Gridded Monthly Arctic Sea Ice Back to 1850, for Analysis or Browsing
Until now, climate diagnostic applications, reanalyses, and atmospheric modeling studies that needed a lower boundary layer did not have an arctic-wide gridded ice concentration data set to use based on observations and one that extends back as far as the mid-nineteenth century. Gridded Monthly Sea Ice Extent and Concentration, 1850 Onwards addresses this need by improving and extending the Arctic and Southern Ocean Sea Ice Concentraions product. It does this by adding newly available historical sources and by using the NOAA/NSIDC Climate Data Record of Passive Microwave Sea Ice Concentration for the satellite era.
The Gridded Monthly Sea Ice Extent and Concentration, 1850 Onwards [link] product uses the following data sources:
- North Atlantic ice edge positions covering 1850 through 1978 derived from various sources, including newspapers, ship observations, aircraft observations, diaries, and more.
- Gridded ice concentration from regular aerial surveys of ice in the eastern arctic by the Arctic and Antarctic Research Institute, St. Petersburg, Russia, beginning in 1933.
- Ice edge positions for Newfoundland and the Canadian Maritime Region from observations over the period 1870 through 1962.
- Detailed charts of ice in the waters around Alaska for 1954 through 1978 called the The Dehn Collection of Arctic Sea Ice Charts, 1953-1986.
- Arctic-wide maps of ice cover from the Danish Meteorological Institute over 1901-1956.
- Whaling logbook entries noting ship position along with an indication of whether the ship was in the presence of ice.
The six sources already existed as data compilations in one form or another prior to our use of them, and with the exception of the Canadian ice edge positions and the whaling logbook data, these are available from the National Snow and Ice Data Center. However, some data sets, such as the Dehn collection, required digitization and interpretation before the information could be used. The documentation for Gridded Monthly Sea Ice Extent and Concentration, 1850 Onwards provides references for all sources and details how each was prepared for processing. The data product is a NetCDF file covering January 1850 through December 2013. It will be updated and extended in 2017.
More information can be found in the July 2016 Geographical Review article cited below, and in a Cooperative Institute for Research in Environmental Sciences (CIRES) news article called Reconstructing Arctic History: Scientists build a new database to depict Arctic sea ice variations back to 1850. CIRES is a partnership of NOAA and CU-Boulder. The National Snow and Ice Data Center is part of CIRES.
Walsh, John E., Florence Fetterer, J. Scott Stewart, and William L. Chapman. 2016. A database for depicting Arctic sea ice variations back to 1850. Geographical Review. doi: 10.1111/j.1931-0846.2016.12195.x.
Data Set DOI: http://dx.doi.org/10.7265/N5833PZ5
NOAA@NSIDC Releases Sea Ice Index Version 2
NOAA@NSIDC is pleased to announce the release of Sea Ice Index Version 2. Improvements include using the most recently available version of the Goddard Space Flight Center (GSFC) input sea ice concentration data and revising three computations in the Sea Ice Index processing code. The new GSFC data have undergone additional manual quality control procedures at the GSFC that go farther to remove spurious ice. The GSFC data are available as their own data set from the NSIDC DAAC as Sea Ice Concentrations from Nimbus-7 SMMR and DMSP SSM/I-SSMIS Passive Microwave Data. The other three updates adjust calculations present in the old Sea Ice Index processing code that were in need of improvement. Because of these updates, minor changes in some of the ice extent and area numbers can be seen with the average change in the trends over all 12 months being on the order of 0.05 percent/decade (approximately 500 sq. km/year). For a complete description of these changes, see the Sea Ice Index Updated to Version 2 section in the Product History section of the Sea Ice Index documentation.
Data Set DOI: http://doi.org/10.7265/N5736NV7
NOAA@NSIDC to Release Sea Ice Index Version 2 Next Week
An improved version of the Sea Ice Index is coming. On Wednesday, 6 July 2016, Sea Ice Index Version 2 will be released. It will look and act the same as Version 1, but will have updated processing code and will use a new version of the input data. Because of these updates, minor changes in some of the ice extent and area numbers will be seen. These will be clearly described in the documentation, which will also be updated on 6 July.
