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This data set contains the vegetation parameters plant height, row spacing, stand density, and leaf area index (LAI) as part of the Soil Moisture Experiment 2002 (SMEX02).
Data Set ID:
NSIDC-0188
SMEX02 Regional Vegetation Sampling Data, Iowa, Version 1
This is the most recent version of these data.
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Data: Data integrity verified
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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.
Anderson, M. 2003. SMEX02 Regional Vegetation Sampling Data, Iowa, Version 1. [Indicate subset used]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. doi: https://doi.org/10.5067/0Q8WOQ3RC8DQ. [Date Accessed].Collapse All / Open All
Detailed Data Description
Format
Data are provided as ASCII text files.
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File Naming Convention
"IA_LAI_Raw.txt" contains the raw data; "IA_LAI_Sum.txt" contains the summary data.
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File Size
File sizes are: "IA_LAI_Raw.txt" 16.0 KB, and "IA_LAI_Sum.txt" 3.76 KB.
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Volume
Total volume of the data files is 19.76 KB.
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Spatial Coverage
Southernmost Latitude: 41.7° N
Northernmost Latitude: 42.7° N
Westernmost Longitude: 93.8° W
Easternmost Longitude: 93.2° W
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Temporal Coverage
Dates for sampling were 29 and 30 June, and 3, 9, 28, and 29 July 2002.
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Parameter or Variable
Parameter Description
The parameters are plant height, row spacing, stand density, and leaf area index (LAI).
The following table describes each column in the "IA_LAI_Raw.txt" data file.
| Column heading | Description |
|---|---|
| SITE | Site location number |
| SAMPLE | Sampling point 1-5 for each site location |
| Latitude | Latitude of the sampling site |
| Longitude | Longitude of the sampling site |
| UTM_East | UTM Easting in meters (Zone 15) |
| UTM_North | UTM Northing in meters (Zone 15) |
| LAI | Leaf Area Index |
| Date | MM/DD/YYYY |
| DAY | Numerical day of the year (Julian date) |
| Time | HHMMSS (Central Standard Time) |
| Adjusted | Readings corrupted by sun glare were adjusted by an interpolated estimate |
The following table describes each column in the "IA_LAI_Sum.txt" data file.
| Column heading | Description |
|---|---|
| SITE | Site location number |
| Latitude | Latitude of the sampling site |
| Longitude | Longitude of the sampling site |
| UTM_East | UTM Easting in meters (Zone 15) |
| UTM_North | UTM Northing in meters (Zone 15) |
| DOY | Numerical day of the year (Julian date) |
| date | MM/DD/YYYY |
| LAI-Mean | Mean Leaf Area Index |
| LAI-StDev | Standard deviation of Leaf Area Index |
| Crop | C=Corn, S=Soy |
| Row_Spacing in m | Space between rows in meters |
| Row_Density | Number of plants in one meter |
| Height in m | Vegetation height in meters |
Unit of Measurement
- LAI - The ratio of the area of the upper side of the leaves projected onto a flat surface to the area of the surface.
- Row spacing - The distance in meters between the center of one plant row to the center of the next crop row.
- Row density - The number of plants in one meter within a row.
- Height - The height of the upper leaves in a crop row.
Parameter Source
LAI is measured by a plant canopy analyzer. Row spacing, row density, and plant height were measured manually.
Sample Data Record
The following sample is taken from the "IA_LAI_Raw.txt" data file.
| SITE | SAMPLE | Latitude | Longitude | UTM_East | UTM_North | LAI | Date | DOY | TIME | Adjusted |
|---|---|---|---|---|---|---|---|---|---|---|
| IA01 | 1 | 42.65988 | -93.71737 | 441207 | 4723296 | 2.45 | 6/30/2002 | 181 | 11:53:30 | ** |
| IA01 | 2 | 42.65988 | -93.71737 | 441207 | 4723296 | 2.71 | 6/30/2002 | 181 | 11:55:24 | ** |
| IA01 | 3 | 42.65988 | -93.71737 | 441207 | 4723296 | 1.87 | 6/30/2002 | 181 | 11:57:01 | |
| IA01 | 4 | 42.65988 | -93.71737 | 441207 | 4723296 | 2.06 | 6/30/2002 | 181 | 11:58:21 |
The next sample is taken from the "IA_LAI_Sum.txt" data file.
| SITE | Latitude | Longitude | UTM_East | UTM_North | DOY | date | LAI-Mean | LAI-StDev | Crop | Row_Spacing in m | Row_Density | Height in m |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| IA01 | 42.65988 | -93.71737 | 441207 | 4723296 | 181 | 6/30/2002 | 2.252 | 0.023 | C | 0.75 | 7 | 1.524 |
| IA02 | 42.58718 | -93.70582 | 442086 | 4715215 | 181 | 6/30/2002 | 2.612 | 0.034 | C | 0.75 | 7 | 2.1336 |
| IA03 | 42.50662 | -93.71921 | 440911 | 4706278 | 181 | 6/30/2002 | 1.29 | 0.072 | S | 0.75 | 30 | 0.381 |
| IA04 | 42.41222 | -93.72801 | 440099 | 4695803 | 181 | 6/30/2002 | 2.39 | 0.089 | C | 0.75 | 6 | 1.524 |
| IA05 | 42.34171 | -93.72867 | 439977 | 4687974 | 181 | 6/30/2002 | 1.398 | 0.025 | C | 0.75 | 6 | 1.397 |
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Software and Tools
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Data Acquisition and Processing
Theory of Measurements
The purpose of vegetative sampling is to provide an estimate of the variation in the vegetative components in the corn and soybean fields across the SMEX02 study sites. Sampling dates are provided in the data files for each field.
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Data Acquisition Methods
Five locations were sampled in each field in the IA regional soil moisture sampling site. Samplers chose locations far enough away from each other to gain independent samples. At each location, leaf area was measured at four locations (in-row, ¼ across row, ½ across row, ¾ across row) with the plant canopy analyzer. The first sampling position was between the first row and the row to the left.
Leaf area was measured in the inter-row region at least one meter away from where the manual samples were taken. The analyzer was set to average four locations into a single value, so one observation was taken above the canopy and four beneath the canopy; in the row, ¼ of the way across the row, ½ of the way across the row, and ¾ of the way across the row. This gave a good spatial average for row crops of partial cover. The sampler always stood with the back to the sun (if it was shining). A lens cap that blocks ¼ of the sensor view was always in place and positioned so the sun and the sampler were never in the view of the sensor.
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Derivation Techniques and Algorithms
Error Sources
In the final processing, certain LAI readings were determined to have been corrupted by sun glare. These readings were adjusted or recovered by replacing an interpolated estimate. This was done for approximately 36 of the 236 readings, and one reading was determined to be too corrupted to adjust. A value of "-99" indicates missing or corrupt data.
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Sensor or Instrument Description
LAI sampling was done using LI-COR LAI-2000 instruments.
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References and Related Publications
Contacts and Acknowledgments
Martha Anderson
Assistant Scientist
Space Science and Engineering Center
University of Wisconsin, Madison, WI, USA.
Acknowledgments:
Many graduate students and volunteers collected the field data.
Document Information
DOCUMENT CREATION DATE
September 2003
No technical references available for this data set.
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