Breakout Summary Report
ARM/ASR User and PI Meeting
19 - 23 March 2018
AWARE
21 March 2018
10:30 AM - 12:30 PM
33
Dan Lubin, Andrew Vogelmann, Johannes Verlinde, Ann Fridlind
21 March 2018
10:30 AM - 12:30 PM
33
Dan Lubin, Andrew Vogelmann, Johannes Verlinde, Ann Fridlind
Breakout Description
The AWARE breakout session will address how Antarctic atmospheric science fits into the larger picture of understanding global change and improving climate model simulations. In addition to covering what the AWARE AMF2 campaign specifically accomplished, the session will address current issues and future directions in Antarctic science and and the unique challenges of atmospheric science over the Antarctic continent. We will emphasize the significant contrasts with the Arctic in cloud and aerosol microphysics. This session therefore solicits presentations from both modelers and experimenters, from all disciplines within ASR including radiation measurement, physical meteorology, and aerosol science. Presentations can address topics specific to high latitudes, or methods/techniques developed elsewhere that might have applications over Antarctica. The two general objectives are (1) to determine how AWARE data can provide case studies and other input to current model development and validation, and (2) to begin strategizing about future collaborative ARM/ASR efforts in Antarctica.Main Discussion
This session presented recent work and immediate future plans for researchers working with AWARE data. With the successful conclusion of field work and most data and VAPs now in the ARM Data Center, the focus was on researchers becoming familiar with each other’s work to generate new collaborations, coordinate data analysis activities where appropriate, and avoid unnecessary duplication of effort. After six short presentations from researchers at Scripps Institution of Oceanography (SIO), BNL, Pennsylvania State University (PSU), Ohio State’s Byrd Polar and Climate Research Center (BPRC), NASA GISS and University of Leicester (UK), approximately 20 minutes remained in the session for planning discussions. We circulated a sign-up sheet that collected an email list of 33 attendees, most of whom we recognize as being involved with ARM/ASR polar research (i.e., NSA, Oliktok, MARCUS). Audience members had various questions and suggestions particularly regarding interpretation of the AWARE radar data. We also announced plans for an AWARE BAMS article, inviting participation from everyone willing to provide some tangible content (a figure or preliminary analysis of some data from the Data Center).Key Findings
Dan Lubin (SIO) reported on work in preparation for the Journal of Climate and Applied Meteorology, intended to help researchers unfamiliar with Antarctic meteorology effectively search the AWARE archive for suitable modeling case studies. Using k-means clustering on ERA-Interim 700 hPa geopotential heights, Southern Ocean storm track influences can be grouped into recurring synoptic influences on Ross Island that help explain contrasts in mixed-phase cloud formation. Lubin also reported on recent AWARE Ross Island aerosol results from Lynn Russell’s group (SIO) in which road vehicle contamination is successfully identified in most cases, and in which summertime organic functional groups are identified in filter sample data. These results are in review with Atmospheric Chemistry and Physics (Liu et al., 2018).Andrew Vogelmann (BNL) reported on work done by Damao Zhang (BNL) on climatological comparison of radar- and lidar-derived stratiform mixed-phase cloud (SMC) properties in the Antarctic (Ross Island) versus the Arctic (NSA). In contrast to the more widely sampled Arctic SMC, the Antarctic single-layer SMCs exhibit higher cloud-top heights and colder cloud-top temperatures, larger median liquid water path and supercooled liquid fraction, and up to a factor of ~6 smaller ice particle number concentration.
Israel Silber (PSU) reported on his group’s progress at: (1) developing an AWARE cloud mask identifying cloud geometrical extent and phase; (2) cloud layer altitude and hydrometeor persistence contrasts between AWARE and NSA (higher and lower, respectively); and (3) climatology of Antarctic clouds in the context of the temperature inversion base (Antarctic clouds are often more tightly confined in the vertical by the inversion, compared with the Arctic).
David Bromwich (BPRC) contributed a presentation on preliminary AWARE results from the Antarctic Mesoscale Prediction System (AMPS), an aviation forecasting resource based on a polar-optimized version of the Weather Research and Forecasting regional model (Polar WRF). Bromwich’s trip to the ARM/ASR Meeting was cancelled due to inclement weather, and Lubin gave the presentation at the meeting. BPRC has configured the AMPS nested grids to simulate WAIS Divide, and preliminary results were shown diagnosing model inadequacies with the surface radiation budget during the 2016 melt event. These model runs used a 5-class single-moment cloud microphysical scheme, which drastically under-predicts cloud liquid water. Now that the computing infrastructure is set up, near-future work will examine the performance of current double-moment schemes. Bromwich also presented AMPS cases over Ross Island illustrating the advantage of downscaling the spatial resolution from 1.1 km to 330 m. Local terrain influences are captured with greater fidelity, including strong gravity waves and more precise wind directions in the vicinity of AMF2 instruments.
The final two presentations were on a brand new AWARE collaborative project. Ann Fridlind (GISS) discussed plans for this project involving GISS ModelE3 and a ground-based forward-cloud-property simulator recently developed by Katia Lamer (PSU). The GISS modeling infrastructure, previously used with several Arctic field programs, has been configured for AWARE. Alessandro Battaglia (U. Leicester) discussed plans for multi-frequency radar analysis of ice cloud processes, and gave a preliminary demonstration of these techniques with Ross Island AMF2 data taken January 10, 2016 under a deep, cold, precipitating cloud system.
Decisions
Group discussion after the presentations identified the need for further coordination discussions and case study selection and hence the need for a follow-on meeting involving all the presenting groups. Ann Fridlind offered to host a meeting shortly afterward at GISS in New York. This meeting was held on Monday, April 23, 2018. The three objectives of this meeting were: (1) discussion and agreement on criteria for case study selection that would serve all the modeling groups involved; (2) actual selection of case studies; and (3) coordination of efforts going forward approximately six months, including acquiring observational and model initialization data.Attending the April 23 GISS meeting in person were: Ann Fridlind (host), Andrew Vogelmann, Dan Lubin, Hans Verlinde, David Bromwich, and Katia Lamer (PSU). Attending by video conference were: Israel Silber, Alessandro Battaglia, Frederic Tridon (U. Leicester), Petros Kalogeras (U. Leicester), Stefan Kneifel (University of Cologne, Germany, collaborating with Battaglia), Damao Zhang, Fan Wang (BNL), and Keith Hines (BPRC).
The first part of this meeting featured brief updates on progress since the March ARM/ASR Meeting, highlights of which included: (1) BPRC now having capability to use the current double-moment cloud parameterizations within Polar WRF (example results were shown); and (2) PSU having identified several candidates for modeling case studies from the Radar and HSRL data.
The second part of this meeting involved selection of viable case studies, informed by the k-means clustering results and preliminary archive investigations by PSU and BNL. From the AMF2 data, three strong cases were identified that have marked contrasts with the high Arctic and can provide new tests for mixed-phase cloud modeling. Two cases are in late summer (February 2016) and one is in mid-winter (August 2016). A fourth case is the entire WAIS Divide deployment, for evaluation of GCMs’ ability to simulate the surface radiation budget including cloud radiative effect. Two additional autumn (March and April 2016) cases were identified as contrasts with the Arctic, to test persistent mixed-phase cloud at low temperature, and to examine intense orographic influences. The meeting ended with discussion about organizing papers based on the cases, models to work with (LES, CRM, GCM), and coordinating the start of these efforts.