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In this Issue
SNOW AND ICE DISTRIBUTED ACTIVE ARCHIVE (SI.DAAC)
ARCTIC SYSTEM SCIENCE/OAII HIGHLIGHTS
ONGOING RESEARCH ACTIVITIES
This is the first issue of the National Snow and Ice Data Center newsletter, NSIDC Notes. This publication supersedes NSIDC's Cryospheric Data Management System (CDMS) newsletter, CDMS Notes. The primary objective of this newsletter is to keep the polar research community informed about current research and available data and services provided by NSIDC including items formerly covered by CDMS Notes. It will be published on a quarterly basis and it is available free of charge. NSIDC functions as a data information and referral center for the snow and ice community. Colocated with NSIDC is the World Data Center-A for Glaciology [Snow and Ice] (WDC), one of three international data centers serving the discipline. The major purpose of these centers is to facilitate the international exchange of data on all forms of snow and ice. The topics covered include: freshwater and sea ice, seasonal snow cover, glacier mass balance and fluctuations, polar ice sheets, ice cores, ground ice (permafrost), paleoglaciology, and avalanche research. WDC/NSIDC is operated for the National Geophysical Data Center, NOAA, by the Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado at Boulder under a NOAA - University of Colorado Cooperative Agreement.
SSM/I Error Report and Correction Plan Special Sensor Microwave/Imager (SSM/I) Ice Concentration Grids, volume 1, 7/9/87 to 12/31/89, distributed during January 1992.
All files in the SSM/I Ice Concentration CD-ROM directories listed below contain erroneous ice concentration data:
NSIDC regrets this processing error and has implemented the plan described below to correct this specific error and to ensure that similar problems do not recur.
NSIDC has reprocessed the SSM/I Ice Concentration Grids, volume 1, to correct the four months of bad grids. The new version of volume 1 will be sent to ALL of you who have the SSM/I CD-ROMs. The target date for shipment of the new volume 1 is mid-June 1992.
Because reprocessing the data was required, we have taken this opportunity to change the missing data flag to "-99" in the NASA Team Algorithm. This means that the ice concentration products from the NASA Team and Comiso algorithms have consistent "land" flags (-88) and "missing data" flags (-99).
At the same time, we have formatted the ice concentration grids to function with IMDISP as they already do, as well as to incorporate the Hierarchical Data Format (HDF). IMDISP requires labels giving the number of lines, samples, and bits per pixel in order to read and display the grids using this IBM PC- based image display software now distributed with the SSM/I CD- ROMs. HDF is slightly different, and provides additional benefits and capabilities. The rationale for incorporating HDF is explained below.
HDF, from the National Center for Supercomputing Applications (NCSA) at the University of Illinois, is designed as "(A)n extensible header, along with carefully crafted internal layers, (that) provides a system that can grow along with the software that NCSA develops." ". . . files can be made upwardly compatible for years to come without giving up added power in the future. HDF also makes it easy for the user to include annotations, titles, and specific descriptions of the data in the file, so that files can be archived with human-readable information about their origins." (NCSA HDF Specifications, March 1989, p. vii-viii.) The NASA EOSDIS Project has determined that all Version 0 data sets will be distributed using a set of Standard Data Formats (SDFs). The NCSA HDF has been selected as the first SDF that must be supported by each DAAC. NSIDC is taking this opportunity to issue the SSM/I sea ice concentrations as our first HDF product. NCSA software tools to read and manipulate HDF format data are in the public domain and are available via anonymous FTP from NCSA. It should be noted that NCSA software is designed primarily for UNIX-based platforms. For this reason IMDISP for DOS-based platforms will continue to be distributed by NSIDC.
Documentation has been provided in the SSM/I CD-ROM User's Guide, and will be updated to reflect the change in the "missing data" flag and to add information about HDF format and software tools. New sections of the User's Guide will be sent out in mid-June 1992.
