[Objective] The aim was to analyze one cold wave weather process in Chengdu in March in 2010.[Method] Based on the NCEP 1°×1° 6 h interval reanalysis data and daily observation data,using synoptic analy...[Objective] The aim was to analyze one cold wave weather process in Chengdu in March in 2010.[Method] Based on the NCEP 1°×1° 6 h interval reanalysis data and daily observation data,using synoptic analysis and diagnosis methods,and combining with the cold wave forecast index in spring of Sichuan,a cold wave event covering the whole region between March 21 and 24,2010 was analyzed from the aspects of circulation background,influencing weather systems and weather causation.[Result] Results showed that the 500 high-altitude cold vortex,700-850 hPa low layer shear,and ground cold front were the main systems that influenced this cold wave;there was a ridge from Lake Balkhash across Lake Baikal at 500 hPa.The early stage of the process was controlled by the high pressure ridge and the temperature was increasing obviously.The daily mean temperature was high.The range of cold high pressure was large and the central intensity was 1 043.0 hPa;the cold air was strong and deep which was in accordance with the strong surface temperature reduction center.The strong north airstream of Lake Balkhash to Lake Baikal,ground cold high pressure center intensity changes,north and south ocean pressure and temperature differences,850 hPa temperature changes,cold advection movement route and intensity were considered as reference factors for the forecast of cold wave intensity.[Conclusion] The study provided theoretical basis for improving the forecast ability of cold wave weather.展开更多
The change of the structure of seismic event sequences in focal area in preparation period of strong earthquakes has been studied. Findings show that weak earthquake clustering in time increases in earlier stage of fo...The change of the structure of seismic event sequences in focal area in preparation period of strong earthquakes has been studied. Findings show that weak earthquake clustering in time increases in earlier stage of forming of focal area. However,spatial clustering of seismic events rises at the latest stage.展开更多
A theoretical method based on the diffractive theory is used for predicting three-dimensional （3D） focusing performances of the compound X-rays refractive lenses （CRLs）. However, the derivation of the 3D intensity...A theoretical method based on the diffractive theory is used for predicting three-dimensional （3D） focusing performances of the compound X-rays refractive lenses （CRLs）. However, the derivation of the 3D intensity distribution near focus for the X-ray refractive lenses is quite complicated. In this paper, we introduce a simple theoretical method that is based on the first and second moments in the theory of probability. As an example, the 3D focusing performance of a CRL with Si material is predicted. Moreover, the results are compared with those obtained by the diffractive theory. It is shown that the method introduced in this paper is accurate enough.展开更多
文摘[Objective] The aim was to analyze one cold wave weather process in Chengdu in March in 2010.[Method] Based on the NCEP 1°×1° 6 h interval reanalysis data and daily observation data,using synoptic analysis and diagnosis methods,and combining with the cold wave forecast index in spring of Sichuan,a cold wave event covering the whole region between March 21 and 24,2010 was analyzed from the aspects of circulation background,influencing weather systems and weather causation.[Result] Results showed that the 500 high-altitude cold vortex,700-850 hPa low layer shear,and ground cold front were the main systems that influenced this cold wave;there was a ridge from Lake Balkhash across Lake Baikal at 500 hPa.The early stage of the process was controlled by the high pressure ridge and the temperature was increasing obviously.The daily mean temperature was high.The range of cold high pressure was large and the central intensity was 1 043.0 hPa;the cold air was strong and deep which was in accordance with the strong surface temperature reduction center.The strong north airstream of Lake Balkhash to Lake Baikal,ground cold high pressure center intensity changes,north and south ocean pressure and temperature differences,850 hPa temperature changes,cold advection movement route and intensity were considered as reference factors for the forecast of cold wave intensity.[Conclusion] The study provided theoretical basis for improving the forecast ability of cold wave weather.
文摘The change of the structure of seismic event sequences in focal area in preparation period of strong earthquakes has been studied. Findings show that weak earthquake clustering in time increases in earlier stage of forming of focal area. However,spatial clustering of seismic events rises at the latest stage.
基金This work was supported by the National Natural Sci-ence Foundation of China (No. 10174079) and the Natu-ral Science Foundation of Zhejiang Province, P. R. China(No. Y104203).
文摘A theoretical method based on the diffractive theory is used for predicting three-dimensional （3D） focusing performances of the compound X-rays refractive lenses （CRLs）. However, the derivation of the 3D intensity distribution near focus for the X-ray refractive lenses is quite complicated. In this paper, we introduce a simple theoretical method that is based on the first and second moments in the theory of probability. As an example, the 3D focusing performance of a CRL with Si material is predicted. Moreover, the results are compared with those obtained by the diffractive theory. It is shown that the method introduced in this paper is accurate enough.
