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381.
利用气象观测资料、NCEP/NCAR 1°×1°再分析资料以及GDAS资料,对2021年10月2-7日山西持续性强降水天气过程进行分析。结果表明:稳定的乌拉尔山低槽后部冷空气扩散,中纬度短波槽东移,与副热带高压外围西南暖湿气流持续交汇,同时高低空急流耦合形成强烈上升运动,低层切变线和地面辐合线稳定维持,及低层水汽不断输送并形成辐合,为持续性强降水的发生发展提供有利动力和水汽条件。此次强降水过程分为对流性降水和稳定性降水2个阶段,2阶段水汽输送通道的源地、路径、高度均有明显差异,但水汽输送贡献率均以对流层中低层山西南侧的水汽输送占主导地位。降水开始前,对流层中上层存在对称不稳定,大气可降水量明显跃增;对流性降水阶段,干空气不断入侵,对流不稳定快速建立与释放,对流层中低层水汽辐合区与强上升气流配合,导致山西出现强对流天气。地形的阻挡、抬升及地形收缩作用,对局地极端强降水具有增幅作用。 相似文献
382.
本文根据滇西地区18个大地电磁测深点资料的数据处理和分析结果,对测区深部导电率在纵、横向上的变化特征进行了研究。结果表明:滇西地区深部电性为多层结构,大致可分四至五个电性结构层;深部电性结构横向变化大,明显受区域构造控制;该区上部地壳内普遍存在低阻层;上地幔高导层明显存在两个隆起区,一个以剑川—鹤庆为中心呈北北西向展布的隆起区,另一个以腾冲—潞西为轴呈南北向展布的隆起区。 本文还讨论了地壳上地幔电性结构与大地构造的关系,滇西北裂陷区盆地的形成,以及该区地震活动与深部构造的关系 相似文献
383.
The light curved in the CM field 总被引:1,自引:0,他引:1
In this paper we introduce the CM field in Sections 2 and 3 based on the paper by Wang and Peng (1985), and calculate the light curved in the CM field in Section 4. The result shows thatP makes CM larger than C at
, and smaller at
. Under a special circumstance which source, CM lens, and observer are in the same line, if we get |
0=0
,
and |
=/2
, we can determine theP(M) andQ(M) of the CM lens,M is the mass of the CM lens. 相似文献
384.
We report on three sequences of high-resolution white-light and magnetogram observations obtained in the summer of 1989. The duration of sub-arcsecond seeing was three to four hours on each day. Study of the white-light and magnetogram data yields the following results:
- For all but one of the sunspots we have observed, both dark fibrils and bright grains in the inner part of the penumbra of sunspots move toward the umbra with a speed of about 0.5 km s-1. In the outer part of the penumbra, movement is away from the umbra. The one exception is a newly formed spot, which has inflow only in its penumbra.
- Granular flows converge toward almost every pore, even before its formation. Pores are observed to form by the concentration of magnetic flux already existing in the photosphere. The pores (or small sunspots), in turn, then move and concentrate to form bigger sunspot.
- We followed an emerging flux region (EFR) from 29 to 31 July, 1989 that was composed of a large number of bipoles with magnetic polarities mixed over a large area in the first day of its birth. As time went on, polarities sorted out: the leading polarity elements moved in one direction; the following, the opposite. During the process a large number of cancellations occurred, with some sub-flares and surges observed simultaneously. After about 24 hours, the positive and negative fluxes were essentially separated.
- We find two kinds of photospheric dark alignments in the region of new flux emergence: (a) alignments connecting two poles of opposite magnetic polarity form the tops of rising flux tubes; (b) alignments corresponding to the magnetic flux of one polarity, which we call elongated pores.
385.
A preliminary theoretical and experimental study was conducted on internal wave modes and their weak nonlinear resonant interaction
in a nonlinearly stratified fluid. An asymptotical solution of the modes and a dispersion relation of internal waves in a
stratified fluid with density profile
similar to that in our experiment were obtained theoretically. The resonant-interaction mechanism to 2nd order approximation
is also discussed. The resonant interaction of the 3rd and 4th mode internal waves excited by the unstable 1st mode wave is
analyzed on the basis of data obtained by conductivity probes. The resonant-interaction condition, i.e.,
,k
1+k
3+k
4=0, is examined. It is shown that the resonant instability increases with pycnocline thickness and wave maker driving frequency.
This work is supported by the National Natural Science Foundation of China. 相似文献
386.
To look for gas hydrate, 22 multi-channel and 3 single-channel seismic lines on the East China Sea (ECS) shelf slope and at the bottom of the Okinawa Trough were examined. It was found that there was indeed bottom simulating reflector (BSR) occurrence, but it is very rare. Besides several BSRs, a gas seepage was also found. As shown by the data, both the BSR and gas seepage are all related with local geological structures, such as mud diapir, anticline, and fault-controlled graben-like structure. However, similar structural "anomalies" are quite common in the tectonically very active Okinawa Trough region, but very few of them have developed BSR or gas seepage. The article points out that the main reason is probably the low concentration of organic carbon of the sediment in this area. It was speculated that the rare occurrence of gas hydrates in this region is governed by structure-controlled fluid flow. Numerous faults and fractures form a network of high-permeability channels in the sediment and highly fractured igneous basement to allow fluid circulation and ventilation. Fluid flow in this tectonic environment is driven primarily by thermal buoyancy and takes place on a wide range of spatial scales. The fluid flow may play two roles to facilitate hydrate formation:to help gather enough methane into a small area and to modulate the thermal regime. 相似文献
387.