In addition to the changes in data formats discussed above, NSIDC is exploring ways to improve our quality control of CD-ROM products. We want to produce "zero defect" products. To this end, we have constituted a quality assurance review board within NSIDC. The first meeting of the board produced a list of goals and initial plans to implement a formal quality control policy and process at NSIDC. The process will include the use of "alpha" and "beta" releases of products for testing and comment from the user community. This approach will better enable us to identify and correct problems before they are incorporated into widely-distributed products.
As always, your comments on our data products are solicited.
The IMS is an EOSDIS Version 0 prototype system being developed to integrate all Distributed Active Archive Center (DAAC) and Affiliated Data Center (ADC) data information and services into a single earth science view. The IMS is being developed to ascertain the feasibility of integrating catalogs and inventories distributed among the discipline-oriented data systems during the pre-EOS era. The purposes of this prototyping effort are twofold. The first of these goals is to provide investigators with search and order functions to all EOSDIS Version 0 data without requiring them to navigate through different user interfaces. The second goal is to provide whatever lessons are learned during the development of the IMS to the EOSDIS Core System contractor to assist in the early design stages of the Version 1 IMS design.
Figure 1 shows the locations of the first seven designated EOSDIS Version 0 Distributed Active Archive Centers: Goddard Space Flight Center (Greenbelt, Maryland), Marshall Space Flight Center (Huntsville, Alabama), Langley Research Center (Hampton, Virginia), EROS Data Center (Sioux Falls, South Dakota), NSIDC (Boulder, Colorado), Jet Propulsion Laboratory (Pasadena, California), and University of Alaska- Fairbanks Geophysical Institute (Fairbanks, Alaska).
Figure 1. Locations of the first seven designated EOSDIS Version 0 Distributed Active Archive Centers: Goddard Space Flight Center (Greenbelt, Maryland), Marshall Space Flight Center (Huntsville, Alabama), Langley Research Center (Hampton, Virginia), EROS Data Center (Sioux Falls, South Dakota), NSIDC (Boulder, Colorado), Jet Propulsion Laboratory (Pasadena, California), and University of Alaska/Fairbanks Geophysical Institute (Fairbanks, Alaska).
During 1991 the IMS Development Team (comprised of representatives from the EOSDIS Project at NASA/GSFC, the Version 0 DAACs and the ADCs) developed query result passing software, message mapping software, and an alphanumeric (not yet graphical or "windows"-based) user interface to both local and remote data inventories. A "proof-of-concept" demonstration was presented to NASA Headquarters representatives in February 1991. Efforts in 1992 will include the addition of a MOTIF-style graphical user interface (GUI) to permit display of data coverage and use of browse products within the IMS.
In addition, a data dictionary is in the process of being developed in an attempt to standardize metadata terminology. A consistent set of valids will be defined for attributes such as platform, sensor name, and parameter name. Redundant values, such as "radiance" and "brightness temperature," will be reviewed to determine which term more accurately describes the element.
The next IMS demonstration is scheduled for November 1992. After this demonstration the IMS Team plans to make the system available to a limited number of researchers. At that time select members of the Polar Ocean Distributed Active Archive Center Advisory Group (PODAG), the science advisory board for both the Alaska SAR Facility (ASF) DAAC and the Snow and Ice DAAC, will be invited to exercise the IMS interface and provide feedback on the usefulness of the system to the IMS development team.
For more information, contact: Vince Troisi at (303) 492-1827.
The National Science Foundation's Arctic System Science (ARCSS) Program, a component of the US Global Change Research Program, has as its goals "to understand the physical, chemical, biological, and social processes of the arctic system that interact with the total earth system . . . in order to advance the scientific basis for predicting environmental change . . . and for formulating policy options in response to the anticipated impacts on humans and societal support systems." (NSF Program Solicitation, 1991). NSIDC has been awarded grants for data management of two components of ARCSS: Greenland Ice Sheet Program 2 (GISP 2, see page 5) and Ocean-Ice-Atmosphere Interactions (OAII).
The ARCSS/OAII data management pilot project at NSIDC is intended to identify data sets required for, or collected by National Science Foundation (NSF)/ARCSS/OAII-funded research projects, and to develop access and delivery strategies for these data sets.
