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31.
青藏高原物质东流的岩石层力学背景探讨 总被引:3,自引:0,他引:3
利用地表大地热流观测资料、岩石生热率及热导率数据研究了三江和四川盆地 6个地区的岩石层平均温度结构及强度分布。结果表明 ,整个三江地区岩石层温度较高 ,而四川盆地温度较低 ;在岩石层强度分布上 ,四川盆地为高强度区 ,而三江地区则为低强度区 ;整个三江地区构成了一条青藏高原物质东流的低强度通道 ;由于四川盆地高强度块体的阻挡 ,青藏高原向东的物质流在此转向近南向 ,沿三江地区流逸 ;不同岩石层块体的强度差异可能是控制高原物质流动态势的重要力学背景之一。 相似文献
32.
Wavelet filter analysis of atmospheric pressure effects in the long-period seismic mode band 总被引:2,自引:0,他引:2
The importance of the reduction of atmospheric pressure effects becomes very clear when investigating seismic normal-mode spectra below 1.5 mHz. The usual simple correction method consists in subtracting a term converted from local atmospheric pressure (pressure multiplied by a frequency-independent admittance) from the gravity record in time domain. Thus, estimating an efficient admittance is the key for an improved correction. Band-pass filters derived from dyadic orthogonal wavelet transform, having narrow pass-bands with good frequency response but without Gibbs phenomenon and causing no phase lag, are very helpful to estimate an efficient admittance, which is both time and frequency-dependent. Processing of high quality superconducting gravimeter (SG) records for the great Sumatra earthquake (Mw = 9.3, Dec 26, 2004) with wavelet filters reveal the three very well resolved splitting singlets of overtone 2S1 with a single gravity record after correction with time-dependent and frequency-dependent admittances. We also observe all coupled toroidal modes below 1.5 mHz, except 0T5, 0T7 and 1T1, with good signal-to-noise ratio (SNR); moreover, toroidal modes 1T2 and 1T3 are for the first time unambiguously revealed in vertical components. 相似文献
33.
WANG Yong LIU Yanping LIU Lintao XU Houze 《地球空间信息科学学报》2007,10(4):265-268
The feasibility of GPS precipitable water vapor (PWV) is discussed based on the comparison of Radiosonde and GPS PWV where the correlation coefficient is 0.94 and the RMS is 4.0 mm. PWV change in the C... 相似文献
34.
Observed pollutants are of both primary and secondary origins, influenced by local topography and meteorology. Identifying
sources and relative contribution often require vast detailed data collection and complicated models. This study applied a
statistical time series analysis to two selected pollution events, spring and fall, at two sites in northern Taiwan. Vector
moving average representations were used to quantitatively examine relationships among chemical pollutants and estimate their
lifetimes. Results from impulse responses show that wind direction change alters the characteristic of pollution observed
in opposite sites of Taipei City, from chemical dominant system to transport dominant one and vice versa. Chemicals are clearly
separated into photochemical pollutants and primary pollutants. Results pointed out that Taipei City is the major source of
photochemical smog, but not these primary pollutants. Derived chemical lifetimes at same location vary from 20% to four times
under different meteorological condition. Estimated concentrations of hydroxyl radical range between 2 to 8 × 107 cm−3. Photochemical pollutants are responsible for parts of PM10 collected in both station observed. Oxidation of SO2 is only important in PM10 observed at one station. This study provides a simpler tool to derive information usually from
complex models, therefore, is suitable as complement in decision-making process. 相似文献
35.
通过对武汉台超导重力仪9年多连续观测的重力长期变化资料分析,得到长周期重力潮汐参数、该频段气压回归因子C、极移重力效应因子P和长周期气压回归因子C1分别为:C:-0.383(±0.014)×10-8m·s-2/100Pa;Mm:1.1173(±0.0720),-1°.1787(±3°.6943);Mf:1.1432(±0.0484),5°.2235(±2°.4253);Mtm:1.2276(±0.2245),-17°.5648(±10°.4758);C1:-0.312(±0.015)×10-8m·s-2/100Pa;P:1.9047(±0.0695).重力长期变化在Chandler周期附近的振幅约为3.26×10-8m·s-2。 相似文献
36.
水准椭球的纬向密度分布 总被引:9,自引:1,他引:8
本文推导了旋转椭球极点重力与赤道重力的密度积分公式。按照1980大地参考系统及水准椭球的“极点重力条件”和“赤道重力条件”,从数学上证明了地球的“赤道径向平均密度”大于“极点径向平均密度”,并给出了水准椭球纬向密度分布的估算公式;进而提出了“地球的径向平均密度按纬向正常分布”的假说。 相似文献
37.
