Yellowstone Ecological Research Center (YERC) Percent Surface Water (PSW) Dataset

Metadata:


Identification_Information:
Citation:
Citation_Information:
Originator: Daniel J. Weiss
Publication_Date: 20130101
Title:
Yellowstone Ecological Research Center (YERC) Percent Surface Water (PSW) Dataset
Geospatial_Data_Presentation_Form: raster digital data
Description:
Abstract:
The Yellowstone Ecological Research Center (YERC) Percent Surface Water (PSW) Dataset consists of three products (see below) that are derivatives of MODIS-BRDF 16-day composite imagery. These data products were produced for the majority of Canada and the United States (22 MODIS tiles in total, merged into seamless mosaics) for April 15th through October 24th, 2000-2011. The underlying methodology for all PSW products was adapted from Weiss & Crabtree (2011) whereby commonly used indices (NDVI and tasseled cap wetness and brightness) were used to derive the fractional of surface water within each pixel. The approach consisted of developing empirically-based, spatially and temporally specific equations for estimating PSW (i.e., each tile had a unique PSW equation for each composite date). The resulting datasets are:

(1) Raw_PSW (8-day temporal resolution). This data product has moderate absolute accuracy (R^2 ~ 0.5), but it may be useful for applications that only require relative PSW accuracy (e.g., a metric for distinguishing wet periods from dry ones for a given location). Note that due to unique PSW equations being applied for each tile, tile boundaries are apparent within this dataset.

(2) PSW_proportion_of_normal (monthly temporal resolution). This data product is the result of dividing the raw PSW for a single month (e.g., May, 2005) by the mean raw PSW value for that month from the full 12-year dataset. This product is most useful for assessing spatial and temporal trends in surface water over the 2000-2011 measurement period.

(3) PSW_adjusted (monthly temporal resolution). This data product is the result of multiplying the proportion of normal dataset by PSW training information derived from higher spatial resolution products landcover products. This approach increased the absolute PSW accuracy (R^2 ~ 0.75), but also introduced (a) no-data gaps for some areas of Canada and (b) classification and mapping errors that were present within the training datasets. Also note that the adjustment algorithm utilized empirically derived thresholds for catching anomalous events such as flooding or drying. In cases where anomalous events were identified, the raw PSW values superseded the proportional adjustment.

For more detail on dataset accuracy see the PSW_validation_graph_raw.png and PSW_validation_graph_adjusted.png graphs available on http://www.coasterdata.net/documents/COASTER_metadata.html.

Additional note - the accuracy of all PSW products varies spatially, with models performing much better in areas with abundant water (i.e., <5% of the total landscape). As such, users should proceed with particular caution when using this product in arid areas.

Weiss, D. J. and R. L. Crabtree. 2011. "Percent surface water estimation from MODIS BRDF 16-day image composites." Remote Sensing of Environment, 115:8 2035-2048.
Purpose:
Assessing spatial and temporal surface water dynamics
Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 20000415
Ending_Date: 20111024
Currentness_Reference:
publication date
Status:
Progress: Complete
Maintenance_and_Update_Frequency: None planned
Spatial_Domain:
Description_of_Geographic_Extent:
Bounding_Coordinates:
West_Bounding_Coordinate: -175.00166
East_Bounding_Coordinate: -55.00222
North_Bounding_Coordinate: 70.00000
South_Bounding_Coordinate: 24.00328
Keywords:
Theme:
Theme_Keyword_Thesaurus: None
Theme_Keyword: Surface Water
Access_Constraints: None
Use_Constraints:
None
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Data_Quality_Information:
Attribute_Accuracy:
Attribute_Accuracy_Report:
See the PSW accuracy assessment ancillary document.
Logical_Consistency_Report:
The processing approach for all tiles and for all dates was consistent
Completeness_Report:
PSW Raw - 25 rasters per year (300 total) for the April-October analysis window
PSW Adjusted and Proportion of Normal - 7 rasters per year (84 total)
Lineage:
Process_Step:
Process_Description:
No process steps have been described for this data set
Process_Date: Unknown
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Spatial_Data_Organization_Information:
Direct_Spatial_Reference_Method: Raster
Raster_Object_Information:
Raster_Object_Type: Pixel
Row_Count: 5502
Column_Count: 14354
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Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Local:
Local_Description:Resolution 500m products: 0.00418, 0.00418
Resolution 1km products: 0.00836, 0.00836

Resolution 500m products:0.00418, 0.00418
Local_Georeference_Information:
Geodetic_Model:
Horizontal_Datum_Name: World Geodetic System of 1984
Ellipsoid_Name: World Geodetic System of 1984
Semi-major_Axis: 6378137
Denominator_of_Flattening_Ratio: 298.25722210088
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Metadata_Reference_Information:
Metadata_Date: 20130101
Metadata_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Yellowstone Ecological Research Center
Contact_Person: Daniel Weiss
Contact_Address:
Address_Type: mailing and physical
Address: 2048 Analysis Dr, Suite B
City: Bozeman
State_or_Province: MT
Postal_Code: 59718
Country: United States of America
Contact_Voice_Telephone: (406)-556-1414
Metadata_Standard_Name: FGDC Biological Data Profile of the Content Standard for Digital Geospatial Metadata
Metadata_Standard_Version: FGDC-STD-001.1-1999
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