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Jingshan Wang Guoxiang Ai Guofeng Song Bin Zhang Xiangming Ye Yingping Nie Tzihong Chiveh Weanshun Tsay Huanshin Li 《Solar physics》1995,161(2):229-239
This article describes the universal birefringent filter (UBF) which will be mounted at Taiwan. The UBF permits observations of solar images, vector magnetic fields and/or line-of-sight velocity fields in any Fraunhofer line in the wavelength region from 4000 to 7000 with half width from 0.05 to 0.14 . We have tested it at ten Fraunhofer lines under a spectral telescope in Huairou Station of Beijing Astronomical Observatory and obtained the passband profiles. The principles of magnetic field and velocity field measurement with the UBF are also described. 相似文献
2.
Shock metamorphism of calcite from coralline limestone samples retrieved from a borehole drilled into the rocks beneath Cactus Crater, a nuclear explosion crater at Eniwetok Atoll, has been detected and quantified using electron spin resonance (ESR). ESR spectra of Mn2+, present as a trace constituent in the coral samples, show a consistent decrease in hyperfine peak splitting with decreasing depth of sample. A similar variation was observed in coral samples experimentally shocked to progressively higher pressures. It is speculated that the decrease in hyperfine peak splitting reflects a decrease in crystal field splitting and hence, small (< 0.01 Å) increases in cation-anion distances produced by mechanical energy input during the shock process. Two alternative crater models are suggested by the ESR results. One depicts a steady decay of the shock wave, from a maximum stress level of 4.5 GPa, at a rate, calculated in terms of post-flow co-ordinates, of d?5.7; this high attenuation rate may be due to the rocks underlying Cactus Crater having been displaced downward 5–6 m. The second delineates a breccia lens, possibly stratified, with a breccia-bedrock interface at 20 ± 5 m. 相似文献
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Guang Guo Qiang Ji Ping Yang Si-Chee Tsay 《Geoscience and Remote Sensing Letters, IEEE》2005,2(2):132-135
The ground-based infrared radiance measurements acquired on July 14, 20, and 28, 2002 during the Cirrus Regional Study of Tropical Anvils and Cirrus Layers Florida Area Cirrus Experiment (CRYSTAL-FACE) campaign have been used for simultaneously retrieving the optical thickness and effective particle size on the basis of the retrieval algorithm reported in the preceding counterpart of this paper. The corresponding ice water path is derived from the retrieved optical thickness and effective particle size. Specifically, the data used for the retrieval include: 1) the infrared radiance spectrum observed by an atmospheric emitted radiance interferometer at the surface; 2) the sky condition and cloud height determined from a sky imager and a micropulse lidar; and 3) the sounding data for the profiles of temperature, pressure, and relative humidity. For these three case studies, the retrieved cirrus optical thickness, effective particle size, and ice water path are in the range of 0.2-1.5, 18-42 /spl mu/m, and 2-15 g /spl middot/ m/sup -2/, respectively. Furthermore, error analyses show that the retrieval uncertainties of the optical thickness and effective particle size are less than 15% if the uncertainty of water vapor vertical profile is within 5%. The retrieval errors are within 10% if the uncertainty of cloud temperature is within 7 K. 相似文献
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Employing harmonic analysis of tidal data in the Taiwan Strait, the cross-strait tidal characteristics are completely illustrated. Based on the two dimensional mild-slope equation which can be reduced to the shallow-water wave equation, a finite element model (Tsay et al., 1989) is applied to investigate the characteristics of tides in the Taiwan Strait. The co-range and equi-phase charts of major tidal constituents, such as M2, S2, N2, and K1, are reproduced. Anomalous amplification of semidiurnal tides in the Taiwan Strait is verified. With rotation effects neglected and by applying a non-reflective condition on the open boundaries, the numerical results of phase-lag and co-range distributions show very good agreement with observed data for semidiurnal tides in the Taiwan Strait. Due to crude representation of the topography at two ends along the China coast, computed tidal distributions deviate from the observations. However, both computed amplitudes and phase-lags compare very well with observed data along the central half of the China coast. 相似文献
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L. J. Tsay 《Pure and Applied Geophysics》1973,110(1):1982-1995
Summary In a four-element model, which consists of two Voigt elements in series, the impulse responses of spherical waves for particle displacement, velocity, acceleration and strain are computed numerically. These impulse responses are shown to be useful in synthesis for the desired wave response through convolution, between the input of the source function and the impulse responses. The rate of decay of peak amplitude versus distance, as waves radiate out, is examined in the region close to the source which may be nuclear or dynamite explosives and found to be linear in log-log scale. The amplitude spectra of the unit impulse response are obtained through Fourier analysis, and the model is found to behave as a low pass filter. With the properly chosen elastic constants for springs in the model and damping coefficients for dashpot, it is seen that, like the earth materials, the attenuation exponent (in neper/1000 ft) versus frequency in the model is approximately linear. One of the results observed byCollins andLee [1] is fitted by the model. The model thus simulates more nearly the wave in earth materials close to the source than the Voigt solid. 相似文献
