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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
Data Set ID:
NSIDC-0319
SMEX03 Surface and Soil Temperature Measurements: Alabama, Version 1
This is the most recent version of these data.
Overview
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Citing These Data
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: https://doi.org/10.5067/1F8EDIZP7W1C. [Date Accessed].Documentation
Detailed Data Description
Format
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.
|
Column Heading |
Units |
Description |
|---|---|---|
| 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 |
- |
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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Volume
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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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
Contributor(s) / Investigator(s):
William Crosson
Universities Space Research Association
Global Hydrology and Climate Center
NASA Marshall Space Flight Center
Hunstville, AL 35812
USA
Charles Laymon
Universities Space Research Association
Global Hydrology and Climate Center
NASA Marshall Space Flight Center
Hunstville, AL 35812
USA
Acknowledgments:
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
