# Presentation: 272775

## The MODIS Aerosol Algorithms

- Collection 004
- Collection 005
- Collection 006
- 	and on to infinity!

- Lorraine Remer, Yoram Kaufman, Didier Tanré,
- Shana Mattoo, Robert Levy, Rong-Rong Li, D. Allen Chu
- Richard Kleidman, Charles Ichoku, J. Vanderlei Martins,
- Ilan Koren, Zia Ahmad, Oleg Dubovik, Eric Vermote
- And introducing Christina Hsu

## Collection 004

- Description and validation of Terra 004
- in **Remer et al. (2005),** appearing in JAS
- this April.  Available on line at
- _[http://modis-atmos.gsfc.nasa.gov/](http://modis-atmos.gsfc.nasa.gov/)_ under References

- Aqua validation in **Ichoku et al. (2005),** also available
- on line.

## Fine mode fraction

**Fine mode fraction**

**AOT550**

- 2001

- 2002

- 2003

- 2004

- 0.45

- 0.30

- 0.60

- 0.15

- 0.10

- From Terra.
- AOT retrieval is NOT
- sensitive to instrument
- characterization
- changes, but
- size retrievals are.

- Most apparent at low AOT.

- Also,  there is an
-  offset between
- Aqua and Terra

## Comparison of monthly

- mean ocean AOT values.
- Not collocated in time!
- True validation of aerosol
- long term statistics?

- Kaufman et al. (2005)
- with Richard Kleidman

## Kaufman et al. (2005)

- with Rong-Rong Li

- Over global oceans,
- residual cirrus reflectance
- increases AOT by
- 0.015±0.003 at 0.55 μm

-  A dramatic example

- Algorithm retrieves when
- cirrus reflectance < 0.01

- Residual cirrus reflectance

## Collection 005

## Elimination of Snow Contamination

- Li et al. (2005)

## New over land cloud

- Mask logic
- implemented

## Negative reflectances at 1.38 μm now permitted

- Increases extent of retrievals over land

## Collection 006

## Deep Blue

- Retrievals over bright surfaces coming in 006

- Christina Hsu

## New Land Inversion Coming

**• ****Assume MIR (2.1********m)  is transparent to aerosol:  ********_surf = ********_obs**
**Estimate AOD in blue and red independently **
**Calculate angstrom exponent to estimate dust aerosol contribution**
_**For 006 and beyond:**_
**2.1  ********m  is NOT transparent to aerosol:  ********_surf =********_obs - ********_AOD**
**Retrieve AOD and ****FMF**** in blue, red and MIR simultaneously **
**Solution is combination of AOD and FMF that exactly matches **
**the observed reflectance at 0.47 ********m, with smallest error at 0.66 ********m**

- RESULT: (1) no difference to AOT retrieval
- 	      (2) major improvement to Fine Mode Fraction (FMF)

- _New Land Inversion Coming_

## Better Land Surface Characterization

- s470 = 0.25 2130
- s660 = 0.50 2130

- 0.15 <  m0.47 < 0.25
- 0.01 < b0.47 < 0.03

- 0. 5 <  m0.66 < 0.6
- - 0.01 < b0.66 < 0.01

- _Currently_

- _For 006_

- 0.47 = m0.47() * 2.1 + b0.47()
- 0.66 = m0.66() * 2.1 + b0.66()

**Scattering angle better parameter than surface type**

## Better Land Surface Characterization

- Robert Levy, in preparation

- _Better Land Surface Characterization_

## New Aerosol Models for Collection 006?

- We ended up with 3 fine mode models and 1 dust.

- Now:
- 	- based on Nakajima inversion
- 	- no retrievals of nr or o
- 	- less than 25 AERONET sites, (nothing from Asia)
- 	- subjective division of the world

- Infinity and beyond?:
- 	- based on Dubovik inversion
- 	- includes retrievals of nr or o at AOT > 0.40
- 	- more than 200 AERONET sites
- 	- objective cluster analysis

- Results: 3 fine mode models and 1 dust

- _New Aerosol Models for Collection 006?_

- R. Levy

## Urban/industrial o = 0.95 (0.96)

- Urban/industrial o = 0.95 (0.96)
- Smoke o = 0.92 (0.90)
- Absorbing smoke o = 0.86 (0.86)

- R. Levy

## New Aerosol Models for Collection 006?

- _New Aerosol Models for Collection 006?_

- R. Levy

## New Ocean Aerosol  Models Coming

- DUST

- Nonsphericity will be addressed,
- 	and perhaps additional absorption

- Remer, Mattoo, Kaufman, Ahmad, Dubovik

## To infinity