In this Issue

Products and Services
U.S. Antarctic Data Coordination Center
Arctic System Science (ARCSS)
Publications
Meetings
News From Other Centers

NSIDC Notes

Issue 22, September 1997

PRODUCTS AND SERVICES

Historical Arctic Rawinsonde Archive

NSIDC has released Volume 5 of the Historical Arctic Rawinsonde Archive (HARA). HARA contains vertical soundings of temperature, pressure, humidity and wind, representing all available rawinsonde ascents from Arctic land stations north of 65°N. Volume 5 contains data from 1992 through June of 1996. Volumes 1-4 contain data from the beginning of station records through 1991. Most station records begin in 1958, but for a few stations, records begin in 1948. HARA contains over 1.5 million soundings. Volume 5 will be shipped to all current subscribers.

Data formats in HARA Volume 5 are identical to those in Volumes 1-4 with the exception that we no longer supply additional quality flags that were based on simple limits checks. Experience has shown that these flags are of limited use to the user community. M. Serreze at NSIDC has developed a Fortran program that: 1) performs more robust quality control checks; 2) provides daily and monthly statistics from the soundings. This code is available through NSIDC and can be easily modified by individual users to suit their needs.

NCEP/NCAR Arctic Marine Rawinsonde Archive

As a complement to the Historical Arctic Rawinsonde Archive (HARA) for fixed land stations, NSIDC has released the new NCEP/NCAR Arctic Marine Rawinsonde Archive. This archive contains ship (marine) rawinsonde reports for the region north of 65°N. Data were extracted from the same National Center for Atmospheric Research (NCAR) archive of National Center for Environmental Prediction (NCEP) (formerly NMC) upper air data used to compile the HARA. This data set also complements a new rawinsonde archive for the Russian "North Pole" (NP) series of drifting manned camps. The latter archive was developed by Jonathan D. Kahl (University of Wisconsin, Milwaukee) and is being prepared for release through NSIDC.

Soundings were extracted and sorted first by pressure and second by altitude (geopotential height), with duplicate records merged to the extent possible. Data were subjected to extensive quality control procedures. Russian NP soundings received through the Global Telecommunications System (GTS) are included in the original NCEP tapes. To avoid duplications with the NP archive, efforts were made to eliminate NP soundings, using the station call signs provided with each sounding. Data coverage is best for the Atlantic side of the Arctic. A large number of soundings are represented by a moored ship in the Norwegian Sea.

The archive extends from 1976 through June of 1996. Data are arranged in synoptic order, such that all available soundings for day 1 are followed by all available soundings for day 2, day 3, etc., to the end of the file. Each sounding starts with a header line followed by a variable number of data lines with associated quality codes.

Data may be accessed by ftp from the catalog entry for our NCEP/NCAR Arctic Marine Rawinsonde Archive.

For more information on the archives, contact NSIDC User Services.

1-km AVHRR Polar Pathfinder Project - Progress Report

In late 1995, a group of researchers at NSIDC was awarded a NASA grant to generate calibrated, geolocated polar physical parameters from both 1-km and 4-km AVHRR data. For more information on the 4-km component of the pathfinder project, please visit the NOAA/NASA Polar Pathfinder home page.

The source of the 1-km data is NSIDC's Polar 1-km AVHRR Level 1B Data Set. This archive of ~25,000 scenes covers both poles each day with AVHRR scenes drawn from several near-polar ground station receivers and from downlinks of tape-recorded data received by NOAA. The archive has scenes extending back to April 1992 for the Southern Hemisphere, and to July 1993 for the Northern Hemisphere. NSIDC provides, upon request, up to 50 scenes from the archive per year per requestor free of charge.

For the Pathfinder effort, the entire archive will be processed. The parameters to be calculated are albedo, surface temperature, cloud cover, and sea-ice motion, twice daily for the first three parameters (the 'energy balance' subset) and once per day for ice motion. For the energy balance parameters, the daily images will be subscened such that the entire polar region will be recorded at roughly the same local time each day. The two daily composites of parameters will be centered on early morning and mid-afternoon times (0400 and 1400 for the Northern Hemisphere and 0200 and 1600 for the Southern). For sea-ice motion, a 24-hour motion field will be compiled from up to 4 image pairs for each pole.

The gridding for the data products is a 1.25 km version of the polar EASE-Grid. The projection parameters for our products are identical to those for the 4-km AVHRR and SSM/I Polar Pathfinder products, making intercomparison and multisensor studies easy.

