Breakout Summary Report

ARM/ASR User and PI Meeting

10 - 13 June 2019

Session Title: Update on ARM Shortwave Spectral Radiometer Strategy
Session Date: 11 June 2019
Session Time: 1:30 PM - 3:30 PM
Number of Attendees: 25
Summary Authors: Laura Riihimaki and Allison McComiskey

Breakout Description

Several recent developments are opening the door to new use of SW spectral measurements for retrievals and radiative studies. These developments include improvements in measurement technologies (including commercially available hyper-spectral instruments), new retrieval methodologies that are not strongly dependent on absolute calibration accuracies, and the potential of spectral radiation for ARM’s new focus on distributed measurements integrated with high-resolution modeling.

This session will describe the results of a meeting in February 2019 reviewing the potential of ARM’s SW spectral radiometer measurements for process studies and radiation budget studies in complex environments. The session will include science talks introducing new uses of SW spectral radiometers and discussion of meeting outcomes (e.g. ,collaborative case studies to test new retrieval/measurements, publication on emerging uses of SW spectral measurements, and measurement priorities).

Agenda:

Review of Workshop Motivation and Summary of Science Outcomes (30 min)

Talks Highlighting Innovative Use of SW Spectral Measurements (40 min)

• Christine Chiu - Using spectral radiance observations to constrain cloud-drizzle-aerosol processes


• Dan Lubin - Cloud optical properties over west Antarctica from shortwave spectroradiometer measurements during AWARE


• Jake Gristey - Surface solar irradiance variability under shallow cumulus clouds at SGP: Insights from observations and LES


• Sasha Marshak - ARM shortwave spectrometers to study the clear-cloud transition zone and mixing processes

Discussion (50 min)

• Science goals and instrument needs


• Case studies - Planning for rretrieval development and comparison at LASIC, TCAP, and ACE-ENA


• Presentation of BAMS article plans and formation of a group for future meeting

Main Discussion

We summarized the outcomes of the February 25-27 ARM Shortwave Spectral Radiometry Strategy Review meeting in an overview talk followed by four sample science talks from the review meeting. These talks highlighted the range of applications discussed during the meeting that use SW spectral measurements (e.g., high-latitude cloud surface-processes, drizzle formation in warm low clouds, using spectral measurements to diagnose 3D radiative effects in LASSO cases, and diagnosing mixing processes on the edges of clouds).

We presented the three outcomes from the meeting and further input was given by the breakout group:

1. Write a BAMS article highlighting available data and applications from SW spectral measurements.


2. Summarize the advantages of hyperspectral and filter-based measurements in retrievals and science applications, data availability, and new potential SW spectral instrumentation on the market.


3. Create good “data epochs” of SW spectral data for a few sites/campaigns to direct the community towards periods of known data that can spur retrieval development and testing other scientific approaches to which spectral radiometry can contribute.

Key Findings

Talks and discussion highlighted work that was being done in two key areas with SW spectral measurements:

1. Retrievals to improve process studies


2. New insights into radiative processes

Efforts were particularly focused around methods that used the shape of SW spectra rather than depending on absolute calibration. This direction builds on discussions from the previous ASR-ARM PI Meeting SW breakout session that found that the difficulty in calibration had hindered past work with SW spectral measurements.

Issues

N/A

Needs

Connor Flynn has provided excellent support by vetting data from several ARM field campaigns. The group requires continued support from ARM to develop a few data epochs of known high-quality SW hyperspectral data so we can provide the scientific community with a starting point for testing new retrievals and other science applications.

Decisions

BAMS article: Article proposal will be submitted by end of June. New contributions from breakout attendees not present at the workshop were encouraged.

Case studies and data epochs: ACE-ENA and TCAP were the most-discussed potential case studies. Christine Chiu has started looking at the SWS data from ENA and believes the data quality is good. Evgueni Kassianov made comparisons of SASHE at TCAP with MFRSR (irradiances and AODs), and suggested that there is a wealth of other SW spectral measurements during the campaign that can be exploited and encapsulated in a data epoch.

Future Plans

Write a BAMS article to advertise availability and uses of ground-based SW spectral data to the broader scientific community.

Identify good data epochs of multiple spectral instruments at several field campaigns.

Develop tables with a list of retrievals and science applications in the literature, and with instrument strengths and weaknesses.

Meet at next year’s ASR meeting to report on progress—however, we need to find better communication avenues with the working groups and wider ASR community between meetings to foster greater participation in workshop and breakout discussions.

Action Items

Laura will add new attendees to ARM SW spectral email list and solicit any additional authors to BAMS article who are using SW spectral data.

Laura and Dan Lubin will submit a proposal for a BAMS article by the end of June. All coauthors will provide contributions by end of August.

Connor will compare data from Cimel and SASZE at LASIC and TCAP to check calibration of SASZE, in order to provide quality-checked data for case studies.