固体矿产绿色勘查钻探技术方法探索与实践

西安矿产资源调查中心针对现有固体矿产地质调查（勘查）项目,积极探索和实践绿色地质勘查工作技术方法,因地制宜应用全液压履带钻机、便携式模块化钻机实施“一基多孔”,采用背包钻实施“以钻代槽”,通过优选环保型冲洗液,净化处理废弃冲洗液,控制临时占地规模等具体措施。与传统机场规格相比占地面积减少了80%~85%,临时便道修筑减少了60%~65%,工后复垦复绿达到了80%以上。通过绿色勘查成本费用分析,人员、临时用地（青苗）补偿、绿色环保材料及复垦复绿等费用成本总和降低了40%左右。最后探索实践了绿色勘查工作保障措施,对下一步绿色勘查工作提出了建议,为加强绿色勘查工作理念、完善相关的制度法规、激发绿色勘查工作活力提供了积极的导向。     

上海一次龙卷风过程分析

在分析环流背景的基础上结合风廓线仪探测资料对“990 90 6”龙卷风作了较为详细的物理剖析。分析发现 ,途经上海市的 990 9号热带风暴的残留涡旋由于西风槽的切入 ,动量迅速增大 ,形成中尺度强对流辐合云团 ,其中生成了 4个龙卷风暴。龙卷风暴在成熟阶段其环境气团的低空暖气柱逆温结构十分明显 ,垂直测风突然逆转了 36 0°。沙氏指数 SI小于 - 6℃ ,气层极不稳定。     

计算非均匀地表通量的一种简化PDF及其应用

提出描述地表非均匀特性的简化概率密度函数（PDF），它可代替各种具体的PDF用于求解次网格尺度平均通量而不影响其精度，这种简化PDF可直接加入陆面过程模式方程组中进行陆－气通量交换的数值试验。它对非均匀地表陆面过程参数化具有一定的普适性。本文仅讨论了对称分布的简化计算（非对称分布另文讨论），列举了非均匀分布的观测事实，并以地表净红外辐射通量计算为例，详细验证了应用这种简化PDF的可行性和可靠性。     

Orographic effects on a conditionally unstable flow over an idealized three-dimensional mesoscale mountain

Summary Idealized numerical simulations using the Weather and Research Forecast (WRF) model indicate that three flow regimes, based on the moist Froude number, can be identified for a conditionally unstable, rotational, horizontally homogeneous, uniformly stratified flow over an idealized, three-dimensional, mesoscale mountain stretched spanwise to the impinging flow: (I) a quasi-stationary upslope convective system and an upstream-propagating convective system, (II) a quasi-stationary upslope convective system, and (III) a stationary upslope convective system and a quasi-stationary downstream convective system. Several major differences from a similar type of flow with no rotation over a two-dimensional mountain range are found. One important finding is that relatively strong mean flow produces a quasi-stationary mesoscale convective system (MCS) and maximum rainfall on the windward slope (upslope rain), instead of on the mountain peak or over the lee side.We found that the Coriolis force helps produce heavy upslope rainfall by making transition from flow-around the eastern part of the upslope to flow-over the western part of the upslope (transits to a higher flow regime) by deflecting the incident southerly flow to become east–southeasterly barrier winds. We found that the addition of the western flank of the arc-shaped mountain helps slow down the barrier wind from east and causes the maximum rainfall to move east of the windward slope. A lower-Froude number flow tends to produce a rainfall maximum near the concave region.Several other important facts can also be found in this study. The ratio of the maximum grid scale rainfall to the sub-grid scale rainfall increases when the moist Froude number increases. When the CAPE decreases, it is found that the upstream moist flow tends to shift to a higher Froude-number regime. Therefore, the Froude number cannot solely be used to define a moist flow regime when different CAPEs are considered. In another word, other parameters, such as CAPE, might play an important role in determining moist flow regimes.     

Correction of the precipitation time series nonhomogeneity caused by replacement of the Nipher shielded rain gauge by a Tretyakov precipitation gauge

In this paper, a modern techniqne for correction of precipitation measured with a Nipher shielded rain gauge, with the use of the Valdai Control System as an intercomparison reference, is presented. This technique allows obtaining unbiased daily and timed precipitation data not affected by the rain gauge systematic errors. In conjunction with the existing method of the bias correction for precipitation measured with the Tretyakov precipitation gauge, the problem of generation of unbiased precipitation time series, which includes both types of measurements, covers the entire period of measurements, and has any (i.e., daily through yearly) temporal resolution, is solved. The results of correction for nine stations located in different climatic zones of the Russian Federation are shown. The results are summarized and presented in the form of long-term averages. Statistically homogeneous precipitation time series for the period from 1936 to 2000 are obtained. Temporal trends of annual and cold-season precipitation are calculated and analysed, and their statistical significance is estimated.     