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Ping Yang Si-Chee Tsay Heli Wei Guang Guo Qiang Ji 《Geoscience and Remote Sensing Letters, IEEE》2005,2(2):128-131
The surface radiance spectrum within the terrestrial infrared window (i.e., wavelengths between 8-12 /spl mu/m or wavenumbers between 833-1250 cm/sup -1/) is sensitive to the optical and microphysical properties of cirrus clouds. Numerous microwindows where atmospheric absorption is minimum exist in the spectral regions of 820-960 cm/sup -1/ and 1100-1240 cm/sup -1/. The minimum radiances at the microwindows in these two spectral regions can be fitted by using two linear lines. The slope of the fitting line for the spectral region of 820-960 cm/sup -1/ is sensitive to the effective size of ice crystals within cirrus clouds, whereas the intercept of the fitting line for the spectral region of 1100-1240 cm/sup -1/ is sensitive to the optical thickness of the clouds. Based on this spectral feature, a new retrieval method has been developed for simultaneously retrieving cirrus optical thickness and the effective particle size of ice crystals. Furthermore, the ice water path of cirrus clouds can be estimated from the retrieved values of cloud optical thickness and effective particle size. 相似文献
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A reliable and efficient two-stream algorithm for spherical radiative transfer: Documentation of accuracy in realistic layered media 总被引：2，自引：0，他引：2
We present a fast and well documented two-stream algorithm for radiative transfer and particle transport in vertically inhomogeneous, layered media. The physical processes considered are internal production (emission), scattering, absorption, and Lambertian reflection at the lower boundary. The medium may be forced by internal sources as well as by parallel or uniform incidence at the top boundary. This two-stream algorithm is based on a general purpose multi-stream discrete ordinate algorithm released previously. It incorporates all the advanced features of this well-tested and unconditionally stable algorithm, and includes two new features: (i) corrections for spherical geometry, and (ii) an efficient treatment of internal sources that vary rapidly with depth. It may be used to compute fluxes, flux divergences and mean intensities (actinic fluxes) at any depth in the medium. We have used the numerical code to investigate the accuracy of the two-stream approximation in vertically inhomogeneous media. In particular, computations of photodissociation and warming/cooling rates and surface fluxes of ultraviolet and visible radiation for clear, cloudy and aerosol-loaded atmospheres are presented and compared with results from multi-stream computations. The O3 +hv O(1D) + O2 and O3 +hv O(3P) + O2 photodissociation rates were considered for solar zenith angles between 0.0–70.0° and surface albedos in the range 0.0–1.0. For small and moderate values of the solar zenith angle and the surface albedo the error made by the two-stream approximation is generally smaller, <10%, than the combined uncertainty in cross sections and quantum yields. Surface ultraviolet and visible fluxes were calculated for the same range of solar zenith angles and surface albedos as the photodissociation rates. It was found that surface ultraviolet and visible fluxes may be calculated by the two-stream approximation with 10% error or less for solar zenith angles less than 60.0° and surface albedos less than 0.5. For large solar zenith angles and/or large surface albedos, conditions typical at high latitudes, the error made by the two-stream approximation may become appreciable, i.e. 20% or more for the photodissociation rates in the lower stratosphere and for ultraviolet and visible surface fluxes for large surface albedos. The two-stream approximation agrees well with multi-stream results for computation of warming/cooling rates except for layers containing cloud and aerosol particles where errors up to 10% may occur. The numerical code provides a fast, well-tested and robust two-stream radiative transfer program that can be used as a software tool by aeronomers, atmospheric physicists and chemists, climate modellers, meteorologists, photobiologists and others concerned with radiation or particle transport problems. Copies of the FORTRAN77 program are available to interested users. 相似文献
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By compiling all the tidal data gathered from island-wide results of simple harmonic analysis, anomalous amplifications of semidiurnal tides along the western coast of Taiwan are illustrated. The mechanisms are investigated both theoretically and numerically by applying the linear shallow-water wave equations. Waves trapped by a continental shelf and resonance of tidal co-oscillation are identified theoretically. Numerically, a two-dimensional finite element model is applied to real topography for tidal computations. The co-range and equi-phase charts of three main semidiurnal constituents (M2, S2, and N2) and one diurnal constituent K1 are calculated. Anomalous amplifications of semidiurnal tides that appear as partially standing waves are demonstrated. 相似文献
9.
A two-dimensional hybrid finite element method is developed to study the scattering of water waves by an island and to calculate wave forces and moments on offshore structures. The offshore structure, which could be either semi-submerged or fully extended in the water, is assumed to be stationary. The numerical model is based on the mild-slope equation. It can be applied to both long-wave and short-wave problems. A special treatment for the problem with the semi-submerged structure is introduced. Comparisons are given with existing analytical solutions and other numerical results. The present model is shown to be an efficient and accurate method for the solution of wave refraction and diffraction problems. 相似文献
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