Summary of the Final Report of Research Results1) Title of the proposed researchStandardization of NDVI products produced from the TANSO-CAI sensor and applications ofthem to land observations
2) Principal Investigator (PI) and Co-Investigators (Co-Is)
PI:
Dr. Masayuki Tamura
Co-I:
Dr. Masayasu Maki
Dr. Kei Oyoshi
3) PI’s affiliation
Kyoto University4) Summary of the Final Report of Research Results
Main results were obtained in the following two issues.
①

Derivationof inter-calibration

formulas between

CAI-NDVI,

MODIS-NDVI,andAVHRR-NDVI with radiative transfer simulation
We derived inter-calibration formulas between CAI-NDVI, MODIS-NDVI, and AVHRR-NDVI
with radiative transfer simulation by considering the effects of SRF (Spectral Response Function)differences. Both of the fitness for regression analyses for deriving inter-calibration formulas werequite good with high determination coefficient greater than 0.99. The standard errors of NDVI
between CAI and AVHRR, CAI and MODIS are 0.015 and 0.031 respectively. AVHRR-NDVI wasslightly worse compared to CAI-NDVI because AVHRR NIR channel include strong water
absorption band. When the derived formulas were applied to real satellite data to evaluate
effectiveness of the formulas, it was found that there remains some discrepancies between
CAI-NDVI and MODIS-NDVI after correction of SRF differences. These remaining discrepancies
would be due to STSG (Sun-Target-Sensor-Geometry) conditions.
②Effects of atmosphere and sun-target-sensor geometry on CAI-measured reflectance andNDVI
Effects of atmosphere and sun-target-sensor geometry on CAI-measured reflectance and NDVIwere assessed using a coupled 1-D atmosphere and 3-D canopy radiative transfer model. Surface
landscapes were simulated by a 3-D forest canopy model. The following atmospheric conditions
were assumed: (1) atmospheric profiles: mid-latitude summer and winter, (2) aerosol types:
continental clean, average, and polluted, and (3) aerosol optical thickness at 550 nm: 0.1, 03, and 0.5.
Reflectances at top of atmosphere (RTOA) and top of canopy (RTOC) were calculated at the viewing

angles from 0 to ±47 ﾟ. The results showed that RTOA was larger than RTOC in band-2 due toscattering, while RTOA was smaller than RTOC in band-3 due to absorption. As a result the NDVI at
TOA was smaller than that at TOC both in winter and summer. The variation magnitudes of NDVI at
TOA across the CAI swath were 0.09 in summer and 0.26 in winter relative to the value at nadir.
Among three atmospheric parameters, the effects of aerosol optical thickness were the largest andshould be properly corrected for standardization of CAI-measured reflectance and NDVI.
5) List of publications relating to the proposed research
M. Tamura, K. Oyosi, M. Maki, Standardization of NDVI Products Produced from theTANSO-CAI Sensor and Applications of Them to Land Observations, 1stMeeting of GOSAT RA Principal Investigators, 2008, Tokyo.
M. Tamura and K. Oyoshi, Standardization of NDVI products produced from theTANSO-CAI sensor and their applications to land observations, Abstract Collectionof the Second Meeting of GOSAT RA Principal Investigators, 13, 2010, Kyoto．
M. Tamura, Effects of atmosphere and sun-target-sensor geometry on CAI-measured reflectance andNDVI, The 4th GOSAT RA PI meeting, 2012, Pasadena.