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BOREAS RSS-07 Regional LAI and FPAR Images From 10-day AVHRR-LAC

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BOREAS RSS-07 Regional LAI and FPAR Images From 10-day AVHRR-LAC Powered By Docstoc
					Canada-Wide Mid-Growing Season LAI from SPOT4-VGT


Summary

This data set contains 3 Canada-wide images of overstory leaf area index (LAI)
at 1km gridded resolution corresponding to the period July 1-August31 for years
1998, 1999 and 2001. Leaf area index (LAI) is defined here as half the total
(all-sided) live foliage area per unit horizontal projected ground surface area.
Overstory LAI corresponds to all tree foliage except for treeless areas where it
corresponds to total foliage. Each LAI image is produced through averaging of
10-day period LAI estimates generated using ABC3V2-corrected (Cihlar et al.,
2001b) VGT ten-day composite images produced at CCRS. The algorithms were
developed from ground measurements and Landsat TM images (Fernandes et. al.,
2002). The data are provided in binary image format files.


Table of Contents

   *    1   Data Set Overview
   *    2   Investigator(s)
   *    3   Theory of Measurements
   *    4   Equipment
   *    5   Data Acquisition Methods
   *    6   Observations
   *    7   Data Description
   *    8   Data Organization
   *    9   Data Manipulations
   *   10   Errors
   *   11   Notes
   *   12   Application of the Data Set
   *   13   Future Modifications and Plans
   *   14   Software
   *   15   Data Access
   *   16   Output Products and Availability
   *   17   References
   *   18   Glossary of Terms
   *   19   List of Acronyms
   *   20   Document Information

1. Data Set Overview

1.1 Data Set Identification

Canada-wide 1km Grid Resolution Mid-Growing Season LAI Images From Ten-Day
SPOT4-VGT Composites

1.2 Data Set Introduction

Leaf area index (LAI) is defined as half the total (all-sided) live foliage area
per unit horizontal projected ground surface area. This data set contains 3
Canada-wide images of overstory LAI at 1km gridded resolution corresponding to
the period July 1-August31 for years 1998, 1999 and 2001. Each LAI
image is produced using ABC3V2 (Cihlar et al., 2001b) corrected AVHRR Level-4c
ten-day composite NDVI images produced at CCRS. The algorithms were developed
based on ground measurements and Landsat TM images (Fernandes et al., 2002).
The data are provided in binary image format files.



1.3 Objective/Purpose
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The objective of this data set was to provide quantitative spatial distributions
of LAI for Canada during the 1998, 1999 and 2000 growing for the purpose of
modeling the carbon, water, energy and trace gas exchange between the land
surface and the atmosphere. The dataset may also be useful for monitoring
changes in the land surface.

1.4 Summary of Parameters

LAI


1.5 Discussion

The LAI images are based on VGT Level-4c products and coregistered land cover
and land use maps (Cihlar et al., 1999; Cihlar et al., 2001b; Kerr et al.,
2002). The Level-4c product is based on the VGT Level-4b product, but is
further processed to remove or mitigate some artifacts caused by the input data
or the compositing process. The artifacts of concern are atmospheric
contamination and bidirectional reflectance effects. The processing was carried
out at the Canada Centre for Remote Sensing (CCRS) using software and procedures
developed in-house (see Section 9 for details). The spatial and temporal
coverage of this product is identical to that of the Level-4b and -4c products.


1.6 Related Data Sets

Fernandes et al., (2001) Water Fractions of Canada Compiled from NTDB Maps,
Canada Centre for Remote Sensing, Natural Resources Canada, unpublished.

Cihlar, J., Beaubien, J., Latifovic, R., and Simard, G., (1999), Land cover of
Canada Version 1.1. Special Publication, NBIOME Project. Produced by the Canada
Centre for Remote Sensing and the Canadian Forest Service, Natural Resources
Canada. Available on CD-ROM from the Canada Centre for Remote Sensing, Ottawa,
Ontario.

Cihlar, J., Beaubien, J., and Latifovic, R. 2001c. Land Cover of Canada 1998.
Digital data set documentation, Natural Resources Canada, Ottawa, ON.

