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Data Set ID:

SMEX03 Surface and Soil Temperature Measurements: Alabama, Version 1

This data set contains land surface temperature and soil temperature data collected during the Soil Moisture Experiment 2003 (SMEX03) in northern Alabama and southern Tennessee

Geographic Coverage

  • Land Temperature > Land Surface Temperature
  • Soils > Soil Temperature
Spatial Coverage:
  • N: 35.16, S: 34.68, E: -85.78, W: -87.07

Spatial Resolution: Not Specified
Temporal Coverage:
  • 21 June 2003 to 2 July 2003
Temporal Resolution: Not specified
Data Format(s):
  • Microsoft Excel
  • ASCII Text
Version: V1
Data Contributor(s): William Crosson, Charles Laymon
Data Citation

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.

Crosson, W. and C. Laymon. 2007. SMEX03 Surface and Soil Temperature Measurements: Alabama, Version 1. [Indicate subset used]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. doi: http://dx.doi.org/10.5067/1F8EDIZP7W1C. [Date Accessed].

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Detailed Data Description


Data are provided in a Microsoft Excel file and as a tab-delimited ASCII text file. The text file contains the same data as the Excel file. Table 1 lists the column headings and data field descriptions for the files.

Table 1. Column Headings and Data Field Descriptions

Column Heading



Date MM/DD/YY Date of measurements
DOY DDD Numerical day of year (Julian Date)
Time HH:MM Time of day in Central Daylight Time (CDT)


Site number (1-59)
Lat decimal degrees Latitude of site
Long decimal degrees Longitude of site
Surface °C Land surface temperature
1 cm °C Soil temperature at 1 cm depth
5 cm °C Soil temperature at 5 cm depth
10 cm °C Soil temperature at 10 cm depth
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File Naming Convention

The Excel file is named Soil_Temps_AL.xls. The ASCII text file is named Soil_Temps_AL.txt.

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File Size

The Excel file is 111 KB. The ASCII text file is 35 KB.

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The total volume of all data files is 146 KB.

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Spatial Coverage

Southernmost Latitude: 34.68 º N
Northernmost Latitude: 35.16º N
Westernmost Longitude: 87.07º W
Easternmost Longitude: 85.78º W

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Temporal Coverage

Data were collected from 21 June 2003 to 2 July 2003.

Temporal Resolution

Temperature readings were taken daily. 

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Parameter or Variable

Parameter Description

Parameters in this data set are land surface temperature (°C) and soil temperature ( °C) at depths of 1 cm, 5 cm, and 10 cm. A daily mean was calculated for each variable.

Sample Data Record

The following sample shows the first five rows of the Soil_Temps_AL.txt file.

Date DOY Time Site Lat Long Surface 1 cm 5 cm 10 cm
6/22/03 173 12:55 1 35.1114 -87.0021 36.0 33.5 32.2 27.3
6/22/03 173 11:24 2 35.1254 -86.8723 32.0 26.5 24.3 24.1
6/22/03 173 12:37 3 35.0505 -86.9961 48.0 29.7 26.6 25.2
6/22/03 173 12:00 4 35.0428 -86.8654 25.0 30.7 29.5 28.4
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Error Sources and Limitations

Due to breakage of the soil temperature sensors in hard soils, some sites were not sampled on particular days. Enough sensors broke to deplete the supply of spares, resulting in several sites not being sampled during the last few days of the experiment. Data that were not collected are flagged as -9999. Errors in land surface temperature are related mainly to representativeness of the readings. Variability at a given site could be extremely large (> 20° C), particularly for crop sites which comprised a mixture of bare soil and vegetation, therefore a single reading may not represent the mean land surface temperature very well.

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Data Acquisition and Processing

Data Acquisition Methods

Data were collected at 59 locations in Alabama and southern Tennessee which included crop, pasture, and forested sites. Surface temperature measurements were made daily at each of the sites and recorded in field books. The infrared thermometers were pointed at the ground at a near-nadir angle. The protocol was for several readings to be made and an average recorded, but some teams took only a single reading. Soil temperatures were measured daily at depths of 1 cm, 5 cm, and 10 cm for each of the field sites. The thermometer was inserted vertically into the soil and allowed time for stabilization at each depth. Values were recorded in the field books. For AMSR-E validation purposes, temperatures were measured each day between 11:00 a.m. and 3:00 p.m. CDT.

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Sensor or Instrument Description

Investigators used a Raytek Raynger MT4 MiniTemp hand-held infrared thermometer to measure land surface temperature. The instrument has a range of -18°C to 400°C and a pre-set emissivity of 0.95. Accuracy is ±2 percent of reading or ±2°C, whichever is greater, for targets at -1°C to 260°C, and ±3°C for targets at -18°C to -1°C. Visit the Raytek Web site for more information. Soil temperatures were measured with a Taylor Switchable Digital Pocket Thermometer. Visit the Taylor Web site for more information.

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References and Related Publications

Contacts and Acknowledgments

William Crosson
Universities Space Research Association
Global Hydrology and Climate Center
NASA Marshall Space Flight Center
Hunstville, AL 35812

Charles Laymon
Universities Space Research Association
Global Hydrology and Climate Center
NASA Marshall Space Flight Center
Hunstville, AL 35812


The investigators would like to acknowledge Frank Archer, Karnita Golson, Linda Cornett, Alabama A&M University, and the many Alabama A&M students, faculty,and staff members who collected and processed the field data.

Document Information

Document Creation Date

October 2007

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