
Near Real-Time MODIS/Terra L3 Global Daily 500m SIN Grid Snow Cover, Snow Albedo, and Snow Surface Properties, Version 1
Data set id:
SPIRES_NRT
DOI: 10.7265/hs6b-zg21
This is the most recent version of these data.
Version Summary
Version Summary
Initial release
Overview
This data set contains the following parameters: snow fraction (on the ground), viewable snow fraction, snow cover duration, snow grain size, dust concentration, snow albedo (on horizontal surface), snow albedo (on sloped surface), and radiative forcing. All variables are spatially and temporally complete after interpolation. Days without observation is also included so that users can determine how many days since a satellite observation occurred.
The data set is derived from a version of the spectral mixture analysis (SMA) approach called the Snow Property Inversion from Remote Sensing (SPIReS, Bair et al, 2021). This dataset uses surface reflectance inputs from MOD09GA v6.1 and includes additional outputs not included in the original version of SPIReS: snow albedo and snow radiative forcing.
The SPIReS SMA model considers three spectral endmembers: snow, shade, and a snow-free background reflectance, which is identified for each MODIS pixel as the average MOD09GA reflectance measured typically between 1 August and 30 September for a given year in the northern hemisphere. dust concentration is solved for simultaneously with fractional snow cover and snow grain size during the spectral unmixing process. SPIReS snow albedo are derived using a lookup table that incorporates snow grain size, dust concentration, and surface illumination (Bair et al., 2019). After the fSCA, grain size, and dust concentration are determined, these properties are filled, smoothed, and adjusted for canopy gap size, shade, and permanent ice. SPIReS radiative forcing are derived using a lookup table that incorporates LAP concentration and clear sky incoming solar irradiance. Data are available from 01 October 2024 to present. These data are provided in the netCDF-4 format with a Sinusoidal projection and are currently available for the western United States (MODIS tiles h08v04, h08v05, h09v04, h09v05, h10v04). Additional tiles will be added over time. For data prior to 01 October 2024, please see the historical dataset (Rittger et al., 2025) created by Snow Today at NSIDC.
Data can be accessed via ftp://dtn.rc.colorado.edu/shares/snow-today/spires/SPIRES_NRT_V01Note: Authors Rittger, K. and Lenard, S. contributed equally to this work
Parameter(s):
ALBEDO
DUST CONCENTRATION
SNOW DURATION
SNOW FRACTION
SNOW GRAIN SIZE
SNOW RADIATIVE FORCING
VISIBLE SNOW DARKENING
Platform(s):
Terra
Sensor(s):
MODIS
Data Format(s):
netCDF-4
Temporal Coverage:
- 1 October 2024 to present
Temporal Resolution:
- 1 day
Spatial Resolution:
- 500 meters
- 500 meters
Spatial Reference System(s):
Not Specified
Spatial Coverage:
- N:90S:-90E:180W:-180
Blue outlined yellow areas on the map below indicate the spatial coverage for this data set.