Kerr, J.T., Cihlar, J., Trant, D. And Hoffmann, N. (2002). Land use and cover
with intensity assessment for Canada from satellite and census data, Ottawa,
Ontario: Natural Resources Canada.

2. Investigator(s)

2.1 Investigator(s) Name and Title

Dr. Richard Fernandes
Mr. Chris Butson
Mr. Sylvain Leblanc


2.2 Title of Investigation

Canada Wide Biophysical Parameter Mapping using Satellite Imagery


2.3 Contact Information

Contact 1
---------
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Richard A. Fernandes
Canada Centre for Remote Sensing
588 Booth Street, 4th Floor
Ottawa, Ontario
K1A0Y7 Canada
(613) 947-1292
(613) 947-1383 (fax)
Richard.Fernandes@ccrs.nrcan.gc.ca


Contact 2
---------
Josef Cihlar
Canada Centre for Remote Sensing
588 Booth Street, 4th Floor
Ottawa, Ontario
K1A0Y7 Canada
(613) 947-1265
(613) 947-1383 (fax)
Josef.Cihlar@ccrs.nrcan.gc.ca


3. Theory of Measurements



4. Equipment



5. Data Acquisition Methods



6. Observations


7. Data Description

7.1 Spatial Characteristics
Data covering the entire Canadian landmass were acquired for the land cover
product.

7.1.1 Spatial Coverage


Geographic projection: Lambert Conformal Conic (LCC)

Earth Ellipsoid E008 NAD83

Map corners (in metres):
Upper Left     -2600000E     10500000N
Upper Right     3100000E     10500000N
Upper Left     -2600000E      5700000N
Lower Right     3100000E      5700000N
Pixel Size        1000E         1000N

Map corners (in degrees) :
Upper Left Corner 177d17'32.21" W Lon 66d45'22.82" N Lat
Upper Right Corner   9d58'39.57" W Lon 62d25'50.45" N Lat
Image Center        89d56'43.00" W Lon 62d46'47.18" N Lat
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Lower Left Corner 122d54'49.00" W Lon 36d12'53.87" N Lat
Lower Right Corner 62d32'49.65" W Lon 34d18'05.61" N Lat

Reference Longitude/Latitude 95d00'00.00" W Lon 0d00'00.00" N Lat
1st/2nd Standard parallels    49d00'00.00" N Lat 77d00'00.00" N Lat


7.1.2 Spatial Coverage Map

N/A.

7.1.3 Spatial Resolution

1km x 1km

7.1.4 Projection


Geographic projection: Lambert Conformal Conic (LCC)
Earth Ellipsoid NAD83
Reference Longitude/Latitude 95d00'00.00" W Lon 0d00'00.00" N Lat
1st/2nd Standard parallels    49d00'00.00" N Lat 77d00'00.00" N Lat

7.1.5 Grid Description

Aligned with NRCan National 1km raster grid.

7.2 Temporal Characteristics

7.2.1 Temporal Coverage

The LAI estimate corresponds to the average of LAI estimates taken from 6
consequitive 10-day composites spanning July 1 to August 31 AFTER removing the
minimum and maximum composite values. The removal of extreme values was
performed both to reduce biased due to atmospheric contamination and to reduce
the impact of spatial differences in growing seasons.

A disturbance early in the averaging period will likely result in the LAI
representative of post-disturbance conditions (the opposite for a late
disturbance). This averaging procedure will result in errors if a disturbance
occurred during the middle of the period.

7.2.2 Temporal Coverage Map


7.2.3 Temporal Resolution


7.3 Data Characteristics

7.3.1 Parameter/Variable

LAI


7.3.2 Variable Description/Definition

LAI is defined as one- half the total leaf area per unit ground surface area
projected on the local horizontal datum. To derive LAI from the digital counts
in the image:

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LAI = (DN)/20


7.3.3 Unit of Measurement

LAI is unitless but corresponds to m2 of leaf area per m2 of ground surface area
projected on the local horizontal datum.

7.3.4 Data Source

The ABC3 corrected Level-4c VGT data used to create this product was processed
and provided by the CCRS.

7.3.5 Data Range

The LAI products are 8-bit images; i.e., the digital values (DN) vary from 0 to
255. The range of LAI depends on land cover, but is typically within the range
(0, 10).

