This dataset (provided as a series of CF-compatible netcdf file) consists of 5 maps of Antarctic landfast sea ice, derived from NASA MODIS imagery. There is one map per year, spanning the 5 year period from 2018 to 2022. The one map per year covers the time period from Day-Of-Year 61-75, which is the time of yearly minimum extent. The data are provided in a polar stereographic projection with a latitude of true scale at 70 S (i.e., to maintain compatibility with the NSIDC polar stereographic projection).

Data from ASAC project 3030. Public summary for the project: This project will measure the sea ice thickness off East Antarctica, over spatial scales up to hundreds of kilometers. Sea ice is a likely sensitive indicator of climate variations and change. No large scale sea ice thickness measurements exist in the Antarctic. An estimation of trends of change in Antarctic sea ice thickness and volume is therefore not currently possible. To address this deficiency and to provide an independent data set for the validation of models and the calibration of remote-sensing data, we will conduct high accuracy air borne laser scanner measurements in the sea ice zone off East Antarctica. More information about the project can be found in lidar.pdf (which is available with the data).

These data describe pack ice characteristics in the Antarctic sea ice zone. These data are in the ASPeCt format. National program: Russia Vessel: Akademic Fedorov Dates in ice: 28 Apr 1998 - 05 Jun 1998 Observers: Unknown Translation to ASPeCt data format: Vladimir Smirnov Summary of voyage track: 28/4 Ice edge at approx. 63S, 112E 28/4-1/5 From ice edge to Mirny (93E) 2-9/5 At Mirny 10-16/5 Mirny to Progress (76E) 18-22/5 Progress to Molodezhnaya (46E) 28/5-1/6 Molodezhnaya to Novolazarevskaya (12E) 4-5/6 Novolazarevskaya to ice edge at approx. 63S, 10E The fields in this dataset are: SEA ICE CONCENTRATION SEA ICE FLOE SIZE SEA ICE SNOW COVER SEA ICE THICKNESS SEA ICE TOPOGRAPHY SEA ICE TYPE RECORD DATE TIME LATITUDE LONGITUDE OPEN WATER TRACK SNOW THICKNESS SNOW TYPE SEA TEMPERATURE AIR TEMPERATURE WIND VELOCITY WIND DIRECTION FILM COUNTER FRAME COUNTER FOR FILM VIDEO RECORDER COUNTER VISIBILITY CODE CLOUD WEATHER CODE COMMENTS

These data describe pack ice characteristics in the Antarctic sea ice zone. These data are in the ASPeCt format. National program: Russia Vessel: Akademic Fedorov Dates in ice: 27 Feb 1998 - 26 Mar 1998 Observers: Unknown Translation to ASPeCt data format: Vladimir Smirnov Summary of voyage track: 27-28/2 From ice edge at approx. 67S, 46E to Molodezhnaya (46E) 2-5/3 From Molodezhnaya to Progress (76E) 11-19/3 Oceanographic work in Prydz Bay (approx. 77E) 19-22/3 Prydz Bay to Mirny (93E) 25-26/3 Mirny to ice edge at approx. 64S, 96E The fields in this dataset are: SEA ICE CONCENTRATION SEA ICE FLOE SIZE SEA ICE SNOW COVER SEA ICE THICKNESS SEA ICE TOPOGRAPHY SEA ICE TYPE RECORD DATE TIME LATITUDE LONGITUDE OPEN WATER TRACK SNOW THICKNESS SNOW TYPE SEA TEMPERATURE AIR TEMPERATURE WIND VELOCITY WIND DIRECTION FILM COUNTER FRAME COUNTER FOR FILM VIDEO RECORDER COUNTER VISIBILITY CODE CLOUD WEATHER CODE COMMENTS

This indicator is no longer maintained, and is considered OBSOLETE. INDICATOR DEFINITION The northern limit of the pack ice as defined by the 15% concentration of sea ice determined by the SSM/I instrument or its replacement. TYPE OF INDICATOR There 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: CONDITION RATIONALE FOR INDICATOR SELECTION Climate is affected by complex interactions between the sea ice and the atmosphere and ocean. The sea ice extent and concentration is determined by the oceanic and atmospheric forcing. There is evidence of variations in the sea ice extent and concentration on a synoptic time scale as storms pass through the region, and variations in sea ice extent on a multi-year time frame with forcing caused by the Antarctic circumpolar wave. Over the past 20 years, there is limited evidence of an increase in spatial ice extent and in the length of time that ice is present. Continued monitoring of sea ice extent and concentration may provide insights into the dynamics of the Southern Ocean and help to predict future climate. DESIGN AND STRATEGY FOR INDICATOR MONITORING PROGRAM NASA uses a combination of satellite passive microwave sensors to measure the brightness values over sea ice covered regions. They then use an algorithm (referred to as the 'team' algorithm) to calculate the ice concentration and to determine the ice edge. The data are available globally on a daily or monthly basis. RESEARCH ISSUES Currently, NASA intends to maintain a series of satellite microwave sensors to continue to monitor sea ice extent and concentration. Ongoing research to interpret the data are currently being carried out at the AAD and the Antarctic and Southern Ocean CRC. Links with other indicators The sea ice extent and concentration has a large impact on the surface salinity and temperatures. Thus strong links with sea surface salinity and sea surface temperatures.

