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211.
212.
The Kelvin-Helmholtz instability is believed to be an important means for the transfer of energy, plasma, and momentum from the solar wind into planetary magnetospheres, with in situ measurements reported from Earth, Saturn, and Venus. During the first MESSENGER flyby of Mercury, three periodic rotations were observed in the magnetic field data possibly related to a Kelvin-Helmholtz wave on the dusk side magnetopause. We present an analysis of the event, along with comparisons to previous Kelvin-Helmholtz observations and an investigation of what influence finite ion gyro radius effects, believed to be of importance in the Hermean magnetosphere, may have on the instability. The wave signature does not correspond to that of typical Kelvin-Helmholtz events, and the magnetopause direction does not show any signs of major deviation from the unperturbed case. There is thus no indication of any high amplitude surface waves. On the other hand, the wave period corresponds to that expected for a Kelvin-Helmholtz wave, and as the dusk side is shown to be more stable than the dawn side, we judge the observed waves not to be fully developed Kelvin-Helmholtz waves, but they may be an initial perturbation that could cause Kelvin-Helmholtz waves further down the tail. 相似文献
213.
Because of its geographic and economic position, the Western part of Europe and France is prone to biological invasions. Among the aquatic species non-native to France, a high proportion of these species are considered to be salt-tolerant. To verify this assumption, we compared the salinity tolerance of 18 native and non-native species in France in order to determine whether the introduced non-native species are more salt-tolerant than the native ones. Contrary to our expectations, our study shows that both native and non-native macroinvertebrate species from the same taxonomic group which had originated from within Eurasia had very similar salinity tolerance. Our results show that species originate from outside Eurasia (introduced by the ballast or drinking water on ships) were more salt tolerant than native from France and non-native species originated from Eurasia. Thus, derivation of the acute test of the salinity tolerance in native ranges may give good indications of their potential ability to survive during the translocation by shipping from the area of origin to another area. Our approach does provide empirical evidence for potential of non-native species to survive translocation in saline water using standard, quick and inexpensive protocols. 相似文献
214.
中国地区云光学厚度和云滴有效半径变化趋势 总被引:3,自引:0,他引:3
利用ISCCP最新的D2云气候资料集和MODIS云的资料,给出中国地区云的光学厚度和云滴有效半径的分布特征;分别对季节平均和年平均时间序列进行线性趋势分析,并进行了显著性检验。结果表明:夏季云的光学厚度和有效半径的变化趋势最显著。结合云量变化情况,可发现云滴有效半径的变化对云光学厚度的影响可能在夏季最大,也就是说,气溶胶的间接气候效应可能在夏季最强;云量、云光学厚度和云滴有效半径的变化也表明长江以南地区和青藏高原地区可能是气溶胶间接气候效应比较显著的地区。中国地区冰云光学厚度与有效直径的相关具有很强的区域特征,说明冰云的微物理机制比水云更复杂。 相似文献
215.
An Evidence of Aerosol Indirect Effect on Stratus Clouds from the Integrated Ground-Based Measurements at the ARM Shouxian Site
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TANG Jin-Ping WANG Pu-Cai DUAN Min-Zheng CHEN Hong-Bin XIA Xiang-Ao LIAO Hong 《大气和海洋科学快报》2011,4(2):65-69
The aerosol effect on clouds was explored using remote sensing of aerosol and cloud data at Shouxian, China. Non-precipitation, ice-free, and overcast clouds were firstly chosen by a combination of sky images from the Total Sky Imager (TSI), cloud base heights from the Ceilometer, and vertical temperature profiles from the Balloon-Borne Sounding System (BBSS). Six cases were chosen in summer, and seven in autumn. The averaged cloud effective radii (re), cloud optical depth (COD), aerosol total light scattering coefficient (σ), and liquid water path (LWP) are, respectivey, 6.47 μm, 35.4, 595.9 mm-1, 0.19 mm in summer, and 6.07 μm, 96.0, 471.7 mm-1, 0.37 mm in autumn. The correlation coefficient between re and σ was found to change from negative to positive value as LWP increases. 相似文献
216.
对广东省境内的全部8个重晶石矿床进行成矿地质条件、重磁异常类比,建立了广东省重晶石矿的预测模型。针对省内不同地区含矿地质体有所差异的特点,对全省分6个预测工作区,圈定了最小预测区,特征分析后,共圈定73个。通过类比法、体积法在最小预测区的尺度进行了资源量的计算与全省汇总。将最小预测区合理归并,确定了35个远景区。分析了不同远景区的找矿潜力,结合目前广东省内的工业布局,得到了7个勘查建议区。 相似文献
217.