We are working with the ARCSS/OAII community, using telephone, electronic mail and written surveys, to identify the most commonly required and/or highest priority satellite and historical data sets for Arctic research, including those required for modeling efforts. The first small-scale survey was conducted during March, and resulted in identifying several candidate data sets as targets for early product development work. (Results from this survey are reviewed in the next article.) By using such informal surveys, we are better able to focus our activities to improve access to the high-priority data sets, for example, where this would assist the research community in modeling efforts.
Using existing data directories, in-house expertise, and contacts in the data community, we will try to determine the best sources for the data sets the user community identifies, presenting an access strategy plan to the ARCSS/OAII Steering Committee for consideration. Some possible ways to improve access might include archiving copies at NSIDC for redistribution on magnetic or optical media, coordinating referrals to current data holders, or establishing ARCSS/OAII Data Center(s) at appropriate location(s). Different data sets may lend themselves to different access and delivery strategies.
The question of standard formats for data storage and transfer, in the interest of portability and ease of use, is now being addressed by many data management groups, particularly within the NASA EOSDIS efforts now underway at the DAACs across the country. The SI.DAAC at NSIDC is currently involved in a test project to distribute satellite passive microwave data using the HDF (see SSM/I Error Report and Correction Plan, p. 1, for more information on HDF), targeting products for the sea ice community and actively seeking feedback on the utility of those products. The format work we undertake for ARCSS/OAII will build on the SI.DAAC effort. Dialogue with the ARCSS and EOSDIS scientific community will be continued and expanded to determine what formats exist that might be suitable for a given data type.
Successful data services depend on frequent and clear communication between data users and data providers. We intend to use several methods to stay in touch with you, the data users. By means of future articles in this newsletter and additional mailings to ARCSS-funded researchers, we will attempt to keep you informed of developments in ARCSS/OAII data management. Using Omnet/Sciencenet and the Internet, we will broadcast news of activities at NSIDC that mesh with the data needs and interests of ARCSS, as well as of activities undertaken specifically for ARCSS/OAII.
Comments, feedback and requests from the ARCSS/OAII community are solicited. NSIDC encourages each of you to communicate your concerns and suggestions, so that data management efforts will address your needs. We will, whenever appropriate, conduct the resulting dialogue in public, perhaps as a "letters" column in this newsletter, so everyone involved will be informed of solutions and new ideas.
In March we surveyed three small groups of Arctic investigators, asking them to prioritize a group of Arctic data sets NSIDC believes is important for polar research. The three groups were: scientists at the Cooperative Institute for Research in Environmental Science (CIRES), University of Colorado, who are affiliated with SI.DAAC, the EOSDIS DAAC at NSIDC; members of the Polar DAAC Advisory Group (PODAG), who provide scientific advice to SI.DAAC and the Alaska SAR Facility; and a subset of ARCSS/OAII investigators identified by NSF/ARCSS as key players in the modeling group.
The survey contained a list of polar data sets that respondents were asked to prioritize relative to their research interests. These polar data sets include the following:
Responses identified the most useful datasets to be the drifting buoy and the monthly station climate data, while the ones least mentioned were the submarine sonar ice draft, iceberg fluxes, and ice sheet elevation profiles. One respondent commented that the Arctic Ice Dynamics Joint Experiment (AIDJEX), Marginal Ice Ocean Sea Surface Temperature (SST) fields (polar margin subsets of Comprehensive Ocean-Atmospheric Data Set (COADS), for example) Drifting buoy data (ice velocity, surface temperature) Submarine sonar ice draft data Iceberg fluxes (Greenland, Antarctica) Ice sheet elevation profiles Arctic runoff - time series for major rivers. Responses identified the most useful datasets to be the drifting buoy and the monthly station climate data, while the ones least mentioned were the submarine sonar ice draft, iceberg fluxes, and ice sheet elevation profiles. One respondent commented that the Arctic Ice Dynamics Joint Experiment (AIDJEX), Marginal Ice Zone Experiment (MIZEX), and Soviet drifting stations, not mentioned on our list, would be helpful. Another person felt that a North Water polynya data set would be useful to produce after the experiment was completed.
