Near-Real-Time SSM/I-SSMIS EASE-Grid Daily Global Ice Concentration and Snow Extent, Version 5 (NISE)
This is the most recent version of these data.
- The NISE snow and sea ice algorithm both use near-real-time brightness temperature observations from the SSMIS instrument on DMSP-F18.
- The coefficients for the NISE snow algorithm were updated to better match results from DMSP-F13 as a result of an inter-calibration between F13 and F17 during an overlap period from 3/27/2008-3/26/2009 and between F17 and F18 during an overlap period from 7/1/2014-6/30/2015.
- ESDT metadata was updated to reflect the change in data set version number.
The NISE Version 5 data record begins 12/01/2016.
The Near-real-time Ice and Snow Extent (NISE) data set provides daily, global maps of sea ice concentrations and snow extent. These data are not suitable for time series, anomalies, or trends analyses. They are meant to provide a best estimate of current ice and snow conditions based on information and algorithms available at the time the data are acquired. Near-real-time products are not intended for operational use in assessing sea ice conditions for navigation. This NISE Version 5 product contains DMSP-F18, SSMIS-derived sea ice concentrations and snow extents derived from the Special Sensor Microwave Imager/Sounder (SSMIS) aboard the Defense Meteorological Satellite Program (DMSP) F18 satellite. For DMSP-F16, SSMIS-derived data, see NISE Version 3. For DMSP-F17, SSMIS-derived data, see NISE Version 4. For the older, DMSP-F13, Special Sensor Microwave Imager (SSMI) derived data, see NISE Version 2.
SEA ICE CONCENTRATION SNOW COVER
1 December 2016 to present
Spatial Reference System(s):
NSIDC EASE-Grid North
NSIDC EASE-Grid South
Yellow areas on the map below indicate the spatial coverage for this data set.
Strengths and Limitations
- Near-real-time combined sea ice and snow product (Armstrong and Brodzik, 2001; Maslanik and Stroeve, 1999)
- Useful for large-scale monitoring of sea ice and snow conditions (Armstrong and Brodzik, 2001; Maslanik and Stroeve, 1999)
- Uses data from up to 5 days previous to fill in all spatial gaps (particularly important for lower latitude snow cover) (Armstrong and Brodzik, 2001)
- Microwave observations provide surface snow and ice coverage during cloudy and night-time (including polar night) conditions (Cavalieri et al., 1999)
- Good source as input to products/models requiring a spatially complete snow and sea ice cover field at moderate/low resolution (Armstrong and Brodzik, 2001)
- Low spatial resolution (25 km gridded) limits detail on concentration and precision of sea ice edge; is unsuitable for operational/navigational support (Cavalieri et al., 1999) and/or for detailed mapping of snow extent (Armstrong and Brodzik, 2002)
- Underestimates sea ice concentration during melt season (Kern et al., 2020) and/or when the ice is thin (Ivanova et al., 2015)
- Underestimates thin snow (Armstrong and Brodzik, 2002)
- Snow in dense forest and mountainous regions may be missed or underestimated (Armstrong and Brodzik, 2002)
- Wet snow is not accurately retrieved (Armstrong and Brodzik, 2002)
- There is a gap in coverage near the coast due to low spatial resolution and mixed land-ocean footprints (Armstrong and Brodzik, 2002)
- Near-real-time product with no planned reprocessing for long-term consistency; should not be used to derive long-term trends in sea ice or snow (Cavalieri et al., 1999)
Data Access & Tools
Sensor and Instrument Information
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.
OPeNDAP, the Open-source Project for a Network Data Access Protocol, is a NASA community standard DAP that provides a simple way for researchers to access and work with data over the internet.
The HDF Group has example code for access and visualization of MODIS, GLAS HDF5, AMSR-E, and NISE data in MATLAB, IDL, Python, and NCL.
Many NSIDC DAAC data sets can be accessed using the NSIDC DAAC's Data Access Tool. This tool provides the ability to search and filter data with spatial and temporal constraints using a map-based interface. Users have the option to
To convert HDF5 files into binary format you will need to use the h5dump utility, which is part of the HDF5 distribution available from the HDF Group. How you install HDF5 depends on your operating system.
Data subscriptions are available for select NSIDC DAAC data collections. Once signed up, the subscription service automatically sends you new data as they are delivered from active NASA satellite missions.
All data from the NASA National Snow and Ice Data Center Distributed Active Archive Center (NSIDC DAAC) can be accessed directly from our HTTPS file system, using wget or curl. Basic command line instructions are provided in the article below.