In order to ensure the sustainable exploitation of geothermal resources and prevent the occurrence of thermal breakthrough during the process of geothermal water reinjection, the authors systematically summarized the calculation formulas of the rights protection radius of the geothermal well in this paper. Three shortcomings in the calculation method of the rights protection radius of the geothermal well were identified through theoretical derivation. (1) The parameter f, which is defined as the ratio of the specific heat of water to that of thermal reservoir rocks, is defective. (2) The value of the thermal reservoir recovery rate defined as 0.15 is relatively unilateral, which is not applicable for geothermal wells with different lithology. (3) The calculation time is fixed as 36 500 d, which is not appropriate for geothermal wells with interval development. Based on the problems above, the authors redefined the parameter f and used variables to replace the previous thermal reservoir recovery rate and exploitation time, which can be identified according to different thermal reservoirs and specific exploitation time. By comparison of the applicable conditions of different calculation formulas of the rights protection radius of the geothermal well, the authors proposed that different calaulation formuas should be chosen based on the relationship of the size between β-1-α and 3λ. And by comparison of the rights protection radius calculation formulas for the mining well and the recharge well, it is found that the rights protection radius of the mining well is always bigger than that of the recharge well. Finally, Shuiwen residential area of Decheng district was taken as an example to verfity the theoretical results. 相似文献
218.
东亚地区云微物理量分布特征的CloudSat卫星观测研究 总被引:6,自引:3,他引:3
本文利用2007~2010年整四年最新可利用的CloudSat卫星资料, 对东亚地区(15°~60°N, 70°~150°E)云的微物理量包括冰/液态水含量、冰/液态水路径、云滴数浓度和有效半径等的分布特征和季节变化进行了分析。本文将整个东亚地区划分为北方、南方、西北、青藏高原地区和东部海域五个子区域进行研究, 结果显示:东亚地区冰水路径值的范围基本在700 g m-2以下, 高值区分布在北纬40度以南区域, 在南方地区夏季的平均值最大, 为394.3 g m-2, 而在西北地区冬季的平均值最小, 为78.5 g m-2;而液态水路径的范围基本在600 g m-2以下, 冬季在东部海域的值最大, 达到300.8 g m-2, 夏季最大值为281.5 g m-2, 分布在南方地区上空。冰水含量的最高值为170 mg m-3, 发生在8 km附近, 南方地区夏季的值达到最大, 青藏高原地区的季节差异最大;而液态水含量在东亚地区的范围小于360 mg m-3, 垂直廓线从10 km向下基本呈现逐渐增大的趋势, 峰值位于1~2 km高度上。冰云云滴数浓度在东亚地区的范围在150 L-1以下, 水云云滴数浓度的值小于80 cm-3, 垂直廓线的峰值均在夏季最大。冰云有效半径在东亚地区的最大值为90 μm, 发生在5 km左右;水云有效半径在东亚地区的值分布在10 km以下, 最大值为10~12 μm, 基本位于1~2 km高度上。从概率分布函数来看, 东亚地区冰/水云云滴数浓度的分布呈现明显的双峰型, 其他量基本为单峰型。本文的结果可以为全球和区域气候模式在东亚地区对以上云微物理量的模拟提供一定的观测参考依据。 相似文献
219.
????????????????е????????????????????????????????????????????????????????????????????????????????????????????????????????????????16????????????????????ж????????????????????????????????????????????????????輼??????????????????????????????μ?? 相似文献
220.
N. Spyrou 《Journal of Astrophysics and Astronomy》1988,9(1):25-39
We explore the change in the period of axial rotation and in the radius of a magnetized compact star in a binary system, induced
by the accretion on it of mass with angular momentum from the surface of its non-compact companion. No specific assumption
is made concerning the accretion model, and the primary’s interior is described by the Fermi-Dirac statistics for degenerate
matter. The rate of change with time of the period and radius is expressed in terms of the compact primary’s physical parameters
and total absolute luminosity. The conditions are fully derived under which the above changes can be positive, negative or
even vanish. In the case of the millisecond pulsars in binary X-ray sources the predicted values of the period time derivative,
depending on the values of the accretion rate and. the absolute luminosity, can be positive or negative—if not vanishing—and
they fall absolutely in the range 10−21 −10−17 ss−1, in good agreement with current observational data. The corresponding rate of change of radius, either positive or negative,
fall in the range of 10−3 −10−1 cm y−1. Finally, it is proved that the well-known bursters can be explained by thermonuclear flash due to gravitational instability
in the accreted matter, but their explanation as a result of direct contraction could be possible only for quite high accretion
rates (>10−7
M ⊙ y−1). This last result indicates that, in contrast to the accretion-induced change in period, which can be of either sign irrespective
of the primary’s age, the accretion-induced non-catastrophic contraction is impossible, while according to repent results
the contraction in general is possible for young compact objects. 相似文献