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In this Issue

ARCTIC SYSTEM SCIENCE (ARCSS) HIGHLIGHTS
PERMAFROST DATA SYSTEM
DEFENSE METEOROLOGICAL SATELLITE PROGRAM (DMSP)
ARCTIC ENVIRONMENTAL DATA DIRECTORY (AEDD)
PRODUCTS AND SERVICES
ONGOING RESEARCH ACTIVITIES

NSIDC Notes

Issue 4, Winter 1993

ARCTIC SYSTEM SCIENCE (ARCSS) HIGHLIGHTS

ARCSS/OAII Workshop on Surface Energy Budget, Radiation and Clouds Over the Arctic Ocean

On 9-11 February 1993, Claire Hanson and Matthew Cross attended the Arctic System Science (ARCSS) Ocean-Ice-Interactions Interagency Workshop on Surface Energy Budget, Radiation and Clouds Over the Arctic Ocean, in Orlando, Florida. The organizing committee consisted of Dr. Richard Moritz, University of Washington, Dr. Judith Curry, University of Colorado, Dr. Alan Thorndike, University of Puget Sound, and Dr. Norbert Untersteiner, University of Washington. The goals of the workshop were to define the best possible avenues for data collection in the Arctic in order to improve our understanding of the state of the climate in the Arctic. A field activity was proposed which would involve placing a field camp on the Arctic ice sheet for one complete year to collect data on cloud cover and type, temperature and precipitation, snow cover, sea ice, and solar irradiation fluxes. The data would ultimately be used to construct more precise general circulation models for determining changes in the arctic due to climatic variations.

Science Data Plan

An ARCSS-wide Science Data Plan (SDP) is currently being developed at NSIDC. The SDP will assist in design of a distributed ARCSS data archive and distribution mechanisms to meet ARCSS data requirements. This matrix will outline when, where, and by whom each data parameter or data type will be collected and become available. Full participation will be sought from each ARCSS investigator during the construc tion of the SDP. This living document will lead to better information for field-season planning (logistics and science efficiencies), data sharing (inter- and intra-disciplinary linkages), and integrated modeling. The first section of the SDP (Phase 1) is now being developed for the LAII Flux Study and should be complete by April 15, 1993. Phase 2 will be an expansion of the Science Data Plan to include data from other LAII projects, from ARCSS/OAII, and from GISP2 and PALE as appropriate.

During the January LAII Flux Study meeting in Seattle, a list of high-priority data sets required for early modeling work was generated. It will be incorporated into Phase 1 of the ARCSS SDP. The first high priority data project for ARCSS/LAII will be the R4D hydrology data base. Dr. Doug Kane, University of Alaska, is currently completing the quality control of this data set, which will be transferred to NSIDC during April. The data will be copied to CD-ROM and will initially be distributed to ARCSS-LAII Flux Study investigators. General distribution of the data set will be discussed by the Flux investigators at a future date. Other CD-ROMs (or equivalent) will follow as funding and data availability permit, at a target rate of 1 disc per year.

For more information, contact NSIDC User Services.

Greenland Ice Sheet Program (GISP2)

During the month of February, derived data products from the Greenland Ice Sheet Project (GISP2) were downloaded to NSIDC through Internet. The data are organized by format structure and have documentation describing the coding scheme for the derived GISP2 data products. At present the data can be accessed at NSIDC only by the GISP2 principal investigators. In the future the data will be copied to CD-ROM for distribution.

Solar Radiation Data Over the Arctic

An inventory of solar radiation data over the Arctic is currently being compiled at NSIDC. The goal of this project is to provide the most comprehensive list available of existing solar radiation data collected at high latitudes. The list will include data from AIDJEX, MIZEX, CEAREX, and LEADEX field experiments, from the Global Energy Balance Archive (GEBA) at ETH/Zurich, and from sources in Canada and other arctic nations.

As part of our ARCSS data management project, we also will try to obtain the data sets in the solar radiation data inventory. Development of a comprehensive database of these observations is being considered. If you know of high-latitude solar radiation observations from any sources not listed here, please contact NSIDC User Services.