Progress to date. Acquisition of an extremely fast workstation (DECAlpha 500 Mhz CPU) and streamlining of the geolocation processing (based on the NAV software, also available from NSIDC) has greatly increased our ability to process the huge (1.6 terabyte) data set. We can now process approximately 5 sensor days per day. Currently we are surveying the archive data, one week of each month over the period January 1994 to December 1994, to gain experience with the ingest and staging process, and to identify the various geolocation and calibration problems embodied within the various sources of data (e.g., from different ground stations, or different NOAA platforms). After this exercise, a test data set consisting of processed products, and the calibrated single-band composites for winter and summer of 1994 (summer 93/94 and winter 94 for the Southern Hemisphere) will be processed. This should be available for use and comment by the community by March of 1998. NSIDC Notes will keep readers updated on availability.

The current survey indicates that coverage of the polar regions, particularly the highest latitudes, is good. Coverage ranges from (typically) 50-90% for regions poleward of 60°latitude. Lower-latitude areas still within the annual maximum sea-ice extent are covered regularly, but not daily. Geolocation accuracy of data corrected for satellite clock drift and ephemeris errors is ~1 - 2 km, i.e., near the size of one grid cell. Developing the skill to recognize and correct errors in clock drift and ephemeris is the purpose of the initial survey exercise.

The 1-km AVHRR Polar Pathfinder data set promises to greatly enhance the study of polar energy balance and sea ice processes over the period 1992 1997, with the caveat that some lower-latitude areas will be poorly covered. However, in conjunction with the more-continuous products from the 4-km AVHRR project (covering the period 1982 to 1997), the Polar AVHRR Pathfinder Project will provide both good temporal and high spatial resolution for a broad variety of polar studies, including climate monitoring, process studies, and change detection.

For more information on these data sets, contact NSIDC User Services.

Russian Sea Ice Data Documentation Updated

Documentation for the Arctic and Antarctic Research Institute (AARI) 10-Day Digital Sea Ice Charts for the Arctic Ocean data set (see NSIDC Notes Issue 20, Winter 1997) has been updated to reflect the fact that we are no longer distributing the source data. We urge you to review the on-line documentation.

User Services Personnel

Jason Wolfe has joined the User Services staff, to replace Chris McNeave who is now on the NSIDC ARCSS team as Data Coordinator. Jason comes to us from the University of Utah, where he received an M.S. in Geography this summer. During September, we will be conducting a search for an additional User Service Representative, whom we hope will be hired and ready to join us around the first week of October.

You may "meet" Jason when you contact us by e-mail. Michelle Holm, Diana Starr and Claire Hanson also staff User Services at NSIDC.

NSIDC User Services
National Snow and Ice Data Center
CIRES, 449 UCB
University of Colorado
Boulder, CO 80309-0449  USA
phone: +1 303.492.6199
fax: +1 303.492.2468
form: Contact NSIDC User Services
e-mail: nsidc@nsidc.org

U.S. ANTARCTIC DATA COORDINATION CENTER

On September 9th, NSIDC briefed the National Science Foundation's Office of Polar Programs on progress made during the first year of operation of the U.S. Antarctic Data Coordination Center. The Center is funded by NSF to coordinate U.S. activities related to the Antarctic Master Directory (AMD). The AMD will consist of on-line data metadata (in the form of Directory Interchange Format (DIF) data descriptions), and is a cooperating node of the CEOS (Committee on Earth Observing Satellites) International Directory Network.

One of the topics discussed during the briefing was the possible adoption of a new policy that would require grant awardees to submit DIFs describing the data they collected as a result of NSF-funded field work in the Antarctic after the completion of their grant. The DIF includes information about the data collected, such as title of the data set, name of the investigator, spatial and temporal information, a list of searchable key words, text summary, bibliographic references, format of the data and contact information. The DIF can be used to describe data that are archived in an appropriate data center, or data that have just been collected and are not yet available to the general public. Addition of DIFs to the AMD by funded scientists will build up the body of useful information on all of the multidisciplinary, multinational work that has been or is being conducted in the Antarctic. This will provide individual scientists with an easy to use on-line tool for planning new work and researching what has already been done, thereby avoiding preparing a proposal to collect data that may already have been collected. Filling out the DIF is easy and is an organizational step that can aid in preparation for publication and reporting. Inclusion in the AMD can also provide added recognition to the investigator and the work being undertaken.

