PRESENTATION XU - Copy
Transcript of PRESENTATION XU - Copy
![Page 1: PRESENTATION XU - Copy](https://reader036.fdocuments.ec/reader036/viewer/2022062306/5872eb691a28abfa548b7183/html5/thumbnails/1.jpg)
Analysing Phenological Patterns in Boreal
Forests Using MODIS Time-Series-Derived & Eddy-Covariance Flux
DataXu Teo
MSc Earth Observation & Geoinformation Management
![Page 2: PRESENTATION XU - Copy](https://reader036.fdocuments.ec/reader036/viewer/2022062306/5872eb691a28abfa548b7183/html5/thumbnails/2.jpg)
Why?
Introduction
![Page 3: PRESENTATION XU - Copy](https://reader036.fdocuments.ec/reader036/viewer/2022062306/5872eb691a28abfa548b7183/html5/thumbnails/3.jpg)
…and what is phenology?• Plant phenology
“..is the study of the timing of recurring biological events in plants...” (Leith, 1974)
• Allows us to assess how trees are responding to climate change through timing.
• Determined via:• Ground measurements of CO2
• Satellite measurements of Normalised Difference Vegetation Index (NDVI)
IntroductionPhenology | TimingCO2
NDVI
![Page 4: PRESENTATION XU - Copy](https://reader036.fdocuments.ec/reader036/viewer/2022062306/5872eb691a28abfa548b7183/html5/thumbnails/4.jpg)
Research Question
How reliable are satellite derived vegetation indices (VIs) in observing forest phenological
change?
IntroductionPhenology | TimingCO2
NDVI
![Page 5: PRESENTATION XU - Copy](https://reader036.fdocuments.ec/reader036/viewer/2022062306/5872eb691a28abfa548b7183/html5/thumbnails/5.jpg)
AimAscertain the reliability of using satellite-derived proxy indicators, together with ground-based CO2 flux data, to identify the beginning and end of the growing season as accurately as possible.
ObjectivesDetermine the Growing Season Start Date (GSSD) and Growing Season End Date (GSED) via CO2 and NDVI data.
Compare both sets of data to obtain a statistical comparison of the viability of using satellite data.
IntroductionPhenology | TimingCO2
NDVI
![Page 6: PRESENTATION XU - Copy](https://reader036.fdocuments.ec/reader036/viewer/2022062306/5872eb691a28abfa548b7183/html5/thumbnails/6.jpg)
Where?
IntroductionMethods
Phenology | TimingCO2
NDVI
![Page 7: PRESENTATION XU - Copy](https://reader036.fdocuments.ec/reader036/viewer/2022062306/5872eb691a28abfa548b7183/html5/thumbnails/7.jpg)
Hyytiälä, FinlandIntroductionMethods
Phenology | TimingCO2
NDVI
![Page 8: PRESENTATION XU - Copy](https://reader036.fdocuments.ec/reader036/viewer/2022062306/5872eb691a28abfa548b7183/html5/thumbnails/8.jpg)
How?
IntroductionMethods
Phenology | TimingCO2
NDVI
![Page 9: PRESENTATION XU - Copy](https://reader036.fdocuments.ec/reader036/viewer/2022062306/5872eb691a28abfa548b7183/html5/thumbnails/9.jpg)
Eddy Covariance: CO2
IntroductionMethods
• Measure of turbulent gas fluxes
• 10-year dataset: 2003 – 2012
• Altitude: 23 m
• Sampled at 30 minute intervals
Fine temporal resolution
Phenology | TimingCO2 | Eddy CovarianceNDVI
![Page 10: PRESENTATION XU - Copy](https://reader036.fdocuments.ec/reader036/viewer/2022062306/5872eb691a28abfa548b7183/html5/thumbnails/10.jpg)
MODIS: NDVIIntroductionMethods
• Highly correlated to absorbed fraction of photosynthetically active radiation (PAR).
• 10-year dataset: 2003 – 2012
• 16-day intervals
• Altitude: 700 km
• Pixel resolution: 250 m
Coarse spatial resolution
Phenology | TimingCO2 | Eddy CovarianceNDVI | MODIS
![Page 11: PRESENTATION XU - Copy](https://reader036.fdocuments.ec/reader036/viewer/2022062306/5872eb691a28abfa548b7183/html5/thumbnails/11.jpg)
250 m
250 m
IntroductionMethods
Phenology | TimingCO2 | Eddy CovarianceNDVI | MODIS
Hypothetical Flux Footprint
Tower Pixel
250 m
![Page 12: PRESENTATION XU - Copy](https://reader036.fdocuments.ec/reader036/viewer/2022062306/5872eb691a28abfa548b7183/html5/thumbnails/12.jpg)
IntroductionMethodsResults
The story thus far?
![Page 13: PRESENTATION XU - Copy](https://reader036.fdocuments.ec/reader036/viewer/2022062306/5872eb691a28abfa548b7183/html5/thumbnails/13.jpg)
IntroductionMethodsResults
2003 2004 2005 2006 2007
![Page 14: PRESENTATION XU - Copy](https://reader036.fdocuments.ec/reader036/viewer/2022062306/5872eb691a28abfa548b7183/html5/thumbnails/14.jpg)
IntroductionMethodsResults
2003 2004 2005 2006 2007
![Page 15: PRESENTATION XU - Copy](https://reader036.fdocuments.ec/reader036/viewer/2022062306/5872eb691a28abfa548b7183/html5/thumbnails/15.jpg)
IntroductionMethodsResults
Example Start:7 April (DoY: 97)
Example End:16 Oct (DoY: 289)
Start here? End here?
![Page 16: PRESENTATION XU - Copy](https://reader036.fdocuments.ec/reader036/viewer/2022062306/5872eb691a28abfa548b7183/html5/thumbnails/16.jpg)
IntroductionMethodsResultsDiscussion
So what’s next?
Phenology | TimingCO2 | Eddy CovarianceNDVI | MODIS
![Page 17: PRESENTATION XU - Copy](https://reader036.fdocuments.ec/reader036/viewer/2022062306/5872eb691a28abfa548b7183/html5/thumbnails/17.jpg)
What’s next?Further research to define start/end date.
Other proxy indicators:• Normalised Difference Water Index• Surface Albedo
Phenology | TimingCO2 | Eddy CovarianceNDVI | MODIS
IntroductionMethodsResultsDiscussion
![Page 18: PRESENTATION XU - Copy](https://reader036.fdocuments.ec/reader036/viewer/2022062306/5872eb691a28abfa548b7183/html5/thumbnails/18.jpg)
To concludePhenology | TimingCO2 | Eddy CovarianceNDVI | MODIS
IntroductionMethodsResultsDiscussionConclusion
• Phenology change timing central to understanding changing climate.
• In-situ measurements (EC) and proxy indicators (NDVI) are complementary to each other.
• Challenge in identifying transition timing.
• Other possible methods available.
![Page 19: PRESENTATION XU - Copy](https://reader036.fdocuments.ec/reader036/viewer/2022062306/5872eb691a28abfa548b7183/html5/thumbnails/19.jpg)