Continuous Lidar Monitoring of Polar Stratospheric Clouds at the South Pole

• Main Authors: Campbell, James R., Welton, Ellsworth J., Spinhirne, James D.
• Other Authors: NAVAL RESEARCH LAB MONTEREY CA
• Format: Text
• Language: English
• Published: 2009
• Subjects: Atmospheric Physics; Meteorology; Physical Chemistry; Radiation and Nuclear Chemistry; Optical Detection and Detectors; *SUNRISE; *OPTICAL RADAR; *STRATOSPHERE; *ANTARCTIC REGIONS; *CLOUDS; *OZONE DEPLETION; *MONITORING; CATALYSIS; SULFATES; NITRIC ACID; OZONE LAYER; REMOTE DETECTION; CHLORINE; BROMINE; WATER VAPOR; NITRATES; CONCENTRATION(COMPOSITION); TEMPERATURE GRADIENTS; SEASONAL VARIATIONS; SATURATION; DESTRUCTION; PHOTOLYSIS; AEROSOLS; REPRINTS; *POLAR STRATOSPHERIC CLOUDS; *SOUTH POLE; *OZONE HOLES; MPLNET(MICROPULSE LIDAR NETWORK INSTRUMENT); HALOGEN ATOMS; OZONE DESTRUCTION; DENITRIFICATION; POLAR VORTEX; ATTENUATED SCATTERING RATIOS; DEHUMIDIFICATION; CLOUD OCCURRENCE; Amundsen Scott South Pole Station; Amundsen-Scott; Amundsen-Scott South Pole Station; Antarctic; Austral; South Pole; The Antarctic; Antarc*; Antarctica; South pole
• Online Access: http://www.dtic.mil/docs/citations/ADA513423; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA513423

Polar stratospheric clouds (PSC) play a primary role in the formation of annual "ozone holes" over Antarctica during the austral sunrise. Meridional temperature gradients in the lower stratosphere and upper troposphere, caused by strong radiative cooling, induce a broad dynamic vortex centered near the South Pole that decouples and insulates the winter polar airmass. PSC nucleate and grow as vortex temperatures gradually fall below equilibrium saturation and frost points for ambient sulfate, nitrate, and water vapor concentrations (generally below 197 K). Cloud surfaces promote heterogeneous reactions that convert stable chlorine and bromine-based molecules into photochemically active ones. As spring nears, and the sun reappears and rises, photolysis decomposes these partitioned compounds into individual halogen atoms that react with and catalytically destroy thousands of ozone molecules before they are stochastically neutralized. Despite a generic understanding of the "ozone hole" paradigm, many key components of the system, such as cloud occurrence, phase, and composition; particle growth mechanisms; and denitrification of the lower stratosphere have yet to be fully resolved. Satellite-based observations have dramatically improved the ability to detect PSC and quantify seasonal polar chemical partitioning. However, coverage directly over the Antarctic plateau is limited by polar-orbiting tracks that rarely exceed 80 degrees S. In December 1999, a NASA Micropulse Lidar Network instrument (MPLNET) was first deployed to the NOAA Earth Systems Research Laboratory (ESRL) Atmospheric Research Observatory at the Amundsen-Scott South Pole Station for continuous cloud and aerosol profiling. MPLNET instruments are eye-safe, capable of full-time autonomous operation, and suitably rugged and compact to withstand long-term remote deployment. With only brief interruptions during the winters of 2001 and 2002, a nearly continuous data archive exists to the present. Published in the Bulletin of the American Meteorological Society, p613-617, May 2009. Prepared in cooperation with the NASA Goddard Space Flight Center, Greenbelt, MD and the Department of Electrical and Computer Engineering, University of Arizona, Tucson, AZ.