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991.
中国历史探空资料中的一些过失误差及偏差问题 总被引:43,自引:4,他引:43
利用综合静力学质量控制技术,分析中国历史探空资料集中的一些过失误差情况;着重研究了1960年代探空仪器变化给温度和湿度时间序列带来的不均一性问题;进一步讨论了中国近期探空温度和湿度资料中垂直层次上存在的一些偏差问题 相似文献
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Climatology and trends of wet spells in China 总被引:3,自引:0,他引:3
Summary Climatological features and variations of wet spells, especially their trends over China, are investigated using a dataset
of 594 meteorological stations across China from 1951 to 2003. The results show that the lower the latitude is, the longer
the annual duration of wet spells is. The mean annual precipitation from wet spells is higher in southeastern coastal areas
and much lower in western and northern China. The longest wet spells are found in Southwest China and the eastern Tibetan
Plateau. The maximum daily precipitation of wet spells decreases from the southeast to the northwest, with the highest in
southeastern coastal areas and the lowest in western China. The trends of wet spells exhibit striking regional differences.
In most areas of western China, the annual number of days in wet spells has slightly increased, but significantly decreased
over North China, Central China and Southwest China. The annual precipitation amount from wet spells displays significant
downward trends in North China, eastern Northeast China and the eastern part of Southwest China, but upward trends in the
eastern Tibetan Plateau and some southeastern coastal areas. Two clearly-contrasting regions in climatic changes of wet spells
are the mid-lower reaches of the Yellow River and the eastern Tibetan Plateau, characterized by a decrease of about 24 days
and an increase of about 6 days in annual wet spell days from 1953 to 2003, respectively. 相似文献
995.
Low-frequency oscillations of the East Asia–Pacific teleconnection pattern and their impacts on persistent heavy precipitation in the Yangtze–Huai River valley
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Based on the daily reanalysis data from NCEP NCAR and daily precipitation data from the China National Meteorological Information Center,an ensemble empirical mode decomposition method is employed to extract the predominant oscillation modes of the East Asia Pacific(EAP) teleconnection pattern.The influences of these low-frequency modes on persistent heavy precipitation in the Yangtze Huai River(YHR)valley are investigated.The results indicate that the EAP pattern and rainfall in YHR valley both exhibit remarkable 10 30- and 30 60-day oscillations.The impacts of the EAP pattern on the YHR persistent heavy precipitation can be found on both the 10 30- and 30 60-day timescales the 10 30-day scale for most cases.Composite analysis indicates that,on the 10 30-day timescale,formation of the EAP pattern in the lower and middle troposphere is determined by convective systems near the tropical western Pacific;whereas in the middle troposphere,the phase transition is jointly contributed by both the dispersion of zonal wave energies at higher latitudes and convective systems over the South China Sea.In the context of the10 30-day EAP pattern,the anomalously abundant moisture is transported by an anomalous subtropical anticyclone system,and strong moisture convergence results from that anomalous anticyclone system and a cyclonic system in the midlatitude East Asia.Such a combination of systems persists for at least three days,contributing to the formation of persistent heavy precipitation in the YHR valley. 相似文献
996.
In order to improve the spatial uniformity of rainfall generator to natural rainfall uniformity, according to the rotation of the test platform, a rotary test platform was designed and developed, and the slip-ring was used to solve the problem of signal transmission in the process of the rotation. Besides, the relationship between rotational speed and spatial uniformity of rainfall generator was established. The results of tipping-bucket rain gauge tested in rainfall field and flow type rainfall intensity standard device testing demonstrated that rainfall generator as the rainfall accumulation and rainfall intensity of the test environment was feasible. Results showed that with the increase of the rotate speed, spatial uniformity first increased, and then decreases, and with the decrease of the test area, different speed presented different trends. When the rotational speed was 1 RPM, test area was 1.6 m×1.6 m and 1.2 m×1.2 m, its uniformity of rainfall generator reached maximum which was bigger than 95%; with the increase of the rotate speed, tipping-bucket rain gauge of RA and RI were of good consistency under the RPM 1 and RPM 2 and the RA maximum deviation reached minimum, 0.2 mm; the average of RA under flow type rainfall intensity standard device test consisted well with rotating test platform at speed RPM 1 and 2, which illustrated the rotary testing platform was consistent with the flow type rainfall intensity standard device. It showed that the method to improve the space uniformity of rainfall generator is feasible and it could find the dynamic difference of RA. 相似文献
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冲绳海槽是因菲律宾海板块俯冲于欧亚板块之下,在陆壳上发育起来的一个初始的弧后盆地,是研究弧后扩张作用早期盆地演化、岩浆作用和壳幔过程的天然实验室.尽管迄今对冲绳海槽已经做了大量的调查研究工作,但仍存在一些颇有争议或亟待解决的科学问题,如:冲绳海槽酸性浮岩与基性玄武岩之间的成因联系,冲绳海槽不同区段构造背景对岩浆作用的控... 相似文献
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Dong Chenfan Wu Haiyan Peng Jixing Guo Mengmeng Zhai Yuxiu Tan Zhijun 《中国海洋湖沼学报》2022,40(6):2267-2276
Journal of Oceanology and Limnology - Understanding the risk factors associated with shellfish consumption is a relevant public health concern because of the potential adverse effects of paralytic... 相似文献