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Data Set ID:
NSIDC-0298

SMEX03 Vegetation Data: Georgia, Version 1

This data set includes data collected over the Soil Moisture Experiment 2003 (SMEX03) area of Georgia, USA.

Geographic Coverage

Parameter(s):
  • Vegetation > Biomass
  • Vegetation > Plant Characteristics
  • Atmospheric Radiation > Reflectance
  • Soils > Soil Moisture/Water Content
  • Vegetation > Vegetation Cover
  • Vegetation > Vegetation Index
Spatial Coverage:
  • N: 31.82, S: 31.2, E: -83.43, W: -83.94

Spatial Resolution: Not Specified
Temporal Coverage:
  • 16 June 2003 to 21 July 2003
Temporal Resolution: Not specified
Data Format(s):
  • ASCII Text
Platform(s) GROUND-BASED OBSERVATIONS
Sensor(s): LICOR PLANT CANOPY ANALYZER, RADIOMETERS
Version: V1
Data Contributor(s): David Bosch, Laura Marshall, Diane Rowland, James Jacobs
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.

Bosch, D., L. Marshall, D. Rowland, and J. Jacobs. 2008. SMEX03 Vegetation Data: Georgia, 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/UAPN8GAYSU83. [Date Accessed].

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Detailed Data Description

This data set includes data collected over the Soil Moisture Experiment 2003 (SMEX03) area of Georgia, USA.

The following table gives an overview of the data contained in each file.
 

Table 1. Data Overview
File Name Data Description
GA_SMEX03_forest_plants.txt Plant identification data for forest sites
GA_SMEX03_forest_raw.txt Site characterization data for forest sites
GA_SMEX03_reflectance_raw.txt Multispectral Radiometer Reflectance data only
GA_SMEX03_roughness_raw.txt Raw surface roughness measurements
GA_SMEX03_vegetation_raw.txt Site characterization data for cotton, peanut, and pasture sites
Format

Data are in tab-delimited ASCII text files.

The following tables describe the column headings for the files in this dataset.
 

Table 2. Column Headings for GA_SMEX03_forest_plants.txt
Column Column Heading Description
1
Site Site location identification code
2
Plot Plot number
3
Common Name Plant common name
4
Scientific Name Plant scientific name
5
Notes Data collection notes


 

Table 3. Column Headings for GA_SMEX03_forest_raw.txt
Column Column Heading Description
1
Site Site location identification code
2
Crop Type of vegetation
3
Date Month / day / year
4
Plot Plot number
5
RowSpacing(m) Space between tree rows in meters
6
TreeDensity(trees/m) Trees per unit length in rows in trees per meter
7
TreeDensity(trees/ha) Trees per unit area in trees per hectare
8
TreeHeight(m) Average tree height in meters
9
DiameterAtBreastHeight(m) Tree diameter at breast height in meter
10
AverageBasalArea(m2) Average basal area in meters squared
11
Canopy(%) Percentage of canopy cover
12
ArealPlantWater(kg/m2) Areal plant water content of understory in kilograms per meters squared
13
ArealPlantGreen(kg/m2) Areal plant green biomass of understory in kilograms per meters squared
14
LAI Leaf area index (m2/m2)
15
UnderstoryVegetation(%GroundCover) Understory vegetation cover in percentage of ground cover
16
UnderstoryPineNeedleLitter(%GroundCover) Understory pine needle litter cover in percentage of ground cover
17
UnderstoryBareSoil(%GroundCover) Understory bare soil in percentage of ground cover
18
Notes Data collection notes


 

Table 4. Column Headings for GA_SMEX03_reflectance_raw.txt
Column Column Heading Description
1
Site Site location identification code
2
Crop Type of vegetation
3
Date Month / day / year
4
Plot# Plot number
5
Row/Position Row ID
6
Latitude Latitude in decimal degrees, WGS84
7
Longitude Longitude in decimal degrees, WGS84
8
Time Time of sampling in Eastern Daylight Time (EDT)
9
SunAngle Angle of the sun during reading in degrees
10
IrradianceAt560nm(watts/m2/micron) Sun irradiance at 560 nm in watts per meters squared per micron
11
485 MSR Reflectance (avgerage of % reflectance at 485 nm)
12
560 MSR Reflectance (avgerage of % reflectance at 560 nm)
13
650 MSR Reflectance (avgerage of % reflectance at 650 nm)
14
660 MSR Reflectance (avgerage of % reflectance at 660 nm)
15
830 MSR Reflectance (avgerage of % reflectance at 830 nm)
16
850 MSR Reflectance (avgerage of % reflectance at 850 nm)
17
1240 MSR Reflectance (avgerage of % reflectance at 1240 nm)
18
1640 MSR Reflectance (avgerage of % reflectance at 1640 nm)
19
1650 MSR Reflectance (avgerage of % reflectance at 1650 nm)
20
Notes Data collection notes
Table 5. Column Headings for GA_SMEX03_roughness_raw.txt
Column Column Heading Description
1
Site Site location identification code
2
Crop Type of vegetation
3
Date Month / day / year
4
PlotNumber Plot number
5
AcrossRowOrAlongRow Direction of measurements
6
NumberOfPoints Number of points sampled
7
RMS(cm) Root mean square height in centimeters
8
CorrelationLength(cm) Correlation length in centimeters
9
Adjusted RMS Adjusted root mean square height in centimeters
10
"Power Function,n" Power function

