Radiative forcing by mineral dust aerosols: Sensitivity to key variables

American Geophysical Union (AGU) - Tập 103 Số D24 - Trang 31637-31645 - 1998
Hong Liao, John H. Seinfeld

Tóm tắt

We examine diurnally averaged radiative forcing by mineral dust aerosols in shortwave and longwave spectral regions using a one‐dimensional column radiation model. At the top of the atmosphere (TOA), net (shortwave plus longwave) dust radiative forcing can be positive (heating) or negative (cooling) depending on values of key variables. We derive an analytical expression for the critical single‐scattering albedo at which forcing changes sign for an atmosphere containing both cloud and aerosol layers. At the surface, net dust forcing can be positive or negative under clear‐sky conditions, whereas it is always cooling in the presence of a low‐level stratus cloud. Longwave radiative forcing is essentially zero when clouds are present. We also study the sensitivity of dust diurnally averaged forcing to the imaginary part of refractive index (k), height of the dust layer, dust particle size, and dust optical depth. These variables play different roles as follows: (1) under both clear‐ and cloudy sky conditions, net TOA forcing is more sensitive to k than net surface forcing; (2) clear‐sky longwave forcing and cloudy‐sky TOA shortwave forcing are very sensitive to the altitude of the dust layer; although clear‐sky shortwave forcing is not sensitive to it; (3) clear‐sky shortwave forcing is much more sensitive to particle size than cloudy‐sky shortwave forcing; longwave forcing is not sensitive to particle size; and (4) all forcings are sensitive to optical depth except cloudy‐sky longwave forcing.

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Tài liệu tham khảo

10.1175/1520-0469(1980)037<0193:RHRFSD>2.0.CO;2

10.1007/BF00140508

10.1175/1520-0469(1981)038<1105:SORCCM>2.0.CO;2

10.1029/95GL00800

10.1126/science.183.4120.75

10.1175/1520-0469(1975)032<0409:TTSAIR>2.0.CO;2

10.1029/97GL50245

10.1029/96JD01818

Fröhlich C. andJ.London Revised instruction manual on radiation instruments and measurements World Clim. Res. Program (WCRP) Pub. Ser. 7 WMO TD 149 World Meteorol. Organ Geneva 1986.

10.1175/1520-0469(1993)050<2008:POTRPO>2.0.CO;2

10.1029/96JD03436

10.1002/qj.49712354307

10.1175/1520-0469(1986)043<0784:CAOSMS>2.0.CO;2

Lacis A. A., 1995, Aerosol Forcing of Climate, 11

Liou K. N., 1980, An Introduction to Atmospheric Radiation

10.1364/AO.32.004652

10.1364/AO.33.007206

10.1029/JC082i021p03153

10.1175/1520-0469(1977)034<1885:IBIALR>2.0.CO;2

10.1029/JD090iD03p05597

Seinfeld J. H., 1997, Atmospheric Chemistry and Physics

10.1016/0960-1686(93)90023-R

10.1038/381681a0

10.1016/0960-1686(93)90021-P

10.1029/98JD00049

10.1029/94JD01928

10.1029/95JD03610

10.1038/380419a0

10.1175/1520-0469(1976)033<2440:TBFITS>2.0.CO;2

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Thông tin xuất bản

American Geophysical Union (AGU)

Tập 103 Số D24

31637-31645

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