LAI/FPAR Research at the Boston University Science Computing Facility: Collection 5 MODIS LAI/FPAR Products and Long-term LAI/FPAR from AVHRR NDVI.
Ranga
B
Myneni, Boston University, ranga.myneni@gmail.com
(Presenting)
Arindam
Samanta, Boston University, arindam@bu.edu
Sangram
Ganguly, NASA AMES/BAERI, sangram.ganguly@gmail.com
Mitchell
A
Schull, Boston University, schull@bu.edu
Cristina
Milesi, CSUMB/NASA AMES, cristina.milesi@gmail.com
Ramakrishna
R
Nemani, NASA AMES, nemani911@gmail.com
Nikolay
V
Shabanov, NOAA/NESDIS, nikolay.shabanov@noaa.gov
Yuri
Knyazikhin, Boston University, jknjazi@bu.edu
MODIS LAI algorithm was substantially refined for the Collection 5 (C5) reprocessing to optimally use suite of MODIS observations from Terra and Aqua sensors. Refinements are based on advancements in RT theory, and the C5 suite of LAI/FPAR products possesses higher quality retrievals than previous versions. The following 1-km products are operationally generated at NASA Science Computing Facilities (SCF): 8-day Terra and Aqua products, 8-days Combined Terra and Aqua product, and 4-day Combined Terra and Aqua product. In addition, monthly Collection 5 Terra products are processed and archived at the Boston University (BU) SCF. We analyzed Collection 5 LAI/FPAR products and compared them with Collection 4 LAI/FPAR products over a range of spatial and temporal scales: Global annual mean, Global monthly time-series, biome-based Global and Northern Hemisphere (>35N) analysis. For analysis we used Collection 4 (C4.1) and Collection 5 (C5) BU monthly Terra products.
The BU SCF has also been involved in the generation and evaluation of a new global monthly leaf area index (LAI) data set for the period July 1981 to December 2006 derived from AVHRR Normalized Difference Vegetation Index (NDVI) data. This is based on the radiative transfer theory of canopy spectral invariants. This LAI data set was evaluated both by direct comparisons to ground data and indirectly through inter-comparisons with similar data sets. The indirect validation showed satisfactory agreement with existing LAI products – MODIS C5 LAI, at a range of spatial scales. The data set reproduced well-documented spatio-temporal trends and inter-annual variations in vegetation activity in the northern latitudes and semi-arid tropics. Overall, the inter-comparison with short-term LAI data sets, evaluation of long term trends with known variations in climate variables, and validation with field measurements together build confidence in the utility of this new 26 year LAI record for long-term vegetation monitoring and modeling studies.
Presentation Type: Poster
Poster Session: Data Records and Systems
NASA TE Funded Awards Represented:
Myneni, Ranga
Global Products of Leaf Area Index and Fraction Vegetation Absorbed PAR from the Terra/Aqua MODIS and NPP VIIRS Sensors: Algorithm Refinement and Cal/Val for ESDR Proposal