PERMAFROST DATA SYSTEM

Permafrost data are currently collected by many researchers in the scientific community for many different purposes. The types of permafrost measurements being taken are as diverse as the purposes of the research, and range from field observations to borehole data, geophysical surveys, and remote sensing. Due to the increasing interest in the use of these data by the scientific community, NSIDC is attempting to develop a permafrost database, including a catalog of existing data sets and current locations. This information will be provided to the Arctic Environmental Data Directory (AEDD) and to the Global Change Master Directory (GCMD) as it is compiled.

Recently, NSIDC distributed a questionnaire to members of the International Permafrost Association (IPA) Working Group to determine the status of their projects and to determine what data sets they could contribute to the permafrost database. There was an excellent response to the questionnaire and the information contained therein will be the basis for development of the permafrost data system.

The first data set defined for input into the permafrost data system is being compiled by Tom Ostercamp, University of Alaska-Fairbanks. The data set consists of temperature (borehole, ground, active layer), electromagnetic profiles and soundings, gravity and other geophysical measurements, and subsea permafrost measurements for Alaska from 1974 to present. This data will eventually be placed on a CD-ROM for distribution.

DEFENSE METEOROLOGICAL SATELLITE PROGRAM (DMSP)

DMSP Digital Data Archive

NSIDC and NOAA/National Geophysical Data Center (NGDC) have made significant progress on their joint effort to archive U.S. Air Force Defense Meteorological Satellite Program (DMSP) data. While the archive will actually be at NGDC (as a NOAA program), NSIDC is involved in much of the design and development work, and will provide user services for data related to the climate-cryosphere system once the archive is fully functional. Funding for this effort is from the Department of Defense, NOAA and NASA.

NSIDC now has five staff working on this project. A hardware and software system has been designed to meet the projected level of user services support to be provided by NSIDC when the archive first becomes operational. Two UNIX-based workstations, one PC, and associated peripherals have been procured and installed. Several other devices will be purchased over the next few months.

The current tasks NSIDC is working on are accurate geolocation, data display and image processing, search and browse of data and a graphical satellite orbit mapper.

Though data from the archive are not available yet, the Air Force Global Weather Central has been reliably copying DMSP data to 8 mm tapes and shipping them to the archive since September 1992. Data from this system will be available in hard-copy or digital form (8 mm media) by approximately mid-1993. Some test data may be available in the late Spring.

For more information, contact: Greg Scharfen at (303) 492-6197 or Internet: scharfen@nsidc.org.

ARCTIC ENVIRONMENTAL DATA DIRECTORY (AEDD)

The Arctic Environmental Data Directory (AEDD), presently hosted by the USGS Earth Science Data Directory (ESDD), will move to a PC-based system designed and maintained by the USGS in Anchorage. The Anchorage design and implementation phase began in January 1993.

The AEDD contains descriptions of data sets and data products relating to the Arctic; at present there are about 370 entries from primarily U.S. federal and Alaska agencies. Ongoing efforts to reference data sets from other Arctic countries (there are currently about ten entries), and from the ecological, biological, health, and socioeconomic fields are a high priority.

The Interagency Arctic Research Policy Committee (IARPC) and the Interagency Working Group on Data Management for Global Change (IWG) formed the AEDD Working Group (AEDDWG) in summer 1988 to guide development of the directory for the purpose of contributing to the management, preservation, distribution, and use of Arctic data sets critical to the understanding of Arctic and global change processes.

NSIDC is represented on the AEDDWG, and is actively working to populate the AEDD with descriptions of data sets and data products that we learn of through our communications with the science community. If you know of a data set that you believe should be given wider publicity, please contact NSIDC User Services to initiate production of a directory entry.

The AEDD effort is being coordinated with NASA's Global Change Master Directory (GCMD). In fact, most if not all of the entries in AEDD are also listed in the GCMD. Directory Interchange Format (DIF) data descriptions can be easily exchanged between AEDD and GCMD, and GCMD is represented on the AEDDWG.