We are alerting users to this impending update because file names will change. Any scripts that automatically download Sea Ice Index data each day will need to be updated to reflect this file name change. The new file names will have an “_v2” appended to the end of the file name such as N_04_area_v2.txt and N_04_plot_v2.png.
Further, NOAA@NSIDC has received support from the NOAA Big Earth Data Initiative (BEDI) program to create web services built around the Sea Ice Index. This will provide a simple HTTP interface for requesting geo-registered Sea Ice Index images from the NSDIC web site. We hope to have a web service-enabled Sea Ice Index in place by the end of 2017.
Data Set DOI: http://dx.doi.org/10.7265/N5QJ7F7W
Sea Ice Index Processing Resumed with DMSP-F18 Satellite Data
On 05 April 2016, the vertically polarized 37 GHz (37V) channel of the SSMIS instrument on the DMSP-F17 satellite began yielding compromised brightness temperature data. This channel is one of those used to estimate sea ice concentration shown in the Sea Ice Index, so data processing was temporarily suspended.
NOAA@NSIDC is pleased to announce that, today, Sea Ice Index processing has resumed and the time series now uses the SSMIS instrument on the DMSP-F18 satellite beginning 01 April 2016. These sea ice concentration values come from the NSIDC Near-Real-Time DMSP SSMIS Daily Polar Gridded Sea Ice Concentrations product. Prior to transitioning this near-real-time data set to the F18 SSMIS instrument, NSIDC investigated whether or not algorithm parameters would need to be calibrated to minimize the difference between sea ice extents derived from F17 and F18.
Because each sensor and spacecraft orbit is slightly different, algorithm parameters called tie points sometimes need adjustments so that the time series is consistent. Inconsistencies would be marked by sudden false jumps or drops in derived ice extent at the point when the algorithm started using data from the new instrument. These tie-point adjustments are derived from regressions of brightness temperatures during satellite overlap periods. To determine if an adjustment to algorithm tie points would be needed for F18 data, NSIDC ran the algorithm both with and without adjustment to produce ice concentration data from both F17 and F18 data. Ice extents derived from the ice concentration data were then compared over a 12-month period from 01 March 2015 through 29 February 2016 when the SSMIS instruments on both satellites were operational.
After investigating the difference in ice extent as the algorithm tie points were varied, it was found that the current F17 tie points provided the best match in sea ice extent for the overlap period, so no adjustment in algorithm parameters was needed for F18. Results are shown in the figures at the bottom. The average difference between F18- and F17-derived sea ice extents for the overlap time period is approximately -20,000 sq km. See the Error Sources section of the Near-Real-Time DMSP SSMIS Daily Polar Gridded Sea Ice Concentrations documentation for more information on the input data. For more information on algorithm tie points see the Consistency of the Data Record section in the Sea Ice Index documentation.
The figures below show the relative agreement of sea ice extent from F17 (green line) and F18 (orange line) for the Northern Hemisphere (top) and Southern Hemisphere (bottom) for March 2015 through February 2016.
Data Set DOI: http://dx.doi.org/10.7265/N5QJ7F7W
Sea Ice Index Processing Suspended
The Sea Ice Index is typically updated every day to display yesterday’s ice extent for both hemispheres. The Index relies on data that come from the DMSP F17 satellite. However, these data have not been reliable since early April; so the NOAA@NSIDC team has not been able to update the Sea Ice Index since 31 March 2016.
Sea Ice Index processing uses an NSIDC NASA DAAC product, Near-Real-Time DMSP SSMIS Daily Polar Gridded Sea Ice Concentrations (NSIDC-0081), as input. The NSIDC DAAC has started the work needed to move to a new source for NSIDC-0081. This involves retrieving F18 and F16 satellite brightness temperatures from our data providers and then implementing parallel processing for ice concentration to determine which satellite will be best suited to continue the time series. The satellite selected will be the primary replacement for F17, but should that satellite fail, we will be able to switch to the other one without a service interruption.
