High Resolution, Active Remote Sensing of Cloud Microphysics at Summit, Greenland with Polarized Raman Lidar

PI Institute/Department Email
Neely III, Ryan
U of Colorado, Boulder, Cooperative Institute for Research in Environmental Sciences
Award#(s)
1303864
Funding Agency
US\Federal\NSF\GEO\OPP\ARC\AON
Program Manager Funding Agency Email
Ambrose, Dr. William
NSF
Discipline(s)
Meteorology and Climate\Atmospheric Radiation
Meteorology and Climate\Cloud Physics
Science Summary

A better understanding of Arctic cloud and aerosol properties, structure and formation is essential to understand the specific response of the Arctic in the context of global climate change. A lack of coherent high vertical and temporal resolution observations of cloud particles, aerosols moisture advection (i.e. water vapor) and thermodynamics, creates large uncertainties in current model estimates of cloud properties and inhibits our understanding of cloud radiative and precipitation impacts on the surface. As a result, current weather and climate models poorly parameterize clouds over the Arctic and more specifically over the Greenland Ice Sheet (GIS). A reduction in this uncertainty is particularly important above the GIS, where clouds act as sinks and sources to the ice mass balance by modulating the surface radiation budget and available precipitable water. To gain the understanding necessary to reduce this uncertainty, a new autonomous multi-wavelength, polarized Raman lidar will be developed and deployed at the NSF's observatory in Summit, Greenland. The new lidar observations will employ multiple wavelengths and polarizations to observe elastic and inelastic scattering from the Arctic atmosphere enabling regular retrieval of temperature, water vapor and extinction profiles. This combination of observational capability will create a coherent dataset of high-resolution thermodynamic, cloud and aerosol observations through the Arctic troposphere and lower stratosphere above Summit. Broadly, this addition to the NSF Observatory at Summit, Greenland as part of the larger Arctic Observing Network fits well within the Study of Environmental Arctic Change (SEARCH) implementation plan. Thus, this instrument will significantly enhance Arctic observing infrastructure and advance observations and understanding of change in the Arctic. This instrumentation and observations are the first of their kind on the GIS and will expand the existing, although modest, network of such measurements across the Arctic. This project will also provide a unique experience and educational opportunity through the combination of fieldwork and subsequent data processing for graduate students at the University of Colorado.

Logistics Summary

Researchers on this project will continue work on the existing lidar system (installed by Walden/ICECAPs project- NSF grant #1304657). Researchers on this project will also develop a multi-wavelength, polarized Raman lidar. The grant originally funded instrument installation at Summit Station in 2015, with subsequent observations running through 2018 before decommissioning. However, due to changes in the original operating requirements of the lidar and facilities capabilities that do not currently exist at the station, installation has been deferred until such time as infrastructure able to support this experiment can be provided. The researchers will complete development and assembly of the polarized Raman lidar with potential subsequent testing in Colorado, with some field work in 2014 and 2015 with relation to this grant and other projects. During summer 2014 a field team of three will deploy to Summit Station, Greenland for measurements and maintenance activities with the existing lidar system, which was originally installed as part of the Walden / ICECAPS project. Due to Air National Guard flight cancellations, in 2014 only, two researchers will fly commercial air to Kangerlussuaq and the via twin otter to Summit Station. The third researcher will fly via the Air National Guard in August. In 2015, science team members will visit Summit Station four times in support of two related instruments. First, they will reinstall the CAPABL instrument. CAPABL is part of the ICECAPS suite of instrumentation and is also an instrument test-bed for components of the larger Raman lidar. This instrument was removed in August 2014 to address alignment and operational issues; it will resume operation at Summit starting in late April. Researchers will re-install and optimize the CAPABL in the Mobile Science Facility (MSF) during May and June. Also approved is the test operation at Summit of a European Space Agency (ESA)-supported, UK National Center for Atmospheric Science (NCAS)-owned Doppler wind lidar (DWL). The DWL measures radial velocity in clear skies and during light precipitation events. The DWL will be tested at Summit Station between April 25 and June 29. The science team will assume all installation, monitoring and disassembly activities for this installation as they will be on site for the duration of the test phase.

CPS will provide Air National Guard support for personnel and cargo between NY, Kangerlussuaq and Summit Station, Kangerlussuaq and Summit Station user days, science technician support at Summit Station, use of the Mobile Science Facility (MSF) space and utilities. All other logistics will be arranged and paid for by the PI.

Season Field Site Date In Date Out #People
2014
Greenland - Summit
3
2015
Greenland - Summit
3