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on the optical properties of smoke aerosol is crucial to the understanding of its influence on the earth's climate system. It is worth noting that the radiative forcing of all aerosols is comparable to the radiative forcing due to the increases in greenhouse gas concentrations in the atmosphere since the beginning of the industrial age, which is estimated to be +2.45 W m −2 ( Schimel et al. 1996 ). Note that there is a very large uncertainty (a factor of 3) in the estimate of radiative forcing
on the optical properties of smoke aerosol is crucial to the understanding of its influence on the earth's climate system. It is worth noting that the radiative forcing of all aerosols is comparable to the radiative forcing due to the increases in greenhouse gas concentrations in the atmosphere since the beginning of the industrial age, which is estimated to be +2.45 W m −2 ( Schimel et al. 1996 ). Note that there is a very large uncertainty (a factor of 3) in the estimate of radiative forcing
analogous situation exists with the shape of solar extinction spectra—for example, as seen through aerosol layers. In this case the wavelength dependence of the aerosol optical depth depends sensitively on the size distribution of particles comparable to and smaller than the wavelength of sunlight. Many different algorithms have been developed (see for example King et al. 1978 ) exploiting this dependence since the pioneering work of Ångström (1929) . Solar extinction spectra are measured routinely by
analogous situation exists with the shape of solar extinction spectra—for example, as seen through aerosol layers. In this case the wavelength dependence of the aerosol optical depth depends sensitively on the size distribution of particles comparable to and smaller than the wavelength of sunlight. Many different algorithms have been developed (see for example King et al. 1978 ) exploiting this dependence since the pioneering work of Ångström (1929) . Solar extinction spectra are measured routinely by
. A. R. , Meijninger W. M. L. , and Schipper F. , 2002 : Experiences from one-year continuous operation of a large aperture scintillometer over a heterogeneous land surface . Bound.-Layer Meteor. , 105 , 85 – 97 . Bradley, S. G. , Stow C. D. , and Lynch-Blosse C. A. , 2000 : Measurements of rainfall properties using long optical path imaging . J. Atmos. Oceanic Technol. , 17 , 761 – 772 . Cain, J. D. , Rosier P. T. W. , Meijninger W. , and de Bruin H. A. R. , 2001
. A. R. , Meijninger W. M. L. , and Schipper F. , 2002 : Experiences from one-year continuous operation of a large aperture scintillometer over a heterogeneous land surface . Bound.-Layer Meteor. , 105 , 85 – 97 . Bradley, S. G. , Stow C. D. , and Lynch-Blosse C. A. , 2000 : Measurements of rainfall properties using long optical path imaging . J. Atmos. Oceanic Technol. , 17 , 761 – 772 . Cain, J. D. , Rosier P. T. W. , Meijninger W. , and de Bruin H. A. R. , 2001
, thereby leading to increased AODs in the AN period. Aerosols over the Indian subcontinent may have implications for cloud microphysical properties and the radiation budget. 5. Conclusions Multiyear measurements of spectral aerosol optical depths (AODs) made at Manora Peak in the central Himalayas have revealed the following. The AODs at 0.5 μ m were very low (≤0.1) in winter and increased rather steeply to reach high values (∼0.5) in summer. The monthly mean AODs vary significantly (by more than a
, thereby leading to increased AODs in the AN period. Aerosols over the Indian subcontinent may have implications for cloud microphysical properties and the radiation budget. 5. Conclusions Multiyear measurements of spectral aerosol optical depths (AODs) made at Manora Peak in the central Himalayas have revealed the following. The AODs at 0.5 μ m were very low (≤0.1) in winter and increased rather steeply to reach high values (∼0.5) in summer. The monthly mean AODs vary significantly (by more than a
1. Introduction Atmospheric turbulence is a key challenge in ground-based astronomy because it dramatically impacts the angular resolution of a telescope. Small-scale temperature and moisture fluctuations in the atmosphere result in fluctuations of the refractive index. The wave front of radiation traveling through the atmosphere changes as it encounters inhomogeneities in the refractive index, degrading optical image quality. The intensity of the turbulent fluctuations of the atmospheric
1. Introduction Atmospheric turbulence is a key challenge in ground-based astronomy because it dramatically impacts the angular resolution of a telescope. Small-scale temperature and moisture fluctuations in the atmosphere result in fluctuations of the refractive index. The wave front of radiation traveling through the atmosphere changes as it encounters inhomogeneities in the refractive index, degrading optical image quality. The intensity of the turbulent fluctuations of the atmospheric
