Aerosol features retrieved from solar aureole data: a simulation study concerning a turbid atmosphere

Tonna, G.; Nakajima, Teruyuki; Rao, Ruizhong

doi:10.1364/ao.34.004486

Cited by 37 publications

(24 citation statements)

References 26 publications

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“…The difference between retrieved tð0:5Þ (and a) is less than 0.01 (and 0.06). Tonna et al (1995) concluded that the sky radiometer is quite reliable in the field. Å ngström (1964) discussed the relationship between the size distribution of aerosols and the wavelength dependency of optical thickness.…”

Section: Instrumentationmentioning

confidence: 99%

“…Measurements were made every 10 minutes at Sapporo and every 15 minutes at other sites. The scanning method is described in detail in Tonna et al (1995). As shown in Fig.…”

Section: Instrumentationmentioning

confidence: 99%

“…A power law size distribution of aerosols is assumed as an initial condition. Although retrieved size of aerosols ranges from 0.02 to 10.0 mm, the details of reliable size range shows Tonna et al 1995, and Boi et al 1999.…”

Section: Instrumentationmentioning

confidence: 99%

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Sky Radiometer Measurements of Aerosol Optical Properties over Sapporo, Japan

Aoki

Fujiyoshi

2003

Journal of the Meteorological Society of Japan

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Ground-based sky radiometers were used to measure direct solar irradiance and solar aureole radiance for several years at Sapporo, Tsukuba, and Tokyo, Japan. From these measurements, we computed aerosol optical thickness at 0.5 mm, tð0:5Þ, and the A ˚ ngström exponent, a, and volume size distributions within a column. The optical thickness at Sapporo increased markedly over a short period of time following Asian dust events, and a forest fire in Siberia. The columnar volume size distributions observed during the Asian dust events showed a peak radius of 2.0-3.0 mm. Backward trajectory analyses suggest that the particles producing this springtime event originated in the Loess Plateau and Gobi Desert, and reached Sapporo via southern China. The columnar size distribution during the forest fire case showed an increase in the density of particles with a peak radius @0.2 mm. Trajectory analysis clearly linked the atmospheric changes over Sapporo with a forest fire in Siberia. The aerosol optical thickness, tð0:5Þ, has a clear seasonal cycle at Sapporo, with a vernal maximum and an autumnal minimum. The A ˚ ngström exponent, a, has a clear seasonal cycle at both Tokyo and Tsukuba, where early-winter maxima and springtime minima are observed, but at Sapporo the seasonal cycle is weaker, with a summer maximum and a vernal minimum. Aerosols were classified into four types (Types I@IV) based on tð0:5Þ, and a data observed at the three sites. Aerosols with a tð0:5Þ smaller than the total mean of tð0:5Þ, but greater than or equal to the total mean of a ðtð0:5Þ < tð0:5Þ; a b aÞ were classified as Type I; aerosols with tð0:5Þ b tð0:5Þ and a b a were Type II; those with tð0:5Þ < tð0:5Þ and a < a were Type III; and those with tð0:5Þ b tð0:5Þ, a < a were Type IV. The most common aerosol type, that is, the background aerosol, was Type I (@40%) at all three sites. Type-IV aerosols at all three sites showed the same seasonal cycle (spring maximum), suggesting large-scale phenomena such as Asian dust events may contribute to the production and transport of this aerosol type. The behavior of Type-II aerosols differed at the three sites, indicating that local phenomena are important in the production and transport of Type-II aerosols. The emission of manufactured aerosols and subsequent gas-to-particle processes may contribute to Type-II aerosol formation. Type-III aerosols at Sapporo were characterized by a seasonal cycle opposite to that of Type-IV aerosols, suggesting that large particles have different sources and/or transport processes in spring and autumn. Corresponding author and present affiliation: Ka-zuma Aoki, The atmospheric turbidity retrieved from the sky radiometer is compared, b(SR), at Sapporo with that calculated using direct solar radiation measurements, b(DSR). Both showed the same seasonal cycle, but b(SR) was slightly smaller (@0.02) than b(DSR). Sky radiometers can retrieve the optical properties of aerosols under cloudy conditions if there are no clouds around the solar aureole. The seasonal mean of tð0:5Þ (or ...

