Modeling the distribution of aluminum speciation in acid soil solution equilibria with the mineral phase alunite     

S. Bi  S. An  W. Tang  M. Yang  H. Qian  J. Wang 《Environmental Geology》2001,41(1-2):25-36

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Solar abundance of praseodymium     

Emile Biémont  Nicolas Grevesse  Øivind Hauge 《Solar physics》1979,61(1):17-22

16 lines of Pr ii possibly present in the solar photospheric spectrum have been studied. When including hyperfine structure in synthetic calculations, investigations of 9 lines result in an abundance A _Pr = 0.71 ± 0.08 in the log A _H = 12.00 scale.  相似文献   

Photoelectric monitoring of a shell star in perseus     

Chu Yu-hua  Zhao Zhao-wang  Wang Bi 《Chinese Astronomy and Astrophysics》1984,8(4):306-309

We report on the 3-colour photoelectric monitoring of the shell star in Perseus, discovered in 1978, [1]. On the night of 1983 Feb 4–5, this star still showed obvious light variations, though the amplitude was less than in 1979. On the next night, the light variation was close to the observing error. We surmise that the shell activity is now at a stable phase for a few years.  相似文献   

四川盆地东北部飞仙关组优质储层特征   总被引：1，自引：0，他引：1  

毕海龙  李斌  彭军  张良华  陈波 《海相油气地质》2010,15(2):30-35

对四川盆地东北部下三叠统飞仙关组地质、测井和地震数据的分析表明,该区优质储层多由残余鲕粒白云岩构成,储集空间以裂缝-孔隙型为主,属于中等孔隙度高渗透率性质的储层。优质储层测井曲线多具有低伽马、低速度、低密度和高中子孔隙度的"三低一高"特征,地震反射响应特征为中—强反射振幅并和地层顶底面反射形成典型的"亮点",可利用约束稀疏脉冲反演表征储层的纵横向分布。认为地质与地震相结合是预测飞仙关组优质储层的有效方法。  相似文献   

低涡过程对流云和降水结构特征及其环境条件分析     

雷蕾  周毓荃  毕宝贵 《气象科技》2009,37(4):398-406

利用遥感及加密观测资料详细分析了2005年6月25～26日一次低涡过程对流云和降水的结构特征,并利用NCEP再分析资料以及实况风场资料分析了其形成的有利条件。分析表明：此次低涡过程中出现的中尺度对流云团（MCC）经历了十几小时的发展演变,云顶亮温低达-90℃,导致了局地暴雨出现,对流云和降水的分布有很好的对应但同时具有显著的时空分布不均匀性。对流云内部高空存在冰晶的大值区,云水含量也比周围环境丰富,冰晶下落过程中通过碰粘其它冰晶、碰冻云水导致了云内的可降水增多,播撒-供应机制起主要作用。而对流降水的“双峰“廓线结构表明暖雨过程非常强。此次过程有形成强对流非常有利的环境：强西南低空急流水汽输送和水汽辐合与高空偏西风急流的相互作用为对流云团和强降水的形成提供水汽和不稳定条件;低层不稳定区域上强垂直上升运动则提供了不可缺少的动力条件;中尺度辐合系统的形成是此次强对流产生的直接原因。  相似文献   

白马雪山冰川槽谷发育的形态特征及其影响因素探讨     

张威  毕伟力  李永化  董应巍  于治龙  李洋洋 《第四纪研究》2013,33(3)

白马雪山地处横断山脉腹地,对于重建西南季风影响区的环境变迁以及探讨冰川作用特点具有重要科学意义.这里保留着典型的晚第四纪冰川侵蚀地貌,其中冰川槽谷发育特征明显.本文运用抛物线形态参数、梯级宽深比、形态比率等定量分析冰川槽谷的研究方法,对保存在白马雪山主峰扎拉雀尼(5429m)东北坡的两条简单冰川槽谷的形态特征进行分析.采用7个典型剖面的形态特征参数与其他地区对比,探讨冰川槽谷发育的可能影响因素如水热条件、冰川性质、冰川规模、岩性特点、冰川作用时间等.结果显示:白马雪山冰川槽谷抛物线形态参数b值为1.779,明显小于冰川性质相同的螺髻山(1.835),主要是由于区域降水条件的不同所造成的差异,而与冰川性质不同天山乌鲁木齐河源区(1.825)冰川槽谷的形态特征的差异,可能与冰川规模、作用时间以及岩性条件密切相关;梯级宽深比中槽谷形态参数沿程变化可以反映冰川流动过程中的动力变化,梯级宽深比中的形态参数Af和Bf值最大处对应的谷肩位置接近雪线位置.根据槽谷谷肩的位置确定末次冰期早期/中期的雪线高度为4140m,这与用地貌法如冰斗底部高程法、侧碛堤最大高度法和冰川末端至冰斗后壁最大高度法等综合确定的雪线高度4092m基本一致.因此,在冰川槽谷发育的冰川作用区,用槽谷谷肩的海拔高度估算雪线高度可以成为一种比较可靠的确定古雪线方法;白马雪山的冰川槽谷形态参数b-FR的特征表明,即使是海洋性冰川作用区也不符合Hiran和Aniya提出的山地冰川模式,但运用b-FR相关关系可以很好的反映冰川的侵蚀过程.白马雪山地区冰川侧蚀作用导致槽谷坡降值较小,底部较平坦宽阔,呈现出相对完整的U型形态.此外,用形态比率FR值也可以验证雪线的位置高度.  相似文献   