.1 . Field , P. R. , R. Wood , P. R. A. Brown , P. H. Kaye , E. Hirst , and R. Greeaway , 2003 : Ice particle interarrival times measured with a fast FSSP . J. Atmos. Oceanic Technol. , 20 , 249 – 261 , doi: 10.1175/1520-0426(2003)020<0249:IPITMW>2.0.CO;2 . Gayet , J.-F. , G. Mioche , V. Shcherbakov , C. Gourbeyre , R. Busen , and A. Minikin , 2011 : Optical properties of pristine ice crystals in mid-latitude cirrus clouds: A case study during CIRCLE-2 experiment
.1 . Field , P. R. , R. Wood , P. R. A. Brown , P. H. Kaye , E. Hirst , and R. Greeaway , 2003 : Ice particle interarrival times measured with a fast FSSP . J. Atmos. Oceanic Technol. , 20 , 249 – 261 , doi: 10.1175/1520-0426(2003)020<0249:IPITMW>2.0.CO;2 . Gayet , J.-F. , G. Mioche , V. Shcherbakov , C. Gourbeyre , R. Busen , and A. Minikin , 2011 : Optical properties of pristine ice crystals in mid-latitude cirrus clouds: A case study during CIRCLE-2 experiment
1. Introduction Atmospheric turbulence can significantly affect the performance of electro-optical imaging systems to detect and identify objects, being responsible for scintillation, blurring, and image wandering. The theory, in the scientific literature, relates the turbulence effects to the optical refractive index structure parameter C 2 n , which characterizes the rapid fluctuation of the index of refraction ( Beland 1993 ). For predicting turbulence effects on an imaging system, it would
1. Introduction Atmospheric turbulence can significantly affect the performance of electro-optical imaging systems to detect and identify objects, being responsible for scintillation, blurring, and image wandering. The theory, in the scientific literature, relates the turbulence effects to the optical refractive index structure parameter C 2 n , which characterizes the rapid fluctuation of the index of refraction ( Beland 1993 ). For predicting turbulence effects on an imaging system, it would
surface. Over oceans, the surface reflectivity is small and aerosol optical properties can be estimated much more reliably than that over land. The Total Ozone Mapping Spectrometer (TOMS) retrieves the aerosol distribution over both land and oceans by means of aerosol index, which is related to the aerosol optical thickness and the single scattering albedo ( Herman et al. 1997 ). Distributions of aerosols over global oceans have been derived from various satellite radiance measurements. For example
surface. Over oceans, the surface reflectivity is small and aerosol optical properties can be estimated much more reliably than that over land. The Total Ozone Mapping Spectrometer (TOMS) retrieves the aerosol distribution over both land and oceans by means of aerosol index, which is related to the aerosol optical thickness and the single scattering albedo ( Herman et al. 1997 ). Distributions of aerosols over global oceans have been derived from various satellite radiance measurements. For example
, 2012 : CALIPSO observations of transatlantic dust: Vertical stratification and effect of clouds . Atmos. Chem. Phys. , 12 , 11 339 – 11 354 , https://doi.org/10.5194/acp-12-11339-2012 . 10.5194/acp-12-11339-2012 Yao , T. D. , and Coauthors , 2012 : Third Pole Environment (TPE) . Environ. Dev. , 3 , 52 – 64 , https://doi.org/10.1016/j.envdev.2012.04.002 . 10.1016/j.envdev.2012.04.002 Yi , B. Q. , P. Yang , and B. A. Baum , 2014 : Impact of pollution on the optical properties of trans-Pacific East
, 2012 : CALIPSO observations of transatlantic dust: Vertical stratification and effect of clouds . Atmos. Chem. Phys. , 12 , 11 339 – 11 354 , https://doi.org/10.5194/acp-12-11339-2012 . 10.5194/acp-12-11339-2012 Yao , T. D. , and Coauthors , 2012 : Third Pole Environment (TPE) . Environ. Dev. , 3 , 52 – 64 , https://doi.org/10.1016/j.envdev.2012.04.002 . 10.1016/j.envdev.2012.04.002 Yi , B. Q. , P. Yang , and B. A. Baum , 2014 : Impact of pollution on the optical properties of trans-Pacific East
1. Introduction Ice clouds play an important role in the earth’s radiation budget and climate ( Liou 1986 ). Accurate information of their optical properties is critical to assessing the climate effects and feedback associated with these clouds ( Stephens et al. 1990 ). Reflected solar radiation and emitted longwave radiation under cirrus cloudy conditions depend strongly upon the complex microphysical properties of these clouds ( Mitchell et al. 1996 ; Fu et al. 1998 , 1999 ; Chepfer et al
1. Introduction Ice clouds play an important role in the earth’s radiation budget and climate ( Liou 1986 ). Accurate information of their optical properties is critical to assessing the climate effects and feedback associated with these clouds ( Stephens et al. 1990 ). Reflected solar radiation and emitted longwave radiation under cirrus cloudy conditions depend strongly upon the complex microphysical properties of these clouds ( Mitchell et al. 1996 ; Fu et al. 1998 , 1999 ; Chepfer et al
