Folders in this directory contain data files and images obtained within the NOAA WPO-funded project 
"A New Global 4-km Multi-Decadal Snow Cover Extent/Snow Water Equivalent/Snow Depth Dataset from Blended 
In-situ and Satellite Observations". The developed dataset includes global daily maps of three snow cover
properties, the snow cover extent, snow depth and the snow water equivalent (SWE). All maps are produced 
at the nominal spatial resolution of 4 km. Maps of snow extent also include ice cover data. As of September 2023 
the dataset covers the time period from the middle of 1987 to the end of 2022. The dataset will be routinely updated
with the most recent maps of snow an ice ocver properties.

The dataset has been developed through reprocessing of historical satellite data and in situ observations of the
snow depth. Snow and ice extent maps were produced with the algorithms implemented within the NESDIS Global Multisensor 
Automated Snow and Ice Mapping System (GMASI). Snow depth was derived using a synergy of in situ snow depth analysis 
and snow depth retrievals from satellite observations in the microwave. SWE was inferred from the derived snow depth
using a simple empirical model of M.Sturm relating the snow density to the day of the hydrological year. Snow depth and SWE 
are derived only for grid cellls identified by the snow extent algorithm as "snow covered".

Content of directories n this folder:

data 

Includes output daily data files orginized by the year. Files are in NetCDF format. 
Metadata included in the files provides information on the data format, geographical grid, and coding. The product
file name includes the date of the map and the date when the file was generated.

images 

Includes browse images of snow extent, snow depth and SWE maps in .png format. The image file name 
includes the date of the map in yyyyDDD format, where yyy is the year and DDD is the day of the year.
At this time images of five types are available:
     snow_depth_full_yyyyDDD.png: Full resolution (4500 x 9000) image of the snow depth map
     snow_depth_full_station_yyyyDDD.png: Full resolution (4500 x 9000) image of the snow depth map with in situ snow depth data overlaid
     snow_depth_small_yyyyDDD.png: Reduced resolution (browse) snow depth image.
     snow_swe_full_yyyyDDD.png: Full resolution (4500 x 9000) image of the snow water equivalent map
     snow_swe_small_yyyyDDD.png: Reduced resolution (browse) snow water equivalent image.    

snowduration

Binary data files and associated imagery characterizing the yearly snow cover duration
over the globe. Maps have been derived using reprocessed GMASI daily global snow/ice cover data
           

snowextent

Time series of the hemisphere and continental-scale snow cover extent derived from four
datasets, GMASI 4 km, NOAA CDR (Rutgers Snow Lab dataset), IMS at 4km and  at 24 km resolution
Charts for both monthly mean and yearly mean snow extent values are provided.