New Collection of Photos added to the Glacier Photograph Collection
NOAA@NSIDC is pleased to announce the addition of 1,173 photographs to the Glacier Photograph Collection. This addition is a special collection that contains photographs of glaciers in and around the Lake Clark National Park and Preserve in Alaska, USA. The collection was compiled by a Natural Resource Specialist Intern in the GeoSpatial Services Department at Saint Mary’s University, MN. The collection is comprised of many images of glaciers in and around the park and preserve taken from both the air and the ground from 1987 through 1990 and in 2004 and 2007. To view the new collection, visit the Glacier Photograph Collection search interface and select “Lake Clark National Park Glscier Photographs” from the Choose a Collection drop-down list.
Data Set DOI: http://dx.doi.org/10.7265/N5/NSIDC-GPC-2009-12
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 condition 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 Onward addresses this need by improving and extending the Arctic and Southern Ocean Sea Ice Concentrations 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 NOAA@NSIDC product, Gridded Monthly Sea Ice Extent and Concentration, 1850 Onward, 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 Onward 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 a “_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. The F18 satellite will be the primary replacement for F17, but should that satellite fail, we will be able to switch to F16 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 can see the latest F18 provisional daily data on the ASINA site for both the Arctic and Antarctic, or users can plot the Arctic data and compare it to other years on Charctic, NSIDC’s interactive Arctic sea ice graphing tool.
Users may also 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 1913, 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.