A comparison of estimated and calculated effective porosity 总被引:1,自引:1,他引:0
Daniel B. Stephens Kuo-Chin Hsu Mark A. Prieksat Mark D. Ankeny Neil Blandford Tracy L. Roth James A. Kelsey Julia R. Whitworth 《Hydrogeology Journal》1998,6(1):156-165
Effective porosity in solute-transport analyses is usually estimated rather than calculated from tracer tests in the field
or laboratory. Calculated values of effective porosity in the laboratory on three different textured samples were compared
to estimates derived from particle-size distributions and soil–water characteristic curves. The agreement was poor and it
seems that no clear relationships exist between effective porosity calculated from laboratory tracer tests and effective porosity
estimated from particle-size distributions and soil–water characteristic curves. A field tracer test in a sand-and-gravel
aquifer produced a calculated effective porosity of approximately 0.17. By comparison, estimates of effective porosity from
textural data, moisture retention, and published values were approximately 50–90% greater than the field calibrated value.
Thus, estimation of effective porosity for chemical transport is highly dependent on the chosen transport model and is best
obtained by laboratory or field tracer tests.
Received, March 1997 · Revised, August 1997 · Accepted, August 1997 相似文献
38.
S. A. Hsu 《Boundary-Layer Meteorology》1981,20(3):341-351
To understand and estimate wind speed differences across the coastal zone, two models, one theoretical and another semi-empirical, have been developed and verified by available data sets. Assuming that: (1) mean horizontal motion exists across the coastal zone; and (2) the geostrophic wind does not change appreciably at the top of the planetary boundary layer (PBL), the equation of motion in the direction of the wind can be reduced so that 341-01, where U, H, and C
D are wind speed, height of PBL, and drag coefficient over the sea and land, respectively. For practice, C
D SEA has been modified from a formula with U
LAND as the only input. H
SEA may be estimated routinely from known H
D LAND
LAND and the temperature difference between land and sea, which can be provided by such means as remote sensing from meteorological satellites. For a given coast, Cmay be estimated also. This formula is recommended for weather forecasters. The semiempirical formula is based mainly on the power law wind distribution with height in the PBL. The formula states that 341-02. Simultaneous offshore and onshore wind measurements made at stations ranging from Somalia, near the equator, to the Gulf of Alaska indicated that values of a and b are 2.98 and 0.34 with a correlation coefficient of -0.95. For oceanographic applications, a simplified equation, i.e., 341-03, is also proposed. 相似文献
39.
A scheme is proposed to calculate the effect of torsion on each lateral load resisting element of asymmetrical buildings in the context of the response spectrum technique. The scheme consists of: (i) Obtain the modal shear and torque on the building by the response spectrum technique, (ii) Compute the total modal shear forces on each frame by resolving the modal shear and torque on the building according to principles of structural mechanics. The shears on each frame due to the lateral load effect and torsional effect are combined algebraically, (iii) Obtain the total shear force on each frame by combining the total modal shears on that frame in a root sum square manner. Since the proper phase relationship between the lateral load effect and torsional effect is accounted for on a modal basis, it is believed that the proposed scheme provides a more realistic load estimate on the frames than the conventional approach. An example of a simplified mono-symmetrical frame structure is chosen to illustrate the accuracy of the proposed scheme, using dynamic time-history analysis as a standard for comparison. 相似文献
40.
S. A. Hsu 《Boundary-Layer Meteorology》1979,17(4):485-494
Mesoscale nocturnal jetlike winds have been observed over a flat, open coast. They occur within the planetary boundary layer between 100 and 600 m. At times the wind shear may reach 15 m s-1 per 100 m. Unlike the common low-level jet that occurs most often at the top of the nocturnal inversion and only with a wind from the southerly quadrant, this second kind of jet exists between nocturnal ground-based inversion layers formed by the cool pool, or mesohigh, and the elevated mesoscale inversion layer over the coast. It occurs mostly when light % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaiikaiabgs% MiJkaaiwdacqGHsislcaaI2aGaaeyBaiaabccacaqGZbWaaWbaaSqa% beaacqGHsislcaaIXaaaaOGaaiykaaaa!3FCF!\[( \leqslant 5 - 6{\text{m s}}^{ - 1} )\] geostrophic winds blow from land to sea and when the air temperature over adjacent seas is more than 5 °C warmer than that over the coast. This phenomenon may be explained by combined Venturi and gravity-wind effects existing in a region from just above the area a few kilometres offshore to 100–600 m in height approximately 40–50 km inland because this region is sandwiched between the aforementioned two inversion layers. 相似文献