MASIE-NH Daily Image Viewer

1. What is the difference between this product and the Sea Ice Index? The Sea Ice Index has a daily view, too.

The Sea Ice Index (SII) relies on satellite passive microwave data as its only data source. These data are automatically processed using an algorithm and have known biases and limitations; these are covered in the SII documentation. MASIE relies on data from the Interactive Multisensor Snow and Ice Mapping System (IMS) that runs at the U.S. National Ice Center (USNIC). The IMS product uses several satellite data sources including passive microwave, but it is also based on visual analysis and other data sources and undergoes a form of manual data fusion. Another difference is in the resolution of the products. The MASIE product has a nominal 4-km resolution which is higher than the nominal 25-km resolution of the SII.

2. When should I use MASIE and when should I use the Sea Ice Index?

Use the Sea Ice Index when comparing trends in sea ice over time or when consistency is important. Even then, the monthly, not the daily, Sea Ice Index views should be used to look at trends in sea ice. The Sea Ice Index documentation explains how linear regression is used to say something about trends in ice extent, and what the limitations of that method are. Use MASIE when you want the most accurate view possible of Arctic-wide ice on a given day or through the week. More accurate pictures of ice extent on any given day might be possible on a regional basis and from other international centers. See the IPY Ice Logistics Portal for access. If you have a question about intended and appropriate use of the data, please contact NSIDC User Services.

3. Should I use this product, or should I go to the U.S. National Ice Center (USNIC) site?

Go to the USNIC website for operational support of any kind. MASIE is produced in cooperation with USNIC and is based on a USNIC operational product, but NSIDC is not an operational center and cannot offer that level of support.

For information on other operational ice products, see the following:

4. What about Antarctica?

MASIE is based on the IMS product from the USNIC. The IMS product only covers the Arctic, thus MASIE only covers the Arctic.

5. What is the spatial and temporal resolution of the MASIE product?

The initial MASIE product had a nominal gridded resolution of 4 km x 4 km that spans 01 October 2006 to present at a daily resolution. As of 02 December 2014, a 1 km x 1km gridded product is also available to present at a daily resolution.

6. How do I credit MASIE images?

Add the following to your image caption: Credit: NSIDC/USNIC MASIE product

7. Why do some of the time series plots look wrong, with sudden changes or flat lines?

Sudden jumps or dips in the area covered by sea ice have three possible causes:

1. They are real and may appear especially abrupt because of the scale of the y-axis. The y-axis is scaled to fit the data, so a small change in ice area may appear as a large jump, depending on the region.
2. Flat lines appear when the region is entirely ice covered or has no ice.
3. Sudden changes may result when the operational process changes.

8. How do I learn about any updates or errors in the data set?

You can subscribe to receive updates for the data set. Users are encouraged to subscribe because subscribed users will receive e-mail notification about any product changes. To subscribe, fill out the Multisensor Analyzed Sea Ice Extent - Northern Hemisphere (MASIE-NH) data set landing page and click the Subscribe icon at the top of the page.

9. How does the U.S. National Ice Center (USNIC) create its products?

This article, written in 2006, gives a brief history of USNIC's operations that will help you understand the setting in which its products are created: The Evolution of Operations at the U. S. National Ice Center: From Paper to Pixel.

10. Why do gaps sometimes appear in the MASIE time series?

MASIE uses the most recent full day of IMS data from the U.S. National Ice Center, obtained nightly. However, as is the rule with operational centers, gaps in production can occur without warning or cause. For a list of missing dates, see the USNIC IMS missing dates text file.