The National Snow and Ice Data Center (NSIDC) manages scientific data in order to make these data accessible and useful to researchers, today and tomorrow. NSIDC ensures quality and reliability by taking a systematic approach to scientific stewardship of its data. This document outlines our data policies and standards.
You can also learn more about our citation policies here.
These policies apply to all data that are archived at NSIDC.
Typically, archives are defined as the non-current but still useful records preserved by an organization or institution, or the repository itself. The term archives can also refer to organizations or institutions that collect and acquire records or data from outside sources, usually to serve researchers outside that organization. Because NSIDC functions as both a long-term and a short-term archive, its data management roles and responsibilities are larger than a typical archive.
Whenever possible, NSIDC strives to provide long-term data management. However, data are archived at NSIDC under several sponsored efforts, which may define the scope of our data management activities. We may also provide shorter-term or "active" archives. NSIDC uses data management procedures that guarantee best practices, adherence to standards, and strong and consistent levels of service, yet are flexible enough to adapt to changing programmatic relationships and needs.
NSIDC recognizes that not all data sets can or should receive the same levels of service or stewardship. Minimum service level criteria are described and preferred service levels are described as appropriate.
Core data management principles
NSIDC bases its data management policies for all data on proven archival principles and best practices. These principles include the following:
- Archival records exist to be used, not merely saved for their own sake.
- Some records ought to be preserved long-term, even after their immediate usefulness has passed.
- Archival records ought to be preserved as completely and coherently as possible, including critical information about context and connections.
- Archival records ought to be organized properly and in a timely way so they can be used.
- Sensitive information and information given in situations presumed to be private should be protected from use as long as that sensitivity remains.
- Archivists should administer their collections equitably and impartially.
- Archival repositories ought to cooperate in preserving historical records.
Specifics of these policies are elaborated in the remainder of this document.
Data solicitation and acceptance
Data become the responsibility of NSIDC through a variety of official program agreements, formal and informal PI relationships, data rescue projects, and data exchanges. Thus, data can be both solicited and tendered, can arrive with or without funding for publication and archival, and can have various degrees of value to current and future user communities. New additions to the NSIDC catalog begin with identifying the data to be added and source of funding, followed by appraisal and acquisition phases.
Scope of Data Acceptance
The scope of NSIDC data management is currently defined as cryospheric data and data from programs or instruments deemed of importance to the cryospheric community. This includes traditional scientific data, as well as local and community knowledge. However, unique program and project needs may also be considered.
NSIDC's collection scope encourages NSIDC to be an active collector of data. NSIDC and the programs that make up NSIDC may actively solicit new data sets for archival and distribution. Many programs for which NSIDC is the official data archive are funded to solicit data from data providers. Submission forms for PIs and other data providers are available on the NSIDC Web site. Details of current programs soliciting data may be found on the NSIDC Web site.
For some programs, NSIDC will not archive all of the data, but will archive only the metadata that describes the data and gives the data location.
Data submission forms encourage the submission of data to NSIDC, while informing data providers and repositories that the submission serves only to begin a discussion of the appropriateness of the material for NSIDC, timeline for publication and archival, and the costs involved. When a data submission form has been received by NSIDC for a data set not covered by any specific program, the Senior Management Team or their appointed representative will review the submission. Acceptance policies are outlined below.
Data are accepted under a specific agreement that spells out the rights and responsibilities of NSIDC, the funding program, and the data provider. This agreement may be in the form of a Deed of Gift executed at time of data submission, or other documentation, such as a formal program document which defines the terms of acceptance, level of service, and long-term archive.
Considerations include terms or restrictions of use; terms of dispersal should the data be retired, deleted, or updated; funding for archiving and support; and documentation requirements, including context and provenance. NSIDC may also require data to be submitted in acceptable formats.
Program Data and Agency Requests
Each program at NSIDC has an individual whose responsibilities include the collection, verification, archival and publication of new data. Program Managers or their representatives follow both NSIDC policies and their program's policies for data management.
NSIDC serves as the sole archive of cryospheric data, and of data of importance to the cryospheric community, for many agencies. Data are occasionally submitted from, or at the request of, one of these agencies. In many cases, the rights and responsibilities of NSIDC and the funding program are spelled out in the contract or grant. In other cases it will be necessary to pursue a separate agreement with the funding program to provide a blanket Deed of Gift or equivalent document covering all relevant data sets. In these cases, the NSIDC program solicits name and contact information as well as data set context and provenance information from the data provider, provides information about NSIDC's implied rights and responsibilities to the data provider, and solicits agreement or disapproval of these rights and responsibilities from the data provider. If the data provider does not agree to the rights and responsibilities that are standard for that program, the NSIDC program must pursue an individual data set Deed of Gift in order to accept the data.
