Noctilucent Cloud observations at Davis

• Other Authors: KLEKOCIUK, ANDREW (hasPrincipalInvestigator), KLEKOCIUK, ANDREW (processor), Australian Antarctic Data Centre (publisher)
• Format: Dataset
• Language: unknown
• Published: Australian Antarctic Data Centre
• Subjects: climatologyMeteorologyAtmosphere; CLOUD FREQUENCY; EARTH SCIENCE; ATMOSPHERE; CLOUDS; CLOUD PROPERTIES; CLOUD HEIGHT; CLOUD VERTICAL DISTRIBUTION; LIDAR; MESOPAUSE; MESOSPHERE; NLC; NOCTILUCENT CLOUD; PMC; POLAR MESOSPEHERIC CLOUD; LIDAR > Light Detection and Ranging; FIXED OBSERVATION STATIONS; CONTINENT > ANTARCTICA > Davis Station; GEOGRAPHIC REGION > POLAR; VERTICAL LOCATION > Antarctic; Davis-Station; Antarc*; Antarctica
• Online Access: https://researchdata.ands.org.au/noctilucent-cloud-observations-davis/701757; https://data.aad.gov.au/metadata/records/SOE_NLC; http://nla.gov.au/nla.party-617536

This indicator is no longer maintained, and is considered OBSOLETE. INDICATOR DEFINITION Lidar observations at Davis Station, Antarctica, are used to determine monthly averages of 'percentage of time noctilucent clouds detected' (i.e. total time clouds detected divided by total observing time, as a percentage), and monthly averages of median altitude of noctilucent clouds. RATIONALE FOR INDICATOR SELECTION Increases in occurrence and spatial extent of noctilucent clouds in the Northern Hemisphere have been linked to cooling of the mesopause region related to enhanced greenhouse warming of the troposphere, and increases in tropospheric methane. Both of these effects have anthropogenic sources. Southern Hemisphere observations of noctilucent clouds are sparse, but potentially provide an independent data set to the Northern Hemisphere observations. A long-term consistent data set is required to determine variations in percentage occurrence and compare this to northern hemisphere observations, particularly as there are subtle differences in the characteristics of the atmosphere in the two hemispheres. Perturbations to the thermodynamics and chemistry of the mesopause region can conceivably be caused by volcanic events and variations in solar activity. Long-term quantification of noctilucent cloud properties will aid in understanding and predicting natural and anthropogenic variability. DESIGN AND STRATEGY FOR INDICATOR MONITORING PROGRAM Spatial scale: Davis Station, Antarctica. Temporal scale: Monthly values. Measurement technique: Lidar (532nm wavelength, minimum altitude resolution 18.7 metres). The raw data used in the analysis of this indicator are obtained from observations by the Davis Lidar in Rayleigh mode. RESEARCH ISSUES changes in the extent and occurrence of noctilucent clouds have implications for the chemistry and climate of the mesopause region. To obtain a more comprehensive picture of the spatial extent of these changes, the underlying physics, and future implications, the Davis observations should be assimilated into research incorporating a diverse body of observations and model predictions. Important additional data will come the remote sensing of temperatures and winds in the mesopause region, from instruments at Davis such as the Czerny-Turner spectrometer, the MF radar and the proposed VHF radar, and other Antarctic measurements.