Table of Contents

The following topics are discussed in this section:

SNODAS Tools Products: Snowpack Statistics

The zonal snowpack statistics for each basin of the watershed basin shapefile input are calculated, exported and made available for download every day. As explained in the SNODAS Tools Process section, the daily snowpack statistics are exported as both tabular and spatial data.

Statistics as Tabular Data

The daily snowpack statistics are written to comma-separated-value (CSV) files. The current date's statistics are compiled with the historical statistics to create two large repositories of Colorado snowpack statistics, statistics organized by date and statistics organized by basin. Both the by date and by basin daily csv files are available for download.

The daily csv files are available for download by accessing the following URL resources.

Download the Snowpack Statistics by Basin .CSV File

byBasinExample

To access the snowpack statistics by Basin csv file, follow the link below.
Replace Local_ID with the 'Local_ID' of the basin of interest.
http://projects.openwaterfoundation.org/owf-proj-co-cwcb-2016-snodas/prototype/SnowpackStatisticsByBasin/SnowpackStatisticsByBasin_Local_ID.csv

Download the Snowpack Statistics by Date .CSV File

byBasinExample

To access the snowpack statistics by Date csv file, follow the link below.
Replace YYYYMMDD with the date of interest.
http://projects.openwaterfoundation.org/owf-proj-co-cwcb-2016-snodas/prototype/SnowpackStatisticsByDate/SnowpackStatisticsByDate_YYYYMMDD.csv

Metadata

Both the by Basin and by Date csv files have the same fields and fieldnames. This metadata is explained in more detail in the table below.

Attribute Description Units Rounded to:
(decimals)
Field Name
SNODAS Date The date of SNODAS data. date
(YYYYMMDD)
- Date_YYYYMMDD
Basin Unique ID The basin's unique identifier. - - LOCAL_ID
Basin Unique Name The basin's common name. - - LOCAL_NAME
Area (Without Water Bodies) Basin's effective area (excluding large water bodies). Calculated with zonal statistics on raster SNODAS data. AcFt 1 SNODAS_
EffectiveArea_
sqmi
Snowpack Statistic - Mean SWE (inches) Basin's daily mean snow water equivalent. In 1 SNODAS_SWE_
Mean_in
Snowpack Statistic - Mean SWE (millimeters) Basin's daily mean snow water equivalent. Mm 0 SNODAS_SWE_
Mean_mm
Snowpack Statistic - SWE Volume Basin's daily SWE volume. Calculated by multiplying daily mean SWE by daily effective area. AcFt 0 SNODAS_SWE_
Volume_acft
Snowpack Statistic - 1 Week Change in SWE Volume The difference in the current SWE Volume value from the SWE Volume value calculated 7 days prior. If positive, the snowpack volume has increased. If negative, the snowpack volume has decreased. AcFt 0 SNODAS_SWE_
Volume_
1WeekChange_
acft
Snowpack Statistic - Snow Coverage Percent of basin's effective area covered by snow. - 2 SNODAS_
SnowCover_
percent
Updated Timestamp The date and time that the SNODAS data was downloaded from the FTP site. datetime
(YYYY-MM-DD
THH:MM:SS.MMM)
- Updated_Timestamp

Statistics as Spatial Data

Along with the tabular data, the SNODAS Tools export the daily statistics as spatial data that can be displayed in a geographic information system or a web mapping application. Both a GeoJSON file and a shapefile, with the daily snowpack statistics contained in the attribute tables, are produced for every day of SNODAS data that is processed.

Download the Snowpack Statistics by Date .GeoJSON File

To access the snowpack statistics by Date .GeoJSON file, follow the link below.
Replace YYYYMMDD with the date of interest.
http://projects.openwaterfoundation.org/owf-proj-co-cwcb-2016-snodas/prototype/SnowpackStatisticsByDate/SnowpackStatisticsByDate_YYYYMMDD.geojson

Download the Snowpack Statistics by Date Zipped Shapefile

To access the snowpack statistics by Date zipped shapefile, follow the link below.
Replace YYYYMMDD with the date of interest.
http://projects.openwaterfoundation.org/owf-proj-co-cwcb-2016-snodas/prototype/SnowpackStatisticsByDate/SnowpackStatisticsByDate_YYYYMMDD.zip

Attribute Table Metadata

Both the .GeoJSON and shapefile have the same fields (but different fieldnames). This metadata is explained in more detail in the table below.

Attribute Description Units Rounded to:
(decimals)
Field Name -
Shapefile
Field Name -
GeoJSON
Basin Unique ID The basin's unique identifier. - - LOCAL_ID LOCAL_ID
Basin Unique Name The basin's common name. - - LOCAL_NAME LOCAL_NAME
Total Basin ID TODO - - TOTAL_ID TOTAL_ID
Total Basin Name TODO - - TOTAL_NAME TOTAL_NAME
Original Source The basin's original source. - - POLY_SOURC POLY_SOURC
Edit Flag Marked with '1' if the basin was edited from orignal source. - - EDIT_FLAG EDIT_FLAG
Gage Unique ID Corresponding USGS Gage ID. Only available for basins from WGRFC original source. - - GAGE_ID GAGE_ID
Area (With Water Bodies) Basin's total area. Calculated with vector basin layer. SqKm 2 AREA_SQKM AREA_SQKM
Area (Without Water Bodies) Basin's effective area (excluding large water bodies). Calculated with zonal statistics on raster SNODAS data. AcFt 1 Area_sqmi SNODAS_
EffectiveArea_
sqmi
Snowpack Statistic - Mean SWE (inches) Basin's daily mean snow water equivalent. In 1 SWEMean_in SNODAS_SWE_
Mean_in
Snowpack Statistic - Mean SWE (millimeters) Basin's daily mean snow water equivalent. Mm 0 SWEMean_mm SNODAS_SWE_
Mean_mm
Snowpack Statistic - SWE Volume Basin's daily SWE volume. Calculated by multiplying daily mean SWE by daily effective area. AcFt 0 SWEVol_af SNODAS_SWE_
Volume_acft
Snowpack Statistic - 1 Week Change in SWE Volume The difference in the current SWE Volume value from the SWE Volume value calculated 7 days prior. If positive, the snowpack volume has increased. If negative, the snowpack volume has decreased. AcFt 0 SWEVolC_af SNODAS_SWE_
Volume_
1WeekChange_
acft
Snowpack Statistic - Snow Coverage Percent of basin's effective area covered by snow. - 2 SCover_pct SNODAS_
SnowCover_
percent

Statistics as Time Series Graphs

As explained in the Processing Steps section, four time series graphs are created for each basin of the watershed basin input shapefile (one time series graph for each snowpack statistic). These graphs can be viewed in the CDSS SNODAS Tools Web Application by first clicking a basin of interest in the map display and then clicking the time series graph of interest in the left side panel.

TsButtons
Time Series Graph Buttons in the left side panel
of the CDSS SNODAS Tools Web Application

Download the Snowpack Statistics Time Series Graphs

TODO egiles 03/28/17 how are we making these graphs available to the public for download