For additional information about the AEDD, contact Paul Brooks or A.C. Brown, US Geological Survey, 4230 University Drive, Anchorage, AK 99508. Telephone (907) 786-7000; fax (907) 786-7050. USGS/Anchorage contributed portions of the text for this article.

PRODUCTS AND SERVICES

Sea Ice CD-ROM Project Status

Sea ice concentration data digitized from the Navy - NOAA Joint Ice Center weekly charts are being tested in their CD-ROM format at NSIDC. The data were transferred from VAX VMS tape, through a Silicon Graphics fileserver, to the new CD-ROM "one-off" system at NSIDC, and written to a one-off disc. The file structure and format are now being tested prior to release to 12 "beta" testers who have agreed to evaluate this new product.

We expect in-house testing to be completed during March, and hope to have feedback from the "beta" testers by the end of May. If there is sufficient interest in this product, NSIDC will bring it to "version 1.0" status and make it available on request. A price for this potential product has not yet been determined, but is expected to be less than $100. Software to aid in reading this SIGRID-format data (a World Meteorological Organization sea ice data exchange format) is being prepared for distribution on diskette, along with complete documentation.

If you would like to be notified when this product becomes generally available, please contact NSIDC User Services.

Arctic Ocean Buoy Data Products: New Versions Available

Gridded data products from the University of Washington/Polar Science Center's Arctic Ocean Buoy Program (now the Coordinated Arctic Buoy Program) have recently been reformatted and revised to bring all years (1979 to 1990) of each gridded product into the same format and to correct some processing errors.

Here is a list of data problems, changes, corrections, and solutions:

  1. 1983 - 1985 Data set AB - 12 hourly pressure and temperature: Temperature (T) and pressure interpolation error variance (EP) fields are reversed. Solution: Data have been re-formatted to correct the reversed fields. Request replacement data from NSIDC, on 9-track tape or via ftp.
  2. 1987 - 1990 Data set AB - 12 hourly pressure and temperature: Temperature (T) data are missing; PSC has a pending project to complete the analysis of these data. Solution: Wait for notification of availability from NSIDC.
  3. 1987 - 1990 Data set D - ice velocity: Velocity fields were calculated incorrectly. Solution: Request replacement data from NSIDC (on 9-track tape or via ftp), or obtain (via ftp) a C program to recalculate the velocity fields. [Please note: 1979-1985 data are for 12:00 Z only; 1986-1990 data are for 0:00 and 12:00 Z.]
  4. 1979 - 1985 Data sets AB, D (not set C): 1979 - 1985 data sets have been re-formatted to match 1986 - 1990 formats. Request replacement data from NSIDC, on 9-track tape or via ftp.

New versions of the data files are available from NSIDC on 9-track tape. They are also available on Internet via ftp. To request relacement data, to obtain information about the changes and corrections to the data, or for ftp access information, contact NSIDC User Services.

SMMR Users Guide in External Review

The Users Guide for the SMMR Polar Radiances and Sea Ice Concentration CD-ROMs is now being reviewed by the Polar DAAC Advisory Group (PoDAG) prior to general release. This SMMR data product, developed at NASA/GSFC by Dr. Per Gloersen, is distributed for NASA by NSIDC. The SMMR Atlas (Gloersen et al., 1992) describes the SMMR instrument, data processing and sea ice algorithm in detail, as well as presenting an atlas of the SMMR time series. The Users Guide is intended to supplement the Atlas by summarizing key information and guiding the novice CD-ROM user in accessing this data product. If the PoDAG review is favorable, NSIDC expects to distribute the Users Guide by June 1993.

