Data Set ID:

SMEX02 Rain Gauge Network, Walnut Creek, Iowa, Version 1

This data set includes hourly precipitation data taken at 20 rain gauge locations as part of the Soil Moisture Experiment 2002 (SMEX02).

This is the most recent version of these data.

Version Summary:

initial release

BASIC Level of Service

Data: Data integrity verified

Documentation: Key metadata and links to supporting documentation available

User Support: Assistance with data access and basic data usage

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Data Format(s):
  • ASCII Text
Spatial Coverage:
N: 41.99, 
S: 41.94, 
E: -93.4, 
W: -93.8
Spatial Resolution:Not SpecifiedSensor(s):RAIN GAUGES
Temporal Coverage:
  • 1 June 2002 to 19 August 2002
Temporal ResolutionNot specifiedMetadata XML:View Metadata Record
Data Contributor(s):John Prueger

Geographic Coverage

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As a condition of using these data, you must cite the use of this data set using the following citation. For more information, see our Use and Copyright Web page.

Prueger, J. 2004. SMEX02 Rain Gauge Network, Walnut Creek, Iowa, Version 1. [Indicate subset used]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. doi: [Date Accessed].

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Detailed Data Description


Data are ASCII tab-delimited text files.

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File Size

File size is 1.7 MB.

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Total volume of combined files is 1.7 MB

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Spatial Coverage

Southernmost Latitude: 41.94°N
Northernmost Latitude: 41.99°N
Westernmost Longitude: 93.8°W
Easternmost Longitude: 93.4°W

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Temporal Coverage

Data were collected from 1 June 2002 to 19 August 2002.

Temporal Resolution

Data were gathered every hour.

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Parameter or Variable

The following table describes the columns in the data file.

Column/Parameter Unit Description
Site_ID Rain gauge identifier
Latitude degrees WGS84
Longitude degrees WGS84
UTM_Easting meters (m) WGS84, Zone 15
UTM_Northing meters (m) WGS84, Zone 15
Date mm/dd/yyyy Date measurement was taken
Hour 0 to 23 Hour measurement was taken (0 is midnight Central Standard Time)
Precip millimeters (mm) Amount of precipitation measured (missing data are represented by -99)

Sample Data Record

The following table shows a small sample of the data file.

SITE_ID lat lon Easting Northing DATE hour precip
703 41.9792 -93.6582 445452 4647680 6/1/2002 0 0
703 41.9792 -93.6582 445452 4647680 6/1/2002 1 0
703 41.9792 -93.6582 445452 4647680 6/2/2002 5 3.6
703 41.9792 -93.6582 445452 4647680 6/2/2002 6 0.8
703 41.9792 -93.6582 445452 4647680 6/2/2002 7 0
703 41.9792 -93.6582 445452 4647680 6/2/2002 8 1.3
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Software and Tools

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Data Acquisition and Processing

Theory of Measurements

Rain gauges are intended to provide continuous measurements of the precipitation at a single point, with many gauges distributed throughout the watershed.

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Sensor or Instrument Description

The sources are twenty rain gauges placed in crop fields in the study area. A Texas Electronics model TE525 tipping bucket rain gauge measured precipitation. The device consists of small cones that fill up and tip when a specific amount of rain falls into the cone. The number of tips is converted to a calculated rainfall amount. These data are logged to a Campbell Scientific CR10 datalogger.

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References and Related Publications

Contacts and Acknowledgments

John Prueger, Hydrologist
U.S. Department of Agriculture (USDA) Agriculture Research Service (ARS) National Soil Tilth Laboratory.


Dr. Prueger would like to acknowledge the National Soil Tilth Laboratory in Ames, Iowa for support in maintaining this rain gauge network.

Document Information


May 2004

No technical references available for this data set.

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