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Section: Instrumentationmentioning

confidence: 99%

“…Measurements were made every 10 minutes at Sapporo and every 15 minutes at other sites. The scanning method is described in detail in Tonna et al (1995). As shown in Fig.…”

Section: Instrumentationmentioning

confidence: 99%

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Sky Radiometer Measurements of Aerosol Optical Properties over Sapporo, Japan

Aoki

Fujiyoshi

2003

Journal of the Meteorological Society of Japan

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“…The measurement interval is typically 10 min. More details about the instrument and working principle can be found in papers by Nakajima et al (1996) and Tonna et al (1995). The sky radiometer commenced running in 2002 and continued measurements till early 2005.…”

Section: Instrument and Sitementioning

confidence: 99%

Study of columnar aerosol size distribution in Hong Kong

Yang

Wenig

2009

Atmos. Chem. Phys.

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Abstract. This paper presents studies on columnar aerosol optical properties in Hong Kong with focus on aerosol volume size distribution, which helps understand local aerosol properties, variation, hygroscopic growth and coagulation. Long-term ground measurements in the wet season in the years of 2002, 2003, 2004 and 2008 have been performed using a sun-sky radiometer. Data validation made using MODIS and local AERONET shows agreement. A bimodal size distribution is found with the fine mode centering at ∼0.2 µm and coarse mode centering at ∼3 µm respectively. The fine and coarse mode have close volume concentrations of nearly 50% fraction in composing local aerosols. Intercomparison of different years shows similar aerosol properties while a small increase of fine mode aerosol could be observed. A systematic shift of size distribution parameters is observed with different atmospheric conditions, where higher aerosol loadings and Angstrom exponent correspond to more fine mode aerosols. The fine mode is found to be more closely correlated with this shift than the coarse mode. A higher fine mode volume fraction and smaller median fine radius correspond to a larger Angstrom exponent. The fine mode aerosol hygroscopic growth is one of the main mechanisms for such systematic shifting. A third mode centering at ∼1-2 µm could be discovered under high aerosol loading and high fine mode aerosol conditions. It becomes more pronounced with high aerosol optical depth and larger Angstrom exponent. Investigation of its variation with corresponding optical parameters and correlation with atmospheric conditions appears to support the hypothesis that it is mainly due to the fine mode aerosol hygroscopic growth and coagulation rather than the contribution from the coarse mode. While the very humid environment facilitates the aerosol hygroscopic growth, aerosol coagulation might further produce Correspondence to: X. Yang (xunyang@cityu.edu.hk) larger aerosols under high fine aerosol conditions. The continental outflow with transported aging aerosols and biomass burning might have also contributed to this additional mode.

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“…Surface reflection increases radiance both in the solar principal plane (SPP) and also in almucantar (ALM). Tonna et al [1995] also report the sensitivity of radiance to the surface albedo. Uncertainty of aerosol optical properties derived from radiance measurements is increased whenever the surface optical properties are not known.…”

Section: Introductionmentioning

confidence: 99%

Correction of the ground-based measurements of radiance by the surface contribution for a better estimate of the aerosol radiative forcing

Elías

Silva

2004

Remote Sensing of Clouds and the Atmosphere VIII

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A 'measure' of the surface effect on downwelling radiance in the solar principal plane (SPP), K, is built by analysing simulations by a radiative transfer code. K describes the solar angle dependence of the ratio of radiance measured at a viewing angle θV=40°over radiance measured at θV=70°, both in SPP. The surface effect is described by a surface albedo value, used as an input parameter of the Successive Orders of Scattering code [Deuze et al., 1989]. K is mainly sensitive to the surface albedo but also to the Ångström exponent α and to the real part of the refractive index mR. α is derived from independent measurements of spectral aerosol optical thickness and mR is estimated in a first step of the method from radiance measurements made at θSun=70°. The method is applied on data acquired at the AERONET site of Sede Boker, Israel, in 2000. Results give a high reflective surface with small spectral dependence. An event of increase of vegetation cover (which we suppose is caused by rain falls) is observed as the surface albedo at 675 nm decreases while it remains constant at 870 nm. Aerosol single scattering albedo derived at 675 nm from radiance measurements varies little around 0.90 only if surface albedo change is considered.

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Aerosol features retrieved from solar aureole data: a simulation study concerning a turbid atmosphere

Cited by 37 publications

References 26 publications

Sky Radiometer Measurements of Aerosol Optical Properties over Sapporo, Japan

Sky Radiometer Measurements of Aerosol Optical Properties over Sapporo, Japan

Study of columnar aerosol size distribution in Hong Kong

Correction of the ground-based measurements of radiance by the surface contribution for a better estimate of the aerosol radiative forcing

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