An interim version of the NSIDC-0081 data stream will be used for the ASINA product, which is based on the Sea Ice Index, to continue to report on sea ice conditions. However, the Sea Ice Index processing itself will not resume until a version of NSIDC-0081 is available that is vetted by the science team. It is not known how long this will take, but we expect it will be a minimum of two months before NSIDC-0081 is updating regularly again with a new vetted source and the Sea Ice Index is processing that new input.
Users may want to explore daily arctic-wide ice extent from the NIC/NSIDC MASIE product as an alternative product for the Northern Hemisphere. The MASIE ice extent record is not consistent with that from the Sea Ice Index, however, nor is it necessarily internally consistent. See the MASIE documentation in order to gain a better understanding of how the product is created.
International Ice Patrol Iceberg Sightings Database Updated through 2015
NOAA@NSIDC is pleased to announce that the International Ice Patrol (IIP) has updated their Iceberg Sightings Database through the 2015 iceberg season. The IIP has been collecting information on iceberg activity in the North Atlantic since 1911, and this database contains data from these sightings starting in 1960. The IIP data files include latitude and longitude of sighted icebergs, coded iceberg size and shape class, and date and time of the sighting. For more information on this data set and to access the data, please visit the International Ice Patrol Iceberg Sightings Database web page.
Data Set DOI: http://dx.doi.org/10.7265/N56Q1V5R
NSIDC Working to Rescue ESSA-1 Data as the Satellite Celebrates its 50 Year Anniversary
Fifty years ago today, the first satellite in the NOAA Environmental Science Services Administration (ESSA) series of satellites, ESSA-1, acquired its first image. The image was of Antarctica. Now, NSIDC’s Garrett Campbell and David Gallaher are attempting to organize the rescue of data from the satellite. They hope to use the recovered imagery to locate the position of the southern hemisphere’s sea ice edge, as was possible after rescuing infrared imagery from the early NASA NIMBUS series.
It won’t be easy to rescue the ESSA-1 data. According to the book Satellite Remote Sensing of the Polar Regions: Application, Limitations, and Data Availability, limitations of the imagery include “coarse ground resolution obscured by cloud and fog. Inoperative in darkness. Often difficult to distinguish ice from cloud. Imagery from the early meteorological satellites was not coupled to detailed ground observations. A major problem in using APT imagery from the ESSA satellites involves gridding and location of the individual frames.” (R. Massom 1991, p. 158).
Campbell believes they have an approach to solving the image navigation problem that will prove successful. With luck, our users will have access to imagery that locates the Southern Hemisphere ice edge more than a decade prior to the start of the Sea Ice Index record. In addition, there will be images showing Arctic ice as well.
Wednesday 14 January is Arctic Matters Day
Arctic Matters Day is a free public program that will be held 14 January 2016 at the National Academy of Sciences building in Washington, DC. It will provide an overview of the dramatic environmental changes affecting the Arctic region and the ways that these changes can potentially affect the entire planet. If you are in the Washington D.C. area, consider attending the free public program, Arctic Matters Day. Through exhibits and talks, the program will “explore how many facets of our lives (for instance, our coastlines, our weather, our fish supplies, and our security) are tied to what is happening in that ‘isolated’ part of the world.”
NOAA@NSIDC’s Glacier Photograph Collection will benefit from CLIR Grant
The Glacier Photograph Collection, managed by NOAA@NSIDC, will get a big boost in 2016 from a Council on Library and Information Resources (CLIR) grant. The Glacier Photograph Collection includes over 15,000 digital images available online, as well as an analog collection of photographic prints of glaciers from around the world beginning in the mid-1850s. This grant begins a collaboration between NSIDC and the Digital Library at the University of Colorado at Boulder (CU). The grant will allow for a dedicated archivist and graduate assistants to digitize, describe, and publish the approximately 9,000 remaining photographic prints that have not yet been scanned, described, and entered into the searchable online catalog.
