Arctic Sea Ice Coverage in Square Kilometers by year
Arctic Sea Ice Coverage in Square Kilometers by year
Chart derived from daily data obtained from JAXA Satellite Monitoring of Environmental Studies
Earth Observation Research Center / JAXA
GCOM secretariat(former ADEOS/OCEAN secretariat)
2-1-1 Sengen, Tsukuba, Ibaraki 305-8505 Japan
FAX : +81-29-868-2961
Chart to be updated once a year in January
Notes from source website with additional information obtained from the web:
The sea-ice extent is calculated as the areal sum of sea ice covering the ocean where sea-ice concentration (SIC) exceeds a threshold (15% for AMSR-E). SICs are derived from various satellite-borne passive microwave radiometer (PMR) sensors using the algorithm developed and provided by Dr. Comiso of NASA GSFC through a cooperative relationship between NASA and JAXA. The following sensor's data were used;
• Nov. 1978 - Jul. 1987 : SMMR (The Nimbus-7 SMMR Pathfinder Brightness Temperature Data were provided by the Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, under contract with the National Aeronautics and Space Administration (NASA).)
• Jul. 1987 - Jun 2002 : SSM/I (The SSM/I Sensor Data Record (SDR) brightness temperatures are being provided by NOAA's National Environmental Satellite, Data, and Information Service (NESDIS)).
• Jun. 2002 - Oct. 2011 : AMSR-E (Advanced Microwave Scanning Radiometer - EOS, Marshall Space Flight Center)
• Oct. 2011 - Jul. 2012 : WindSat (The WindSat Sensor Data Record (SDR) brightness temperatures are being provided by the Naval Research Laboratory (NRL) and NOAA's National Environmental Satellite, Data, and Information Service (NESDIS)).
• Jul. 2012 - the present : AMSR2 (The Advanced Microwave Scanning Radiometer 2 (AMSR2) onboard the GCOM-W satellite is a remote sensing instrument for measuring weak microwave emission from the surface and the atmosphere of the Earth. From about 700 km above the Earth, AMSR2 will provide us highly accurate measurements of the intensity of microwave emission and scattering. The antenna of AMSR2 rotates once per 1.5 seconds and obtains data over a 1450 km swath. This conical scan mechanism enables AMSR2 to acquire a set of daytime and nighttime data with more than 99% coverage of the Earth every 2 days). Earth Observation Research Center, Japan Aerospace Exploration Agency
In order to eliminate calculation errors due to a lack of data (e.g., for traditional microwave sensors such as SMMR and SSM/I),sea-ice extent is defined as a temporal average of several days. In this data, we adopt the average of five days.
Definition of sea-ice cover (extent and area)
The area of sea-ice cover is often defined in two ways, i.e., sea-ice "extent" and sea-ice "area". These multiple definitions of sea-ice cover may sometimes confuse data users. The former is defined as the areal sum of sea ice covering the ocean (sea ice + open ocean), whereas the latter "area" definition counts only sea ice covering a fraction of the ocean (sea ice only). Thus, the sea-ice extent is always larger than the sea-ice area. Because of the possible errors in SIC mentioned above, satellite-derived sea-ice concentration can be underestimated, particularly in summer. In such a case, the sea-ice area is more susceptible to errors than the sea-ice extent. Thus, we adopt the definition of sea-ice extent to monitor the variation of the Arctic sea ice on this site.
WindSat: The WindSat Sensor Data Record (SDR) brightness temperatures are being provided by the Naval Research Laboratory (NRL) and NOAA's National Environmental Satellite, Data, and Information Service (NESDIS).
SSM/I: The SSM/I Antenna Temperature (TA) data were produced by Remote Sensing Systems (RSS).
SMMR: The Nimbus-7 SMMR Pathfinder Brightness Temperature Data were provided by the Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, under contract with the National Aeronautics and Space Administration (NASA).
Copyright @2012 Japan Aerospace Exploration Agency, Earth Observation Research Center All rights reserved.
Since the coverage of Arctic Sea Ice have been systematically monitored by satellite starting in the late 1970's, the maximum, minimum and annual average for each year has been in a generally declining trend.
2014 year-end note: The annual minimum coverage reached a modern record low of 3,208,751 square kilometers in 2012 before rebounding modestly in 2013 and 2014. Speculation as to when the Arctic Sea Ice could disappear completely even briefly has been rampant. In my opinion, unless we enter into a runaway Methane emission scenario which will accelerate the trend, the year of zero minimum ice will happen sometime in the early 2020's unless immediate global action is taken on reducing the Carbon Dioxide and Methane levels.
2015 saw a new low on the Maximum Coverage graph with 13,942,060 square kilometers of ice.
Jan 3, 2017: 2016 reached a new low for average arctic ice, dropping from 10,111,277 square kilometers to 9,727,571 a shrinkage of 3.79%. The maximum was just 0.12 percent larger than last year's record low maximum. The minimum of 4,017,264 square kilometers 5.6% below last year's low of 4,257,003.
March 3, 2017: The current slope of the annual minimum ice cap measurement graph suggests that "zero ice" for the Arctic summer low might not be reached until mid to late 2040's, quite a bit later than the early 2020's I suggested a couple years ago. This assumes a choppy linear decline and does not consider the real possibility of a runaway feedback loop.
The Arctic Sea Ice coverage daily graph update may be seen at https://ads.nipr.ac.jp/vishop/#/extent
Another link: http://nsidc.org/arcticseaicenews/