aerosol over land with meris, present and future

09 Sept. 2004ENVISAT symposium, Salzburg

Aerosol over land with MERIS, present and future

Ramon, D.1 and Santer, R.2

(1) HYGEOS, France

(2) LISE, Université du Littoral, France


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

ARVI=0

ARVI=-0.2

ARVI=-0.5

100x100 RRaround Alta Floresta


LARS Reflectance for a biome

svsvLARS m ,,,,

)))(,(1(,,,)( ARVILARVImmC svsvDDV

Seasonal Initial DDV slope DomainInitial DDV


Biomes

10

2

3 45

6 7

8

9

10


Biome transition on level 3


Spatially Complete Global Surface Albedos Derived from Terra/MODIS Data

Michael D. King1, Eric G. Moody1,2, Steven Platnick1, and Crystal Schaaf3

1NASA Goddard Space Flight Center2L3-Communications GSI

3Boston University

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)


12'x12' box fit ()goodness of fit16 days period starting from julian day


12' resolution, day 177, slope at 659 nm

Black: no fitWhite: no good fit


0

0.0812' resolution, day 177, albedo at 659 nm for ARVI=0.6


C443

0

1.5


C670

0

1.5


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)


AOT_865


RO_LARS_670

DDV albedo (red) corrected LARS albedo (magenta)


Rayleigh corrected reflectance above LARS at 443nm


Rayleigh corrected reflectance above LARS at 670 nm


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 and the associated Junge size distribution


The 3 possible algorithms

Simultaneous retrieval of AOT and alpha AOT for model no 36 (=1) Use AOT for model no 36 as back up only


Spatial & temporal binning (nov.)


Spatial & temporal binning (sept.)


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

aerosol over land with meris, present and future

Documents

nmwhat aerosol product

lars luts

daily level

salzburgmeris level

use aot

good surface albedo

modisaerosol product

better surface albedo