A New Temperature Channel Selection Method Based on Singular Spectrum Analysis for Retrieving Atmospheric Temperature Profiles from FY-4A/GIIRS     

Peipei YU  Chunxiang SHI  Ling YANG  Shuai SHAN 《大气科学进展》2020,37(7):735-750

Hyperspectral data have important research and application value in the fields of meteorology and remote sensing.With the goal of improving retrievals of atmospheric temperature profiles, this paper outlines a novel temperature channel selection method based on singular spectrum analysis(SSA) for the Geostationary Interferometric Infrared Sounder(GIIRS), which is the first infrared sounder operating in geostationary orbit. The method possesses not only the simplicity and rapidity of the principal component analysis method, but also the interpretability of the conventional channel selection method. The novel SSA method is used to decompose the GIIRS observed infrared brightness temperature spectrum(700-1130 cm~(-1)), and the reconstructed grouped components can be obtained to reflect the energy variations in the temperature-sensitive waveband of the respective sequence. At 700-780 cm~(-1), the channels selected using our method perform better than IASI(Infrared Atmospheric Sounding Interferometer) and Cr IS(Cross-track Infrared Sounder)temperature channels when used as inputs to the neural network retrieval model.  相似文献   

影响衍射层析成像质量的目标空间谱重建     

葛德彪 《CT理论与应用研究》1993,(2)

衍射层析成像可划分为两步,即由散射数据确定目标空间谱,再由目标空间谱重建目标特性。本文通过计算机模拟讨论由Fourier 衍射定理所重建的目标空间谱,及其对成像的影响。  相似文献   

NUMERICAL STUDY ON EFFECTS OF THE QINGHAIXIZANG PLATEAU ON FORMATION OF THE URAL BLOCKING HIGH          下载免费PDF全文

Zheng Qinglin  Gu Yu  Song Qingli  Jiang Ping 《Acta Meteorologica Sinica》1993,7(1):61-69

By employing the improved T42L5 spectral model and utilizing the ECMWF data covering the period from 1 Julyto 7 July 1982,a numerical research on the formation of the Ural blocking system has been made.The results show thatthe model forecasts for the upstream U ral area turn out to be worse if the dynamic effect of the Qinghai-Xizang Plateauis not considered.The correlation coefficient between the model forecasts and observed 500 hPa geopotential heightanomaly decreases by 9% for the 5-day mean,and their averaged root mean square (RMS) error increases 15 m.Due tothe dynamic effect of the Plateau,the trough being on the northwest of the Plateau is barricaded and turns to be atransversal trough.Consequently southwest flow occurs along the northwest of the Plateau in front of the trough,whilenortheast flow prevails over the west of the trough,causing the formation of the blocking high over the Ural area.Whenthe dynamic effect of the Plateau is not taken into consideration,the trough develops and moves southeastward and theUral blocking high changes into a migratory high.All these result in the failure of the simulation.The dynamic effect ofthe Plateau helps to increase the negative vorticities over the Plateau and its north periphery as well as the Ural area,andalso helps to increase the positive vorticities over the Black Sea and the Caspian Sea area.On the other hand,thethermodynamic effect mainly influences the Plateau and its downstream area and plays an less important role in theformation of the blocking high over the upstream Ural area.  相似文献   

阔克沙勒—吉萨尔地震活动时间的多重分形研究   总被引：2，自引：0，他引：2  

朱令人  周仕勇 《内陆地震》1993,7(4):319-324

应用多重分形的标度指数谱f(α)～α方法分析阔克沙勒——吉萨尔地区地震活动时间序列,发现一定范围内地震多重分形f(α)～α在大震前有明显的异常显示。说明f(α)谱研究地震的多重分形,简单、有效、能全面地描述地震时间分布这类不均匀分形集。  相似文献   

Instantaneous spectrum analysis and its application in estimation of earthquake tendency     

Zhi-Zhen Zheng  Jin-Bo Hu 《地震学报(英文版)》1993,6(2):465-473

In this paper, first discussing briefly the instantaneous spectrum theory. Then, the instantnaeous spectra and Fourier spectra of three seismic sequences are calculated, and comparing them to explain the superior characteristics of instantaneous spectrum. Finally, the earthquake tendency of North China is estimated by using the instantaneous spectrum theory. The results show that not only the occurrence time of the coming large earthquake, but also its magnitude instantaneous can be estimated by using instantaneous spectrum of the seismic sequence. The Chinese version of this paper appeared in the Chinese edition ofActa seismologica Sinica,15, 68–75, 1993.  相似文献   

Dependence of the energy released during earthquake on ambient shear stress   总被引：1，自引：0，他引：1  

