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The Soil Moisture Experiment 2002 (SMEX02) took place in Ames, Iowa USA between 25 June and 12 July 2002. The NASA Land Surface Hydrology Data Archive maintains an archive of soils and land cover characteristics for SMEX02. SMEX02 studies are designed to evaluate the accuracy of AMSR-E soil moisture data specific to the SMEX02 study areas, and SMEX02 provided the unique opportunity to test microwave soil moisture retrieval over agricultural land cover. The Soils Database includes Environmental Systems Research Institute (ESRI) shapefiles containing geographic information such as railroads, roads, and stream locations; drainage features; political boundaries; and soil classifications. Data for the following 10 Iowa counties are included in this data set: Boone, Dallas, Franklin, Hamilton, Hardin, Jasper, Marshall, Polk, Story, and Wright. These data were created by appending existing county digital soils data provided by the Iowa Cooperative Soil Survey (ICCS) and clipping them by the SMEX02 project area boundary; thus, the dates of data acquisition are highly variable. The entire data set is 293 MB. Data are available via FTP.
These data were collected as part of a validation study for the Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E). AMSR-E is a mission instrument launched aboard NASA's Aqua Satellite on 04 May 2002. AMSR-E validation studies linked to SMEX are designed to evaluate the accuracy of AMSR-E soil moisture data. Specific validation objectives include assessing and refining soil moisture algorithm performance; verifying soil moisture estimation accuracy; investigating the effects of vegetation, surface temperature, topography, and soil texture on soil moisture accuracy; and determining the regions that are useful for AMSR-E soil moisture measurements.
We kindly request that you cite the use of this data set in a publication using the following citation example. For more information, see our Use and Copyright Web page.
Miller, D. 2006. SMEX02 Land Surface Information: Soils Database. [indicate subset used]. Boulder, Colorado USA: NASA DAAC at the National Snow and Ice Data Center.
|Data format||Data files are ESRI shapefiles.|
|Spatial coverage and resolution||Southernmost Latitude: 41.69459° N
Northernmost Latitude: 42.73229° N
Westernmost Longitude: 93.84162° W
Easternmost Longitude: 93.16104° W
|Temporal coverage and resolution||
Dates of data acquisition are highly variable; therefore, they are unspecified.
|Tools for accessing data||Data require Geographical Information System (GIS) software for viewing.|
|File naming convention||Please see the File Naming Convention section below for a description of the files found within the soils database.|
|File size||File sizes range from 1 KB to about 174 MB. Total volume is 293 MB.|
|Parameter(s)||The data contain railroad, road, and stream locations; drainage features; political boundaries; and soil classifications.|
|Procedures for obtaining data||Data are available via FTP.|
Pennsylvania State University
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NSIDC User Services
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Boulder, CO 80309-0449 USA
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fax: +1 303.492.2468
form: Contact NSIDC User Services
These data files are ESRI shapefiles. A general description of each file type follows:
A detailed description of the "soils.dbf", "soils_wc_all.dbf", and "iaregnsoil.dbf" file variables is described in the Soils Database: Fields Table.
The "soils_database" directory contains two subdirectories, "Iowa" and "Walnut Creek". The "Iowa" subdirectory contains regional data, whereas the "Walnut Creek" subdirectory contains only the data for the Walnut Creek watershed.