Understanding the dynamical-microphysical-electrical processes associated with severe thunderstorms over the Beijing metropolitan region     

Xiushu QIE  Shanfeng YUAN  Zhixiong CHEN  Dongfeng WANG  Dongxia LIU  Mengyu SUN  Zhuling SUN  Abhay SRIVASTAVA  Hongbo ZHANG  Jingyu LU  Hui XIAO  Yongheng BI  Liang FENG  Ye TIAN  Yan XU  Rubin JIANG  Mingyuan LIU  Xian XIAO  Shu DUAN  Debin SU  Chengyun SUN  Wenjing XU  Yijun ZHANG  Gaopeng LU  Da-Lin ZHANG  Yan YIN  Ye YU 《中国科学:地球科学(英文版)》2021,64(1):10-26

The Dynamical-microphysical-electrical Processes in Severe Thunderstorms and Lightning Hazards(STORM973)project conducted coordinated comprehensive field observations of thunderstorms in the Beijing metropolitan region(BMR)during the warm season from 2014 to 2018.The aim of the project was to understand how dynamical,microphysical and electrical processes interact in severe thunderstorms in the BMR,and how to assimilate lightning data in numerical weather prediction models to improve severe thunderstorm forecasts.The platforms used in the field campaign included the Beijing Lightning Network(BLNET,consisting of 16 stations),2 X-band dual linear polarimetric Doppler radars,and 4 laser raindrop spectrometers.The collaboration also made use of the China Meteorological Administration’s mesoscale meteorological observation network in the Beijing-Tianjin-Hebei region.Although diverse thunderstorm types were documented,it was found that squall lines and multicell storms were the two major categories of severe thunderstorms with frequent lightning activity and extreme rainfall or unexpected local short-duration heavy rainfall resulting in inundations in the central urban area,influenced by the terrain and environmental conditions.The flash density maximums were found in eastern Changping District,central and eastern Shunyi District,and the central urban area of Beijing,suggesting that the urban heat island effect has a crucial role in the intensification of thunderstorms over Beijing.In addition,the flash rate associated with super thunderstorms can reach hundreds of flashes per minute in the central city regions.The super(5%of the total),strong(35%),and weak(60%)thunderstorms contributed about 37%,56%,and 7%to the total flashes in the BMR,respectively.Owing to the close connection between lightning activity and the thermodynamic and microphysical characteristics of the thunderstorms,the lightning flash rate can be used as an indicator of severe weather events,such as hail and short-duration heavy rainfall.Lightning data can also be assimilated into numerical weather prediction models to help improve the forecasting of severe convection and precipitation at the cloud-resolved scale,through adjusting or correcting the thermodynamic and microphysical parameters of the model.  相似文献   

The Asymmetrical Eruption of a Quiescent Filament and Associated Halo CME     

J. Yang  Y. Jiang  B. Yang  R. Zheng  D. Yang  J. Hong  H. Li  Y. Bi 《Solar physics》2012,279(1):115-126

We will present detailed observations of the asymmetrical eruption of a large quiescent filament on 24 November 2002, which was followed by a two-ribbon flare, three coronal dimmings, endpoint brightenings, and a very fast halo-type coronal mass ejection (CME). Before the eruption, the filament lay along the main neutral line (MNL) underneath a single-arcade helmet streamer with a simple bipolar configuration. However, photospheric magnetic fields on both sides of the filament showed an asymmetrical distribution, and the filament and MNL were not located just at the center of the streamer base but were closer to the eastern leg of the streamer arcade. Therefore, instead of erupting along the streamer’s symmetrical axis, the filament showed a nonradial and asymmetrical eruption. It lifted from the eastern flank of the streamer arcade to impact the western leg directly, leading to an asymmetrical CME that expanded westward; eventually the streamer was disrupted significantly. Accordingly, the opposite-polarity coronal dimmings at both sides of the filament forming in the eruption also showed an asymmetrical area distribution. We thus assume that the streamer arcade could guide the filament at the early eruption phase but failed to restrain it later. Consistent with previous results, these observations suggest that the global background magnetic field can impose additional action on the initial eruption of the filament and CME, as well as the dimming configuration.  相似文献   

全国地下水超采区现状与治理对策   总被引：5，自引：0，他引：5  

毕守海 《地下水》2003,25(2):72-74

地下水超采问题是我国当前资源、生态保护面临的主要问题之一。本文分析了全国地下水开发利用现状和存在问题，提出了加强地下水保护和超采区治理的对策和建议。  相似文献   

全球变化背景下北方泥炭地释放溶解有机碳的驱动机制          下载免费PDF全文

向武  Jiasong Fang  万翔  贺灵  孙兴庭  闭向阳 《地学前缘》2011,18(6):72-78

泥炭地（peatland）是一类储碳效率很高的特殊陆地生态系统,其碳储量约占全球土壤碳库的近1／3,对全球碳循环有着举足轻重的作用。有证据表明在过去20余年,北半球大范围的天然水体中溶解有机碳的浓度呈显著增升趋势。普遍认为与全球变化背景下北方泥炭地大规模释放溶解有机碳有关,但其驱动机制尚不十分清楚。已经提出的具有代表性...  相似文献