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Issue No. 43, March 2003


Eye on Antarctica

Larsen Ice Shelf Retreat Continues in 2002-2003 Season

MODIS data from late January 2003 show that an iceberg, roughly 8km by 22km, calved from the remnant Larsen B Ice Shelf near the Jason Peninsula. This area of the shelf had large rifts in it prior to calving.

Some melt ponds were observed in earlier images, but this calving does not appear to be similar in style to the climate-induced pattern of splinter calving and disintegration. Instead, it may be an “adjustment” to changes in the forces affecting this section of the shelf as a result of the loss of most of the Larsen B Ice Shelf in March of last year.

MODIS image showing the A52 Iceberg February 24 MODIS image showing the A52 Iceberg drifting north from the remaining Larsen B Ice Shelf. Additional rifts can be seen in the ice shelf just below the iceberg. Some cloud cover is visible on the right side of the image.

RAMP AMM-1 SAR Image Mosaic of Antarctica

NSIDC is pleased to announce the RAMP AMM-1 SAR Image Mosaic of Antarctica collection. Swath images have been assembled into an image mosaic depicting the entire continent at 25m-resolution. The mosaic provides a detailed look at ice sheet morphology, rock outcrops, research infrastructure, the coastline, and other features of Antarctica. The 25m-resolution images and ancillary data comprise approximately 90 separate "tiles" and are available to approved users only. Available to all users are a 125m-resolution mosaic; a 250m- resolution mosaic; and 200m-, 500m- and 1km-resolution GeoTIF images. Data are available from both the Alaska SAR Facility (ASF) and NSIDC.

More information about this product is available at the data catalog page, RAMP AMM-1 SAR Image Mosaic of Antarctica.

Antarctic Glaciological Data Center Releases New Data Sets

The National Science Foundation's Office of Polar Programs funds the Antarctic Glaciological Data Center (AGDC) at NSIDC to archive and distribute antarctic glaciological and cryospheric system data collected by the U.S. Antarctic Program.

AGDC provides two types of data sets, a Principal Investigator Data Sets collection, which holds data collected by specific grants, and a Compiled Products selection, offering collections of important glaciological parameters. Compiled data archived at AGDC include ice velocity, firn temperature, shallow ice core measurements, geochemical composition of ice cores, snow pit data, and satellite images of ice shelves. AGDC recently released the following new data sets:

The WAISCORES Science Management Office transferred data holdings to the AGDC for archival and distribution last fall. The collection contains data pertaining to several ice cores and other activity at and near the Siple Dome research site from 1995 - 2000. AGDC offers access to permanently archived WAISCORES data and metadata, publications, and related information about WAISCORES research.

These data were provided to AGDC by investigators funded by NSF's Antarctic Glaciology Program. Users can access data and documentation, citation information, locator maps, derived images and references through the AGDC website.

Data Pool Implemented

In an effort to streamline user access to Earth Observing System (EOS) data, NSIDC implemented the Data Pool, a short-term data cache that provides FTP access to select products. Currently, the Data Pool contains MODIS snow and sea ice data, but it will support Advanced Microwave Scanning Radiometer - EOS (AMSR-E) and Geoscience Laser Altimeter System (GLAS) products when they become available in the future.

The Data Pool uses a large disk cache to replicate EOS data in easily accessible storage for a limited period of time, allowing users to quickly retrieve current data. MODIS products are currently available through the Data Pool for 60 days after initial release.

A simple Web search interface allows users to quickly locate data of interest. Users can view most browse images and metadata directly in their Web browser. Users can still access the entire archive of EOS data through the EOS Data Gateway (EDG). Please visit the Data Pool content for further information.

Evaluation of MODIS Snow Product

The results of a comparison study of MODIS snow cover data and the snow-covered area (SCA) product from the National Weather Service National Operational Hydrologic Remote Sensing Center (NOHRSC) have been published in the journal "Hydrological Processes" (Volume 17, Issue 1, 2003. Pages: 59-71).

The two products were compared to ground observations in two major North American river basins and evaluated for accuracy of snow and cloud classification. The MODIS/Terra Snow Cover Daily L3 Global 500m ISIN Grid data product was found to classify fewer pixels as cloud than the NOHRSC product over one basin, and overall misclassified as snow/no-snow fewer pixels than the NOHRSC product.

The paper, "Evaluation of the snow-covered area data product from MODIS," by Edwin P. Maurer, Joshua D. Rhoads, Ralph O. Dubayah, and Dennis P. Lettenmaier, may be viewed online.

MODIS Version 004 Snow Products

The NSIDC DAAC, in collaboration with the MODIS Land Science Team, is pleased to announce the availability of Version 004 (V004) MODIS/Terra Snow Cover products. Version 004 processing will generate a consistent data collection from February 2000 to the present. Version 004 represents an overall improvement to the suite of snow products and also includes product-specific enhancements.

Two processing streams are being run with the V004 algorithms - one for forward processing and one for reprocessing. Forward processing began with data acquired on 1 January 2003. Reprocessing began with data acquired on 24 February 2000 (day 055) and will move forward to reprocess the data to 31 December 2002.

Version 003 (V003) granules will be available for at least six months after they have been reprocessed to the V004 algorithm. For more information on MODIS/Terra product versions, including temporal coverage, please see MODIS Data at NSIDC.

Version 004 Sea Ice products should be available in the near future.

GLAS Status

NASA's Ice, Cloud and land Elevation Satellite (ICESat) lifted off from Vandenberg Air Force Base, California, on 12 January 2003, at 4:45 p.m. PST aboard a Boeing Delta II rocket.

