Name: Sea Ice Index, Version 3
Creator: National Snow and Ice Data Center
Keywords: ICE EXTENT,ICE GROWTH/MELT,SEA ICE CONCENTRATION

Sea Ice Index, Version 3

Data set id:

G02135

DOI: 10.7265/N5K072F8

Data Citation and Acknowledgment
As a condition of using these data, you must cite the use of this data set. Such a practice gives credit to data set producers and advances principles of transparency and reproducibility.

Fetterer, F., Knowles, K., Meier, W. N., Savoie, M. & Windnagel, A. K. (2017). Sea Ice Index. (G02135, Version 3). [Data Set]. Boulder, Colorado USA. National Snow and Ice Data Center. https://doi.org/10.7265/N5K072F8. [describe subset used if applicable]. Date Accessed 09-10-2025.

Copied

Other standard citation formats may be found on the DOI Citation Formatter website (paste 10.7265/N5K072F8 into the top form field).

Describing subset: When applicable, include the information a reader would need to extract the same subset at the end of your citation. If multiple or complex steps were incolved, it may be more appropriate to include this information in the paper itself.

See our Citation Policies for more details about how to structure your data citation.

There is a more recent version of these data.
Version Summary

Updated the method used to calculate the monthly average sea ice extent and area data values.

Overview

Notice: Due to funding limitations, this data set was recently changed to a “Basic” Level of Service. Learn more about what this means for users and how you can share your story here: Level of Service Update for Data Products.

The Sea Ice Index provides a quick look at Arctic- and Antarctic-wide changes in sea ice. It is a source for consistent, up-to-date sea ice extent and concentration images, in PNG format, and data values, in GeoTIFF and ASCII text files, from November 1978 to the present. Sea Ice Index images also depict trends and anomalies in ice cover calculated using a 30-year reference period of 1981 through 2010. The images and data are produced in a consistent way that makes the Index time-series appropriate for use when looking at long-term trends in sea ice cover. Both monthly and daily products are available. However, monthly products are better to use for long-term trend analysis because errors in the daily product tend to be averaged out in the monthly product and because day-to-day variations are often the result of short-term weather.

Parameter(s):

ICE EXTENT

ICE GROWTH/MELT

SEA ICE CONCENTRATION

Platform(s):

DMSP

DMSP 5D-3/F17

DMSP 5D-3/F18

Nimbus-7

Sensor(s):

SMMR

SSM/I

SSMIS

Data Format(s):

PNG

GeoTIFF

CSV

Shapefile

Temporal Coverage:

26 October 1978 to 31 July 2025

Temporal Resolution:

1 day

Spatial Resolution:

25 km

25 km

Spatial Reference System(s):

NSIDC Sea Ice Polar Stereographic North
EPSG:3411
NSIDC Sea Ice Polar Stereographic South
EPSG:3412

Spatial Coverage:

N:
-39.23
S:
-90
E:
180
W:
-180
N:
90
S:
30.98
E:
180
W:
-180

Blue outlined yellow areas on the map below indicate the spatial coverage for this data set.

View Metadata Record

Data Access & Tools

This data set has been retired. There is a more recent version of these data.

Documentation

Help Articles

General Questions & FAQs

Are the same regions used in the Sea Ice Index and MASIE-NH?

The regions differ slightly between the Sea Ice Index and the Multisensor Analyzed Sea Ice Extent - Northern Hemisphere (MASIE-NH). The two data sets are a source for sea ice extent, but they use different methods and data to estimate this parameter and their intended uses are also different.

NSIDC currently archives passive microwave sea ice concentration products based on two algorithms: the NASA Team algorithm and the Bootstrap algorithm. Both algorithms were developed by researchers at the NASA Goddard Space Flight Center in the 1980s.

The Sea Ice Index and the Arctic Sea Ice News Analysis (ASINA) Web pages provide images derived from passive microwave satellite data that depict the most recent daily sea ice conditions.

If you plot the average daily change in sea ice extent in the northern hemisphere, based on the data from 'Sea_Ice_Index_Daily_Extent_G02135_v3.0.xlsx', you may notice that at the beginning of each month, particularly in the summer, the daily change is larger.

How to Articles

How to access and download NOAA@NSIDC data

NOAA@NSIDC data recently transitioned to HTTPS. The directory structure has NOT changed, but the beginning of the URL has changed from:ftp://sidads.colorado.edu/pub/DATASETS/to: