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This data set comprises gravimetric soil moisture and soil bulk density data collected during the Soil Moisture Experiment 2003 (SMEX03), which was conducted during June and July of 2003 in northern Alabama and southern Tennessee, USA. Data were collected at crop, pasture, and forested sites at depths of 0-3 and 3-6 cm. Data are provided in ASCII text and are available via FTP.
The Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E) is a mission instrument launched aboard the National Aeronautics and Space Administration (NASA) Aqua Satellite on 4 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.
To broaden awareness of our services, NSIDC requests that you acknowledge the use of data sets distributed by NSIDC. Please refer to the citation below for the suggested form, or contact NSIDC User Services for further information. We also request that you send us one reprint of any publication that cites the use of data received from our Center. This helps us to determine the level of use of the data we distribute. Thank you.
Archer, Frank and Charles Laymon. 2006. SMEX03 Regional Ground Soil Moisture Data: Alabama. Boulder, Colorado USA: National Snow and Ice Data Center. Digital media.
Category |
Description |
|---|---|
| Data format | Comma-delimited ASCII text |
| Spatial coverage and resolution | Southernmost Latitude: 34.71° N |
| Temporal coverage and resolution | 22 June 2003 to 2 July 2003 |
| File naming convention | GSM_AL_v2.txt, and BD_AL_v2.txt |
| File size | 11 KB and 54 KB |
| Parameter(s) | Gravimetric soil moisture and soil bulk density |
| Procedures for obtaining data | Data are available via FTP. |
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
Frank Archer
Alabama A&M University, Global Hydrology and Climate Center
Huntsville, Alabama
USA
Charles Laymon
Universities Space Research Association, Global Hydrology and Climate Center
NASA Marshall Space Flight Center
Huntsville, Alabama
USA
NSIDC User Services
National Snow and Ice Data Center
CIRES, 449 UCB
University of Colorado
Boulder, CO 80309-0449 USA
phone: +1 303.492.6199
fax: +1 303.492.2468
form: Contact NSIDC User Services
e-mail: nsidc@nsidc.org
We would like to thank Linda Cornett and Rashida Fambro at the Alabama A&M University, William Crosson and Ashutosh Limaye at the Marshall Space Flight Center, Huntsville, Alabama, and the many Alabama A&M students, faculty, and staff members who collected and processed the field data for this experiment.
Table 1 lists the files contained in this data set.
File Name |
Parameter |
File Size |
|---|---|---|
| GSM_AL_v2.txt | Ground Soil Moisture |
54 KB |
| BD_AL_v2.txt | Bulk Density |
11 KB |
Data are provided as comma-delimited text files. Table 2 and Table 3 list the column headings in each data file, and give a description of the type of information found under each column heading.
Column Heading |
Description |
|---|---|
| Date | Date readings made |
| DOY | Numerical day of the year |
| Site ID | Alabama site number (1-59) |
| Latitude | Latitude in decimal degrees |
| Longitude | Longitude in decimal degrees |
| 0-3 cm Can wt. (g) | Weight (g) of can at the 0-3 cm depth |
| 0-3 cm Wet wt. (g) | Weight (g) of soil and can at the 0-3 cm depth prior to drying |
| 0-3 cm Dry wt. (g) | Weight (g) of soil and can at the 0-3 cm depth after drying |
| 0-3 cm GSM (g/g) | Gravimetric soil moisture (g/g) of sample at the 0-3 cm depth |
| 3-6 cm Can wt. (g) | Weight (g) of can at the 3-6 cm depth |
| 3-6 cm Wet wt. (g) | Weight (g) of soil and can at the 3-6 cm depth prior to drying |
| 3-6 cm Dry wt. (g) | Weight (g) of soil and can at the 3-6 cm depth after drying |
| 3-6 cm GSM (g/g) | Gravimetric soil moisture (g/g) for sample at the 3-6 cm depth |
| Data Quality Flag | Data defined as missing and erroneous |
Column Heading |
Description |
|---|---|
| Date | Date readings made |
| DOY | Numerical day of the year |
| Site ID | Alabama site number (1-59) |
| Latitude | Latitude in decimal degrees |
| Longitude | Longitude in decimal degrees |
| 0-3 cm Can wt. (g) | Weight (g) of can at the 0-3 cm depth |
| 0-3 cm Dry wt. (g) | Weight (g) of soil and can at the 0-3 cm depth after drying |
| 0-3 cm BD g/cm3 | Bulk density (g/cm3) for sample at the 0-3 cm depth |
| 3-6 cm Can wt. (g) | Weight (g) of can at the 3-6 cm depth |
| 3-6 cm Dry wt. (g) | Weight (g) of soil and can at the 3-6 cm depth after drying |
| 3-6 cm BD g/cm3 | Bulk density (g/cm3) for sample at the 3-6 cm depth |
Southernmost Latitude: 34.71° N
Northernmost Latitude: 35.14° N
Westernmost Longitude: 87.05° W
Easternmost Longitude: 85.82° W
Data were collected daily from 22 June 2003 to 2 July 2003.