Contact at NSIDC for further information:
ARCSS/OAII Project Manager
Phone: (303) 492-1834
Fax: (303) 492-2468
Currently, there are three DMSP-related projects at NSIDC. First, there is the analog Operational Linescan System (OLS) image collection with about 1.5 million images from 1973 to the present. This collection has been one of NSIDC's more visible projects over the years, and remains very active in terms of the number of data requests and visitors we get every month.
Second, a digital archive of the complete DMSP data stream (OLS, SSM/I, Special Sensor Microwave Temperature Radiometer (SSM/T), and several space environment sensors) is going to become available to users in 6 to 9 months. The research community has always been interested in comparing digital data from multiple DMSP sensors, and this will be the first opportunity for many scientists to be able to acquire these data. It is particularly exciting for NSIDC since there are a number of overlaps with our other data management and science programs.
The third project incorporates both the analog and digital DMSP/OLS data. The DMSP/OLS imagery is a unique source of information about nighttime lightning. NASA is supporting development of a data base of global nighttime lightning occurrence from the characteristic lightning signatures on the imagery. The lightning data are being used to study seasonal and annual variability in thunderstorm activity and their relation to the general circulation. NASA hopes to continue this analysis into the future using the digital DMSP data.
For more information, contact: Greg Scharfen at (303) 492-6197.
GISP2 represents the renewal of the seven year GISP1 Program which began in 1976 and produced a 2037 m deep core at the location Dye 3 in southeastern Greenland. The GISP2 site is located on the ice divide in central Greenland where the depth to bedrock is anticipated to be 3100 m which equates to a stratigraphic record of at least 200,000 years. Such a length of record includes two glacial/interglacial cycles. GISP2 is a five year program (1989-1994), involves 25-30 scientists, and is funded by the National Science Foundation (NSF) Division of Polar Programs. Drilling efforts during the 1991 field season resulted in the core reaching a depth of 1510 m.
NSIDC has been funded by NSF to provide data management services for GISP2. This includes the development of a data management plan specific to the needs of the GISP2 scientists undertaken in cooperation with the GISP2 Executive Committee and the GISP2 Science Management Office. This plan assures efficient and timely access to ice core data as they are released by the GISP2 Principal Investigators (PIs) and it provides for the safe, long-term archival of key data. Because of the widespread and growing interest in paleoclimate and global change, GISP2 data sets will receive ever-increasing attention from fields outside glaciology.
For more information, contact: Richard Armstrong at (303) 492-1828.
Work has begun on a preliminary inventory of permafrost data sources. Because of the sensitivity of permafrost to changes in climate, the need for permafrost data input to support global change research is crucial. Working in cooperation with the International Permafrost Association Working Group on Data and Information, NSIDC is attempting to establish a permafrost data system. The first step in the process was a letter and brief questionnaire sent to approximately 300 scientists working in the field. Responses will be put into a data base with information on types of data, areas covered, availability, etc. We are also considering the publication on CD-ROM of some sample data sets along with our 15-year cumulative Permafrost Bibliography.
For more information, contact: Ann Brennan at (303) 492-1846.
Snow cover is an important variable for climate and hydrologic models due to its effects on surface albedo, energy, and moisture budgets. Satellite passive microwave observations afford the best method to monitor temporal and spatial variations in snow cover on the hemispheric scale, avoiding the problems of cloud cover and polar night. NSIDC is currently funded by NASA's Interdisciplinary Research Program to develop a capability for the production of daily snow parameter products from the DMSP SSM/I. A data system is being developed which will produce, archive, and distribute validated snow cover products for community use. Initial emphasis is on Northern Hemisphere snow extent. We are also exploring the potential of the SSM/I for mapping other snow cover properties such as snow water equivalent, snow depth, and dry/wet snow boundary. These tasks will contribute towards the production of a prototype snow cover climatology based on the first five years of SSM/I data.
