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41.
热害矿井巷道温度场分布规律研究 总被引:8,自引:0,他引:8
为解决深部开采带来的热害问题,基于地质学和热力学理论,建立了热害矿井巷道温度场的数学模型,研究了巷道内部温度场随埋深和通风热速的变化规律。计算结果表明,巷道温度场对埋深的敏感度要高于风速、温度随埋深的增加而呈阶段性递增。控制入口温度是解决矿井热害的关键。以上结论为矿井热害的综合治理提供了重要依据。 相似文献
42.
Velocity structure of uppermost mantle beneath North China from Pn tomography and its implications 总被引:1,自引:0,他引:1
20301 Pn arrival time data are collected from the seismological bulletins of both national and regional seismic networks. Pn travel time residuals are tomographically inverted for the Pn velocity structure of uppermost mantle beneath North China. The result indicates that the average Pn velocity in North China is 7.92 km/s, and the velocity varies laterally from ?0.21 to +0.29 km/s around the average. The approximately NNE trending high and low velocity regions arrange alternatively west-eastward. From west to east we can see high velocity in the middle Ordos region, the Shanxi graben low, the Jizhong depression high, the west Shandong uplift and Bohai Sea low, and the high velocity region to the east of the Tanlu fault. In the southern boundary zone of the North China block, except for the high velocity in the Qingling Mountains region, the velocity is generally lower than the average. Obvious velocity anisotropy is seen in the Datong Cenozoic volcanic region, with the fast velocity direction in NNE-SSW. Notable velocity anisotropy is also seen around the Bay of Bohai Sea, and the fast velocity directions seem to show a rotation pattern, possibly indicating a flow-like deformation in the uppermost mantle there. The Pn velocity variations show a reversed correlation with the Earth's heat flow. The low Pn velocity regions generally show high heat flow, e.g., the Shanxi graben and Bohai Sea region. While the high Pn velocity regions usually manifest low heat flow, e.g., the region of Jizhong depression. This indicates that the Pn velocity variation in the study region is mainly aroused by the regional temperature difference in the uppermost mantle. Strong earthquakes in the crust tend to occur in the region with the abnormal low Pn velocity, or in the transition zone between high and low Pn velocity regions. The earthquakes in the low velocity region are shallower, while that in the transition zone are deeper. 相似文献
43.
44.
The characteristic features of the marine boundary layer (MBL) over the Bay of Bengal during the southwest monsoon and the
factors influencing it are investigated. The Bay of Bengal and Monsoon Experiment (BOBMEX) carried out during July–August
1999 is the first observational experiment under the Indian Climate Research Programme (ICRP). A very high-resolution data
in the vertical was obtained during this experiment, which was used to study the MBL characteristics off the east coast of
India in the north and south Bay of Bengal. Spells of active and suppressed convection over the Bay were observed, of which,
three representative convective episodes were considered for the study. For this purpose a one-dimensional multi-level PBL
model with a TKE-ε closure scheme was used. The soundings, viz., the vertical profiles of temperature, humidity, zonal and
meridional component of wind, obtained onboard ORV Sagar Kanya and from coastal stations along the east coast are used for
the study. The temporal evolution of turbulent kinetic energy, marine boundary layer height (MBLH), sensible and latent heat
fluxes and drag coefficient of momentum are simulated for different epochs of monsoon and monsoon depressions during BOBMEX-99.The
model also generates the vertical profiles of potential temperature, specific humidity, zonal and meridional wind. These simulated
values compared reasonably well with the observations available from BOBMEX. 相似文献
45.
Abstract. Magnetotelluric (MT) surveys were carried out around the Muine volcano, Hokkaido, Japan, where it is expected that the heat and metal source forming the polymetallic Ag-Pb-Zn-Cu-In Toyoha deposit is present at depth. Measurements were performed at 20 sites, 18 of which were located along a WSW-ENE profile traversing the north ridge of Mt. Muine. A resistivity model obtained from 2D inversion of the MT data shows subsurface specific conductive and resistive features. Conductive layers are present at the surface of Mt. Muine. The low resistivity is probably due to the clay-rich rocks associated with the hydrothermal alteration. A high resistivity layer, which corresponds to the pre-Tertiary Usubetsu Formation, crops out east of Mt. Muine and dips westward. At the west foot of Mt. Muine, relatively high resistive layers are widely exposed. The resistivity increases with depth and exceeds 1000 ohm-m. This fact indicates that this region is not influenced by the recent hydrothermal activity. An extremely conductive zone about 3–6 km wide and 6–9 km thick exists at a depth of 2 km below Mt. Muine. This zone mostly corresponds to an elastic wave attenuation zone detected by a seismic survey. It is interpreted as a large hydrothermal reservoir or melted magma, which is a heat source of the hydrothermal system in this area. 相似文献
46.