Cores were taken daily between 11:00 A.M. and 3:00 P.M. local time.
Parameters in this data set include gravimetric soil moisture (g/g) and soil bulk density (g/cm).
Below is a partial sample record from the GSM_AL_v2.txt data file. The first four columns and last four columns of the data file are shown, and only the first four data records are shown.
Date |
DOY |
Site ID |
Latitude |
... |
3-6 cm Can wt. (g) |
3-6 cm Wet wt. (g) |
3-6 cm Dry wt. (g) |
3-6 cm GSM (g/g) |
|---|---|---|---|---|---|---|---|---|
6/22/03 |
173 |
AL 01 |
35.111351 |
... |
38.18 |
169.60 |
144.89 |
0.232 |
6/22/03 |
173 |
AL 02 |
35.125375 |
... |
37.04 |
104.51 |
92.88 |
0.208 |
6/22/03 |
173 |
AL 03 |
35.050518 |
... |
37.95 |
133.97 |
119.62 |
0.176 |
6/22/03 |
173 |
AL 04 |
35.042841 |
... |
37.70 |
124.58 |
94.25 |
N/A |
Missing and erroneous data were identified based on field notes and post-experiment examination of output. Missing data are represented by the text -999.000, and suspect or questionable data values are noted in the last data column, titled Data Quality Flag.
Data are available via FTP.
The entire data set is 65 KB.
Please visit the SMEX03 Web site for other data sets that are related to the SMEX03 experiment.
The 0-6 cm soil moisture profile was measured using a standard soil core sampler, the barrel of which was loaded with two metal cylinders 3 cm high and hammered into the soil. Following extraction of the sampler, the cylinder containing the soil sample was removed from the barrel. The core was sliced with a wide spatula at 3 cm intervals and each slice was analyzed separately. Refer to Figure 2. If soil moisture conditions were favorable and the soil was relatively free from gravel and plant residue, samples suitable for bulk density determination were obtained. The samples that were suitable for bulk density determination were noted in the field. For AMSR-E validation purposes, soil moisture was sampled each day between 11:00 a.m. and 3:00 p.m. local time.
Figure 1: Demonstration of the Sliced Core Sampling Technique
The soil samples were weighed, dried, and then weighed again. Then the bulk density was computed using the following formula:
Bulk Density = dry soil mass extracted / soil volume extracted
And the gravimetric soil moisture was computed using the following formula:
Gravimetric soil moisture = (wet weight - dry weight) / dry weight
Please visit the SMEX03 Web site for more information, and see the NSIDC SMEX Web site to access data.
The following acronyms and abbreviations are used in this document.
| ASCII | American Standard Code for Information Interchange |
| AMSR-E | Advanced Microwave Scanning Radiometer – Earth Observing System |
| AVG | Average |
| BD | Bulk Density |
| FTP | File Transfer Protocol |
| GSM | Gravimetric Soil Moisture |
| NASA | National Aeronautics and Space Administration |
| NSIDC | National Snow and Ice Data Center |
| SMEX03 | Soil Moisture Experiment 2003 |
| URL | Uniform Resource Locator |
April 2006
http://nsidc.org/data/docs/daac/nsidc0287_smex03_reg_gsm_al.gd.html