The online portion of the collection now consists of both a relatively small collection of born-digital photos and a large number of digitized print photographs that pre-date the digital photographic era. Beginning in 2002, digitization of photographic prints began with a grant from the NOAA Climate Database Modernization Program (CDMP). However, when this program ended in 2011, NOAA@NSIDC was left with close to 9,000 photos that had not been digitized. The CLIR grant will provide support to finish digitizing these remaining prints that have been languishing in the NOAA@NSIDC archive for many years. Once digitized, these images will be added to the online Glacier Photograph Collection search interface and CU’s Digital Library for all to access.
Two press releases from both NSIDC and CU provide further description of the project: CU-Boulder Libraries, NSIDC win grant to digitize historical Glacier Photograph Collection and Historic glacier photos get digital treatment. To access the digital photos already in this collection, see the Glacier Photograph Collection Search Interface.
Data Set DOI: http://dx.doi.org/10.7265/N5/NSIDC-GPC-2009-12
NOAA@NSIDC Updates Google Earth File Showing the Minimum Arctic Sea Ice Extent
NOAA@NSIDC is pleased to announce that we have updated the Google Earth file for the annual minimum Arctic sea ice extent for 2015. The September 2015 minimum KMZ file has been updated to show the 2015 September Arctic sea ice minimum. To view these, and other, Google Earth files, visit the NSIDC Data on Google Earth web page.
NOAA@NSIDC has Filled the Data Gaps in MASAM2, a 4 km Daily Sea Ice Concentration Product
The 4 km Daily Sea Ice Concentration Product, MASAM2, has had all data gaps filled. It is a now a continuous, daily time series from 02 July 2012 to the present. MASAM2 is updated daily with a 2-day lag time. For more information or to access this data set, see the MASAM2: Daily 4 km Arctic Sea Ice Concentration product page.
Data Set DOI: http://dx.doi.org/10.7265/N5ZS2TFT
Dehn Ice Charts Search Interface Updated
NOAA@NSIDC is pleased to announce that the online search interface for the Dehn Arctic Sea Ice Charts database has been updated. Improvements include the ability to define your search by region and time period at the same time, the search results now list how many images were returned, and a “Select/Deselect All” button has been added to the ordering page for ease in selecting images. For more information about the product, see the Dehn Collection of Arctic Sea Ice Charts, 1953-1986 documentation page.
Data Set DOI: http://dx.doi.org/10.7265/N5F769GD
MASIE Daily Gridded Sea Ice Extent at 1 km from NIC and NOAA@NSIDC
NOAA@NSIDC is pleased to announce the release of a 1 km gridded MASIE sea ice product in addition to the 4 km version. The Multisensor Analyzed Sea Ice Extent (MASIE) helps to give the best available Arctic-wide answer to the question: Where is Arctic sea ice now? MASIE products provide measurements of daily sea ice coverage for the Northern Hemisphere and 16 Arctic regions in a polar stereographic projection in 4 km grid cells and now in 1 km grid cells as well. In addition, a full Northern Hemisphere time series graph has been added to the MASIE Time Series Plots Web page. MASIE repackages the National Ice Center’s IMS product. The IMS product is archived with and distributed by NOAA@NSIDC, in cooperation with NIC. For more information and to access the new data, visit the MASIE Web site.
Data Set Doi: http://dx.doi.org/10.7265/N5GT5K3K
NOAA@NSIDC has Updated the Sea Ice Concentration CDR through 2014
NOAA@NSIDC is pleased to announce that the NOAA/NSIDC Climate Data Record of Passive Microwave Sea Ice Concentration, Version 2 data set is now available through 2014. This data set provides a Climate Data Record (CDR) of sea ice concentration from passive microwave data. It provides a consistent, daily and monthly time series of sea ice concentrations from 09 July 1987 through through 2014 for both the north and south polar regions on a 25 km x 25 km grid.
