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SMEX03 Regional Ground Soil Moisture Data: Alabama

Summary

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.

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

We kindly request that you cite the use of this data set in a publication using the following citation example. For more information, see our Use and Copyright Web page.

Archer, F. and C. Laymon. 2006. SMEX03 Regional Ground Soil Moisture Data: Alabama. [indicate subset used]. Boulder, Colorado USA: NASA DAAC at the National Snow and Ice Data Center.

Overview Table

Category
Description
Data format Comma-delimited ASCII text
Spatial coverage and resolution

Southernmost Latitude: 34.71° N
Northernmost Latitude: 35.14 N
Westernmost Longitude: 87.05 W
Easternmost Longitude: 85.82 W

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.

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)

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

Technical Contact

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

Acknowledgements

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.

2. Detailed Data Description

File Descriptions

Table 1 lists the files contained in this data set.

Table 1: 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

Format

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.

Table 2: Column Headings and Description for the GSM_AL _v2.txt
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


Table 3: Column Headings and Description for the BD_AL_v2.txt
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

Spatial Coverage

Southernmost Latitude: 34.71 N
Northernmost Latitude: 35.14 N
Westernmost Longitude: 87.05 W
Easternmost Longitude: 85.82 W

Temporal Coverage

Data were collected daily from 22 June 2003 to 2 July 2003.

Temporal Resolution

Cores were taken daily between 11:00 A.M. and 3:00 P.M. local time.

Parameter or Variable

Parameter Description

Parameters in this data set include gravimetric soil moisture (g/g) and soil bulk density (g/cm).

Sample Data Record

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


Error Sources

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.

3. Data Access and Tools

Data Access

Data are available via FTP.

Volume

The entire data set is 65 KB.

Related Data Collections

Please visit the SMEX03 Web site for other data sets that are related to the SMEX03 experiment.

4. Data Acquisition and Processing

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.

Demonstraton of the Sliced Core Sampling Technique

Figure 1: Demonstration of the Sliced Core Sampling Technique


Processing Steps

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

5. References and Related Publications

Please visit the SMEX03 Web site for more information, and see the NSIDC SMEX Web site to access data.

6. Document Information

List of Acronyms

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

 

Document Creation Date

April 2006

Document URL

http://nsidc.org/data/docs/daac/nsidc0287_smex03_reg_gsm_al.gd.html