Aerosol modeling in ALADIN-Climat

Aerosols can be represented in ALADIN-Climat through two different ways:

- using monthly and interannual aerosol optical depth (AOD) climatologies:
This parameter is the aerosol total extinction of radiation due to aerosols, integrated over the whole atmospheric column. The different AOD files are provided for every aerosol type represented in the model, namely dust, sea-salt, sulfate, organic matter and black carbon aerosols.

- using the TACTIC interactive aerosol scheme:
This second method consists in using a prognostic aerosol scheme, adapted from the original GEMS/MACC aerosol module (Morcrette et al. 2009), able to represent the main aerosol types and to tale into account their direct and semi-direct radiative effects. Natural aerosols, such as desert dust and sea-salt, are dynamically emitted, in function of surface wind speed, and soil characteristics such as soil moisture and soil textures. Anthropogenic and biomass burning aerosol emissions (black carbon, organic matter, secondary aerosol precursors) are provided with global emission inventories. This scheme relies on size bin distribution : 3 bins for desert dust (0.01-1.0 / 1.0-2.5 / 2.5-20.0 μm) and for sea-salt (0.03-0.5 / 0.5-5.0 / 5.0-20.0 μm), two bins for black-carbon (hydrophilic / hydrophobic), as well as for organic matter, one bin for sulphate, one for sulphate precursors, two bins for nitrates (fine/coarse mode), one for ammonium and one for gaseous ammoniac. All these aerosols are transported, and affected by dry and wet deposition. Such a prognotic scheme enables us to have evolving aerosol concentrations at each time step of the simulation, in total consistence with model physics.

In both methods, aerosols interact with solar and thermal radiation, depending on their optical properties. The first indirect effect (cloud albedo or Twomey effect) is also taken into account.

 Publications

P. Nabat, S. Somot, C. Cassou, M. Mallet, M. Michou, D. Bouniol, B. Decharme, T. Drugé, R. Roehrig, and D. Saint-Martin Modulation of radiative aerosols effects by atmospheric circulation over the Euro-Mediterranean region, Atmos. Chem. Phys. Discuss., in review, DOI:10.5194/acp-2019-1183.

Mallet, M., Nabat, P., Zuidema, P., Redemann, J., Sayer, A. M., Stengel, M., Schmidt, S., Cochrane, S., Burton, S., Ferrare, R., Meyer, K., Saide, P., Jethva, H., Torres, O., Wood, R., Saint Martin, D., Roehrig, R., Hsu, C., and Formenti, P. (2019) Simulation of the transport, vertical distribution, optical properties and radiative impact of smoke aerosols with the ALADIN regional climate model during the ORACLES-2016 and LASIC experiments, Atmos. Chem. Phys., 19, 4963-4990, DOI:10.5194/acp-19-4963-2019.

Drugé, T., Nabat, P., Mallet, M., and Somot, S. (2019) Model simulation of ammonium and nitrate aerosols distribution in the Euro-Mediterranean region and their radiative and climatic effects over 1979–2016, Atmos. Chem. Phys., 19, 3707-3731, DOI:10.5194/acp-19-3707-2019.

Nabat, P., Somot, S., Mallet, M., Michou, M., Sevault, F., Driouech F., Meloni, D., Di Sarra, A., Di Biagio, C., Formenti, P., Sicard, M., Léon, J.-F. and Bouin, M.-N. (2015), Dust aerosol radiative effects during summer 2012 simulated with a coupled regional aerosol-atmosphere-ocean model over the Mediterranean region, Atm. Chem. Phys., 15, 3303-3326, DOI:10.5194/acp-15-3303-2015.