Since the launch, the mission has progressed smoothly. The GPS BlackJack receiver built by JPL has been successfully turned on and is regularly acquiring precise orbit and timing data. Spacecraft commissioning, including incremental activation of subsystems, establishing attitude stability and pointing, power and thermal management, and ground communication, is almost complete. The spacecraft is perfoming very well against its rigorous on-orbit requirements.

Commissioning of the GLAS instrument, which will take several weeks, began on 1 February 2003 when the main electrical unit (MEU), structural heaters, and loop heat pipes were powered up. On 20 February, the laser was turned on, and the first laser sensor images were received the following day. In mid-March, ICESat begins a 90-day calibration and validation period. For more information, see the ICESat product site.

2002 NASA DAAC Alliance Annual Released

The 8th edition of the NASA DAAC Alliance Annual publication, titled "Distributed Active Archive Centers Alliance: Supporting Earth Observing Science 2002," is available from the NSIDC DAAC. The DAAC Alliance Annual is a multidisciplinary publication designed to highlight applications and research uses of satellite data archived at NASA's Distributed Active Archive Centers (DAACs).

The 2002 edition of the DAAC Alliance Annual highlights research on volcanic domes, African ecosystems, the breakup of the Larsen B Ice Shelf in Antarctica, the spread of viruses and dangerous organisms, and improving meteorological forecasts. Articles from the DAAC Alliance Annual are also available electronically on NASA's Earth Observatory and on the DAAC Alliance Web site.

Researchers working with NASA DAAC data are invited to contact Laurie Schmidt, editor, to explore possibilities for developing a future DAAC article.

For a free copy of the DAAC Alliance Annual, contact NSIDC User Services. Previous issues of the DAAC Alliance Annual (1998 through 2001) are also available free of charge, while supplies last.

New NSIDC-NOAA Data Sets

Sea Ice Index
NSIDC-NOAA recently released the Sea Ice Index, a catalog of images intended to help researchers illustrate sea ice conditions, and to inform users with general questions about recent ice concentration and extent.

The Sea Ice Index contains graphics that show trends and anomalies in monthly mean Arctic and Antarctic sea ice concentration and extent. NSIDC used two different sea ice concentration data sets that use satellite passive microwave data to generate the monthly mean, trend, and anomaly images so that users of the product can monitor ice conditions as they evolve. Trends and anomalies are based on the period of record beginning in 1988. Access the data set.

Norwegian North Polar Expedition 1893-1896: Oceanographic Data
Norwegian researcher and explorer Fridtjof Nansen originated and tested the idea of using a ship, beset in ice and drifting, as a polar research station after pieces of wreckage from the USS Jeannette, crushed in the ice of the Laptev Sea, washed up on the southwest coast of Greenland after three years. To Nansen, this event suggested the existence of a trans-Arctic current. The Fram, designed specifically by naval architect Colin Archer for the Norwegian North Polar Expedition, drifted from a starting point in ice north of the New Siberian Islands to Svalbard in what was later named the Transpolar Drift Stream.

NSIDC-NOAA has published oceanographic measurements gathered by Nansen and his crew on the Norwegian North Polar Expedition from 1893-1896. Meteorological data from the Nansen expedition is also available in the Environmental Working Group (EWG) Arctic Meteorology and Climate Atlas.

Reconstructed North American Snow Extent, 1900-1993
Station-based snow observations are available for dates since the early twentieth century but lack comprehensive spatial coverage. A remotely sensed product based on visible-band imagery provides more complete spatial coverage but has been available only since the early 1970s. For the Reconstructed North American Snow Extent data set, investigators used a combination of satellite and station observations for November through March, 1900-1993, and based their reconstruction on linear regressions between the two types of observations. The data set also includes standard errors of estimates as well as the observed values on which the regressions were based. Access the data.

Reconstructed North American, Eurasian, and Northern Hemisphere Snow Cover Extent, 1900-1997
The Reconstructed North American, Eurasian, and Northern Hemisphere Snow Cover Extent data set consists of three time series of monthly snow cover extent based on snow cover reconstruction and NOAA satellite data. The reconstruction method used in situ snow depth and daily climate data from the U.S., Canada, China, and the Former Soviet Union to generate a monthly snow cover index that was calibrated with NOAA satellite-derived estimates of snow cover extent over the 1972-1992 period.

The data set also includes two time series of annual variability in area-weighted monthly snow depth and snow water extent for the North American grid domain used to derive the snow cover index. Researchers estimated snow water extent by applying mean monthly density values derived from an analysis of Canadian snow course data. Access the data set.



Workshop on Assessing Global Glacier Recession, March 17-19, 2003

NSIDC hosted a three-day workshop to assess global glacier recession. The goals of the workshop included evaluating current methods of determining the worldwide recession of mountain glaciers over the last half-century or longer. Recent evidence suggests an acceleration of glacier mass loss in several key regions. A more comprehensive evaluation of glacier changes is important in order to understand the implications for global sea level rise and the future of water resources from glacierized basins. The workshop included a training session on new GIS-based mapping techniques using ASTER imagery and digital databases.



Anne Nolin has accepted an assistant professorship in the Department of Geosciences at Oregon State University.

Mike Hartman has joined the Paleoclimatology Branch of NOAA's National Climatic Data Center (NCDC) as database manager for the International Multiproxy Paleofire Database (IMP).

Frank Schaffer has joined the Raytheon group as Configuration Management Administrator.