NSIDC is interested in assessing community support for an NSF-mandated requirement to submit DIFs as part of the grant reporting process. In particular, we solicit opinions on whether the DIF could be submitted as part of the final report, usually due three months after the end of the grant.

Please send comments on this subject to the U.S. Antarctic Data Coordination Center, NSIDC, by contacting NSIDC User Services.

ARCTIC SYSTEM SCIENCE (ARCSS)

Personnel Changes at the ARCSS Data Coordination Center

Over the last few months many changes have occurred within the ARCSS Data Coordination Center (ADCC). On June 1, Matthew Cross was appointed the ADCC Manager and on September 1, Chris McNeave was appointed the new ARCSS Data Coordinator. Chris brings extensive Web, remote sensing and user services experience to the ADCC. We are very happy to have him as a part of our newly formulated team. Rachel Hauser continues as the education/documentation specialist.

In addition to our changes in personnel, the ADCC is planning other changes and enhancements to our service to the ARCSS community. Look for updates in future issues of NSIDC Notes.

Any ARCSS investigators with ingest or ARCSS data questions should contact NSIDC User Services.

Greenland Ice Cores CD-ROM

The Greenland Ice Cores CD-ROM is currently being reviewed by both GRIP and GISP2 researchers and will be ready for concurrent release with the Journal of Geophysical Research, Special Issue. Release is due sometime around the beginning of November 1997. Until then, interested parties can access a limited number of GISP2 data sets through the ADCC.

All data are expected to be available from the ARCSS Data and Information Archive at approximately the same time that the CD-ROM is released in early November 1997.

PUBLICATIONS

DAAC Yearbook

NSIDC is one of nine NAASA Distributed Active Archive Centers (DAACs) responsible for processing, archiving and distributing data and information for NASA's Mission to Planet Earth. Each DAAC specializes in a particular Earth Science discipline, for instance, NSIDC's DAAC responsibilities center on snow and ice, cryosphere and climate.

Using DAAC data, 1996 was an important year for scientific research that was carried out, both on national and international fronts. Work included studies at a division of the Harvard Medical School tracking the spread of infectious diseases based on ocean color; research into the climate change and hazards assessment possibilities provided by the first instrument designed to detect daytime lightning; and investigations into the climatic effects of atmospheric aerosols. Several new products have been developed based on the use of DAAC data, including a new satellite image map of Antarctica created by combining cloudless satellite imagery with digital elevation data.

NSIDC has released these accounts and many other reports of DAAC data applications in a new edition of the annual DAAC publication, Distributed Active Archive Centers Supporting Earth Observing Science in 1996. The DAAC yearbook is circulated to hundreds of scientists, educators and administrators and is available to the public.Contact NSIDC User Services for a free copy, or check the on-line version.

DAAC yearbook cover design

Cover Design of the 1996 DAAC Yearbook.

Researchers interested in having work based on the use of DAAC data featured in subsequent issues of the publication are invited to contact NSIDC User Services. Please do not submit articles, we will contact you for an interview.

New Accessions List

NSIDC/WDC has published the New Accessions List (NAL) since 1977. Most recently it has been an annual publication providing a subject index to all new materials added to the Information Center during the year. We have now decided to discontinue publication and distribution of paper copies of NAL, but will continue to make information about our library collection accessible to a broad audience.

MEETINGS

Fall AGU Meeting, San Francisco, 8 - 12 December 1997

NSIDC will again have an exhibit booth at the Fall Meeting of the American Geophysical Union. Our latest data catalog will be available and we look forward to the opportunity to discuss our products and services with you. See you there!

NEWS FROM OTHER CENTERS

Microwave Snow Signature Database: Call for Data

The Institute of Applied Physics, University of Bern, Switzerland, is currently establishing a database of snow signatures. This database is part of the Snow-Tools project, which focuses on hydrological algorithms and applications of microwave and optical remote sensing data. The data base will mainly comprise active and passive in-situ measurements of natural snow in the 1 - 100 GHz range, together with metadata describing the measurement target. The database will be open to the scientific community. If you can provide examples of such data, we would be pleased to include it in the database.

For further information please contact Dr. Daniel Hiltbrunner, Institute of Applied Physics, University of Bern, Sidlerstr. 5, CH-3012 Bern, Switzerland, hiltbrunner@iap.unibe.ch