一次梅雨锋低空急流形成的分析

对1979年6月24—25日的一次梅雨锋低空急流的形成进行了分析,它的形成是由于在300mb高空急流中心附近产生的地转不平衡,使急流入口区的右侧造成高空辐散的作用。当高空急流中心东移,急流入口区右侧的高空辐散区移到江淮流域上空,由此高空辐散引起对流层下部的质量调整,致使低空造成降压区与辐合。这降压区造成的变压风迭加到低空的西南气流上,沿通过该负变压区(或负变高区)中心的西南气流作为一条轴线,轴线的右侧变压风使西南风偏向低压一侧,从而使西南风的动能增加;轴线的左侧变压风使西南风偏向高压一侧,从而使西南风的动     

碳酸盐岩与泥质烃源岩生气规律对比研究

配制了两套成熟度相近的碳酸盐岩和泥质岩丰度系列样品。采用半封闭外加温加压式热压模拟装置对碳酸盐岩的生烃情况进行了热模拟实验，研究了碳酸盐岩生气量随成熟度和温度变化的趋势，探讨了碳酸盐岩生气的变化规律。碳酸盐岩与泥质岩的生烃潜力是有机质质量和有机质丰度的函数，与岩性无关；碳酸盐岩的产气规律与泥质岩相似，而且两者产烃的量级也相当，并不存在碳酸盐岩生排烃效率高的现象；碳酸盐岩和泥质岩总有机碳(TOC)含量在热模拟过程中基本上不发生变化；不同岩性的有机质的产烃效率主要受温度和有机质类型决定。     

大气热源30～60天振荡与华南6月旱涝的关系

利用1958—2000年NCEP/NCAR再分析资料和华南测站降水资料,分析了大气热源30～60 d振荡对华南6月旱涝的影响。结果表明,在涝(旱)年对流层低层,南海至日本东南面的西北太平洋(WNP)是一个异常的低频反气旋(气旋),伴随有异常的低频热汇(热源)区,华南至日本南部存在一个异常气旋(反气旋),对应于异常的低频热源(热汇)区,华南地区低层异常辐合(辐散);平均而言,旱年华南5—6月30～60 d振荡的位相演变要比涝年的偏晚约7～11天;涝年,低频热源和气旋从南海南部北传和从西太平洋暖池区西北传,以及从140°E附近WNP的西传都十分明显,它们对华南6月降水偏多有非常重要的影响。而旱年南海及邻近区域的低频热源和气旋北传较涝年偏晚,WNP上低频热源的西伸不明显。前期南海低频热源推进的迟早以及热带WNP上的低频热源是否西传对华南6月的降水有显著影响。     

海洋固氮蓝藻Calothrix sp.与Lyngbya sp.固氮生理的研究

研究盐度、昼夜变化、温度及阿特拉津(光合系统Ⅱ抑制剂)对2种海洋固氮蓝藻Calothrixsp.strain(代号为MCT1)和Lyngbyasp.strain(代号为MCT6)固氮活性的影响。结果表明,MCT1在盐度10—48范围内具有相对较高的固氮活性,在盐度为30时固氮活性最高,达到0.687 2μmolC2H2.(g.h)-1;而MCT6随盐度改变固氮活性变化幅度较大,盐度为24时具有最高固氮活性,其活性为0.876 8μmolC2H2.(g.h)-1。MCT1和MCT6固氮活性的昼夜变化明显不同,具有异型胞的海洋固氮蓝藻MCT1白天的固氮活性明显高于夜晚;而无异型胞的MCT6最高固氮活性发生在晚上,白天固氮活性较低。一定浓度的阿特拉津通过抑制光合作用阻断能量和还原剂的提供,使藻体在较短时间内丧失固氮能力。加入阿特拉津后2种藻体的固氮活性与对照组相比有明显的变化,实验第3天开始MCT1的所有经阿特拉津处理的样品固氮活性丧失;MCT6经(50—1 000)×10-6阿特拉津处理的样品从实验第3天开始固氮活性完全消失。     

The changes of vegetation cover in Ejina Oasis based on water resources redistribution in Heihe River

