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NSIDC Virtual Globes Help and Documentation

Summary

This page provides additional information and help for using our virtual globes files. The National Snow and Ice Data Center offers some of our scientific data in the form of images. We have created Google Earth™ files that enable you to overlay these data-based images on a virtual globe. Many of these data images are based on satellite remote-sensing data, and show global imagery of snow, ice, and sea ice. Other data images may be based on ground data collection, photography, or multiple data sources. Other Google Earth files may geographically locate our field research data sets.

You can obtain more information on the source data sets by following the "Data Source" link, listed in the table next to each Google Earth file link; you can also link to the source data sets while viewing the data within the Google Earth application.

Use Terms, Citations, and Credits

These data and Google Earth files are available free of charge, on the condition that you properly cite our data and credit images when used in publications, presentations, and other Web sites. Please credit "National Snow and Ice Data Center" as the data source in all presentations, stills, and video clips. In publications, include a complete citation, using the following as a guide:

National Snow and Ice Data Center. [Title of Google Earth file.]View NSIDC data on virtual globes: Google Earth. Digital media. http://nsidc.org/data/virtual_globes/. Accessed [date of access].

Example:

National Snow and Ice Data Center. Sea ice extents file for Google Earth. View NSIDC data on virtual globes: Google Earth. Digital media. http://nsidc.org/data/virtual_globes/. Accessed 12 February 2007.

Table of Contents

  1. Contacts and Acknowledgments
  2. Detailed Data Description
  3. Data Access and Tools
  4. Technical Notes
  5. References and Related Publications
  6. Document Information

1. Contacts and Acknowledgments

Investigators

Lisa Ballagh
Ross Swick

National Snow and Ice Data Center
CIRES/University of Colorado Boulder
Boulder, CO 80309

Technical Contact

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

Acknowledgements

This project is supported by the related data centers and programs at NSIDC, including NOAA@NSIDC, the NSIDC NASA Distributed Active Archive Center (NSIDC DAAC), and the Antarctic Glaciological Data Center (AGDC).

2. Detailed Data Description

Format

NSIDC files for Google Earth consist of Keyhole Markup Language (KML, or when compressed, KMZ) files that link Google Earth to specific data images that are distributed at NSIDC. These data images are geocoded so that they can be viewed on a virtual globe, such as Google Earth. The KML files point to the data images, located at NSIDC, enabling the Google Earth application to render the data visually on the virtual globe. Users can then view the data images with the special features of Google Earth. For more information about Google Earth capabilities, visit the Google Earth Web site.

For more information about the NSIDC data used in these visualizations, follow the "Source Data" link listed for each KML file, for more information and to access detailed scientific documentation describing the data.

Sample Image

Following is a sample, still image of Near-Real-Time SSM/I EASE-Grid Daily Global Ice Concentration and Snow Extent (NISE) data on Google Earth, from the Snow, ice, glaciers, and permafrost file.

Quality Assessment

Information about data quality can be found in the documentation related to each data set. Follow the "Source Data" link to access more information and documentation regarding the source data set.

Currently, there are some known limitations in Google Earth's capabilities to animate a time series of images. For example, the Sea ice extents file includes a time series of September minimum extents from 1979 to 2006. Users need some knowledge of the "Time" tool and its settings, and even still, the speed of the animation is too fast. NSIDC has provided feedback to Google Earth in the hopes that future releases will have improved functionality for time-series animations.

3. Data Access and Tools

Data Access

NSIDC KML/KMZ files for Google Earth can be downloaded from the NSIDC Web site at http://nsidc.org/data/virtual_globes/. Source data for the files can also be obtained from our Web site; means of access and data delivery vary by data set. Follow the links under "Data Source" for more information on data access.

Software and Tools

Instructions for visualizing data in Google Earth

Users who are not familiar with Google Earth should visit the Google Earth site (http://earth.google.com) to obtain Google Earth software and instructions. After installing the application. you may download NSIDC KML/KMZ files from View NSIDC Data on Virtual Globes page, then open those files using the Google Earth software. Visit the Google Earth Help Center for more information on using Google Earth.

Features of NSIDC KML/KMZ files

NSIDC files for Google Earth take advantage of several Google Earth features, such as "Places," the "Time" tool, and general Google Earth capabilities such as moving around the globe, zooming in or out to view features and terrain, and enabling various layers. NSIDC data are constructed as layers that can be turned on and off. A KML or KMZ file may include more than one data set, each as a separate layer. You can view layers individually or together. Clicking on a "Places" icon will pop up additional information, images, or links to the NSIDC Web site. Each data set has been implemented in Google Earth in a manner appropriate to the characteristics of those data, so features will vary by data set.

Frequently Asked Questions

What is Google Earth?
Are the NSIDC data actually in Google Earth?
Do you plan to make more data viewable with Google Earth?
What is the difference between KML and KMZ?
What should I do if the Google Earth application terminates after I download and try opening an updated NSIDC visualization file?
Does the Circum-Arctic Map of Permafrost and Ground-Ice Conditions get updated?
Will the Glacier Photograph Collection and/or Repeat Photography of Glaciers Special Collection get updated?

Related Data Collections

4. Technical Notes

See KML Screen Overlays for some technical notes from our developers regarding the use of Google Earth screen overlays to include ancillary information with Google Earth files, such as captions.

5. References and Related Publications

Ballagh, L. M., B. H. Raup, R. E. Duerr, S. J. S. Khalsa, C. Helm, D. Fowler, and A. Gupte. 2010. Representing Scientific Data Sets in KML: Methods and Challenges. Computers & Geosciences, Virtual Globes special issue (in press).

6. Document Information

Acronyms and Abbreviations

The following acronyms and abbreviations are used in this document.

AGDC Antarctic Glaciological Data Center
DAAC Distributed Active Archive Center
KML Keyhole Markup Language
KMZ Keyhole Markup Language (compressed file)
NASA National Aeronautics and Space Administration
NISE Near-Real-Time SSM/I EASE-Grid Daily Global Ice Concentration and Snow Extent
NOAA National Oceanic and Atmospheric Administration
NSIDC National Snow and Ice Data Center
URL Uniform Resource Locator

Document Creation Date

08 February 2007

Document URL

http://nsidc.org/data/virtual_globes/vg_doc.html