折射/谐衍射红外双波段成像光谱仪系统研究     

刘英  孙强  卢振武  曲锋  吴宏圣  李淳 《海洋学报》2010,32(10):6980-6987

为了获取足够的目标信息,充分利用中波红外和长波红外的光谱信息,建立了谐衍射中、长波红外超光谱成像系统.利用谐衍射元件独特的色散特性,将谐衍射透镜应用于中、长波红外超光谱成像系统中,使系统在中波红外3.7—4.8 μm和长波红外8—12 μm的2个红外大气窗口内获取数百个光谱图像.设计结果表明,中波红外波段,在18对线/mm处光学系统的调制传递函数(MTF)大于0.55;长波红外波段,在13对线/mm处光学系统的MTF大于0.5;光学系统的衍射环绕能,在中波红外波段30 μm半径范围内大于85%,在长波红外  相似文献   

Comparative Study of Changes in Stress-drop of the Jinggu MS6.6 and Ludian MS6.5 Earthquake Sequences     

Zhou Shaohui  Jiang Haikun  Qu Junhao 《中国地震研究》2017,31(2):151-168

The earthquake stress-drop values of two sequences were accurately calculated after taking away the effects due to regional earthquake anelastic attenuation and station site response, using waveform data and seismic phase data of sequences of the Jinggu M_S6.6, and Ludian M_S6.5 earthquakes in Yunnan. These results show that the stress drop with magnitude increases within the scope of this study of magnitude. After eliminating the influence of the magnitude, the average value of stress-drop in the Jinggu sequence is higher than that of the Ludian sequence at the same magnitude range. This may be related to the stress state in different regions. In terms of the changes of time and space of stress-drop, before M_S5.8 strong aftershock, the stress-drop is "slowing down-turning up-keeping a high value" after the mainshock, meanwhile, almost all of the abnormally high stress drop value is distributed around the M_S5.8 strong aftershock, showing that the stress environment in the region was increasing after the mainshock. And after the M_S5.9 strong aftershock, stress-drop rapidly declines to a relatively stable state, meanwhile, the high value of stress-drop is distributed around the strong aftershock, showing that the regional tectonic stress gets more fully release, its stress environment begins to rapidly decrease. For the Ludian sequence without a strong aftershock occurring, the average value of stress drop is lower than that of the Jinggu earthquake sequence at the same magnitude range, while at the same time, the stress-drop of the aftershock sequence almost hasn''t changed much. In the time after the mainshock, combined with the release characteristics of the main energy, the stress in the region is excessively released, the subsequent stress in the region gradually returns to normal. This may be the reason why the activity of Ludian aftershocks significantly was weaker and subsequently there were no strong aftershocks occurred.  相似文献   

Geochemical evidence of an extraterrestrial component in impact melt breccia from the Paleoproterozoic Dhala impact structure,India          下载免费PDF全文

Jayanta Kumar Pati  Wen Jun Qu  Christian Koeberl  Wolf Uwe Reimold  Munmun Chakarvorty  Ralf Thomas Schmitt 《Meteoritics & planetary science》2017,52(4):722-736

The Paleoproterozoic Dhala structure with an estimated diameter of ~11 km is a confirmed complex impact structure located in the central Indian state of Madhya Pradesh in predominantly granitic basement (2.65 Ga), in the northwestern part of the Archean Bundelkhand craton. The target lithology is granitic in composition but includes a variety of meta‐supracrustal rock types. The impactites and target rocks are overlain by ~1.7 Ga sediments of the Dhala Group and the Vindhyan Supergroup. The area was cored in more than 70 locations and the subsurface lithology shows pseudotachylitic breccia, impact melt breccia, suevite, lithic breccias, and postimpact sediments. Despite extensive erosion, the Dhala structure is well preserved and displays nearly all the diagnostic microscopic shock metamorphic features. This study is aimed at identifying the presence of an impactor component in impact melt rock by analyzing the siderophile element concentrations and rhenium‐osmium isotopic compositions of four samples of impactites (three melt breccias and one lithic breccia) and two samples of target rock (a biotite granite and a mafic intrusive rock). The impact melt breccias are of granitic composition. In some samples, the siderophile elements and HREE enrichment observed are comparable to the target rock abundances. The Cr versus Ir concentrations indicate the probable admixture of approximately 0.3 wt.% of an extraterrestrial component to the impact melt breccia. The Re and Os abundances and the ¹⁸⁷Os/¹⁸⁸Os ratio of 0.133 of one melt breccia specimen confirm the presence of an extraterrestrial component, although the impactor type characterization still remains inconclusive.  相似文献   

Effects of mixing on the subduction of South Pacific waters identified by a simulated passive tracer and its adjoint     

Shan Gao  Tangdong Qu  Ichiro Fukumori 《Dynamics of Atmospheres and Oceans》2011,51(1-2):45-54

Effects of mixing on water mass subduction are analyzed in the South Pacific Ocean. Model simulations using a passive tracer and its adjoint are employed in conjunction with a particle tracking method to distinguish effects of mixing from those of advection. The results show that mixing processes can contribute to as much as 20% of the overall subduction rate in the South Pacific. Of this mixing contribution, about 30% can be attributed to meso-scale eddies, including their associated bolus transport, while the major part (70%) is due to other diabatic processes. The impact of mixing reaches its maximum near the Sub-Antarctic Front, accounting for nearly 30% of the total subduction rate. Consequently, estimates based on tracing particles or on advection alone may significantly underestimate the subduction rate in the South Pacific Ocean.  相似文献   

