# Presentation: 663879

## Simultaneous Retrievals of aerosol and surface from a combination of AERONET- MODIS-MISR-POLDER data 

***Simultaneous Retrievals of aerosol and surface from a combination of AERONET- MODIS-MISR-POLDER data***** **

***Algorithm:*****     **_**Oleg Dubovik**_**1****, **
**   ****	****          ****Alexander Sinyuk****1****,**
***MODIS:          *****Yoram Kaufman****1**
**                       ****Eric Vermote****2**
**                                   ****Jean-Claude Roger****2**
***MISR:            *****John Martonchik****3****,**
**                                  ****Ralph Kahn****3****,**
***                      *****Dave Diner****3****,**
***POLDER:*****      Francois-Marie Breon****4****,**
***AERONET:*****   Brent Holben****1****,**
**                      ****Ilya Slutsker****1**

*1-  NASA/GSFC, Greenbelt, MD, USA*
*2 - UMD, Greenbelt, MD, USA*
*3 - NASA/JPL, CA, USA*
*4 - CEA/DSM/LSCE,  France*

## Idea: Less assumptions are needed in simultaneous retrieval of aerosol and surface from combination of up- and down - looking observations

- Retrieval of surface needs** **atmospheric correction for aerosol effect

- Retrieval of aerosol relies** **on** **assumption of surface reflectance

**Idea:** _***Less assumptions are needed***_ in simultaneous retrieval of aerosol and surface from combination of up- and down - looking observations

## Retrieval using combinations of up-looking 

**Retrieval using combinations of up-looking **
**Ground-based and down-looking satellite**
**observations**

***Retrieved:***

_*Aerosol Properties*_*:*
*- size distribution*
*- real ref. ind. *
*- imag. ref. ind*
*(AERONET sky channels)*

_*Surface Parameters*_*:*
*BRDF (MISR, POLDER) *
*Albedo (MODIS)*

## AERONET Ground-based Sun-sky radiometer:

± 0.02 at 
6 channels: 0.34, 0.38, 0.44, 0.67, 0.87, 1.02, 1.65 m

± 0.05% at
4 channels: 0.38, 0.44, 0.67, 0.87, 1.02, 1.65 m
3° ≤ scattering angles ≤ ~70°
P± 0.02% at 0.87

MISR 
Reflectance at
4 channels: 0.45, 0.55, 0.67, 0.87 mm
9 viewing angles: ±70.5o, ± 60o, ± 45.6o, ± 26.1o, 0o

MODIS
Reflectance at
7 channels: 0.47, 0.55, 0.66, 0.87,1.2, 1.6, 2.1

POLDER
Reflectance at
7 channels: 0.44, 0.49, 0.56, 0.67,0.76, 0.87, 0.91
13 viewing angles
Polarization at: 0.44, 0.67, 0.87

**********± 0.02 at**** **
_**6 channels**_**: 0.34, 0.38, 0.44, 0.67, 0.87, 1.02, ****1.65**** ********m**
******± 0.05% at**
_**4 channels**_**: ****0.38****, 0.44, 0.67, 0.87, 1.02, ****1.65**** ********m**
**3° ≤ scattering angles ≤ ~70°**
**P********± 0.02% at ****0.87**
_**MISR**__** **_
**Reflectance at**
_**4 channels**_**: 0.45, 0.55, 0.67, 0.87 mm**
_**9 viewing angles**_**: ±70.5****o****, ± 60****o****,**** ****± 45.6****o****, ± 26.1****o****, 0****o**
_**MODIS**_
**Reflectance at**
_**7 channels**_**: 0.47, 0.55, 0.66, 0.87,1.2, 1.6, 2.1**
_**POLDER**_
**Reflectance at**
_**7 channels**_**: 0.44, 0.49, 0.56, 0.67,0.76, 0.87, 0.91**
_**13 viewing angles**_
**Polarization at****: 0.44, 0.67, 0.87**

**AERONET- MISR - POLDER - MODIS data**

## Retrieval scheme:

***Observations***

***Numerical inversion:***
***-Accounting for noise***
***-Solving Ill-posed problem***
***- Setting a priori constraints***

***Forward model:***
***- Detailed aerosol (same as in AERONET)***
***Multiple scattering ******accounts for BRDF***
***BRDF modeled using parameterized model ***
***(Rahman-Pinty-Verstraete, 1993) ***