|.shp||cartographic vector data with a database table lookup association using .dbf and .shx files|
|.shx||file holding data for the actual vertices|
|.dbf||file holding index data pointing to specific structures in the .shp file|
|.prj||a text description of the coordinate system; external projection file|
|.sbn||file holding additional shapefile components and spatial indices|
|.sbx||file holding additional shapefile components and spatial indices|
"Iowa Regional Data" subdirectory (260 MB):
|regnDrain.*||This line coverage contains data about drainage features from the ICSS.|
|regnSect.*||This polygon coverage contains geographical boundaries from the Public Land Survey System (PLSS) of the Iowa Department of Natural Resources GIS Library.|
|regnTwps.*||This polygon coverage contains PLSS township boundaries from the of the US Geological Survey (USGS) National Atlas.|
|regnRR.*||This line coverage contains geographic information about railroads from the Census 2000 Topologically Integrated Geographic Encoding and Referencing (TIGER) database.|
|regnPts.*||These files contain SMEX02 regional sample points.|
|regnRoads.*||This line coverage contains geographic information about road centerlines from the Census 2000 TIGER database.|
|iaregnsoil_read_me.htm||This file contains the SMEX02 Regional Soils data set notes.|
|iaregnsoil.*||This polygon coverage contains digital soil map units from the ICSS.|
|regnStreams.*||This line coverage contains geographic information about stream centerlines from the Census 2000 TIGER database.|
|Iowa_soils_metadata.pdf||This file contains the ICSS digital soil map data documentation.|
"Walnut Creek Data" subdirectory (39.7 MB):
|drainage.*||This line coverage contains data about drainage features from the ICSS.|
|fields.*||This polygon coverage contains SMEX02 field boundaries.|
|plss_sect.*||This polygon coverage contains geographical boundaries from the PLSS of the Iowa Department of Natural Resources NRGIS Library.|
|plss_twp.*||This polygon coverage contains PLSS township boundaries from the of the USGS National Atlas.|
|railroad.*||This line coverage contains geographic information about railroads from the Census 2000 TIGER database.|
|roads.*||This line coverage contains geographic information about road centerlines from the Census 2000 TIGER database.|
|soils_wc_all.*||This polygon coverage contains digital soil map units from the ICSS.|
|soils.*||This polygon coverage contains digital soil map units from the ICSS clipped by research field boundaries.|
|streams.*||This line coverage contains geographic information about stream centerlines from the Census 2000 TIGER database.|
|townLimits.*||This polygon coverage contains the town limits from the Census 2000 TIGER database.|
Both directories contain the "ispaid_user_guide.pdf" file, which is the Iowa Soil Properties and Interpretation Database (ISPAID) guide and includes a description of the attributes contained in digital soils data shapefiles.
The "*" symbol represents the various file extensions described in the Format section.
File sizes range from 1 KB to about 174 MB. The entire data set, including both of the subdirectories, is 293 MB.
The following 10 counties comprise the data set: Boone, Dallas, Franklin, Hamilton, Hardin, Jasper, Marshall, Polk, Story, and Wright.
Southernmost Latitude: 41.69459° N
Northernmost Latitude: 42.73229° N
Westernmost Longitude: 93.84162° W
Easternmost Longitude: 93.16104° W
The minimum size delineation of soil polygons is two acres.
Data are based on the North American Datum of 1983 (NAD83). The data were collected from Universal Transverse Mercator (UTM) Zone 15.
Because this data set was created by appending existing county digital soils data provided by ICCS and clipping them by the SMEX02 project area boundary, the dates of data acquisition are highly variable; therefore, they are unspecified.
The data contain geographic information such as railroad, road, and stream locations; drainage features; political boundaries; and soil classifications. Please refer to the File Naming Convention section.
Data were derived from aerial photography and topographic maps of the study area.
As displayed in ENVI, the image below was created with data from the Walnut Creek subdirectory including streams, drainage, soils, and field coverage.
The sample data below is from the "soils.dbf" file. Because the file includes 85 columns, only the first 9 columns and last column of data are shown below.
