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Snow Data Assimilation System (SNODAS) Data Products at NSIDC, Version 1

Notice: If you are having difficulties subsetting SNODAS data via Polaris, please contact

This data set contains output from the NOAA National Weather Service's National Operational Hydrologic Remote Sensing Center (NOHRSC) SNOw Data Assimilation System (SNODAS). SNODAS is a modeling and data assimilation system developed by NOHRSC to provide the best possible estimates of snow cover and associated parameters to support hydrologic modeling and analysis. The aim of SNODAS is to provide a physically consistent framework to integrate snow data from satellite, airborne platforms, and ground stations with model estimates of snow cover (Carroll et al. 2001). SNODAS includes procedures to ingest and downscale output from the Numerical Weather Prediction (NWP) models, and to simulate snowcover using a physically based, spatially-distributed energy- and mass-balance snow model. SNODAS also includes procedures to assimilate satellite-derived, airborne, and ground-based observations of snow covered area and Snow Water Equivalent (SWE).

These data are not suitable for snow fall events or totals for specific regions. For snow fall data, please see the state climatology reports for a particular state. These are gridded data sets for the continental United States at 1 km spatial resolution and 24 hour temporal resolution. Data are stored in flat binary 16-bit signed integer big-endian format with header and metadata files, and are available from 1 October 2003 to present via FTP.

Geographic Coverage

Spatial Coverage:
  • N: 58.2329, S: 24.0996, E: -62.2504, W: -130.5171

  • N: 52.8754, S: 24.9504, E: -66.9421, W: -124.7337

Spatial Resolution:
  • 1 km x 1 km
Temporal Coverage:
  • 28 September 2003 to 25 October 2016
Temporal Resolution: 1 day
  • Atmospheric Water Vapor > Sublimation > Blowing Snow Sublimation
  • Precipitation > Rain > Liquid Precipitation
  • Precipitation > Precipitation Amount > Scaled Precipitation Non-Snow
  • Precipitation > Precipitation Amount > Scaled Precipitation - Snow
  • Snow/Ice > Snow Depth
  • Snow/Ice > Snow Melt > Snow Melt Rate
  • Snow/Ice > Snow/Ice Temperature > Snowpack Average Temperature
  • Atmospheric Water Vapor > Sublimation > Snow Pack Sublimation
  • Snow/Ice > Snow Depth > Snowpack Thickness
Sensor(s): Not specified
Data Format(s):
  • Binary
Version: V1
Data Contributor(s): Tom Carroll

Data Citation

As a condition of using these data, you must cite the use of this data set using the following citation. For more information, see our Use and Copyright Web page.

National Operational Hydrologic Remote Sensing Center. 2004. Snow Data Assimilation System (SNODAS) Data Products at NSIDC, Version 1. [Indicate subset used]. Boulder, Colorado USA. NSIDC: National Snow and Ice Data Center. doi: [Date Accessed].
No technical references available for this data set.


When visualizing SNODAS data, why is the image skewed?

This is most likely due to a problem with Windows Winzip which corrupts the file upon dowloading (you will see that the file size will have changed from the original located on ftp)

You can correct this by changing some settings in WinZip:

How can I find information about the model input for the SNODAS data set?

NOHRSC provides/creates the data, we just archive it. If you have questions about the model (such as how it is run) not available in the documentation, you have to... read more

What if I need SNODAS data in real or neal-real time?

NSIDC has scripts that run several times a day. If new SNODAS files are found, these scripts will automatically post them to our FTP server. If you need data sooner than the normal timeframe that NSIDC uploads files to our FTP site, you can ... read more

How To

How do I import SNODAS data into ArcGIS?

Follow the steps below (which are also linked to from the data set documentation). These steps will work for all 8 SNODAS variables using ArcGIS 10.0 or higher. If you ordered data using Polaris, scroll... read more