These data describe pack ice characteristics in the Antarctic sea ice zone. These data are in the ASPeCt format. National program: Australia Vessel: Aurora Australis Dates in ice: 02 Dec 1999 - 13 Jan 2001 Observers: David Hannan, Andy Brocklesby, Alan Elcheikh, Russell Brand, Mike Gross, Tavis Potts, Petra Heil, Katrina Phillips Summary of voyage track: 2/12 Ice edge at approx. 64S, 154E 2-28/12 Headed west through pack ice conducting Pack Ice Seal survey 2-6/1/00 Steamed from Davis to Mawson 8-13/1 Steamed from Mawson to ice edge at approx. 63S, 91E The fields in this dataset are: SEA ICE CONCENTRATION SEA ICE FLOE SIZE SEA ICE SNOW COVER SEA ICE THICKNESS SEA ICE TOPOGRAPHY SEA ICE TYPE RECORD DATE TIME LATITUDE LONGITUDE OPEN WATER TRACK SNOW THICKNESS SNOW TYPE SEA TEMPERATURE AIR TEMPERATURE WIND VELOCITY WIND DIRECTION FILM COUNTER FRAME COUNTER FOR FILM VIDEO RECORDER COUNTER VISIBILITY CODE CLOUD WEATHER CODE COMMENTS

These data describe pack ice characteristics in the Antarctic sea ice zone. These data are in the ASPeCt format. National program: Australia Vessel: Polar Sea Dates in ice: 19 Dec 1998 - 01 Jan 1999 Observers: Tony Worby Summary of voyage track: 19/12 Ice edge at approx. 63S, 140E 19-21/12 From ice edge to coast 22-28/12 Steamed west to approx 177W 28/12 - 1/1 Steamed south into the Ross Sea The fields in this dataset are: SEA ICE CONCENTRATION SEA ICE FLOE SIZE SEA ICE SNOW COVER SEA ICE THICKNESS SEA ICE TOPOGRAPHY SEA ICE TYPE RECORD DATE TIME LATITUDE LONGITUDE OPEN WATER TRACK SNOW THICKNESS SNOW TYPE SEA TEMPERATURE AIR TEMPERATURE WIND VELOCITY WIND DIRECTION FILM COUNTER FRAME COUNTER FOR FILM VIDEO RECORDER COUNTER VISIBILITY CODE CLOUD WEATHER CODE COMMENTS

These data describe pack ice characteristics in the Antarctic sea ice zone. These data are in the ASPeCt format. National program: Australia Vessel: Aurora Australis Dates in ice: 02 Oct 1997 - 26 Oct 1997 Observers: Michael Wall Summary of voyage track: 2/10 Ice edge at approx. 62S, 114E 2-5/10 Vessel steamed from ice edge to Casey 8-18/10 Vessel steamed from Casey to 66E 18-22/10 Vessel stopped in ice (rudder damage) 22-26/10 Vessel steamed east to Davis The fields in this dataset are: SEA ICE CONCENTRATION SEA ICE FLOE SIZE SEA ICE SNOW COVER SEA ICE THICKNESS SEA ICE TOPOGRAPHY SEA ICE TYPE RECORD DATE TIME LATITUDE LONGITUDE OPEN WATER TRACK SNOW THICKNESS SNOW TYPE SEA TEMPERATURE AIR TEMPERATURE WIND VELOCITY WIND DIRECTION FILM COUNTER FRAME COUNTER FOR FILM VIDEO RECORDER COUNTER VISIBILITY CODE CLOUD WEATHER CODE COMMENTS

These data describe pack ice characteristics in the Antarctic sea ice zone. These data are in the ASPeCt format. National program: Russia Vessel: Akademic Fedorov Dates in ice: 26 Feb 1989 - 10 Mar 1989 Observers: Unknown Translation to ASPeCt data format: Vladimir Smirnov Summary of voyage track: 26/2 Ice edge at approx. 71S, 138W 26/2-2/3 Ice edge to Russkaya (136W) partly in company with Prof Zubov. 7-10/3 West through Ross Sea 10/3 Ice edge at approx. 74S, 176E The fields in this dataset are: SEA ICE CONCENTRATION SEA ICE FLOE SIZE SEA ICE SNOW COVER SEA ICE THICKNESS SEA ICE TOPOGRAPHY SEA ICE TYPE RECORD DATE TIME LATITUDE LONGITUDE OPEN WATER TRACK SNOW THICKNESS SNOW TYPE SEA TEMPERATURE AIR TEMPERATURE WIND VELOCITY WIND DIRECTION FILM COUNTER FRAME COUNTER FOR FILM VIDEO RECORDER COUNTER VISIBILITY CODE CLOUD WEATHER CODE COMMENTS

These data describe pack ice characteristics in the Antarctic sea ice zone. These data are in the ASPeCt format. National program: Germany Vessel: Polarstern Dates in ice: 12 Dec 2000 - 22 Dec 2000 Observers: Gerd Rohardt, others Summary of voyage track: North-south sections near the prime meridian from the ice edge to Neumeyer station and back to the ice edge. The fields in this dataset are: SEA ICE CONCENTRATION SEA ICE FLOE SIZE SEA ICE SNOW COVER SEA ICE THICKNESS SEA ICE TOPOGRAPHY SEA ICE TYPE RECORD DATE TIME LATITUDE LONGITUDE OPEN WATER TRACK SNOW THICKNESS SNOW TYPE SEA TEMPERATURE AIR TEMPERATURE WIND VELOCITY WIND DIRECTION FILM COUNTER FRAME COUNTER FOR FILM VIDEO RECORDER COUNTER VISIBILITY CODE CLOUD WEATHER CODE COMMENTS