Pei-Shan Chen  Seweryn J. Duda 《地震学报(英文版)》1993,6(3):593-600

Starting with dislocation model, using the result of the fracture mechanics: the slip displacement at the crack tip is proportional to the length of the crack and the applied ambient shear stressτ ₀ ² , we consider the dislocation in the earthquake to be the slip displacement at the crack tip and have obtained the analysis expresses of displacement and velocity pulse for the circular crack and have calculated the seismic wave energy radiated by earthquake. The seismic wave energyE ∞M ₀ τ ₀ ² f(v) _r , i. e.E is proportional to the seismic momentM ₀ and the square of the ambient shear stressτ ₀ ² and increases with the rupture velocityv _r . In frequency domain, integrating the square of source velocity spectrum derived from our the scaling law model, we have also obtained the seismic wave energyE released by earthquake and earthquake radiated effficiencyη.E ∞M ₀ τ ₀ ² also. If takingτ ₀ = 10.0 MPa, E=4.79M ₀. This result is consistent with the estimate by Vassiliou and Kanamori (1982). Theη=5.26%. The distribution of the seismic wave energy is that most of the energy contains in the frequency range between the first corner frequencyf _c1 and thirdf _c3, amount to 92.3% the energy in the rangef<f _c1 is about 3.85% and 3.85% whenf>f _c3. Thef _c3 is about 8Hz forM ⩾ 6, thus most of radiated energy is below 2Hz. This phenomenon had been verified by Vassiliou Kanamori. Previous results show the energy radiated by earthquake to be strongly dependent on ambient shear stress. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 146–152, 1993. This work was supported by the Deutsche Forschungsgemeinschaft, Bonn, F. R. Germany. The support is grateful acknowledged. The authors are also grateful to Professor Klussmann and Mr. Hasthoff for their lots of help.  相似文献   

Determination of moment magnitude from acceleration spectrum     

Pei-Shan Chen  Ke-Zhong Peng  Hai-Tong Chen  Tong-Xia Bai 《地震学报(英文版)》1993,6(2):379-387

The theoretical acceleration spectrum of observation site has been obtained from source acceleration spectrum derived from scaling law, using attenuation modelQ=Q _ν f ^η . A comparison of a set of theoretical acceleration spectra with observation spectra has been made, and we have obtained the attenuation model for observation site and seismic moment magnitude. We obtain thatQ _o=300,η=0.25 for Wuqia area, Xinjing Zizhizhou, and seismic moment magnitudes of 18 greater aftershocks of Wuqia earthquake occurred in 1985. In order to obtain seismic moment magnitued conveniently, three functional tables of acceleration spectra at 1Hz as the distances for variousQ value have been made. The seismic moment magnitude can be quickly measured from acceleration spectrum at 1Hz according to these tables (epicenter has to be known). The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,14, 435–445, 1992.  相似文献   

红外窗区大气透过率的测量   总被引：3，自引：1，他引：3       下载免费PDF全文

张广顺  张玉香 《应用气象学报》1993,4(2):212-217

文章主要介绍了红外窗区太阳光谱测量的实验装置，观测方法和数据处理方法。处理了2390—3470 cm-1和750—1300 cm-1区域内的太阳光谱资料，得到了它们的大气透过率数据，并对处理结果进行了初步分析。我们认为这些大气透过率对气象卫星遥感仪器红外窗区通道选择和卫星气象资料反演等都是有用的。  相似文献   

Effects of cation disordering in a natural MgAl2O4 spinel observed by rectangular parallelepiped ultrasonic resonance and Raman measurements     

Hyunchae Cynn  Orson L. Anderson  Malcolm Nicol 《Pure and Applied Geophysics》1993,141(2-4):415-444

At moderate temperatures, the elastic properties of natural MgAl₂O₄ spinel differ in several significant ways from properties of synthetic spinels. Below 1000 K, the ultrasonic resonant frequencies of an ordered natural spinel change significantly after heat treatment; at higher temperatures, both types of spinels have similar resonant responses. The temperature derivatives of the elastic constants of an ordered spinel also differ from those of disordered spinels at moderate temperatures; again, at higher temperatures, both types of spinels have similar behaviors. The Raman spectra also differ below 1000 K for ordered natural and disordered spinels and are similar at higher temperatures and after cooling to ambient temperature. We associate these changes in ultrasonic resonance and Raman spectra of spinel with cation disordering at high temperature which may be quenched by cooling. We deduce estimates of the inversion parameter from the relative intensities of the two A_1g Raman modes in very good agreement with estimates made from other measurements. We find thatC ₁₁ andC ₁₂ decrease by 4 and 8%, respectively, with 20% inversion in spinel;C ₄₄ is less sensitive to cation order. These results imply that previous measurements of the adiabatic elastic constants of spinels at ambient conditions have been affected by the state of cation disorder of the specimen.  相似文献   

Spectral analysis using orthonormal functions with a case study on the sea surface topography   总被引：1，自引：0，他引：1  

Cheinway Hwang 《Geophysical Journal International》1993,115(3):1148-1160

b
Spherical harmonics are orthonormalized using the Gram-Schmidt process in a function space. The problem of linear dependence of spherical harmonics over the oceans is studied using the Gram matrices and consequently three sets of orthonormal (ON) functions have been constructed. For the process an efficient formula for computing inner products of spherical harmonics has been developed. Important spectral properties of the ON functions are addressed. The ON functions may be used for representing the sea surface topography (SST) in the analysis of satellite altimeter data. The geoid error can be transformed to a representation by the ON functions and hence the comparison of powers of the geoid error and the SST signal only over the oceans is possible, leading to a better way of determining the cut-off frequency of the SST in the simultaneous solution using satellite altimeter data. As a case study, the modified Levitus SST is expanded into the ON functions. The results show that 99.90 per cent of that signal's energy is contained within degree 24 of the orthonormal functions. Such expansions also render better spectral behaviour of oceanic signals as compared to that from spherical harmonic expansions. The study shows that these generalized Fourier functions are suitable for spectral analyses of oceanic signals and they can be applied to future altimetric mission where the geoid and the SST are to be recovered.  相似文献