SMEX02 Rain Gauge Network, Walnut Creek, Iowa

Summary

This data set includes hourly precipitation data taken at 20 rain gauge locations as part of the Soil Moisture Experiment 2002 (SMEX02). This study was conducted during June, July, and August 2002 in the Walnut Creek watershed in south-central Iowa, USA. Data were recorded every hour from 1 June through 19 August 2002 and 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.

Citing These Data

Prueger J., 2003. SMEX02 Rain Gauge Network, Walnut Creek, Iowa. Boulder, CO: National Snow and Ice Data Center. Digital media.

Overview Table

Category	Description
Data format	ASCII tab-delimited text files
Spatial coverage and resolution	42°N, 93°W
Temporal coverage and resolution	1 June 2002 to 19 August 2002 Data were gathered every hour
File size	1.7 MB
Parameter(s)	Precipitation intensity in mm
Procedures for obtaining data	Data are available via FTP.

Table of Contents

1. Contacts and Acknowledgments
2. Detailed Data Description
3. Data Access and Tools
4. Data Acquisition and Processing
5. References and Related Publications
6. Document Information

1. Contacts and Acknowledgments

Investigator(s) Name and Title

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

Technical Contact

Acknowledgements

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

2. Detailed Data Description

Format

Data are ASCII tab-delimited text files.

File Size

File size is 1.7 MB.

Spatial Coverage

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

Temporal Coverage

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

Temporal Resolution

Data were gathered every hour.

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

3. Data Access and Tools

Data Access

Data are available via FTP.

Volume

Total volume of combined files is 1.7 MB

Related Data Collections

• AMSR-E Validation Data
• AMSR-E Data at NSIDC

4. 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.

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.

5. References and Related Publications

Please see the SMEX02 site for more information, and the NSIDC SMEX site to access data.

6. Document Information

Acronyms and Abbreviations

The following acronyms and abbreviations are used in this document.

AMSR-E	Advanced Microwave Scanning Radiometer - Earth Observing System
FTP	File Transfer Protocol
SMEX	Soil Moisture Experiment
WC	Walnut Creek

Document Creation Date

May 2004

Document URL

http://nsidc.org/data/docs/daac/nsidc0236_smex_wc_rain_gauge.gd.html