Table 6. Column Headings for GA_SMEX03_vegetation_raw.txt
Column Column Heading Description
1
Site Site location identification code
2
Crop Type of vegetation
3
Date Month / day / year
4
Plot Plot number
5
Row For row crop sites, row ID; no rows for pasture
6
Latitude Latitude in decimal degrees, WGS84
7
Longitude Longitude in decimal degrees, WGS84
8
CropDensity(plants/m^2) Crop density in plants per meters squared
9
PlantHeight(cm) Plant height in centimeters
10
GreenBiomass(kg/m^2) Plant green biomass in kilograms per meters squared
11
DryBiomass(kg/m^2) Plant dry biomass in kilograms per meters squared
12
AboveGroundMoisture(kg/m^2) Above ground moisture content in kilograms per meters squared
13
LAI Leaf area index (m2/m2)
14
Sun/Shade Sun conditions during LAI reading
15
GrowthStage Description of growth stage

The collection sites noted in column 1 of each file are distinguished by a location identification code where:

GA = Georgia
V = vegetation site
## = site number
 
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File Size

File sizes range from 1 KB to 34 KB.

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Volume

Total volume is approximately 176 KB.

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Spatial Coverage

Southernmost Latitude: 31.20 º N 
Northernmost Latitude: 31.82 º N
Westernmost Longitude: 83.94 º W
Easternmost Longitude: 83.43 º W

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Temporal Coverage

16 June 2003 to 21 July 2003

Temporal Resolution

Data was collected on multiple days at multiple sites.

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Parameter or Variable

Parameter Description

Parameters in this data set are Leaf Area Index (LAI), Multispectral Radiometer (MSR) Reflectance, plant height, plant density, areal wet biomass, areal dry biomass, and areal water content. The following table describes the units of measurement and sources of each parameter.

Table 7. Parameter Descriptions
Parameter Unit of Measurement Sensor
LAI m2/m2 LI-COR LAI-2000
MSR Reflectance percentage CROPSCAN MSR-16R
Plant Height cm manual data collection
Plant Density plants/m2 manual data collection
Areal Wet Biomass kg/m2 manual data collection
Areal Dry Biomass kg/m2 manual data collection
Areal Water Content kg/m2 manual data collection

Sample Data Record

Sample files of this data set are shown below. The value -99 is a fill value for missing data.

The following sample of 4 rows shows all five columns from the file GA_SMEX03_forest_plants.txt.

 
        Site    Plot    Common Name             Scientific Name         Notes
        GAV29   1       American beauty bush    Callicarpa americana	
                        verbena                 Verbena sp.	
                        iron weed               Veronia sp.	
                        bahaia grass            Paspalum notatum        50% of vegetation

The following sample of 4 rows shows the first four columns and the last two columns from GA_SMEX03_forest_raw.txt.

 
        Site    Crop         Date        Plot   ...   UnderstoryBareSoil(%GroundCover)   Notes	
        GAV29   slash pine   6/24/2003   1      ...   5                                  Every 4th row cut	
        GAV29   slash pine   6/24/2003   2      ...   5                                  Every 4th row cut	
        GAV49   slash pine   6/26/2003   1      ...   10                                 Every 2nd row cut	
        GAV49   slash pine   6/26/2003   2      ...   10                                 Every 2nd row cut	

The following sample of 4 rows shows the first four columns and the last two columns from GA_SMEX03_reflectance_raw.txt.

	
        Site    Crop                Date        Plot#   ...   1650    Notes
        GAV20   Strip till cotton   6/18/2003   -99     ...   -99     cloudy, no data collected
        GAV20   Strip till cotton   6/25/2003   1       ...   38.74	
        GAV20   Strip till cotton   6/25/2003   1       ...   39.87	
        GAV20   Strip till cotton   6/25/2003   1       ...   36.64	

The following sample of 4 rows shows the first four columns and the last two columns from GA_SMEX03_roughness_raw.txt.

        Site    Crop                Date        PlotNumber   ...   AdjustedRMS   "PowerFunction,n"
        GAV20   strip-till-cotton   6/18/2003   1            ...   0.945         1
        GAV20   strip-till-cotton   6/18/2003   1            ...   1.68          1
        GAV20   strip-till-cotton   6/18/2003   2            ...   0.855         1.2
        GAV20   strip-till-cotton   6/18/2003   2            ...   1.056         1.1

The following sample of 4 rows shows the first four columns and the last two columns from GA_SMEX03_vegetation_raw.txt.

