Breakout Summary Report
ARM/ASR User and PI Meeting
19 - 23 March 2018
Warm Boundary-Layer Processes Working Group
22 March 2018
1:45 PM - 3:45 PM
60
Rob Wood and Yunyan Zhang
22 March 2018
1:45 PM - 3:45 PM
60
Rob Wood and Yunyan Zhang
Breakout Description
The warm boundary-layer processes working group focuses on understanding and model representation of processes controlling the structural and radiative properties of clouds, aerosols, and their interactions with the underlying surface in the lowest few kilometers of the atmosphere. Research areas include: 1) characterization of boundary-layer and cloud dynamics; 2) cloud and aerosol microphysics and their interactions; 3) factors influencing cloud formation; and 4) radiative processes that together influence the vertical transfers of energy, moisture, and atmospheric components.Main Discussion
The session consisted of (a) a presentation and discussion about value-added data products being produced for researchers focused on WBLP; (b) brief summaries of breakout sessions that project onto WBLP working group foci.Key Findings
Laura Riihimaki and Jim Mather provided an update on data status and uncertainty issues, and solicited input from the breakout participants.Specifically, translators are working on producing the following products:
Cloud types and Shallow Cu identification VAP, already produced for 2000-2017 at SGP
ARSCL product should be available at most sites with a ~1 month delay
New CCN average and spectra data product
CSPHOT three-channel sunphotometer for cloud optical depth, R_e, and LWP
MWRRETv2 - 3-channel MWR LWP being tested at SGP and ENA, but there are issues with errors in the 89 GHz channel
AERIOE - combined vap using IR and microwave channels, currently being tested - most useful for low-LWP clouds
PBL winds VAP from the radar wind profiler (RWP), also possibly for PBL height
MPL cloud boundaries algorithm being tested using deep-learning algorithm
RLPROF being developed, using FEX code developed by Tyler Thorsen. Feature detection (cloud/aerosol) from the Raman lidar. Soon to be available at SGP and ENA
Aerosol retrievals from the HSRL/Raman:
Possibility of adding wide field channel for HSRL to minimize overlap issues, which is particularly problematic for low-lying features, e.g. PBL features.
3-wavelength/2 with polarization is another option for aerosol profiles, but is quite expensive.
WBLP-related breakout summaries. It is suggested that those interested in learning more about these breakouts should consult the dedicated breakout session reports for these sessions.
a. CAUSES (Hsi-Yen Ma)
CAUSES project is completing four initial papers diagnosing the causes of pathological biases in the ability to accurately simulate surface air temperature over the central United States and south-central Canada. The group is concerned about the representativeness of the surface turbulent flux measurements at the SGP site, and is interested to know if there are plans (or existing) surface heat flux/soil moisture measurements over various vegetation types or irrigated sites in the vicinity of the SGP.
b. LASSO (Bill Gustafson)
Currently LASSO is working on 2017 shallow cloud cases from SGP. The pilot phase of LASSO is completed, and the group is considering options for where to go beyond SGP, including consideration of simulations for the ENA site (where a question arises about whether to include the island land surface in the simulations, or just have simulations representative of the open ocean), and for the NSA.
c. Interactions among the surface, continental boundary layer, clouds, and aerosol (Larry Berg and Yunyan Zhang)
Larry Berg reported on the LACI-focused breakout session. He mentioned a possible lidar product focused on determining convective PBL depth. The group is using Doppler lidar to study similarity functions near the upper PBL interface (entrainment zone). There are highlights on recent studies using Doppler lidars to tackle PBL and cloud development. A continuous VAP for PBL height and LAI data around SGP are among the common data interests from this group.
d. Warm marine low-cloud processes and modeling (Xue Zheng, Rob Wood)
Reported on the presentations presented at the session, which were primarily science presentations from speakers. Broadly, these fell into the following categories: (a) Microphysical and dynamical variability of clouds; (b) model representation and evaluation; (c) precipitation processes; (d) aerosol variability; (e) new retrieval approaches.
e. ACE-ENA (Jian Wang)
Jian Wang briefly summarized the ACE-ENA deployments (summer 2017 and winter 2018), and showed some very preliminary analysis of data from the campaign. The group is planning a workshop focused on analyses from ACE-ENA, most likely in the November 2018 time frame.
f. Absorbing aerosols and interactions with clouds (Paquita Zuidema)
Paquita Zuidema summarized the LASIC breakout session, focusing mainly on the presentations that focused on low clouds. Paquita discussed a possible upcoming workshop, to be held most likely in spring 2019, focused on joint analyses in the various international/interagency projects (LASIC, ORACLES, CLARIFY, AEROCLO-SA) focused on biomass burning aerosol-cloud-climate interactions over the SE Atlantic Ocean.
g. MARCUS/MICRE/COMBLE (Greg McFarquhar, Roj Marchand and Bart Geerts)
These project completed only very recently, and attention is mostly focused on producing QC'd products (both projects were deployments at challenging locations over the Southern Ocean). The current plan is to have fully QC'd products available by Fall 2018. Another concern for the team is to identify periods where emissions from the ship's smokestack (MARCUS) may be contaminating the ship-based aerosol measurements.
Greg McFarquhar also reported for Bart Geerts on the upcoming AMF deployment in northern Norway (COMBLE) focused on cold air outbreaks generated as post-frontal air streams southward over the sea ice edge and is invigorated by warm surface waters.
h. End-to-End forward simulators (Mariko Oue and Katia Lamer)
Mariko Oue presented on presentations in simulator session. Forward-simulators offer an alternative path by transforming model quantities to observables. They rely on our knowledge of instrument characteristics and particle scattering to produce virtual observations from model output. The virtual ARM observations can subsequently be compared with actual ARM observations to facilitate model validation. The complexity of forward-simulators is ever increasing. Forward-simulators for multiple sensor (e.g., radar and lidar) compatible with models of multiple scales (e.g., LES and GCM) are being developed. Beyond returned power, virtual observation of quantities relevant to cloud phase identification are starting to emerge (e.g., polarimetric and Doppler quantities).
Issues
The topic of wetting of the passive microwave radiometer under precipitating conditions was raised. It is unclear at this time whether a solution exists to mitigate this problem (currently the MWR has a blower that attempts to clear water from the antenna housing).Needs
Several groups representing researchers looking at data from ENA and LASIC are interested in the cloud droplet concentration product (NDROP) that has been produced for some previous periods (e.g., CAP-MBL). This is one of the highest-priority VAP needs from the WBLP working group.During open discussion, a variety of from-the-floor suggestions were made:
1. Develop a standardized cloud classification scheme for use at all ARM sites.
2. Data users would like to be able to quickly identify periods when data from multiple ARM sensors is of high quality. It was suggested that a “red/orange/green light” system be introduced whereby a user can quickly scan to find out when, e.g., Raman, MWR, KAZR and UHSAS data are all of usable quality.
3. The CAUSES group are interested to understand what the effects of irrigation are on the surface fluxes and variability at the SGP site.
4. Develop a community platform for testing new retrieval algorithms.
5. PBL height VAP and LAI data around SGP region are needed for LACI studies.