Breakout Summary Report

ARM/ASR User and PI Meeting

19 - 23 March 2018

Session Title: Land-Atmosphere-Clouds Interactions
Session Date: 20 March 2018
Session Time: 1:30 PM - 3:30 PM
Number of Attendees: 40
Summary Authors: Larry Berg and Yunyan Zhang

Breakout Description

In this breakout, we will focus on analysis of both data and model results looking at interactions among land surface, atmospheric boundary layer, clouds, and aerosol processes.

The primary goals of the breakout are to improve our understanding of:
1. the impact of land surface on boundary-layer turbulence, aerosol, as well as cloud dynamics, microphysics, and macrophysics.
2. representation of land-atmosphere coupling in fine-scale and large-scale models.

Potential topics of discussion include:
1. recent studies based on data from boundary-layer profiling instruments such as Doppler lidars and Raman lidars and land
surface data sets derived from EBBR, ECOR and SWATS.
2. results from recent field campaigns with land-atmosphere interaction foci such as HI-SCALE and LAFE.
3. fine-scale large-eddy simulations and large-scale model evaluation and diagnosis.

Main Discussion

The overarching theme for this breakout session was focused on application of lidar systems to studies linking the land surface, boundary layer, aerosol, and clouds. The various ARM systems, and in particular the network of Doppler lidars, provide the opportunity for innovative new research. One of the key presentations in the session was a science-focused update by Rob Newsom on the Doppler and Raman lidar systems that included a review of data products that are available. There was discussion related to potential changes in the scan strategy that could result in measurements of the Turbulence Kinetic Energy (TKE) from the Doppler lidar measurements and of a new data product with estimates of the convective boundary-layer depth at a time and spatial resolution that is not possible with the current radiosonde-based value-added product.
There were a number of short presentations of ongoing research. Mohammad Osman reported on his work focused on the validation of new similarity functions applied in the entrainment zone. Neil Lareau presented results related to vertical velocity derived from the network of lidars deployed at the ARM Southern Great Plains site. Ewan O’Connor shared new corrections that can be applied to the Doppler lidar data to improve the performance of the systems in cases with small signal-to-noise ratio. These presentations were followed by a series of lightening talks designed to highlight key points from various posters. The final presentations of the session were focused on the LAFE and HI-SCALE field studies by Dave Turner and Jerome Fast that highlighted the great potential associated with both studies.

Scientific Updates
Rob Newsom: ARM lidar update
Mohammod Osman: Validating variance similarity functions in the entrainment zone using observations and LES
Neil Lareau: Boundary-layer and cloud-layer observations across a network of five Doppler lidars
Ewan O’Connor: Corrections for deriving reliable turbulent properties form Doppler lidar
Dave Turner: LAFE
Jerome Fast: HI-SCALE

Lightning talks
Ian Williams: Revisiting mechanisms and regimes of soil moisture influence on convective initiation
Steve Klein: LACE work at Lawrence Livermore Lab
Shuaiqi Tang: What causes the differences seen in EBBR and ECOR turbulence fluxes?
Dave Cook: Evidence of drought, disease, and recovery in ARM measurements at Okmulgee, Oklahoma forest
Ryan Sullivan: Comparison of EBBR and ECOR flux measurements at SGP E39
Laurie Gregory: Oklahoma Mesonet (OKM) soil moisture VAP status

Key Findings

N/A

Issues

No new issues were identified, and it was noted that the ARM lidars are enabling important new work in boundary-layer processes.

Needs

There was some discussion of the need for latent heat flux measurements near irrigated fields to fully understand that aspect of land-atmosphere interactions. It was noted that there was little irrigation in the vicinity of the SGP so additional work is needed to determine the optimal location for such measurements.

Decisions

No specific decisions were made.

Future Plans

Discussion of future plans focused on developing a plan to use the Doppler lidar scanning capability to provide estimates of TKE. The group noted that there would be some potential trade-offs with reduced time spent in the vertical staring mode. There was also discussion of the development of new convective boundary-layer data products based on the remote-sensing instruments.

Action Items

Action items resulting from the session (and subsequent follow-on discussion over the course of the meeting):
• A subgroup will be formed to investigate changing the scanning strategy for the Doppler lidar system(s) at the SGP. This approach could allow for the calculation of TKE and additional investigation of the heterogeneity around the lidar systems.
• A subgroup will be formed to investigate the development of a new PI product or VAP to determine the convective boundary-layer depth from the ARM Doppler lidars. The group felt that the systems and approaches are mature enough during convective conditions that the development of such a product should be relatively straightforward and would benefit the community. A follow-up discussion was made with the ARM infrastructure team (led by Laura Riihimaki) to explore the possibilities on the long-term continuous VAP for the convective boundary-layer depth using remote-sensing instruments.
• Yunyan Zhang, Larry Berg, and Ian Williams will submit an AGU session proposal on general LACI studies to bridge observations and models.