ONGOING RESEARCH ACTIVITIES

Concept Plan for a 1-km Polar AVHRR Archive Radar Altimetry Data

A concept plan to archive 1-km AVHRR image data of both polar regions at the NSIDC DAAC is being submitted to Eros Data Center (EDC), NASA Headquarters, and members of the Polar DAAC Advisory Group. The proposed plan is to archive raw, 10-bit, 5-band AVHRR data from the NOAA-11 and NOAA-12 satellites as it is collected in polar regions from several polar HRPT stations, and polar LAC coverage areas.

The concept plan was submitted to EDC as part of a proposal to archive the polar portion of an EDC-managed 'Global Land 1-km AVHRR Data Set', a much larger data set encompassing the entire world land surface and much of the polar oceans. The envisioned NSIDC archive would be mostly current data, with no effort at first to round up older AVHRR scenes. The polar portion of EDC's global data set includes data from HRPT stations located at: Fairbanks, AK; Tromsø, Norway; Prince Albert, Saskatchewan; and Casey Base, Antarctica; and recorded LAC data of the West Antarctic and Russian arctic regions. NSIDC has also strongly urged EDC to include HRPT station data from McMurdo, Palmer, and Syowa in Antarctica to insure complete land and especially sea-ice coverage. In addition to EDC, other sources of polar-region 1-km data, such as other HRPT stations not included in EDC's global data set, or temporary receivers set up during field work campaigns, will be sought out and included in the proposed archive. From this archive, NSIDC hopes to provide the polar science community with a variety of AVHRR-derived products such as calibrated and geo-located imagery, ice surface temperature images, ice sheet albedo maps, and sea-ice motion mapping.

For more information contact: Ted Scambos at (303) 286-1113. Internet: teds@icehouse.colorado.edu

Radar Altimetry Data

NSIDC will soon be able to provide interested users with radar altimetry data of the polar ice sheets and sea-ice areas from the Seasat, Geosat, and Geosat ERM missions. Access to the satellite radar altimetry data sets, which reside at NASA Goddard Space Flight Center, is provided through remote login from a workstation at NSIDC. Minor compatibility problems between the workstation and the HP-resident archive browse and retrieve software at GSFC are being sorted out. Data types available in the NASA data set are gridded elevations, ice data records, and raw waveform data for the GEOS, Seasat, Geosat Mission, and GM Exact Repeat Mission of Greenland and Antarctic land- and sea-ice regions. ERS-1 altimetry data is expected to be included in the archive at NASA beginning in the next few months.

For more information contact: Ted Scambos at (303) 286-1113. Internet: teds@icehouse.colorado.edu

Application of SSM/I Data for Snow Cover

NSIDC has received many comments and suggestions from the researchers who received a copy of the EASE-Grid (Equal Area SSM/I Earth Grid) prototype CD-ROM (see NSIDC notes #3). We are currently defining what the next version of the EASE-Grid should contain and how it should be formatted based on the responses to the questionnaire distributed with the CD-ROM.

In general the comments were very positive and many good suggestions were made. The prototype CD-ROM contains data in two candidate projections and most respondents would be happier with only 1 projection per CD-ROM - though not everyone would choose the same projection. The high temporal resolution of the datasets was considered essential and the resolution of the brightness temperature files was generally seen as adequate. Very few people had any trouble accessing the data files on the CD-ROM and most of those that used them had no problems with the IDL utilities that were supplied. Most would have preferred more extensive documentation.

The next version will probably change the resolution from the 40, 20 10 km scheme to 25 and 12.5 km brightness temperature files. 85 GHz will be gridded at 12.5 km and all the other frequencies (including 85 GHz) will be gridded at 25 km. We will also most likely put only 1 projection on each CD-ROM and will compress the data (compress/uncompress software will be on the disc). Changing the resolution and compressing the data would allow one year's worth of SSM/I brightness temperatures in the North azimuthal equal area projection to fit on 7 CD-ROMs. We plan on expanding the accompanying documentation for the next version and making it easier to locate on the disc (some respondents complained about it being 'buried').

We welcome any further comments on the original prototype or on the future plans discussed here. For more information or to make comments, contact: Molly Hardman (303) 492-3875) Internet: hardman@avalanche.colorado.edu.