7.4 Sample Data Record

Not applicable.

8. Data Organization

8.1 Data Granularity

The smallest unit of data is the entire images for 1 year.

8.2 Data Format(s)

8.2.1 Uncompressed Data Files

The image files are    all 8-bit binary images with 5800 pixels per line and 4700
lines.
vgtlai98.raw - 1998    LAI
vgtlai99.raw - 1999    LAI
vgtlai00.raw - 2000    LAI



8.2.2 Compressed CD-ROM Files

9. Data Manipulations

Refer to Fernandes et al. 2002 for derivations.

9.1 Formulae

9.1.1 Derivation Techniques and Algorithms


9.2.2 Processing Changes

Screening was performed to replace all LAI values greater than 10.0 by with a
3x3 modal filtered value. These values are rare and corresponded to edges of
water/land or ice/land.

Screening was performed to assign all LAI values greater than 10.0 to zero if
they occurred in Barren Land, tundra or ice.

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LAI in wetlands was assigned the minimum of the mid-growing season values over
the three years (i.e. the minimum of the 1998, 1999 and 2000 averages over the
growing season period). The identification of persistent wetlands was
accomplished by comparing shortwave and red based spectral indices. Large
deviations indicated wetlands. While it is possible to replace the SWIR index
LAI with the simple ratio based LAI we found that spatial variability was large
(likely due to variations in leaf type and understory to which the red based
index is sensitive). The 1998 period was exceptionally dry and may therefore
produce lower bias errors in terms of LAI over wet regions. In most instances
the minimum of the three dates was found to be 1998.


The uncorrected LAI maps are available on request as they may have use in
detecting wetlands.

None.

9.3 Calculations

See Section 9.2.1.

9.3.1 Special Corrections/Adjustments

See Section 9.2.1.

9.3.2 Calculated Variables

See Section 9.2.1.

9.4 Graphs and Plots

None.

10. Errors


10.2 Quality Assessment

10.2.1 Data Validation by Source

None given.

10.2.2 Confidence Level/Accuracy Judgement


10.2.3 Measurement Error for Parameters

See Section 10.2.2.

10.2.4 Additional Quality Assessments

None given.

10.2.5 Data Verification by Data Center


11. Notes

11.1 Limitations of the Data



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The calculated LAI maps should be considered as the best, traceable, LAI
estimate for this moderate resolution. The sensor point spread function and
resampling scheme used for the original channel images makes the actual
resolution coarser than 1 km. It is on the order of 2-3 km or coarser in reality
(Fernandes et al., 2002). Changes in subpixel water bodies and mixture of
different cover types in a pixel can incur errors in the calculated results.
Lack of data makes the calculations for rangeland, tundra, and mixed wood types
least reliable.



11.2 Known Problems with the Data

None.

11.3 Usage Guidance


11.4 Other Relevant Information

None.

12. Application of the Data Set

None given.

13. Future Modifications and Plans

None given.

14. Software

14.1 Software Description


14.2 Software Access


15. Data Access

15.1 Contact Information


See Section 15.1.

15.3 Procedures for Obtaining Data

Users may place requests by letter, telephone, electronic mail, fax, or personal
visit.

15.4 Data Center Status/Plans


16. Output Products and Availability



17. References



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Fernandes, R.A., Butson, C.B., Leblanc, S.G. and Latifovic, R., submitted, A Landsat TM/ETM+ based
accuracy assessment of leaf area index products for Canada derived from SPOT4/VGT data 4, submitted
January 2002, Canadian Journal of Remote Sensing.
20. Document Information

20.1 Document Revision Date

      Written:              26-May-2002
      Last Updated:         26-May-2002

20.2 Document Review Date(s)

      BORIS Review:
      Science Review:

20.3 Document ID

20.4 Citation


Fernandes, R.A., Butson, C.B., Leblanc, S.G. and Latifovic, R., submitted, A Landsat TM/ETM+ based
accuracy assessment of leaf area index products for Canada derived from SPOT4/VGT data 4, submitted
January 2002, Canadian Journal of Remote Sensing.

20.5 Document Curator

20.6 Document URL




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