CO2浓度增加背景下季风区大气辐射加热响应的差异          下载免费PDF全文

Xia Qu  Gang Huang  Xiaocong Wang 《大气和海洋科学快报》2021,14(3):19-24

大气CO2浓度增加,大气辐射平衡调整,将影响到大气的辐射加热,对季风环流的产生影响.CMIP6结果显示,大气CO2浓度增加,可减弱季风区主雨季对流层高,低层的辐射加热,加强对流层中层的辐射加热.各季风区加热响应的峰值层次不同:亚洲季风区平均层次最高(500-775 hPa),北非,南美,澳洲季风区次之(550-600 hPa),北美(600hPa)和南非季风区(600-775 hPa)较低.各季风区水云的垂直分布及其长波辐射效应的变化是形成峰值层次差异的主因.  相似文献   

雅鲁藏布江河谷盛夏降水年际变化及其与环流的联系          下载免费PDF全文

边巴卓嘎  赤曲  周顺武  吴萍  孙阳 《大气科学学报》2022,45(3):469-479

基于近57 a （1961—2017年）西藏雅鲁藏布江中游河谷地区（简称雅江河谷）4个站（拉萨、日喀则、泽当和江孜）盛夏（7—8月）月平均降水和同期NCEP/NCAR再分析资料,采用合成、相关分析等统计诊断方法,分析了雅江河谷盛夏降水的年际变化特征及其与大气环流的联系。结果表明：1）近57 a雅江河谷盛夏降水无显著线性趋势,降水主要以3～4 a显著周期的年际振荡为主。2）雅江河谷盛夏降水年际波动与区域内水汽收支的变化直接相关,其中印度半岛-东南亚异常反气旋引起的水汽输送通量和水汽在高原腹地辐合上升的动力过程是盛夏降水年际变化的主要原因。3）对流层中低层印度半岛-东南亚异常反气旋环流是该地区盛夏降水年际异常的重要水汽输送通道,该通道将西太平洋、南海和孟加拉湾等地水汽不断输送到高原,期间西太副高和伊朗高压等大尺度系统异常对水汽输送过程起到了重要作用,同时高原盛夏季风低压和南亚高压异常给水汽在高原腹地辐合抬升提供了动力条件。  相似文献   

Summer Arctic sea fog     

Xie Simei  Xue Zhenhe  Jiang Dezhong  Zou Bin  Qu Shaohou 《海洋学报(英文版)》2001,20(2):183-196

I~IOXSea fog is a kind of dangerous weather. Chinese sea fog experts, Wang Binhua (1983),Hu Ruijin and Zhou Faxiu (1998) and Hu Jifu et al. (1996) studied sea fog rather Systematically. FOreign Experts also Paid great attention to sea fog. Ernlnons and Montgomery(1974), chipper (1994) and Rayrnond et al. (1989) have studied sea fog thorOUghly.HOwever, studies on Arctic sea ice have rarely been carried Out becauSe of the sever environment and less htnnan activity in the region. There …  相似文献   

Molecular identification of bloom-forming species Phaeocystis globosa(Prymnesiophyta)and its dispersal based on rDNA ITS sequence analysis   总被引：3，自引：1，他引：3  

Chen Yueqin  Shao Peng  Wang Ning  Zhou Hui  Qu Lianghu  Linda K. Medlin 《海洋学报(英文版)》2003,22(2)

Abstract-The colony-forming Phaeocystis species are causative agents of dense bloom occurrences incoastal waters worldwide. It is difficult to separate them because of the different morphologies associatedwith their colonial stages. In this study we applied molecular approaches to analyze the genetic variationof Phaeocystis globosa and Phaeocystis pouchetii from several geogrtaphic regions, and to assist in tracingthe dispersal of bloom-forming Phaeocystis species in coastal waters of China. The Sequences of the inter-nal transcribed sacers (ITS1 and ITS2) of rDNA and the 5.8S ribosomal RNA gene of Phaeocystisstrains were determined. Sequence comparison shows that P.globosa was the most divergent toP. pouchetii, exhibiting sequence divergence higher than 0.08. However, lower genetic divergences ex-isted between strains of P.globosa. The sequence comparison of the Phaeocystis rDNA ITS clearlyshows that the species isolated from the southeast coast of China is identified as P. globosa rather thanP. cf. po  相似文献   

青岛文昌鱼的生活史──年龄、生长和死亡研究   总被引：17，自引：1，他引：17  

吴贤汉  张士璀  王永元  张宝录  曲艳梅  江新霁 《海洋与湖沼》1995,26(2):175-178

于１９８９年８月－１９９０年７月对青岛文昌鱼的生活史进行研究。结果表明：（１）青岛文昌鱼种群由４个齿组组成，它至少生产４ａ以上，甚至可达６ａ左右。（２）在Ⅰ、Ⅱ齿时生长较快，平均年生长１３－１５ｍｍ，Ⅲ龄后生长速度减慢，即使同一年龄组的文晶鱼，在不同季节其生长速度也不同。（３）在冬春采集的文昌鱼中Ⅲ龄组的峰值较小。（４）繁殖季节过后，老龄文昌鱼因衰老而死亡。  相似文献   

前苏联七十年海冰研究回顾     

曲维政  李若钝 《海洋预报》1993,10(3):31-42

本文简要介绍了前苏联近七十年来海冰研究的主要成果及其采用的一些预报方法。  相似文献