The Ejina Oasis (EO), located in arid northwest China, is a typical arid area in the world. The ecosystem in the oasis has become worse since the 1990s. However, it began to improve after the Chinese government took the mandatory measure to redistribute the water in Heihe in 2000. To understand this change, the remote sensing images in 1990, 2000 and 2006 were selected, and exertion related Land Use/Cover Change (LUCC) model was employed. Results showed that: (1) non-vegetation cover was the main body of the vegetation cover in oasis, showing a trend of increase at the beginning and diminution later, while low, medium and high vegetation cover was the other way around; (2) the area of low, medium and high vegetation cover in 2006 was less than that in 1990; the status and trend index P _t of oasis vegetation cover was 0.62 in 1990–2000, which means that the oasis ecosystem of Ejina was getting worse and was under an unbalanced status; P _t was 0.27 in 2000–2006 indicating that the oasis ecosystem was restored obviously and the whole system tended to be balanced; (3) all of these changes should be attributed to the water resources redistribution in Heihe River, which played a leading role, as well as the measures and relevant policies taken by the local government, which promoted the rapid recovery of the medium and high vegetation.     

基于小波变换法定义的波群参数

通过小波变换分析的波能过程定义了两个描述波浪群性的参数,由数值模拟波浪和实测波浪资料对其与常用的波群参数进行对比分析,结果表明基于小波波能过程定义的群性参数是有效的,从而展示了小波变换用于在时频域上分析波群的能力。详细探讨了波浪记录长度对群性参数稳定性的影响,分析结果表明,波浪观测长度对于波群参数的影响较大,在考虑波浪群性的波浪模拟及分析时,建议模拟时间长度应在400~500个波以上。     

A non-hydrostatic model for the numerical study of landslide-generated waves

This paper proposes and demonstrates a two-layer depth-averaged model with non-hydrostatic pressure correction to simulate landslide-generated waves. Landslide (lower layer) and water (upper layer) motions are governed by the general shallow water equations derived from mass and momentum conservation laws. The landslide motion and wave generation/propagation are separately formulated, but they form a coupled system. Our model combines some features of the landslide analysis model DAN3D and the tsunami analysis model COMCOT and adds a non-hydrostatic pressure correction. We use the new model to simulate a 2007 rock avalanche-generated wave event at Chehalis Lake, British Columbia, Canada. The model results match both the observed distribution of the rock avalanche deposit in the lake and the wave run-up trimline along the shoreline. Sensitivity analyses demonstrate the importance of accounting for the non-hydrostatic dynamic pressure at the landslide-water interface, as well as the influence of the internal strength of the landslide on the size of the generated waves. Finally, we compare the numerical results of landslide-generated waves simulated with frictional and Voellmy rheologies. Similar maximum wave run-ups can be obtained using the two different rheologies, but the frictional model better reproduces the known limit of the rock avalanche deposit and is thus considered to yield the best overall results in this particular case.     

干旱区啤酒花农艺性状与品质的关系

明确啤酒花农艺性状与品质的相关性,可以为啤酒花种质资源优选鉴定提供依据。分析了甘肃省河西地区引进的50份啤酒花种质材料单蔓花数、花穗长、花穗粗、单花重、百花重、干鲜比与产量和品质的关系。结果表明：干旱半干旱地区啤酒花种质资源农艺性状和品质指标均存在较大变异,为优异资源的筛选创造了条件。农艺性状和品质指标存在一定相关性,其中,花穗粗和单花重均与干鲜比显著正相关（R²=0.293和R²=0.288）,花穗长和干鲜比与黄腐酚含量呈极显著正相关且干鲜比对黄腐酚含量贡献大于花穗长,而6个主要农艺性状均与α-酸含量无显著相关性。花穗长、花穗粗可以作为干鲜比大、产量和黄腐酚含量高、药用价值好的啤酒花种质资源筛选的农艺性状指标,但高α-酸含量的啤酒花种质资源无法通过农艺性状去筛选。     

新亚欧大陆桥新疆段水害时空分维特征研究

基于区域自然灾害发生的复杂性和不确定性,运用分形、混沌理论,对新亚欧大陆桥新疆段近３８年的洪水灾害资料进行了时空分维特研究。结果表明：陆桥新疆段洪水灾害不仅在时间序列上具有自相似性,其容量维Ｄｆ在０．０４９７～０．０６８７间,而且在空间序列上也具有自似性,存在明显分维结构,其信息Ｄ１在０．０５３７～０．０７９７之间。洪水灾严重区段的信息分维值较低,并且信息分维与洪水灾害发生频率呈反相关。这一特征将