Breakout Summary Report

The DOE ARM user facility continues to develop high-resolution modeling scenarios to complement ARM’s suite of observations at various locations. The maritime cloud scenario centered at ARM’s Eastern North Atlantic atmospheric observatory, LASSO-ENA, is currently being processed. This scenario is slated for release later in 2025, with early simulations available by request. Planned LASSO-ENA simulations include a combination of periodic and nested model domains. As production winds down for LASSO-ENA, development of a new scenario for the Bankhead National Forest deployment, LASSO-BNF, will begin.

This session will introduce and discuss LASSO-ENA simulations, inform on the availability of these new datasets, and address related topics on their usage. The latter half of the breakout will seek input from the community regarding priorities for an upcoming LASSO-BNF scenario. LASSO-BNF scenario planning is in the discernment phase where community input is particularly valuable to shape the science topic(s) and modeling approach(s) that will shape LASSO-BNF.

This session focused on the Large-Eddy Simulation (LES) Atmospheric Radiation Measurement (ARM) Symbiotic Simulation and Observation (LASSO) activity of the ARM user facility. The session opened with a short introduction about LASSO, which primarily focused on highlighting examples of how users have applied LASSO to advance a variety of atmospheric science research areas. LASSO has been particularly useful for research related to cloud physics, cloud populations and their interactions with the planetary boundary layer, and three-dimensional radiation studies involving cloud fields. More recent work has begun using LASSO to investigate land-atmosphere interactions involving heterogeneous surface conditions. The first breakout session block included an invited presentation on how the BER LLNL THREAD Science Focus Area uses LASSO simulations (and preparations for future LASSO scenarios) to evaluate the DOE Energy Exascale Earth System Model (E3SM). This highlighted the value of LASSO for bridging scales from the observations, large-eddy simulations, single-column models, and up through regionally refined global models for both shallow and deep convection.

This block was followed by an extended presentation and discussion of the modeling being performed for the new Eastern North Atlantic (ENA) scenario, LASSO-ENA. Details of the modeling approach were presented, and a discussion period was aimed toward gaining feedback for potential adjustments to these approaches and event bundles to improve these concepts prior to final production-quality simulations and their release. Topics addressed during this discussion included the details for how to best handle the cloud microphysics, with a particular focus on spectral-bin microphysics and aerosol inputs to the microphysics, the frequency of model outputs to save for researchers, and other details regarding the modeling approach. The currently available prototype simulations span 63 case dates, which will be subsetted for production, along with being generated for a suite of aerosol settings, which seemed acceptable to the attendees.

The second half of the breakout focused on the planned implementation for a LASSO scenario conducted around science drivers for the new Bankhead National Forest (BNF) deployment in Alabama. The LASSO team provided basic introductory materials on the site and its science drivers, including overarching expectations for the frequency of shallow to deeper convective cloud events over the region and the complexity involved for attributing cloud controls. The LASSO team invited two speakers (one with ties to the BNF Site Science team, the second with ties to ongoing TRACER and multi-agency NASA/NSF modeling activities) to share with this audience ongoing and potentially synergistic modeling work at BNF. In the first of these talks, a semi-routine ongoing LES modeling effort was presented as part of BNF ASR PI activities. This activity has been ongoing since this past summer and uses the Micro-HH model with a 12.8-km domain forced by the ERA5 Reanalysis. Initial work during summertime 2024 period (May 1st through July 15th) indicated that roughly seven shallow-to-deep transition events (i.e., events where cloud thickness exceeded 4 km) occurred during this timeframe as drawn from 31 total summertime shallow (clouds below 2 km) convective event days. This independent effort provides solid confirmation for how frequently BNF may experience different modes of shallow cloud conditions, while also providing a series of simulations appropriate for studying shallow convection. Overall, learning from this PI effort may free LASSO-BNF to potentially build different capabilities, or focus on other cloud types and phenomena. The second keynote presentation was given on the NASA/NSF INCUS satellite mission and its need for model simulations that form the basis of its analyses to validate its retrieval activities, while supporting fundamental research on deep convective cloud processes.  This talk highlighted the INCUS plan/mission and argued for the potential value or need in LASSO-BNF providing paired LES and ARM datasets across many case dates (a library), as compared to the current model intercomparison project (MIP) strategies that typically focus on one case being simulated by a large number of models. This talk, as also tied to ongoing associated TRACER MIP activities, led into a spirited discussion of the value of intercomparisons/MIPs, and how LASSO could potentially help support those efforts. Overall, a clear consensus did not emerge as to what type of modeling would be best for a LASSO-BNF scenario, but a preference in the discussion towards a deep-convection cloud scenario was a reoccurring theme, particularly within the context of INCUS.

The LASSO-BNF scenario would be useful for more efficiently designing and implementing a BNF model intercomparison for INCUS or other purposes. For example, deciding which case to use for an intercomparison is very time consuming, and this could be simplified by choosing from LASSO-BNF case dates. LASSO-BNF model inputs could also be leveraged for the intercomparison.

Aerosol modelers could benefit from including plume transport as a part of LASSO-BNF, particularly from the forest. For example, pulse models have been used for this in the past, which could be implemented within the LASSO-BNF modeling framework.

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Decision regarding LASSO-ENA:

• The impression in the session leaned toward saving full three-dimensional model output less frequently, for example, every 30 minutes compared to every 15 minutes, so that more simulations could be provided to researchers within the allotted storage space acquired for LASSO-ENA.

The LASSO-ENA simulations should be completed in 2025 with their publication in 2026. Users can obtain access to currently available simulations by contacting the LASSO PIs, William and Scott, at lasso@arm.gov.

We anticipate having a dedicated virtual workshop later in 2025 focused specifically on planning for the LASSO-BNF scenario. An announcement will be made via ARM communications and the LASSO email list with more details nearer to the workshop.

Action items related to LASSO-ENA:

• Follow up with Mark Miller regarding several potential additional summertime case dates.

• Follow up on competing methodologies for the handling of aerosol information (specifically its depletion and replenishment) within the spectral-bin microphysics parameterization being used for LASSO-ENA.

• Investigate using VARANAL to drive the SAM model for the LASSO-ENA cases.

• Follow up with Yunyan Zhang to confirm the SAM statistical output includes the fields she needs for interfacing LASSO-ENA with E3SM for THREAD.

Action items related to LASSO-BNF:

• Continue to socialize LASSO-BNF concepts and obtain feedback from interested researchers.

• Organize a workshop to plan the LASSO-BNF scenario, which is slated to be held in late 2025.