Met Office logo
  bullet  Home  bullet  Research  bullet  Observational based research  bullet  Aerosol  bullet  DABEX Space
  NWP | Climate | Seasonal forecasting | Atmospheric processes | Oceanography | Projects | The stratosphere Space
Page Top
  Dust and Biomass EXperiment - DABEX
underline


Biomass burning aerosols have a significant influence on the radiation budget of the Earth/atmosphere system by scattering and absorbing solar radiation (e.g. Haywood and Boucher, 2000; Haywood et al, 2003a; Myhre et al, 2003a) with anthropogenic emissions being the dominant source. Similarly mineral dust exerts a significant influence on both the solar and the terrestrial radiation budget (Tanre et al., 2003; Haywood et al., 2003b; Highwood et al, 2003; Myhre et al, 2003b), but natural emissions are the dominant source.

The biomass burning aerosol component emitted from the African continent has been studied in detail during the Southern AFricAn Regional science Initiative (SAFARI 2000) which took place in early September 2000. Similarly the mineral dust component emitted from the African continent has been studied in detail during the SaHAran Dust Experiment (SHADE) which took place in late September 2000. However, the pattern of biomass burning in Africa follows a well determined seasonal cycle related to the seasonal shift in the Inter-Tropical Convergence Zone (ITCZ). Thus maximum emissions of anthropogenic biomass burning aerosol from the sub-Sahelian regions of northern Africa occur during December/January/February, with very few emissions occurring during August/September/November.

The aerosol optical depth links below show the MODIS-derived aerosol optical depths for September 2000 and January 2001 and show that the aerosol optical depth off the coast of west Africa is high during both months. However, the global burned area data maps also shown in the links below indicate that in January a significant fraction of the aerosol originates from anthropogenic biomass burning activities. Thus in December/January/February the interaction of mineral dust and biomass burning aerosols is at a maximum.

It is postulated that biomass burning aerosol may form an internal mixture with mineral dust. This would result in the optically active sub-micron biomass burning aerosol particles being taken up by the less optically active mineral dust particles and thus mineral dust would act to ameliorate the direct radiative forcing due to anthropogenic emissions of biomass burning aerosol.

Dust

Map of aerosol optical depths for September 2000
Map of aerosol optical depths for January 2001
Map of fires for September 2000
Map of fires for January 2000
MODIS image showing the mixing of dust and biomass burning aerosol (8 January 2005)
MODIS composite for January 2005

Objectives

The BAe 146 will be based in Niamey (Niger), and Dakar (Senegal) from 9 January until 17 February 2006. Approximately 40 hours of intensive flight hours are envisaged, and will concentrate on the objectives described below.

The main objectives of DABEX are:

  1. to perform high quality in-situ and remote sensing measurements of the optical and physical properties of anthropogenic biomass burning aerosols from sub-Sahelian west Africa;
  2. to perform high quality in-situ and remote sensing measurements of the optical and physical properties of natural mineral dust aerosols from over sub-Sahelian west Africa;
  3. to determine the interaction between the anthropogenic biomass burning aerosols and natural mineral dust aerosols using a combination of chemical, physical and optical measurements;
  4. to provide high quality spectral measurements of the solar and terrestrial radiative effects of both biomass burning aerosol and mineral dust aerosol;
  5. to determine the consistency between in-situ measurements/ satellite and surface-based remote-sensing methods of the effects on the radiation budget of the Earth of the composite biomass and mineral dust aerosols;
  6. to model the effect of the biomass and mineral dust aerosols on a regional and global scale and estimate the impact on the global radiation balance of the Earth/Atmosphere system.

Dust biomass

MODIS image showing the mixing of dust and biomass burning aerosol (8 January 2005)

References

Haywood, J. and Boucher, O., 2000: Estimates of the direct and indirect radiative forcing due to tropospheric aerosols: A review. Rev Geophys, 38 (4), 513-543, 10.1029/1999RG000078.

Haywood, J.M., Francis, P.N., Glew, M.D., Dubovik, O. and Holben, B., 2003: Comparison of aerosol size distributions, radiative properties, and optical depths determined by aircraft observations and sun photometers during SAFARI-2000. J Geophys Res, 108 (D13), 8471, doi:10.1029/2002JD002250.

Haywood, J.M., Osborne, S.R., Francis, P.N., Keil, A., Formenti, P., Andreae, M.O. and Kaye, P.H., 2003a: The mean physical and optical properties of regional haze dominated by biomass burning aerosol measured from the C-130 aircraft during SAFARI 2000. J Geophys Res, 108 (D13), 8473, doi:10.1029/2002JD002226.

Haywood J., Francis, P., Osborne, S., Glew, M. , Loeb, N., Highwood, E., Tanré, D., Myhre, G. Formenti, P. and Hirst, E., 2003b: Radiative properties and direct radiative effect of Saharan dust measured by the C-130 aircraft during SHADE: 1. Solar spectrum. J Geophys Res, 108 (D18), 8577, doi:10.1029/2002JD002687.

Highwood, E.J., Haywood, J.M., Silverstone, M.D., Newman, S.M. and Taylor, J.P., 2003: Radiative properties and direct effect of Saharan dust measured by the C-130 aircraft during SHADE
2: Terrestrial spectrum. J Geophys Res, 108 (D18), 8578, doi:10.1029/2002JD002552.

Myhre, G., Berntsen, T.K., Haywood, J.M., Sundet, J.K., Holben, B.N., Johnsrud, M. and Stordal, F., 2003a: Modeling the solar radiative impact of aerosols from biomass burning during the Southern African Regional Science Initiative (SAFARI-2000) experiment. J Geophys Res, 108 (D13), doi 10.1029/2002JD002313.

Myhre, G., Grini, A., Haywood, J.M., Stordal, F., Chatenet, B., Tanré, D., Sundet, J.K. and Isaksen, I.S.A., 2003b: Modelling the radiative impact of mineral dust aerosol during the Saharan Dust Experiment (SHADE) campaign. J Geophys Res, 108 (D18), 8579, doi:10.1029/2002JD002566.

Tanré, D., Haywood, J., Pelon, J., Léon, J.F., Chatenet, B., Formenti, P., Francis, P., Goloub, P., Highwood, E.J. and Myhre, G., 2003: Measurement and modeling of the Saharan dust radiative impact: Overview of the Saharan Dust Experiment (SHADE). J Geophys Res, 108 (D13), 8574, doi:10.1029/2002JD003273.

 

 
About Us
Publications by OBR
Aerosol
Boundary layer meteorology
Cloud physics
Radiative transfer
News
News release archive
Research news
Contact
Contact us
FAQ
www.metoffice.gov.uk ©Crown copyright
Crown copyright www.metoffice.gov.uk