Data Set DOI: http://dx.doi.org/10.7265/N55M63M1
Improvement in Navy’s Sea Ice Edge Position Forecasts is Documented and Publicized
A CU Boulder CIRES press release, Better Daily Sea Ice Forecasts for the Arctic Following CU-Boulder-led Innovation, was occasioned by the publication of a paper by Posey et al. titled Improving Arctic Sea Ice Edge Forecasts by Assimilating High Horizontal Resolution Sea Ice Concentration Data into the US Navy’s Ice Forecast Systems (2015). The press release highlights improvements brought about by blending a product based on National Ice Center analysts interpretation of sea ice extent with passive microwave AMSR2 sea ice concentration data. The blending technique is the same one that is used for the NOAA@NSIDC MASAM2: Daily 4 km Arctic Sea Ice Concentration product.
NOAA@NSIDC Releases 1960, 1969, and 1970 Sea Ice Draft Data
NOAA@NSIDC is pleased to announce that the Submarine Upward Looking Sonar Ice Draft Profile Data and Statistics data set has been updated with historical data from 1960, 1969, and 1970. This data set consists of upward looking sonar draft data collected by submarines in the Arctic Ocean. It includes data from both U.S. Navy and Royal Navy submarine. These pre-satellite-era data are a significant and important addition to the slim record of sea ice thickness that researchers have to work with for this time period.
Data Set DOI: http://dx.doi.org/10.7265/N54Q7RWK
NOAA@NSIDC Updates the Glacier Photograph Collection Search & Order Interface
NOAA@NSIDC is pleased to announce some enhancements to the Glacier Photograph Collection Search & Order interface. Enhancements include making it easier and more apparent how to add photos to an order and how to place an order. In addition, the metadata fields were fine-tuned and improved to increase the discoverability of the photos. Other minor changes were made to provide streamlining and consistency to the interface.
Data Set DOI: http://dx.doi.org/10.7265/N5/NSIDC-GPC-2009-12
SCICEX Program Highlighted in Witness the Arctic
The Science Ice Exercise (SCICEX) Program, that uses U. S. Navy submarines to collect data about the Arctic Ocean, has been highlighted in two articles in the Spring 2015 issue of Witness the Arctic published by the Arctic Research Consortium of the United States (ARCUS). The first article, Teaching an Old Submarine Data Collection Program New Tricks, provides a high level description of the project and the data available including Arctic Ocean bathymetry, hydrography, and sea ice draft. The second article located below the first one, A Labor of Love Brings Together Civilian Scientists and the U.S. Navy, provides a history of how and why the SCICEX program came into being. For more information on this program, see the SCICEX Web site.
NOAA@NSIDC Has Resumed MASIE Processing and Filled All Data Gaps
NOAA@NSIDC is pleased to announce that the MASIE daily 4 km sea ice extent product has resumed and all gaps in the data from the November 2014 to April 2015 outage have been back filled. In addition, all sea ice extent values for the entire time series have been made available via one comma separated value file: masie_allyears_extent_sqkm.csv. There is one value per day for the entire Arctic, as well as one for each of the 16 MASIE regions. NOAA@NSIDC publishes this popular product in collaboration with the U.S. National Ice Center in Suitland, Maryland. For complete information, visit the MASIE Web site.
Data Set DOI: http://dx.doi.org/10.7265/N5GT5K3K
NOAA@NSIDC Updates Google Earth Files Showing the Maximum and Minimum Sea Ice Extent
NOAA@NSIDC is pleased to announce that the Google Earth files for the minimum and maximum annual sea ice extents have been updated. The September 2014 minimum KMZ file has been updated to use final instead of near-real-time data, and the March 2015 maximum KMZ file has been added to the time series. To view these, and other, Google Earth files, visit the NSIDC Data on Google Earth web page.