We analyze the possibilities of orbital photopolarimetric measurements to study properties of aerosols in the Earth's atmosphere. As an example, we consider the case when such measurements are performed within a n...
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We analyze the possibilities of orbital photopolarimetric measurements to study properties of aerosols in the Earth's atmosphere. As an example, we consider the case when such measurements are performed within a narrow spectral channel centered at 1.378 mu m that allows to retrieve microphysical characteristics of stratospheric aerosols separately from those of tropospheric aerosols. We consider the case of stratospheric aerosols caused by volcanic eruption, and adopt the model of the stratosphere in the form of a homogeneous plane-parallel layer composed of polydisperse spherical particles. We use numerically exact solutions of the vector radiative transfer equation to theoretically simulate measurements carried out at various numbers of scattering angles, including: (i) radiance measurements alone;(ii) polarization measurements alone;and (iii) radiance and polarization measurements together. The results of computations show that the simultaneous use of radiance and polarization measurements at a sufficiently large number of scattering angles enables one to retrieve the optical thickness, effective radius, and refractive index of aerosols with adequate accuracy. We demonstrate how the accuracy of the derived values of the optical parameters of aerosols depends on the accuracy of measurements of the intensity and polarization of the reflected light, optical thickness of aerosol layer itself, effective radius of aerosols, width of the particle size distribution, and number of viewing angles. (C) 2020 Published by Elsevier Ltd.
This paper makes an attempt to improve the retrieving algorithm for an intelligent communication instrument. The instrument is developed for visually impaired computer users, and it converts texts displayed on a compu...
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This paper makes an attempt to improve the retrieving algorithm for an intelligent communication instrument. The instrument is developed for visually impaired computer users, and it converts texts displayed on a computer screen into audio messages to help them operate the computer. The conversion is performed based on a user dictionary, and a retrieving algorithm is needed to search the dictionary. In order to accelerate the retrieving speed, we adopt an index table when retrieving the first two alphabets of a word in the dictionary. The time for retrieving words is measured in the experiments. The experimental results reveal that the retrieving operations can be finished within an acceptable time.
In Earth Observing System (EOS) plan, MODerate-resolution Imaging Spectroradiometer (MODIS) is loaded on both the two polar-orbit satellites: Terra (EOS-AM1) and Aqua (EOS-PM1). MODIS data has 16 Thermal InfraRed (TIR...
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ISBN:
(纸本)0819462551
In Earth Observing System (EOS) plan, MODerate-resolution Imaging Spectroradiometer (MODIS) is loaded on both the two polar-orbit satellites: Terra (EOS-AM1) and Aqua (EOS-PM1). MODIS data has 16 Thermal InfraRed (TIR) channels (3.5 similar to 14.5 mu m) among all of its 36 channels. Land Surface Temperature (LST) is an important indicator of earth surface energy balances and climate changes, as well as a key parameter in physical processes of land surface on both global and regional scale. LST is widely applied in the research of disciplines such as meteorology, hydrology, ecology, biochemistry, etc(1). Therefore, retrieving LST from appropriate MODIS TIR bands is one of the important applications. First of all, this paper introduces theoretical foundations of retrieving LST from remote sensing data, such as the method of selecting appropriate TIR bands by conditional analysis of atmospheric window. Then, this paper provides an overview of LST retrieving algorithms up to now, including Single Window algorithm, Split Window algorithm, Improved Split Window algorithm, Generalized Split Window algorithm and Day/Night algorithm. And at last, towards to the limitations of LST retrieving algorithm, the authors indicates their specific perspectives on the directions of further correlative research in two aspects: improving LST retrieving algorithm and increasing LST retrieving accuracy.
In capacitive position sensors many problems of mechanical origin can be solved by using well-designed multi-capacitance sensing elements. This paper discusses a new and efficient algorithm to retrieve the measurand f...
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In capacitive position sensors many problems of mechanical origin can be solved by using well-designed multi-capacitance sensing elements. This paper discusses a new and efficient algorithm to retrieve the measurand from data measured using multi-capacitance capacitive elements. An overview is presented of the entire capacitive position-sensor system and shows that the design aspects of the various system parts and the retrieving algorithm are closely related to each other. After formulating four basic requirements, the complete set of retrieving algorithms satisfying these four basic requirements is derived in a mathematical way. From this complete set, an optimum algorithm is selected, with respect to the smallest non-linearity possible, by applying the technique of fine tuning. Numerical simulations and experiments show that this algorithm is very effective in obtaining a high accuracy and a low cross-sensitivity.
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