Within this project, NSIDC coordinates the activities of the SSM/I Products Working Team (SPWT) which is a multi-agency and multi-disciplinary working group focusing on the problems associated with extracting land surface (primarily vegetation, soil, and snow cover) information from SSM/I. Currently, emphasis is on developing optimal binning, gridding, and global map projection methods, as well as the selection of one or more snow cover algorithms for use in the distribution of standardized data sets by NSIDC. A prototype version of the Equal Area SSM/I Earth (EASE) Grids will be distributed for community evaluation in July of 1992. The basic purpose of this task is to provide a standard earth-located grid and an optimal technique to interpolate from the data in swath format to the appropriate earth-located grid cell. The methodology of the EASE Grids, which was approved by the SPWT at their most recent meeting, is intended to provide the general user with a data structure which is easier to use than swath format, while maximizing the radiometric, spatial, and temporal integrity of the original swath data. Snow cover algorithm comparison and validation is being undertaken in cooperation with several SPWT scientists. Regional test areas selected are the western United States, Prairie Provinces of Canada, and Central Europe.
For information, contact: Richard Armstrong at (303) 492-1828.
NSIDC has recently acquired (via National Climate Data Center) a set of meteorological data from 284 stations in the former Soviet Union. The data extend through 1984. Twenty five percent of station records begin before 1900.
With help from Vince Troisi and Sue Hafezzadeh, NSIDC staff, the original data have been reformatted onto a magneto-optical disk drive at NSIDC to allow easier user access. Since the data storage format is somewhat obscure, a set of utilities has been written which will extract snow depth data for each station for a particular date(s). Included is a utility to convert the station latitudes and longitudes into an equal area earth grid. The utilities may be modified to extract any additional meteorological data required. The gridded output data are then easily displayed using IDL (a software visualization tool). We have created a sequence of snow cover maps from January of 1981 using these datasets and the utilities described.
For more information, contact: Molly Hardman at (303) 492-3895.
Glaciological Data, Report GD-24 provides an update to the bibliography on passive microwave research published in Glaciological Data, Report GD-19, 1987. Some 600 citations are listed with both author and subject access. Short contributions are also included from the Data Center staff and colleagues in the Cooperative Institute for Research in Environmental Sciences about research activities based on use of passive microwave data and work contributing to their validation and improvement. Copies are available upon request. The cost is $10 per volume.
Barry, R.G. (1992) Mountain climatology and past and potential future climatic changes in mountain regions: A review. Mountain Research and Development, 12(1), p.71-86.
Barry, R.G. (1992) Mountain Weather and Climate, 2nd ed., Routledge, London/New York, 402p.
Barry, R.G.; Maslanik, J.A.; Serreze, M.C.; Scharfen, G.R.; Weaver, R.L. (1992) Analysis and assessment of sea ice fluctuations in relation to atmosphere - ocean processes. Final Report to NOAA/CGCP (NA 85 RAH05066). CIRES, 50p. and Appendices.
Ebbesmeyer, C.C.; Coomes, C.A.; Harmilton, R.C.; Kurrus, K.A.; Sullivan, T.C.; Salem, B.L.; Romea, R.D.; Bauer, R.J. (1991). Internal waves (solutions) in the South China Sea observed. MTS '91 An Ocean Cooperative: Industry, Government and Academia, New Orleans, LA, 10-14 November 1991. Proceedings, vol. 1. Washington, DC, Marine Technology Society, p.165-175.
Hanson, H.P.; Hanson, C.S; Yoo, B.H. (1992). Recent Great Lakes ice trends. Bulletin of the American Meteorological Society, 73(5), p.577-584.
Serreze, M.C.; Maslanik, J.A.; Demaria, T.L.; Barry, R.G. (1992) Winter atmospheric circulation patterns in the Arctic Basin and possible relationships to the Great Salinity Anomaly in the northern North Atlantic. Geophysical Research Letters, 19, p.293-296.
Weaver, R.L.; Troisi, V.J.; Hanson, C.S. (1992) Development of sea ice data sets from passive microwave satellite data: Preliminary lessons. (In: Weller, G., et al., eds. International Conference on the Role of the Polar Regions in Global Change, 1st, Fairbanks, University of Alaska, 11-15 June 1990, p.120-125.)
* Bold names are individuals at WDC/NSIDC.