The column headings correspond to the following (as is described in "ispaid_user_guide.pdf"):
|OBJECTID||Object identification number|
|SITE_ID||Site Identification number|
|Measure_Ty||This field is not applicable and should be disregarded.|
|SMS||The Soil Map Symbol is the symbol as used on the soil map sheets.|
|SMU||The Soil Map Unit symbol identifies the soil type, the slope class, and the erosion phase.|
|SCSSOIL5||The Soils-5 Number is a record number from a National Resources Conservation Services form, NRCS-SOI-5. The first two letters indicate the state.|
|SOILNAME||The Soil Name can be the soil series name or may include specific soil phase modifiers, such as texture of the surface horizon, profile depth limits, flooding frequency, overwash characteristics, etc.|
|LCC||In general, the Land Capability Classification shows the suitability of soils for most kinds of field crops.|
|PRIMELND||The United States Department of Agriculture (USDA) Prime Farmland rating defines land that is best suited to food, feed, forage, fiber, and oilseed crops.|
|Shape_Area||This field is not applicable and should be disregarded.|
With the exception of Polk county, the source of all soil property attributes is the Iowa Soil Properties and Interpretations Database (ISPAID). Soil Survey Geographic Database (SSURGO, version 2) and Map Unit Interpretation Record (MUIR) databases were used to populate a selected set of soil property attributes for Polk county. Due to dissimilarity between these data sets, attribute values for Polk county may differ from those of similar soils observed in neighboring counties.
Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of soils of other taxonomic classes. Consequently, every map unit is made up of the soil or soils for which it is named and some soils that belong to other taxonomic classes. Please see "iowa_soils_metadata.pdf" for more details.
Data are available via FTP.
The volume of the entire data set is 293 MB.
The data can be viewed using ArcView/GIS software.
This data set was created by appending existing county digital soils data provided by the ICSS and clipping these data by the SMEX02 project area boundary.
At a ground resolution of two meters, 1:15,840 and 1:20,000
scale mylar map sheets were scanned with an Optronics camera at 200
dots per inch (DPI). The map sheets were originally drawn on
and white, rectified aerial photographs. These aerial photographs were
thus, soil lines contain terrain distortions inherited from the
imagery. The maps were edited with Map Editing Software (MES) at the University
of Minnesota. The map sheets were clipped to individual sections having
a raster resolution
of 320 x 200 pixels (a typical ground resolution of 5 x 8 meters).
The raster images were converted to vector format,
and then converted to Arc/Info format.
Soil data was transformed to fit the UTM coordinate system using the map registration marks from Iowa Department of Natural Resources (DNR), Natural Resources Geographic Information Systems (NRGIS) county PLSS files. PLSS coverages were digitized from 24,000 USGS topographic maps and have 22-meter root-mean-square (RMS) accuracy.
Section files were appended to the township level by the Iowa Geological Survey Bureau and the Iowa State University GIS Facility. Township level data that was appended to county-wide level data and projected to UTM Zone 15 North American Datum of 1983 (NAD83) Geodetic Reference System 1980 (GRS80) was converted to ESRI shapefile format by USDA Natural Resources Conservation Service in Ames, Iowa.
The following acronyms and abbreviations are used in this document.
|AMSR-E||Advanced Microwave Scanning Radiometer - Earth Observing System|
|DNR||Department of Natural Resources|
|DPI||Dots Per Inch|
|ESRI||Environmental Systems Research Institute|
|FTP||File Transfer Protocol|
|GIS||Geographical Information System|
|GPS||Global Positioning System|
|ICSS||Iowa Cooperative Soil Survey|
|ISPAID||Iowa Soil Properties and Interpretation Database|
|LCC||Land Capability Classification|
|MES||Map Editing Software|
|MUIR||Map Unit Interpretation Record|
|NAD83||North American Datum of 1983|
|NASA||National Aeronautics and Space Administration|
|NRCS||National Resources Conservation Services|
|NRGIS||Natural Resources Geographic Information Systems|
|PLSS||Public Land Survey System|
|SMS||Soil Map Symbol|
|SMU||Soil Map Unit|
|SMEX02||Soil Moisture Experiment 2002|
|SSURGO||Soil Survey Geographic Data Base|
|TIGER||Topologically Integrated Geographic Encoding and Referencing|
|URL||Uniform Resource Locator|
|USDA||United States Department of Agriculture|
|USGS||United States Geological Survey|
|UTM||Universal Transverse Mercator|