        Site    Crop                Date        Plot   ...   Sun/Shade   GrowthStage
        GAV20   strip-till-cotton   6/18/2003   1      ...   SHADE       3-node,young
        GAV20   strip-till-cotton   6/18/2003   1      ...   SHADE	
        GAV20   strip-till-cotton   6/18/2003   1      ...   SHADE	
        GAV20   strip-till-cotton   6/18/2003   1      ...   SHADE	
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Software and Tools

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Data Acquisition and Processing

Sampling

Sampling was performed on fields typical of the South-Georgia Agricultural area. The sampling was concentrated in the Upper Suwannee Watershed, with a greater concentration of sites within the Little River Experimental Watershed. Sampling consisted of recording vegetation height and plant density, collecting vegetation biomass samples, and taking MSR reflectance and LAI measurements. Two locations in each of the row crop and forest sites were sampled, while three locations were sampled at the pasture sites. Every effort was made to have these locations coincide with soil moisture sampling points. Sampling was conducted between 10:00 and 14:00 EDT.

Vegetation Moisture

Samples were collected manually. In the laboratory they were weighed, dried at 60 degrees Celsius for 48 to 96 hours, and then weighed again.

Computing Areal Water Content

The following steps were used to compute areal water content:

Row Crops:

  • Determine by manual collection the water content for a known number of plants, convert to a per plant basis
  • Calculate the number of plants per square meter using the row and plant spacing
  • Multiply the water content per plant by the number of plants per square meter to get water content per square meter

Non-Row Crops:

  • Determine by manual collection the water content for a 0.44 meter by 0.44 meter area
  • Divide the water content by 0.1936 to get water content per square meter

LAI

LAI measurements made above and below the canopy were used to determine canopy light interception at five angles. Measurements were made by positioning the optical sensor and pressing a button, which sent the data to the data logger. Multiple below-canopy readings were taken so that LAI calculations were based on a large sample of the foliage canopy.

MSR Reflectance

The MSR reflectance wavelengths measured were: 485, 560, 650, 660, 830, 850, 1240, 1640, 1650 nm. These bands provided data for selected channels of the LandSat TM and MODIS instruments. Channels were chosen to provide a Normalized Difference Vegetation Index (NDVI) as well as a variety of vegetation water content indices under consideration.

Theory of Measurements

The goal of vegetation sampling is to generate the vegetation products used to estimate surface soil moisture detected by passive microwave radiometers. Sampling was designed to coincide with satellite overpasses, such as LandSat Thematic Mapper (TM) and Terra-MODIS, which can be used to estimate vegetation water content on the regional scale.

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Derivation Techniques and Algorithms

Errors and Limitations

LAI

Direct-beam radiation reflected into the sensor from upper leaves in the canopy can be confused with open sky. This causes the LAI to be underestimated. Samplers were instructed to sample with the sun to their backs, but occasionally direct sunlight may enter the sensor. The data were examined for this and for evidence of variable sky conditions during the measurement sequence.

MSR Reflectance

The MSR measures near simultaneous inputs of incident as well as reflected irradiation. Useful measurements of percent reflectance may be obtained during cloudy conditions with incident irradiance levels down to approximately 300 watts per square meter. Measurements obtained with an incident irradiance level of less than 300 watts had to be discarded. Several days were too cloudy to take any multispectral radiometer measurements.

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Sensor or Instrument Description

Leaf Area Index Meter

Investigators used LI-COR LAI-2000 plant canopy analyzers to measure LAI using an indirect noncontact method based on light transmittance through the canopy. The LAI-2000 calculates LAI from radiation measurements made with a fish-eye optical sensor (148 degree field-of-view).

For more information, visit the LI-COR LAI-2000 product Web site.

Multispectral Radiometer

Investigators used the MSR-16R manufactured by CROPSCAN to measure reflectance. The MSR is an inexpensive instrument that has up-and-down-looking detectors and the ability to measure sunlight at different wavelengths. It uses silicon or germanium photodiodes as light transducers. Matched sets of the transducers with filters to select wavelength bands are oriented in the MSR housing to measure incident and reflected irradiation.

For more information, visit the CROPSCAN MSR product Web site.

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References and Related Publications

Contacts and Acknowledgments

Investigator(s)

David D. Bosch 
USDA ARS Southeast Watershed Research Lab
Tifton, Georgia 
USA

Laura Marshall 
USDA ARS Southeast Watershed Research Lab
Tifton, Georgia 
USA

Diane Rowland 
USDA ARS National Peanut Research Lab
Dawson, Georgia 
USA

James Jacobs 
Montana State University
Bozeman, Montana 
USA

Acknowledgments: 

The investigators would like to acknowledge the following people: The many graduate students and volunteers worked to collect the field data. The Soil Moisture Experiment 2003 Science Team and the Grazinglands Research Laboratory for their assistance. The National Aeronautics and Space Administration (NASA) for their generous contributions to the study. This work was supported by the NASA Aqua AMSR, Terrestrial Hydrology and Global Water Cycle Programs.

Document Information

DOCUMENT CREATION DATE

5 June 2008

DOCUMENT REVISION DATE

N/A

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