drew pilant, ph.d. timothy lewis, ph.d., john iiames, mark murphy (us epa) jayantha ediriwickrema,...
TRANSCRIPT
Drew Pilant, Ph.D.Timothy Lewis, Ph.D., John Iiames, Mark Murphy (US EPA)
Jayantha Ediriwickrema, Ph.D. (Computer Sciences Corporation)
MODIS Vegetation Workshop II, Missoula MT August 16, 2004
EPA MODIS LAI Evaluation Activities in the Albemarle-
Pamlico Basin, NC/VA
Outline
• EPA LAI project at a glance
• Applications of MODIS LAI at EPA
• Describe field studies
• Results and observations
• Data sets for archiving
LAI Project at a Glance
Remotely Sensed Data:•MODIS LAI (MOD15A2) 8 day time series•MODIS NDVI (MOD13Q1) 16 day time series•Landsat ETM+ time series (2-8 images/site)•4 IKONOS XS scenes•Digital Elevation Model
Field Measurements at Multiyear Study Sites, 2001-2004:•TRAC sunfleck profiling•Hemispherical photography •Baseline forest biometrics•Ground and canopy photos for each site visited
Potential Applications of MODIS LAI (MOD15A2) at US EPA
• Biogenic emissions models (BEIS2)
• Air quality models (CMAQ)
• Atmospheric deposition models
• Landscape characterization and monitoring
• Vegetation phenology in land cover mapping and change detection
LAI Field Studies
Iiames, J.S., A.N. Pilant, T.E. Lewis. 2004. In-situ estimates of forest LAI for MODIS data validation. in: Lunetta, R. and J. Lyon (eds.), Remote Sensing and GIS Accuracy Assessment, CRC Press, Boca Raton, FL.
Long term field sites:
EPA Research LabAt Research Triangle Park, NC
Study Area: Albemarle-Pamlico Basin, NC/VA
EPA RTP
Hemiphoto: Optical Measurements of In Situ LAI
Hemispherical photographyUpward lookingDawn/dusk/overcast days
TRAC: Optical Measurements of In Situ LAI
Sunfleck profiling: TRAC (Tracing Radiation and Architecture of Canopies)Full sun/mid-day
Real time differential GPS geolocation for grids/transects
Baseline Forest Biometrics
Tube densiometer
Species distributions
Grid stake
8/6/2002
7/29/2002
Photo time series0o 45o
Field LAI Sampling Grids and Transects
100 m
100
m
N
L1_0
L2_0
L3_0
L4_0
L5_0
L1_100
L2_100
L3_100
L4_100
L5_100
A_10 A_90
E_10 E_90
TRACHEMI
20m
20m
100m
L1_0
L1_50L2_0
L2_50
Quadrant SubN
L1_0
L2_0
L3_0
L4_0
L5_0
L1_100
L2_100
L3_100
L4_100
L5_100
A_10 A_90
E_10 E_90
TRACHEMI
20m
20m
100m
L1_0
L1_50L2_0
L2_50
Quadrant SubN
L1_0
L2_0
L3_0
L4_0
L5_0
L1_100
L2_100
L3_100
L4_100
L5_100
A_10 A_90
E_10 E_90
TRACHEMI
20m
20m
100m
L1_0
L1_50L2_0
L2_50
Quadrant SubN
L1_0
L2_0
L3_0
L4_0
L5_0
L1_100
L2_100
L3_100
L4_100
L5_100
A_10 A_90
E_10 E_90
TRACHEMI
20m
20m
100m
L1_0
L1_50L2_0
L2_50
Quadrant Sub
50 m
PP
FD
(li
gh
t in
ten
sity
)
Canopy gap
Scaling: Field Transects to Landsat ETM+
Landsat ETM+ image30 m pixels
Quadrants and subplots inside hypothetical1 km MODIS LAI pixel
SubplotsTwo 50 m lines
Quadrants100x100 m
Fairystone, VA site: montane province
LAI Scaling: Field to MODIS
Results and Observations
• LAI phenology shows green-up
• Understory removal effects on NDVI
• MODIS NDVI in LAI backup algorithm
• Field data: MODIS LAI direct comparison
MODIS LAI Time Series in Albemarle-Pamlico Basin1
43
2
Before understory cut
After understory cut
Iiames, J. S., Pilant A.N. , Lewis T. Congalton R. Leaf Area Index (LAI) change detection on loblolly pine forest stands with complete understory removal, Proc. ASPRS 2004 Annual Conference, 05/23/04, Denver, CO.
Understory Removal in 100x100 m plot: Effect on IKONOS NDVI
Understory Removal in 100x100 m plot: Effect on IKONOS NDVI
Understory removal: 3% NDVI reduction (p<0.05)
IKONOS NDVI image
After understory cutBefore understory cut
0523_2002 0803_2002
Iiames, J. S., Pilant A.N. , Lewis T. Congalton R. Leaf Area Index (LAI) change detection on loblolly pine forest stands with complete understory removal, Proc. ASPRS 2004 Annual Conference, 05/23/04, Denver, CO.
• Begin your presentation here
Failure RT Algorithm (Backup)Success RT Algorithm
MOD15A2: Radiative Transfer vs NDVI Algorithm5x5 km (25 pixels) sample
MODIS NDVI: Data Challenges
Version 3 Version 4
++
Jan Feb Mar Apr May Jun Jul Aug Sep
LAI *
10
MODIS LAI spectral profiles from 5 adjacent pixels
= in situ hemispherical photo LAI
+
+
MODIS and Hemiphoto LAI Time Series at Fairystone Site (deciduous)
Jan Feb Mar Apr May Jun Jul Aug Sep
+
+
+++
LAI *
10
MODIS LAI spectral profiles from 5 adjacent pixels
= in situ TRAC LAI
MODIS and TRAC LAI Time Series at Appomattox Site (pine)
LAI Field Data Sets for Archiving
DATA SET DESCRIPTION COMMENTS
HEMI photos Digital hemispherical photographs from survey grids
TRAC sunfleck profiles TRAC profiles from survey transects
Digital ground/canopy photos
Digital photos at 0, 45, 90o
Baseline forest biometrics Crown closure, stems/ha, diameter at breast height (DBH), diameter: height, canopy analysis, species distribution
Meteorological data NWS, State and cooperative weather observations
LAI Image Data Sets for Archiving
DATA SET DESCRIPTION COMMENTS
MODIS LAI Time series Georeferenced; period 2000-2005
MODIS NDVI time series Georeferenced; period 2000-2005
Landsat ETM+ images Intermittent 1999-2004
Precision georeferenced
Air photos circa 1990-2002 As apropos
IKONOS data Derived NDVI images As apropos
Digital elevation data 30 m Shuttle Radar Topography Mission;
Possibly LIDAR for NC
Ongoing work
• Validation of TRAC and Hemiphoto methods Comparison with destructive harvest at NCSU sites TRAC/Hemiphoto repeatability measurements Develop 500-1000 m TRAC transect method
• Methods for scaling Field: Landsat ETM:MODIS
• Organize / QA Data Archiving
• Begin your presentation here
Thank you!
Acknowledgments:NASAState of VAState of NCNCSUDuke UniversityWestvaco International Paper