# Presentation: 170600

## Dust sources location: combining TOMS and MODIS data

-  Paul Ginoux
- NOAA-GFDL
- Princeton, NJ

- Dust Workshop
- Boulder, October 22-23, 2004

-  Paul Ginoux
- NOAA-GFDL
- Princeton, NJ

## TOMS Aerosol Index

-  λ, shorter wavelength (331 or 340 nm)
- λ0, longer wavelength (360 or 380 nm)

**Mineral Dust Aerosols: TOMS Aerosol Index**

- http://toms.gsfc.nasa.gov

## Mineral Dust Aerosols: TOMS Aerosol Index

- The maxima of TOMS AI are persistently (over 20 years of observations) at the same locations (Prospero et al., RG, 2002).

- Niger river basin (Mali)

- Bodele depression (Chad)

- Cott El Jerid (Tunisia)

- Wadis in Libya

**Mineral Dust Aerosols: TOMS Aerosol Index**

## Mineral Dust Aerosols: TOMS Aerosol Index 

- Most TOMS AI maxima are associated with topographic depressions, dry lakes or river beds (Prospero et al., 2002)

## Mineral Dust Aerosols: Global dust sources 

- Ginoux et al. (2001) prescribed the dust sources based on topography
- and vegetation (bare surface from AVHRR 1x1 degree)

- GOCART, GFDL models, KARMA, GEOS-CHEM, US Army, several regional models, IPCC 2001, AEROCOM.

## Mineral Dust Aerosols: Global dust emission

## Mineral Dust Aerosols: Other global dust inventories

- Zender et al. (2003): Geo-morphological approach + comparison with Ginoux et al. (2001)
- Tegen et al. (2004): sources are associated with Paleo-lakes and anthropogenic sources are less than 10%.
- Mahowald et al. (2004): TOMS does not allow to characterize all sources and anthropogenic sources could be as high as 50%.

- What can we learn from MODIS 500m RGB?

- MODIS over Bodele

- ONC map over Bodele

- The dust plumes are associated with ephemeral lakes

- What can we learn from MODIS 500m RGB?

- Bodele : Clean day

- Bodle dusty day

- What can we learn from MODIS 500m RGB?

- Afghanistan

- Mauritania

- The dust plumes are associated with ephemeral lakes

- Morocco

- Aral sea

- Some dust plumes are not associated with ephemeral lakes and appear to be of anthropogenic origin: vehicles or dry lake due to excessive irrigation.

- Laayoune

- Es Semara

- What can we learn from MODIS 500m RGB?

- Dust plumes NOT always associated with ephemeral lakes

- What can we learn from MODIS 500m RGB?

- Nevada

- Eastern Taklamakan

- Dust plumes NOT always associated with ephemeral lakes

**Mineral Dust Aerosols: ****TOMS AI frequencies and ephemeral lakes**

- Some ephemeral lakes are active others not. TOMS AI can help determine which one are active, but if one wants to simulate past or future climate, or perform regional studies we need to understand why.

**Mineral Dust Aerosols: ****TOMS AI frequencies and ephemeral lakes**

## Use of TOMS: dust sources are essentially associated with topographic depressions (Prospero et al., 2002). Based on this finding several global inventories are available (e.g. G-2001; Z-2003; T-2004) which reproduce essential global characteristics of dust observations. These global inventories offer the advantage to by-pass complex physical models which needs highly variable surface soil characteristics. 
TOMS AI drawbacks:  no physical meaning, poor resolution

Use MODIS: Are the dust sources associated with ephemeral lakes? Some lakes are active others are not. Anthropogenic sources can be detected. 
MODIS drawbacks: no retrieval of aerosol properties over bright surface (NB. Ch. Hsu and “Deep blue” algorithm alleviates the problem), false color can be misinterpret due to Rayleigh scattering.

Use of TOMS and MODIS: classification of active and non-active ephemeral lakes. But painstaking job and impossible to automize.
Future: OMI (TOMS successor) provides nUV and visible radiances at higher resolution. AIRS: astonishing possibilities to retrieve 3D dust!!!

- TOMS AI drawbacks:  no physical meaning, poor resolution
- Use MODIS: Are the dust sources associated with ephemeral lakes? Some lakes are active others are not. Anthropogenic sources can be detected.
- MODIS drawbacks: no retrieval of aerosol properties over bright surface (NB. Ch. Hsu and “Deep blue” algorithm alleviates the problem), false color can be misinterpret due to Rayleigh scattering.
- Use of TOMS and MODIS: classification of active and non-active ephemeral lakes. But painstaking job and impossible to automize.
- Future: OMI (TOMS successor) provides nUV and visible radiances at higher resolution. AIRS: astonishing possibilities to retrieve 3D dust!!!

- Conclusions

## 
J. M. Prospero and his dust newsletter
J. Descloitres (MODIS)
TOMS Science team for Aerosol Index
MODIS Science team for level1B radiances

- J. M. Prospero and his dust newsletter
- J. Descloitres (MODIS)
- TOMS Science team for Aerosol Index
- MODIS Science team for level1B radiances

- Acknowledgements