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751.
After the winter and summer current structures on two or three latitudinal sections in Taiwan Strait were obtained from the
measured current data, the seawater fluxs through the sections were calculated. In summer, the currents in the central and
northern part of Taiwan Strait normally flow northward at a net flux of 3.32×106m3/s. In winter, the high temperature and salinity Kuroshio and South China Sea water enter Taiwan Strait from the southem section
at 1.69×106m3/s and 0.59×106 m3/s respectively, while the East China Sea water enters Taiwan Strait from the northern section at 1.02×106m3/s. About 0.40×106 m3/s of the seawater enters the South China Sea along the coast of Fujian and Guangdong; the other 0.62×106 m3/s of the seawater is mixed with the Kuroshio water and the South China Sea water in the northern sea areas. The net northward
flux is 1.74×106m3/s in winter. 相似文献
752.
Beijing’ population has experienced a dramatic increase eversince the founding of the People’s Republic of China. Population
growthin Beijing can be broadly broken down into three major components:natural increase, immigration, and the growth of floating
population. Thecontinuous growth of Beijing’s population is closely linked with its centralized multi-function. The comprehensive
countermeasures to control Beijing’s population growth are proposed, for example, decentralizing economicfunctions, including
developing the suburbs, developing the metropolitan areaand creating counter-magnetic centers, reforming the administrative
and economic systems. 相似文献
753.
本文首次报道了在我国豫西晚前寒武系白草坪组中发现的一种可能的蠕虫状后生动物实体化石:Ruyangia Cylindrica Hu et Meng,1989。化石产于砂岩表面浪成波痕之波谷中,圆筒状,已压扁,中空,可见长度4.5~9.5cm,直径4mm左右,虫体外壁具体环,环背间距1.5~2mm,虫体一端较大,具平行纵向边缘的纵纹,可能为头部;另一端渐尖,可能为尾部。与该实体化石伴生的有大量遗迹化石。已知白草坪组的时代超过1400Ma,因此,该实体化石的发现对研究地球上后生动物起源与早期演化等具重要意义。 相似文献
754.
本文讨论了一些重要元素的环境化学特征和一些重要金属和痕量元素对人类健康的影响。在地球温室效应一节中重点叙述了本世纪初以来CO_2浓度剧烈的增加,使地球的气候变暖,海洋表面的温度也上升了0.6±0.3℃。因此,必须严格限制CO_2排放。还讨论了对流层中的臭氧是一种对植物有害和对人体不利的污染物,然而平流层中的臭氧却是地球表面免受紫外线辐射的重要屏障。因此,应防止CFCl_3和CF_2Cl_2的一组化学剂,以便保护臭氧。 相似文献
755.
胡庆陪 《广东海洋大学学报》1991,(1)
本文提出用向量作图法解等角应变花的问题,这是一种比较完整的图解法,只需利用比例尺、三角板和量角器,就可用作图法简捷地得到所求的结果。本文还举了两个数值例题,与数解法作了比较,说明图解法的精确性相当好。 相似文献
756.
757.
本文采用二维三分量耗散MHD模型,对带高电流层的局地非对称的四极无力场的磁能释放过程进行数值模拟,结果表明,磁能释放过程大体可以分为两个阶段:高电流层引起的异常电阻耗散使该层等离子体加热至3×106K的高温,形成一高温环;在高电流层耗散的触发下,磁分隔面的电流急剧增长并爆发异常电阻耗散和磁场重联,导致耀斑发生,主要的能量释放发生在磁分隔线和高剪切无力场中的磁分隔面上,等离子体温度可以达到1.9×107K。上述无力场的触发释能过程可能是太阳耀斑的一种重要的释能机制。 相似文献
758.
On October 24, 1991, a white-light flare was observed both from space and from the ground. A multi-waveband spectral analysis shows that the peak time of the continuum emission coincides well with that of a radio burst at 2840 MHz and with the hard X-ray emission. Three semi-empirical models, corresponding to the pre-flare condition and to the peak time of continuum emission both with and without non-thermal excitation and ionization of hydrogen by an electron beam, have been obtained. The results indicate that there is fast heating both in the chromosphere and the photosphere. Some evidence is given that this WLF is very likely a result of bombardment by an electron beam. By taking into account non-thermal effects, the chromospheric temperature of the semi-empirical model is significantly reduced. 相似文献
759.
A modified land surface temperature split window retrieval algorithm and its applications over China 总被引:1,自引:0,他引:1
Due to the difficulties in correcting the influences of the atmosphere absorbability and the Earth surface emissivity diversification, the retrieval of LST (land surface temperature) from satellite data is a challenging task. In this paper, a modified Becker's split window LST inversion algorithm is developed for retrieving LST from the NOAA-16/17 AVHRR data. A new set of parameters for Becker's LST algorithm is proposed. The algorithm is developed from a surface brightness temperature dataset generated from the MODTRAN program, which uses a range of surface parameters and atmospheric quantities as inputs. The 10-day composites of the channels 4 and 5 brightness temperature data of NOAA-17 AVHRR (1-km resolution) are used to generate the clear-sky LST. As a validation of the algorithm, the retrieved LST is compared with MODIS LST of same period and area. The two LST products are found to be consistent, with the absolute difference being about 2.5 K for most areas. The NOAA retrieved LST is also compared with in-situ ground surface 0-cm measurements taken from 257 meteorological stations, which cover overall China area for the three periods of satellite observations. The comparison shows that the correlation between the retrieved LST and in-situ measurements is over 0.90 and the RMSE (root mean square error) is about 3.4 K. 相似文献
760.
扼要报导了国际大地测量学术界的一次重要会议-IAG2001年科学大会。根据会议的学术报告,对坐标系统的统一与协调,全球重力场研究,导航卫星的应用,地壳形变与地球动力学等方面的研究进展作了详细介绍。 相似文献