目前 ,我国气象部门相当普遍地拥有气象卫星观测资料 ,但是 ,这些资料如何在城市气象服务以及为城市建设规划等方面的决策研究中发挥作用 ,急待进一步研究并开展工作。本文试图通过合理的反演处理 ,给出卫星观测对地面温度的测量结果 ,由此可比较细致地分析了解地面热状况及其与土地利用类型 ,地面覆盖性质等的关系。本文利用有限的 NOAA- AVHRR气象卫星遥感资料 ,采用修正的 Ulivieri分裂窗方法反演出同期的地表温度场 ,通过对北京地区的卫星观测资料进行算例分析 ,揭示出一个 2 0 0 km× 2 0 0 km范围内的地面温度分布特征。反演结果可以明显地揭示出城市热岛现象的变化规律 ,并且能较为清楚地反映出相对的高温区和低温区 相似文献
47.
The roughness length for momentum (z0m), zero-plane displacementheight (d), and roughness length for heat (z0h) are importantparameters used to estimate land-atmosphere energy exchange. Although many different approaches have been developed to parameterizemomentum and heat transfer, existing parameterizations generally utilizehighly simplified representations of vegetation structure. Further, a mismatch exists between the treatments used for momentum and heat exchange and those used for radiative energy exchanges. In this paper, parameterizations are developed to estimate z0m, d, and z0h for forested regimes using information related to tree crown density and structure. The parameterizations provide realistic representationfor the vertical distribution of foliage within canopies, and include explicit treatment for the effects of the canopy roughness sublayer and leaf drag on momentum exchange. The proposed parameterizationsare able to realistically account for site-to-site differences in roughness lengths that arise from canopy structural properties.Comparisons between model predictions and field measurements show good agreement, suggesting that the proposed parameterizations capture the most important factors influencing turbulent exchange of momentumand heat over forests. 相似文献
48.
The Multi frequency Scanning Microwave Radiometer (MSMR) onboard Oceasat-1 was used to develop a retrieval method fornear-surface specific humidity by means of multivariate regressiontechnique. The MSMR measures the microwaveradiances in 8 channels at the frequencies of 6.6, 10.7, 18 and 21 GHzfor both vertical and horizontal polarizations. Regression coefficients were derived using the ship reports of the Comprehensive Ocean-Atmosphere Data Set (COADS) for the months of July, October and December, in 1999. Daily near-surface specific humidity data from COADS in 2° × 2° latitude/longitude bins and collocated brightness temperature data from MSMR were used to derive the coefficients. The derived coefficients werevalidated with humidity given in COADS.A linear relationship is established to determine the near-surface specifichumidity from MSMR brightness temperature (Tb) with an rms error of 1.2 g kg-1 for individual situations and an rms errorof 0.84 g kg-1 for monthly time scales over global oceans.The retrieval algorithm is validonly for the open sea regions. 相似文献
49.
利用MM5中尺度模式对1999年6月两个出海气旋发展过程进行 数值模拟. 数值模拟的气旋出海后移动路径与实际情况基本一致. 在数值模拟基础上重点讨 论了出海气旋发展过程潜热通量和感热通量的分布及其演变情况. 气旋出海后在气旋中心区 南方和东方存在负潜热通量和感热通量区. 出海气旋的东移和发展,其前方强大正热通量区 的存在可能是重要原因之一. 相似文献
50.
1991年江淮暴雨时期的能量和水汽循环研究 总被引:16,自引:3,他引:16
通过对 1991年 5~ 7月江淮暴雨期全球范围的水汽输送和不同降水过程中江淮暴雨区及其临近区域的水汽收支和视热源和视水汽汇的计算分析得到了以下结论 :( 1)从水汽输送的机制来看 ,一方面 ,有大量的水汽以定常涡动的方式从孟加拉湾及南海输送到中国江淮地区 ;另一方面 ,江淮地区的瞬变涡动水汽向北输出 ,这可能与江淮地区频繁活动的α和β中尺度系统有关 ,它们将江淮地区汇集的充沛的水汽除了大部分以降水形式降下外 ,剩余部分继续向水汽较少的高纬地区输出 ,以维持全球水汽的平衡。( 2 )在降水过程中 ,局地蒸发项在水汽的供应中或再循环中十分重要 ,其数值一般为降水量的 13 ~ 12 ,这与1998年的降水情况相似。( 3 )在降水过程中 ,暴雨区的水汽主要是从南边界和西边界流入的 ,东边界和北边界则流出 ,并且水汽的流入、流出主要在中低层进行。 (a)在流入边界上 ,水汽通量的垂直分布存在差异 ,暴雨区西边界和南边界的水汽流入的垂直差异可能与其所在的地理位置有密切关系。 (b)对于暴雨区 ,不同强度的降水过程水汽的主要来源有所不同。( 4)在 5次降水过程中 ,视热源和视水汽汇的较大值对应降水的大值区 ,表明了水汽凝结加热对大气加热所起的主要作用。梅雨期降水 ,以对流性降水为主 ,对流活动随季节变化 相似文献