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 National Ice Center (NIC). 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 National Ice Center (NIC) site?

Go to the NIC Web site for operational support of any kind. MASIE is produced in cooperation with NIC and is based on a NIC 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:

Product Description
NIC IMS Products Web page with links to NIC's Interactive Multisensor Snow and Ice Mapping System (IMS) data that is the input data for MASIE.
NIC Daily Ice Analysis Products Web page with links to NIC's Daily Ice Analysis Products.
NIC Weekly/Bi-Weekly Ice Analysis Products Web page with links to NIC's Weekly/Bi-Weekly Ice Analysis Products.
NWS Anchorage Ice Desk Web page for the National Weather Service (NWS) Forecast Office Anchorage, AK Ice Desk.

4. What about Antarctica?

We plan to add MASIE-SH as soon as resources allow.

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/NIC 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 register for the data set. Users are encouraged to register because registered users will receive e-mail notification about any product changes. To register, fill out the MASIE User Registration Form.

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

This article, written in 2006, gives a brief history of NIC'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 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 NIC IMS missing dates text file.

NSIDC has received support to develop MASIE but not to maintain MASIE. We are actively seeking support to maintain the Web site and products over the long term. If you find MASIE helpful, please let us know with a quick message to NSIDC User Services.