Aerosols and Climate Change: Present Understanding, Challenges, and Future Outlook
Atmospheric aerosols are a mixture of solid or liquid particles suspended in the medium of air. Their physical (size, shape, and texture) and chemical properties vary over sub-micron and super-micron radius range, consequently their removal processes, and their residence times differ greatly. Aerosols play a vital role in cloud formation and air pollution among others. The space-time variations in aerosol characteristics, and aerosol types arise due to different aerosol sources, and atmospheric dynamics which include boundary layer, temperature, relative humidity variations, and long-range transport. The optical, physical, and chemical characteristics of aerosols over continent and ocean exhibit distinct variations. Atmospheric aerosols through direct and indirect radiative effects influence the Earth-atmosphere radiation budget and climate. The challenges involved in estimating the direct and indirect radiative effects of aerosols, and further detection and attribution of the temperature response due to aerosols which include delineating more quantitatively the natural and man-made contribution, and scattering versus absorbing aerosols are detailed in this chapter. The presence of different aerosol species over a location produced by sources of local origin, and long-range transport can give rise to different mixing states of aerosols owing to aging and interaction among them which in turn can change their characteristics and life cycle. Results reveal that single scattering albedo, which is non-linearly related to aerosol radiative forcing, is significantly different for external, core-shell, and internal mixtures. Aerosol measurements from a remote sensing perspective and the advances that have been made in this regard are enlisted. The future requirements in terms of measurements, remote sensing techniques, and modeling studies for better detection and attribution of climate change due to aerosols is envisioned.
KeywordsAerosols Distribution Remote sensing Radiative forcing Climate change Challenges Future outlook
Aerosol optical depths from MODIS and MISR, and single scattering albedo from OMI are downloaded from GES-DISC, NASA (disc.sci.gsfc.nasa.gov/giovanni). CALIPSO aerosol extinction data are downloaded from ICARE (http://www.icare.univ-lille1.fr/drupal/calipso). SAGE II version 7.0 aerosol extinction data sets are downloaded from https://eosweb.larc.nasa.gov/project/sage2/sage2_v7_table. I accord my thanks to S. Kedia, Centre for Development of Advanced Computing, Pune, and P. Kulkarni, CMR Institute of Technology, Bengaluru for their help in drawing Figs. T.A. Rajesh, Physical Research Laboratory, Ahmedabad is acknowledged for his help in running and maintaining ATOFMS, aethalometer and nephelometer from which a select set of data have been used, and for his help in drawing figures.
- Diner DJ et al (2001) MISR aerosol optical depth retrievals over southern Africa during the SAFARI-2000 winter season campaign. Geophys Res Lett 28:3127-3130Google Scholar
- Forster P, Ramaswamy V, Artaxo P, Berntsen T, Betts R, Fahey DW, Haywood J, Lean J, Lowe DC, Myhre G, Nganga J, Prinn R, Raga G, Schulz M, Van Dorland R (2007) Changes in atmospheric constituents and in radiative forcing. In: Solomon S, Qin D, Manning M, Chen Z, Marquis M, Averyt KB, Tignor M, Miller HL (eds) Climate change 2007:the physical science basis. Contribution of Working Group I to the fourth assessment report of the intergovernmental panel on climate change. Cambridge University Press, Cambridge, pp 129–234Google Scholar
- Giles DM, Holben BN, Eck TF, Sinyuk A, Smirnov A, Slutsker I, Dickerson RR, Thompson AM, Schafer JS (2012) An analysis of AERONET aerosol absorption properties and classifications representative of aerosol source regions. J Geophys Res 117:D17203. https://doi.org/10.1029/2012JD018127 CrossRefGoogle Scholar
- IPCC (2013) Summary for Policymakers. In: Stocker TF, Qin D, Plattner G-K, Tignor M, Allen SK, Boschung J, Nauels A, Xia Y, Bex V, Midgley PM (eds) Climate change 2013: the physical science basis. Contribution of Working Group I to the fifth assessment report of the intergovernmental panel on climate change. Cambridge University Press, Cambridge, p 27Google Scholar
- Kahn RA, Garay MJ, Nelson DL, Yau KK, Bull MA, Gaitley BJ, Martonchik JV, Levy RC (2007) Satellite-derived aerosol optical depth over dark water from MISR and MODIS: comparisons with AERONET and implications for climatological studies. J Geophys Res 112:D18205. https://doi.org/10.1029/2006JD008175 CrossRefGoogle Scholar
- Kinne S, Schulz M, Textor C, Guibert S, Balkanski Y, Bauer SE, Berntsen T, Berglen TF, Boucher O, Chin M, Collins W, Dentener F, Diehl T, Easter R, Feichter J, Fillmore D, Ghan S, Ginoux P, Gong S, Grini A, Hendricks J, Herzog M, Horowitz L, Isaksen I, Iversen T, Kirkevag A, Kloster S, Koch D, Kristjansson JE, Krol M, Lauer A, Lamarque JF, Lesins G, Liu X, Lohmann U, Montanaro V, Myhre G, Penner JE, Pitari G, Reddy S, Seland O, Stier P, Takemura T, Tie X (2006) An AeroCom initial assessment optical properties in aerosol component modules of global models. Atmos Chem Phys 6:1815–1834CrossRefGoogle Scholar
- Liou KN (1980) An introduction to atmospheric radiation. 392 pp. Academic Press, San DiegoGoogle Scholar
- Ramachandran S, Jayaraman A, Acharya YB, Subbaraya BH (1994) Features of aerosol optical depths over Ahmedabad as observed with a Sun-tracking photometer. Contr Atmos Phys 67:57–70Google Scholar
- Ramaswamy V et al (2001) Radiative forcing of climate change. In: Houghton JT, Ding Y, Griggs DJ, Noguer M, van der Linden PJ, Dai X, Maskell K, Johnson CA (eds) Climate change 2001: the scientific basis. Contribution of Working Group I to the third assessment report of the intergovernmental panel on climate change. Cambridge University Press, Cambridge. 881ppGoogle Scholar
- Textor C, Schulz M, Guibert S, Kinne S, Balkanski Y, Bauer SE, Berntsen T, Berglen TF, Boucher O, Chin M, Dentener F, Diehl T, Easter R, Feichter J, Fillmore D, Ghan S, Ginoux P, Gong S, Grini A, Hendricks J, Horowitz L, Huang P, Isaksen I, Iversen T, Kloster S, Koch D, Kirkevag A, Kristjansson JE, Krol M, Lauer A, Lamarque JF, Liu X, Montanaro V, Myhre G, Penner JE, Pitari G, Reddy S, Seland Ø, Stier P, Takemura T, Tie X (2006) Analysis and quantification of the diversities of aerosol life cycles within AeroCom. Atmos Chem Phys 6:1777–1813CrossRefGoogle Scholar
- Whitby KT (1978) The physical characteristics of sulfur aerosols. Atmos Environ 12:135–139Google Scholar