CACTI before going to production.

Action Items

Finalize the call for white papers associated with the Future of LASSO Workshop and advertise this request to the community.