Leaf Area Index Calibration of RapidEye Satellite Imagery

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					Leaf Area Index Calibration of
 RapidEye Satellite Imagery
           Joe Piwowar
     Department of Geography
       University of Regina
                  Background
• AgriSAR 2009
  –   European Space Agency – Sentinel 1
  –   MacDonald Dettwiler and Associates
  –   RapidEye AG
  –   Agriculture and Agri-Food Canada
  –   Indian Head Agricultural Research Foundation
  –   University of Regina – Department of Geography
• Objective
  – To evaluate the potential of RapidEye satellite
    imagery for estimating the leaf area index of a variety
    of agricultural crops.
               Leaf Area Index
• Green leaf area index (LAI)
  is the single-sided leaf area
  per ground area.
   – a dimensionless number
• LAI is directly related to vegetation biomass and
  productivity.
• LAI is directly related to:
   – rates of photosynthesis, transpiration,
     evapotranspiration
   – net primary production
   – changes in canopy structure




                                                      www.gardenwithinsight.com
   – crop yield estimates
North Battleford   Study Location
                      Saskatoon




                                           Indian Head

                                  Regina
Indian Head AAFC
 Research Farms
Indian Head AAFC
 Research Farms
Field Sampling
                    Field Data
• General Field and          • Sampling Dates
  Crop Information             –   June 1
  –   crop type                –   June 10
  –   seeding date             –   June 17
  –   row orientation          –   June 24
  –   row spacing              –   June 30
  –   stubble type             –   July 8
  –   swathing date            –   July 10
  –   harvest date             –   July 15
  –   grain yield (average     –   July 24
      for entire field)        –   August 21
             Field Sampling Dates


June 1           June 10    June 17     June 24


 no photo
 available

 July 8          July 15     July 24     July 30




August 6        August 13   August 21   August 27
                Field Data
• NDVI
  – GreenSeeker®
• LAI
  – LAI-2000®
Weather Data
            RapidEye Imagery
• 5 identical satellites
   – daily coverage
• Launched in August 2008
• RapidEye sensors:
   – 440-510 nm (Blue)    ‒ spatial resolution: 6.5 m
   – 520-590 nm (Green)   ‒ radiometric resolution: 12 bit
   – 630-690 nm (Red)
   – 690-730 nm (Red Edge)
   – 760-880 nm (Near IR)
          RapidEye Imagery



 June 2         July 17      July 27




August 10      August 25   September 5
LAI Calibration Fields
LAI Validation Fields
           Analysis Methods
• Ground Data              • Satellite Data
  – LAI measurements         – Radiometric calibration
    were averaged to the     – Geometric correction
    field level
                           • Correlation analysis
                                          ( NIR)   ( red )
                             – NDVI 
                                          ( NIR)   ( red )
                                       ( NIR)
                             – SR 
                                       ( red )

                             – Red-edge band
                                   NDVI
                                                                    31
                       0.8



                             0.6



                                    0.4



                                          0.2




                                                              g
                                                       0




                                                           Au
                                                                    24
                                                NDVI




                                                              g
                                                LAI




                                                           Au
LAI – NDVI Phenology




                                                                    17
                                                              g
                                                           Au
                                                                    10
                                                              g
                                                           Au
                                                                    03
                                                              g
                                                           Au
                                                                     7
                                                                l2
                                                           Ju
                                                                     0
                                                                l2
                                                           Ju
                                                                     3
                                                                l1
                                                           Ju
                                                                     6
                                                                l0
                                                           Ju
                                                                    29
                                                                n
                                                           Ju
                                                                    22
                                                                n
                                                           Ju
                                                                    15
                                                                n
                                                           Ju
                                                                    08
                                                                n
                                                           Ju
                                                                    01
                                                                n
                                                           Ju




                       4



                             3



                                    2



                                          1



                                                       0
                                   LAI
LAI – Satellite Data Correlations
• LAI: July 15             • RapidEye: July 17


       Test          r      R2     Significance

   LAI – Red-Edge   0.34    0.12        X

     LAI - NDVI     0.80    0.65       90%

      LAI – SR      0.83    0.69       95%
     LAI Estimate Calculation

   LAI estimated  SR  0.0305  1.2640
• Validation:
       Test          r     R2     Significance

    LAImeasured :
                    0.85   0.72       95%
     LAIestimated
Estimated LAI
    Applications / Next Steps
• Crop yield estimation
• Estimate net primary production
• Test non-linear regressions
                Thank You!
•   ESA – Malcolm Davidson
•   MDA – Ron Caves, Harold Zwick
•   AAFC – Guy Lafond
•   IHARF – Chris Holzapfel
•   MITACS
•   University of Regina – Lindsey Ziegler

				
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