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This document explores the development and future of aerosol remote sensing using MERIS and MODIS data. It discusses recommendations from the October 2003 MAVT workshop, including increasing aerosol model numbers and expanding product spatial coverage. The relationship between surface reflectance and spectral indices like ARVI is analyzed, alongside seasonal biome transitions based on Terra/MODIS surface albedo data. Key topics include aerosol product performance, retrieval challenges, and future directions for improving surface albedo maps and validating aerosol products.
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Ramon, D.1 and Santer, R.2 HYGEOS, France LISE, Université du Littoral, France Aerosol over land with MERIS, present and future
Where did we start after Salzburg • MERIS level 2 products • Reprocessing #2 after MAVT Workshop oct. 2003 recommendations • Increase aerosol model number (Angstrom coeff. from 0 to 2.5 by step of 0.1) • Extend the aerosol product spatial cover • From Dense Dark Vegetation to Land Aerosol Remote Sensing target
LARS concept • Surface reflectance varies linearly with some spectral index, here ARVI 100x100 RR around Alta Floresta DARVI=0 DARVI=-0.2 DARVI=-0.5
LARS Reflectance for a biome slope Initial DDV Domain Seasonal Initial DDV
Spatially Complete Global Surface Albedos Derived from Terra/MODIS Data • Operational MODIS surface albedo data product (MOD43B3/MCD43B3) • 0.47, 0.56, 0.67, 0.86, 1.24, 1.64, 2.1 µm , 0.3-5.0, 0.7-5.0, 0.3-0.7 µm • 1 km spatial resolution (sinusoidal projection stored as 10° x 10° tiles) • 16-day periodicity (001, 017, …, 353) Michael D. King1, Eric G. Moody1,2, Steven Platnick1, and Crystal Schaaf3 1NASA Goddard Space Flight Center 2L3-Communications GSI 3Boston University
16 days period starting from julian day r0(l1) 12'x12' box fit goodness of fit
12' resolution, day 177, slope at 659 nm Black: no fit White: no good fit
12' resolution, day 177, albedo at 659 nm for ARVI=0.6 0.08 0
C443 1.5 0
C670 1.5 0
New RO_LARS LUTs from MODIS • Aerosol product: AOT_865 and alpha
Remaining issues? • See biome transitions on AOT_865 • Lot of alpha out of range
Flags Clouds(White); water (Black),LARS with good aerosol retrieval(Green); Bad aerosol retrieval (Red) LARS in cloud vicinity(Blue)
RO_LARS_670 DDV albedo (red) corrected LARS albedo (magenta)
What aerosol product? RO_AER_440 is correct but improvements are possible RO_AER_670 is questionable Laerosol _440 is OK AOT_440 instead of AOT_865 (no compromise at 670 nm) What about a and the associated Junge size distribution
The 3 possible algorithms • Simultaneous retrieval of AOT and alpha • AOT for model no 36 (a=1) • Use AOT for model no 36 as back up only
Conclusion • Separate AOT retrieval and alpha retrieval • Coherence with AOT over water • No real biome transition found, but need to consolidate with L3 • Better cloud rejection at level 2 is mandatory • Less problem with a better surface albedo map !
What next? • How to make a good surface albedo map for dark pixels? • Utility of a level 2 aerosol product? • On a pixel by pixel basis? • A daily level 3 which is not a simple bining • Utility of a daily level 3 aerosol product? • Validation • Atmospheric correction • Upper level