***aerosol particle sizes,****** ***
***complex refractive index,****** ***
***parameters of BRDF***
***(or Lambertian albedo)***

*Retrieval scheme:*

**MISR, POLDER**
**MODIS**

## Inversion

**    ****Statistically Optimized  Minimization** **- **
**   ****Multi-term LSM Fitting **(Dubovik and King 2000; Dubovik 2004)

_***Measurements:***_
**i=1 *****- optical thickness***
**i=2 *****- AERONET radiances***
**i=3 *****- stellite radiances***
***their covariances***
**(should depend on  ******** and ********)**
***-lognormal error distributions***

_***a priori ***__*restrictions on*_* *
***norms of derivatives of:***
- i=4*** -size distr. ******variability;***
- i=5*** -n ******spectral variability******;****** ***
- i=6*** -k ******spectral variability;***
- i=7*** - surface reflectance***
***         ******spectral variability;***

***Lagrange**** parameters*

***consistency***
***Indicator***

- weighting

## Questions & Issues:

_***Retrieved surface properties:***_
-   reliable?
-  	are there any limitations?
-   what is the difference with conventional
-                 atmospheric correction?

_***Retrieved aerosol properties:***_
- are there any improvements compare to
-       conventional  AERONET retrieval

## Simultaneous fitting

- August 9, 2003
- (0.44) ~ 0.3

**AERONET**

**MODIS**

## Simultaneous fitting

**MISR-MODIS**

- August 9, 2003
- (0.44) ~ 0.3

- Summer, 2003
**MONGU**

**MISR**

- MODIS

## Comparisons of Surface Retrievals (with improved vertical profile)

**Surface BRDF:**

**Comparisons of Surface ****Retrievals ****(with improved vertical profile)**

## Effect of Aerosol Vertical Distribution on the Surface Retrievals

**Assumed Profiles:**

## Surface Effect on Retrievals of  the Refractive Index (low aerosol loading)

- POLDER: June 24, 2003
- (0.44) ~ 0.26 , SZA=470

- MISR: August 9, 2003
- (0.44) ~ 0.3, SZA=400

## Surface Effect on the Retrievals of the Size Distribution (low aerosol loading)

- POLDER: June 24, 2003
- (0.44) ~ 0.26 , SZA=470

- MISR: August 9, 2003
- (0.44) ~ 0.3, SZA=400

## Surface Effect on the Retrievals at High Aerosol Loading

- POLDER: August  18, 2003
- (0.44) ~ 0.63, SZA=350

## Surface Effect on the Retrievals of Single Scattering Albedo

- POLDER: August  18, 2003
- (0.44) ~ 0.63, SZA=350

- MISR: August 9, 2003
- (0.44) ~ 0.3, SZA=400

## Effect of Particle Non-Sphericity on the Retrievals

- June, 2003
- Solar Village, Saudi Arabia

## Surface Effect on the Retrievals of Single Scattering Albedo

- POLDER: September 27, 2003
- (0.44) ~ 0.24 , SZA=700

- POLDER: June 7, 2003
- (0.44) ~ 0.67 , SZA=700

- (Almucantar inversion with corrected surface)

## Retrievals for Islands or Costal sites

- Cape Verde (Island)

##    Results:

***Simultaneous inversion of satellite and***
***     ******AERONET data has been developed***
***Surface BRDF and Albedo****** can be retrieved simultaneously with aerosol (low and moderate ************,******)***
***       ***
***Improved retrievals of aerosol:***
***   ******-  refractive index and size (low ************  ******over vegetation)***
***   ******- ************o******(************) and size (over bright surface************)***
***The approach is very useful****** for sites with complex surface structure (Islands, costal)***
***       ***
**Plans:**
***Completing analysis***
***Making operational retrievals***
***Including ******Lidar information ****** ***

## Comparisons of MISR and POLDER geometries 

- Mongu, August  7,9 ,10, 2003

## Almucantar and principle plane retrievals: Size Distribution

- POLDER: September 27, 2003
- (0.44) ~ 0.24 ,
- PP: SZA=340; ALM: SZA=700

- POLDER: June 7, 2003
- (0.44) ~ 0.67 ,
- PP: SZA=230; ALM: SZA=700