PI-Tendered Data Management Requests
Many data sets come to NSIDC as a result of PI offerings that are unrelated to any program. The NSIDC Senior Management Team (SMT) or their representative will review these data sets and determine their appropriateness within NSIDC and the appropriate NSIDC program to which they should be affiliated.
While NSIDC prefers that all data sets come to NSIDC with identified funding for their continuation and management, we recognize that occasionally data of value to the cryospheric community need archiving, but lack specific funding or support. When possible, the SMT or designated NSIDC program works with the data provider to identify possible future funding opportunities, such as data rescue or exchange. If the SMT or designated NSIDC program feels that the value of the data is great enough, the data are accepted as "orphan" and given a lower level of service to support it. (Please see Levels of Service.) The SMT or designated NSIDC Program will continue to examine future funding opportunities to ensure the proper long-term management of the data at a higher level of service.
In the appraisal of new, PI-tendered data, the SMT considers the following:
- Appropriateness to NSIDC's mission statement and collection scope
- Its relationship to other data archived at NSIDC and thus its ability to illuminate or increase the value of existing data
- The cost of archiving the data (including space and resource needs)
- The value in strengthening bonds with funding agents and other agencies
- Outreach opportunities that fit within the NSIDC Outreach goals and objectives
Targets of Opportunity
The cryospheric community may also alert NSIDC to valuable data related to our holdings, being generated by a current or upcoming research project. NSIDC may reach out to the individuals involved to determine the appropriateness of the forthcoming data, and the SMT makes sure that proper data management policies are involved in the transfer of these data to NSIDC.
On occasion, NSIDC receives data from a data provider in exchange for NSIDC data products, to encourage international cooperation and dissemination of NSIDC data. The SMT's appraisal of these data determines their appropriateness within NSIDC and the appropriate program to which they should be affiliated. It is recognized that these data seldom have available funding for archival processes.
Some data sets and data products within the collection scope of the Center are created in-house by NSIDC personnel. The acceptance of these data sets requires the same process as does the acceptance of new data, and steps are taken to ensure a high quality product that maintains its ties, through metadata and documentation, to the original or raw data product.
Levels of service
Metadata and data format standards
In keeping with data management best practices, it is important for archives to preserve data as completely and coherently as possible, maintaining critical information about context and connections. NSIDC will use accepted standards in its data management practices. Data sets archived at and distributed by NSIDC will conform to NSIDC standard formats. The SMT will regularly review these standards and update them as needed.
If data to be accepted by NSIDC are not in a preferred format, the relevant program or designated point of contact should review the costs of conversion to a preferred format to ensure consistency, availability and long-term access.
Data set documentation
NSIDC requires that all data have some form of metadata and documentation describing the data. The format of this documentation may vary by the level of service and the nature of the data. In all cases, metadata and documentation follow standards and best practices, and are made publicly available. Formats may include the following:
Metadata record and summary documentation: When resources and agreed-to level of service permits, NSIDC produces two types of data set documentation for published data sets, based on information that PIs submit with their data: (1) a Data Interchange Format (DIF) file and (2) a summary document. Both standardize a data set's metadata, increase ease of use, and allow future access to that data set. The DIF is the metadata file format used by the NASA Global Change Master Directory (GCMD) and is compatible with International Standards Organization (ISO) and Federal Geographic Data Committee (FGDC) metadata standards. NSIDC submits every DIF it writes to the GCMD, which is part of the U.S. Global Change Research Program. The summary documents contain metadata for each data set, and are often much more comprehensive than the DIFs, providing detailed information about data collection methodology, file structure, tools for accessing data, and other data characteristics. They also describe how to appropriately cite the data set.
Archival records: Physical collections, also known as analog archives, may be described under standards appropriate to those objects (photographs, paper records, etc.) and those records maintained in a separate analog archive system. Some types of data, such as local and community knowledge, may fall under different metadata and documentation standards, and have specific requirements as social science data. These records may also be developed under distinct standards, and may or may not be publicly available, as dictated by access and privacy requirements.