Floating tephra was deposited together with ice core,snow layer,abyssal sediment,lake sediments,and other geological records.It is of great significance to interpret the impact on the climate change of volcanic eruptions from these geological records.It is the first time that volcanic glass was discovered from the peat of Jinchuan(金川)Maar,Jilin(吉林)Province,China.And it is in situ sediments from a near-source explosive eruption according to particle size analysis and identification results.The tephra were neither from Tianchi(天池)volcano eruptions,Changbai(长白)Mountain,nor from Jinlongdingzi(金龙顶子)volcano about 1 600 aBP eruption,but maybe from an unknown eruption of Longgang(龙岗)volcano group according to their geochemistry and distribution.Geochemical characters of the tephra are similar to those of Jingiongdingzi,which are poor in s.Jica,deficient in alkali,Na20 content is more than K20 content,and are similar to distribution patterns of REE and incompatible elements,which helps to speculate that they originated from the same mantle magma with rare condemnation,and from basaltic explosive eruption of Longgang volcano group.The tephra,from peat with age proved that the eruption possibly happened in 15 BC-26 AD,is one of Longgang volcano group eruption that was not recorded and is earlier than that of Jinglongdingzi about 1 600 aBP eruption.And the sedimentary time of tephra is during the period of low temperature alteration.which may be the influence of eruption toward the local climate according to the correlativity of eruption to local temperature curve of peat cellulose oxygen isotope. 相似文献
388.
Calculating Pollution Indices by Heavy Metals in Ecological Geochemistry Assessment and a Case Study in Parks of Beijing 总被引:4,自引:0,他引:4
Pollution index is a powerful tool for ecological geochemistry assessment. The commonly used pollution indices by heavy metals in soils and sediments were classified as two types of single index and integrated index in an algorithm point of view. Four single indices of contamination factor (or concentration factor), ecological risk factor, enrichment factor, and index of geo-accumulation were illustrated, and the reference values for calculating single indices were distinguished into background levels and threshold pollution values. Eight integrated indices were divided into two groups. One group is suitable for the normal distribution single indices including the sum, average, weighted average,vector modulus, and Nemerow pollution indices, and the other for log-normal distribution including the product, root of product, and weighted power product pollution indices. Using background levels as reference values, five contamination classes were divided, and the terminologies are suggested for the single and integrated indices to unify the assessment results. Software of EGAPI was developed in a single document interface to calculate the four single and eight integrated indices by heavy metals to assess the quality of soil and sediment ecological geochemistry. Pollution indices by heavy metals of Cu,Pb, and Zn in soils in parks of Beijing were calculated using EGAPI software, and these five contamination classes and terminologies suggested in this study were evaluated and used. Results ofintegrated indices of Cu, Pb, and Zn in soils indicated that the soil qualities are unpolluted as a whole and varied from low polluted to unpolluted status from the center to the outskirts of Beijing City. 相似文献
389.
Calcimicrobialites across the Permian-Triassic boundary in Huayingshan (华蓥山) region were investigated using the fluorescence microscopic measurements to understand the occurrence of organic matter. The microbialites are composed of micrite matrix and coarse spar cement. Abundant rhombic or magnetic needle-like carbonate minerals were observed adrift within the cement. The fluorescence microscopic measurement indicates the micrite matrix in microbialites shows the most abundant organic matter, with the rhombic or magnetic needle-like carbonate minerals and coarse spar cement coming to the 2nd and the 3rd, respectively. Organic matter is mainly preserved in the space between the grains of the micrite minerals but almost evenly distributed in the rhombic or magnetic needle-like carbonate minerals. As one of the common diagenesis types, dolomitization is observed to occur in the microbialites in Huayingshan. However, the carbonate cement in microbialites still has high content of element Sr as shown by the microprobe analysis, reflecting that the dolomitization might have happened in a restricted environment. Observation under the fluorescence microscope shows that dolomitization just led to the redistribution of organic matter in the grain space of dolomite minerals, inferring that the diagenesis has a slight effect on the preservation, and thus on the content of organic matter in the microbialites. 相似文献
390.
Error sources which decrease the accuracy of GPS in absolute velocity determination have been changed since SA was turned off. Firstly, quantities of all kinds of error sources that influence velocity determination are analyzed. The potential accuracy of GPS absolute velocity determination is derived from both theory and field GPS data simulation. After that, two tests were carried out to evaluate the performance of GPS absolute velocity determination in the case of a static and an airborne GPS receiver and INS (Inertial Navigation System) instrument in kinematic mode. In static mode, the receiver velocity has been estimated to be several mm/s with the carrier-phase derived Doppler measurements, and several cm/s with the receiver generated Doppler measurements. In kinematic mode, GPS absolute velocity estimates are compared with the synchronized measurements from the high accuracy INS. The root mean square statistics of the velocity discrepancies between GPS and INS come up to dm/s. Moreover, it has a strong correlation with the acceleration or jerk of the aircraft. 相似文献