@article{fdi:010062650,
  title = {{V}ariability of the infrared complex refractive index of {A}frican mineral dust : experimental estimation and implications for radiative transfer and satellite remote sensing},
  author = {{D}i {B}iagio, {C}. and {B}oucher, {H}ugues and {C}aquineau, {S}andrine and {C}hevaillier, {S}. and {C}uesta, {J}. and {F}ormenti, {P}.},
  editor = {},
  language = {{ENG}},
  abstract = {{E}xperimental estimations of the infrared refractive index of {A}frican mineral dust have been retrieved from laboratory measurements of particle transmission spectra in the wavelength range 2.5-25 mu m. {F}ive dust samples collected at {B}anizoumbou ({N}iger) and {T}amanrasset ({A}lgeria) during dust events originated from different {W}estern {S}aharan and {S}ahelian areas have been investigated. {T}he real (n) and imaginary (k) parts of the refractive index obtained for the different dust samples vary in the range 1.1-2.7 and 0.05-1.0, respectively, and are strongly sensitive to the mineralogical composition of the particles, especially in the 8-12 and 17-25 mu m spectral intervals. {D}ust absorption is controlled mainly by clays (kaolinite, illite, smectite) and, to a lesser extent, by quartz and calcium-rich minerals (e. g. calcite, gypsum). {S}ignificant differences are obtained when comparing our results with existing experimental estimations available in the literature, and with the values of the {OPAC} ({O}ptical {P}roperties of {A}erosols and {C}louds) database. {T}he different data sets appear comparable in magnitude, with our values of n and k falling within the range of variability of past studies. {H}owever, literature data fail in accurately reproducing the spectral signatures of the main minerals, in particular clays, and they significantly overestimate the contribution of quartz. {F}urthermore, the real and the imaginary parts of the refractive index from some literature studies are found not to verify the {K}ramers-{K}ronig relations, thus being theoretically incorrect. {T}he comparison between our results, from western {A}frica, and literature data, from different locations in {E}urope, {A}frica, and the {C}aribbean, nonetheless, confirms the expected large variability of the dust infrared refractive index. {T}his highlights the necessity for an extended systematic investigation of dust properties at infrared wavelengths. {F}or the five analysed dust samples, aerosol intensive optical properties relevant to radiative transfer (mass extinction efficiency, k(ext), single scattering albedo, omega, and asymmetry factor, g) have been calculated, by using the {M}ie theory, based on the estimated refractive index and measured particle size distribution. {T}he optical properties show a large sample-to-sample variability, with k(ext), omega, and g varying in the range 0.05-0.35, 0.25-1.0, and 0.05-0.75. {T}his variability is expected to significantly impact satellite retrievals of atmospheric and surface parameters (e. g. from the {I}nfrared {A}tmospheric {S}ounding {I}nterferometer, {IASI}) and estimates of the dust radiative forcing.},
  keywords = {{NIGER} ; {ALGERIE}},
  booktitle = {},
  journal = {{A}tmospheric {C}hemistry and {P}hysics},
  volume = {14},
  numero = {20},
  pages = {11093--11116},
  ISSN = {1680-7316},
  year = {2014},
  DOI = {10.5194/acp-14-11093-2014},
  URL = {https://www.documentation.ird.fr/hor/fdi:010062650},
}