Legacy data: For some older data sets that NSIDC acquired previous to metadata systems and standards, additional documentation may be maintained in physical folders or digitized documents.
Unlike digital data, value is ascribed to original analog data that is not given to copies. As such, NSIDC recognizes that it is important for original analog data to be archived in the best conditions possible to preserve them for perpetuity, and that only copies be made available for users whenever possible.
Users either travel to NSIDC to use these data or pay for the creation of a usage copy that can be shipped to them. To increase access to material, usage copies may be provided in formats other than the format of the original, as when a digital image is provided to users instead of a glass-plate negative. Currently, NSIDC has no budgeted resources to make usage copies of all analog data archived here. However, analog data sets accepted from this point forward should include proper funding to address this need as well as proper storage, or should point to possible funding resources. Additional funding is actively being pursued for all currently held data sets.
Data Recovery Efforts
NSIDC has made a formal assessment of its analog archives facilities and taken steps to avert potential physical harm and deterioration of materials. NSIDC also maintains a disaster and recovery plan for the archives, and ongoing training for staff. In the event of a natural or man-made catastrophe that damages any analog data sets archived at NSIDC, staff will immediately implement data recovery efforts. These efforts will attempt to salvage and repair as much material as possible, especially of original archival material.
An offsite copy will be made for all digital data sets for which NSIDC is the primary archive and for other data sets as warranted by circumstances and as funding permits, as soon as practical upon ingest. Consistent with NSIDC standards, if such a data set is modified prior to publication, an offsite copy will be made of the modified data set and documentation describing the modifications made.
To ensure data survival in the event of a catastrophe and consistent with industry best practices, NSIDC will maintain recovery strategies for data sets and associated preservation metadata where NSIDC is the primary archive, and for other data sets as warranted by circumstances and as funding permits.
Acceptable recovery strategies include
- Storing backup copies of the data in a secure, environmentally controlled offsite location as per federal guidelines;
- Securing written agreements with external organizations to provide copies of the data on request, either by reprocessing data from a lower level product or by duplicating data from their archives.
NSIDC conducts ongoing archive media testing and refresh programs to assess the viability of its media archives and to refresh individual media on an as-needed basis. As media and archive technologies become obsolete, new technologies are chosen based on reliability and performance criteria and data are migrated.
Data deletion and retirement
The possibility of future data retirement or deletion must be covered with the contributing agency or individual at the time of data donation. Formal data programs will negotiate terms of continued archival or dispersion with sponsors at the end of program. Policies may differ according to program.
For data accepted and maintained outside sponsored programs, data acceptance agreements will define reasons and procedures for possible disposition and retirement. Reasons for retirement of data might include data that have no historical value or data that have been archived for the long-term at another repository.
NSIDC makes its data as widely available as possible and as quickly as possible. NSIDC follows best practices and adheres to program requirements. NSIDC data sets can be accessed through the online catalog or by contacting the User Services Office. NSIDC also contributes metadata to other portals and repositories, thereby increasing the avenues by which users can find data.
NSIDC strongly prefers to make data freely accessible to all. However, data providers may require specific terms and conditions.
Depending on terms of data submission, gaining access to or copies of some NSIDC products may require payment. Charges are made clear to potential users in data set documentation.
Data Provider: Restrictions to data access will be negotiated between NSIDC and the data provider at the time the data are deposited at NSIDC. In general, time limits are placed on such restrictions to maintain NSIDC's policy of free access.
Non-Commercial Use Agreements: Some NSIDC data come with restrictions that limit their use to non-commercial purposes. This information is provided in the data set documentation and is made clear to users before they are provided with data. Generally a user must complete a form agreeing to these limitations before access is permitted.
Copyright: Most of the data held by NSIDC are government-funded and in the public domain. NSIDC archives some data for which it has no distribution rights. NSIDC makes copyright restrictions clearly known to potential users in the data set documentation, and refers the user to the copyright owner for additional rights.
Program Data: Depending on the program, NSIDC data may have access restrictions based on criteria such as time and/or membership (e.g., XYZ data is restricted to science team members only for the first year). NSIDC works with the program to ensure that these access restriction requirements are met.
Page revision history:
Version 1, July 15, 2003 - approved by NSIDC Management Team
Version 2, February 11, 2004 - incorporates edits by IT team reflecting new NSIDC organizational structure
Version 3, February 12, 2015 - incorporates edits reflecting new NSIDC organizational structures and evolution of practices