Fast ice thickness at Davis, Mawson and Casey

This indicator is no longer maintained, and is considered OBSOLETE.INDICATOR DEFINITIONRegular measurements of the thickness of the fast ice, and of the snow cover that forms on it, are made through drilled holes at several sites near both Mawson and Davis.TYPE OF INDICATORThere are three types of indicators used in this report:1.Describes the CONDITION of important elements of a system;2.Show the extent of the major PRESSURES exerted on a system;3.Determine RESPONSES to either condition or changes in the condition of a system.This indicator is one of: CONDITIONRATIONALE FOR INDICATOR SELECTIONEach season around the end of March, the ocean surface around Antarctica freezes to form sea ice. Close to the coast in some regions (e.g. near Mawson and Davis stations) this ice remains fastened to the land throughout the winter and is called fast ice.The thickness and growth rate of fast ice are determined purely by energy exchanges at the air-ice and ice-water interfaces. This contrasts with moving pack ice where deformational processes of rafting and ridging also determine the ice thickness. The maximum thickness that the fast ice reaches, and the date on which it reaches that maximum, represent an integration of the atmospheric and oceanic conditions.Changes in ice thickness represent changes in either oceanic or atmospheric heat transfer. Thicker fast ice reflects either a decrease in air temperature or decreasing oceanic heat flux. These effects can be extrapolated to encompass large-scale ocean-atmosphere processes and potentially, global climate change.DESIGN AND STRATEGY FOR INDICATOR MONITORING PROGRAMSpatial Scale: At sites near Australian Antarctic continental stations: Davis; Mawson.Frequency: at least weekly, reported annuallyMeasurement Technique: Tape measurements through freshly drilled 5 cm diameter holes in the ice at marked sites.RESEARCH ISSUESTo more effectively analyse the changes in Antarctic fast ice a detailed long-term dataset of sea ice conditions needs to be established. This would provide a baseline for future comparisons and contribute important data for climate modelling and aid the detection of changes that may occur due to climate or environmental change.LINKS TO OTHER INDICATORSSOE Indicator 1 - Monthly mean air temperatures at Australian Antarctic stationsSOE Indicator 40 - Average sea surface temperatures in latitude bands 40-50oS, 50-60oS, 60oS-continentSOE Indicator 41 - Average sea surface salinity in latitude bands: 40-50oS, 50-60oS, 60oS-continentSOE Indicator 42 - Antarctic sea ice extent and concentrationThe fast ice data are also available as a direct download via the url given below. The data are in word documents, and are divided up by year and site (there are three sites (a,b,c) at each station). Snow thickness data have also been included. A pdf document detailing how the observations are collected is also available for download.