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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 114 (1976), S. 1-14 
    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The error terms involved in precision multi-wavelength sun photometry, as used to study atmospheric aerosols, are analyzed. The error terms treated include instrumental errors, calibration errors, and errors imposed by the atmosphere. It is shown that in order to derive accurate aerosol parameters, one must exercise great care in the photometer calibration. A procedure for accurate calibration is described, based on an intercalibration between extrapolations of the extraterrestrial solar spectral irradiance and irradiance of a standard lamp. Methods are described to assess, and reduce, uncertainties brought about by diffuse radiation in the photometer's field of view, temporal variations in aerosol optical depth, and gaseous absorption features at the operating wavelength. It is shown that if care is taken sun photometry can be used to derive monochromatic aerosol optical depth to an accuracy of several thousandths.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1420-9136
    Keywords: Scattering ; Stratospheric haze ; Twilight colors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Layers of stratospheric aerosol with optical thicknesses as small as 10−4 cause noticeable perturbations in the monochromatic logarithmic brightness gradient,G, and the color ratio,C, of the twilight sky. Modeling of the twilight's radiant properties shows that definite single-valued relationships exist between maxima inC or minima inG and optical thickness, τ, physical thickness Δh, and mean altitude, $$\overline h $$ , of stratospheric layers. It is therefore possible to determine τ, Δh and $$\overline h $$ and monitor their variations by performing either single wavelength measurements ofG or two-wavelength spectrophotometric measurements ofC. The presence of haze in the lower troposphere and the occurrence of multiple scattering both have relatively minor influences on the recovery of the stratospheric dust properties, provided that 10〈 $$\overline h $$ 〈30 km. Formal mathematical inversions of the single-scattering twilight equations are possible in principle, but difficult in practice because of non-linearities. Inversions incorporating an iterative linearization process with constrained smoothing, successfully recovered the features of the haze layer, but tended to oversmooth the vertical profile and underestimate the mean altitude of the haze layer.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 102 (1973), S. 223-235 
    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Summary The phenomenon of the green flash at sunset (or sunrise) is reviewed. Several possible mechanisms that have been put forth to explain the green flash are discussed. A quantitative model for the phenomenon is then described, which includes parameters that are representative for a polar atmosphere (low humidity and small aerosol optical depth). It is supposed that the primary mechanism responsible for causing the green flash are natural molecular disperion, and, the filtering action imposed by the atmosphere for low elevation angles. Results from the model indicate that a green rim of vertical extent ≅0.15 milliradians would appear at the upper limb of the sun during sunset or sunrise. The theoretical results are compared with observations of a green flash made at wintertime in interior Alaska.
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 268 (1977), S. 713-715 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The initial, purely visual observation of Arctic haze were made more than 20 years ago. It was then forgotten about until 1972 when radiation measurements near Barrow, Alaska revealed unexpectedly high atmospheric turbidities, confirmed in 1974 (ref. 2). The anomalous turbidity was partly found in ...
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Climatic change 5 (1990), S. 297-303 
    ISSN: 1573-1480
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The Gaia hypothesis proposed by Lovelock and Margulis presumes the existence of an unspecified biological means of ameliorating climate that has operated since the emergence of life 3500 Myr ago: Recently it was suggested that the mechanism of thermostasis may involve biospheric cycling of atmospheric carbon dioxide. We suggest an alternative hypothesis of biothermostasis operating through the sulfur cycle, rather than the carbon cycle. The mechanism would operate by altering planetary albedo through the selective creation of biospheric organic sulfide gases which go on to metamorphize into submicron particles and introduce cooling. In contrast to the carbon-cycle mechanism, sulfur-based cooling would have the ability to ameliorate climate well into the future, in principle over stellar Main Sequence time intervals. The main feature of interest is that the S cycle represents a particularly favorable thermodynamic pathway, involving three to four orders of magnitude less mass of active material cycled through the biospheric-atmospheric system (in response to a given temperature-imposed stress) than would be the case for a greenhouse gas hypothesis. There is no evidence that the suggested biospheric controlled particle-albedo change mechanism is actually operating, but we speculate that the probability of its rising importance and perhaps eventual dominance will improve when the partial pressure of atmospheric CO2 drops low enough to impose stress on metabolic processes. The intriguing thing about the process is its extremely high efficiency.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Climatic change 5 (1983), S. 297-303 
    ISSN: 1573-1480
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The Gaia hypothesis proposed by Lovelock and Margulis presumes the existence of an unspecified biological means of ameliorating climate that has operated since the emergence of life 3500 Myr ago: Recently it was suggested that the mechanism of thermostasis may involve biospheric cycling of atmospheric carbon dioxide. We suggest an alternative hypothesis of biothermostasis operating through the sulfur cycle, rather than the carbon cycle. The mechanism would operate by altering planetary albedo through the selective creation of biospheric organic sulfide gases which go on to metamorphize into submicron particles and introduce cooling. In contrast to the carbon-cycle mechanism, sulfur-based cooling would have the ability to ameliorate climate well into the future, in principle over stellar Main Sequence time intervals. The main feature of interest is that the S cycle represents a particularly favorable thermodynamic pathway, involving three to four orders of magnitude less mass of active material cycled through the biospheric-atmospheric system (in response to a given temperature-imposed stress) than would be the case for a greenhouse gas hypothesis. There is no evidence that the suggested biospheric controlled particle-albedo change mechanism is actually operating, but we speculate that the probability of its rising importance and perhaps eventual dominance will improve when the partial pressure of atmospheric CO2 drops low enough to impose stress on metabolic processes. The intriguing thing about the process is its extremely high efficiency.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Climatic change 8 (1986), S. 93-93 
    ISSN: 1573-1480
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 9
    Publication Date: 1983-01-01
    Print ISSN: 0003-0007
    Electronic ISSN: 1520-0477
    Topics: Geography , Physics
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  • 10
    Publication Date: 1995-12-01
    Print ISSN: 0003-0007
    Electronic ISSN: 1520-0477
    Topics: Geography , Physics
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