Polar Low genesis over the North Pacific under different global warming scenarios

Following an earlier climatological study of North Pacific Polar Lows by employing dynamical downscaling of NCEP1 reanalysis in the regional climate model COSMO-CLM, the characteristics of Polar Low genesis over the North Pacific under different global warming scenarios are investigated. Simulations based on three scenarios from the Special Report on Emissions Scenarios were conducted using a global climate model (ECHAM5) and used to examine systematic changes in the occurrence of Polar Lows over the twenty first century. The results show that with more greenhouse gas emissions, global air temperature would rise, and the frequency of Polar Lows would decrease. With sea ice melting, the distribution of Polar Low genesis shows a northward shift. In the scenarios with stronger warming there is a larger reduction in the number of Polar Lows.     

Impact of stratospheric variability on tropospheric climate change

An improved stratospheric representation has been included in simulations with the Hadley Centre HadGEM1 coupled ocean atmosphere model with natural and anthropogenic forcings for the period 1979–2003. An improved stratospheric ozone dataset is employed that includes natural variations in ozone as well as the usual anthropogenic trends. In addition, in a second set of simulations the quasi biennial oscillation (QBO) of stratospheric equatorial zonal wind is also imposed using a relaxation towards ERA-40 zonal wind values. The resulting impact on tropospheric variability and trends is described. We show that the modelled cooling rate at the tropopause is enhanced by the improved ozone dataset and this improvement is even more marked when the QBO is also included. The same applies to warming trends in the upper tropical troposphere which are slightly reduced. Our stratospheric improvements produce a significant increase of internal variability but no change in the positive trend of annual mean global mean near-surface temperature. Warming rates are increased significantly over a large portion of the Arctic Ocean. The improved stratospheric representation, especially the QBO relaxation, causes a substantial reduction in near-surface temperature and precipitation response to the El Chichón eruption, especially in the tropical region. The winter increase in the phase of the northern annular mode observed in the aftermath of the two major recent volcanic eruptions is partly captured, especially after the El Chichón eruption. The positive trend in the southern annular mode (SAM) is increased and becomes statistically significant which demonstrates that the observed increase in the SAM is largely subject to internal variability in the stratosphere. The possible inclusion in simulations for future assessments of full ozone chemistry and a gravity wave scheme to internally generate a QBO is discussed.     

The influence of horizontally non-uniform heating upon the development of strong convective mesoscale disturbances

It is shown by observational data and synoptic analysis that the development of strong convective echo is influenced by the horizontally non-uniform heating, such as the one caused by lake-land distribution. In this paper, a simple linear cell-convection model is established using an appropriate heating field, and the instability of heating convection is theoretically studied. It is found that the heating convection development will be unstable if the heating-caused temperature gradientdT ₀/dy is greater than the critical value (dT ₀/dy) _c which is approximately 0.64°C/10 km, and that the development of convective band has a preferred width of 12.5 km. It will take 25 min for the initial disturbance to increase intensity by 10 times. All these results are in rather good agreement with the squall line process in the lake-land region of Jiangsu Province on June 8, 1979.     

An analysis of prediction skill of monthly mean climate variability

In this paper, lead-time and spatial dependence in skill for prediction of monthly mean climate variability is analyzed. The analysis is based on a set of extensive hindcasts from the Climate Forecast System at the National Centers for Environmental Prediction. The skill characteristics of initialized predictions is also compared with the AMIP simulations forced with the observed sea surface temperature (SST) to quantify the role of initial versus boundary conditions in the prediction of monthly means. The analysis is for prediction of monthly mean SST, precipitation, and 200-hPa height. The results show a rapid decay in skill with lead time for the atmospheric variables in the extratropical latitudes. Further, after a lead-time of approximately 30?C40?days, the skill of monthly mean prediction is essentially a boundary forced problem, with SST anomalies in the tropical central/eastern Pacific playing a dominant role. Because of the larger contribution from the atmospheric internal variability to monthly time-averages (compared to seasonal averages), skill for monthly mean prediction associated with boundary forcing is also lower. The analysis indicates that the prospects of skillful prediction of monthly means may remain a challenging problem, and may be limited by inherent limits in predictability.     

包头地区二次大雪过程的成因分析

文章应用常规资料,从天气环流形势演变、物理量等方面,对2000年1月10—11日包头地区普降大雪过程作了客观的分析,揭示了大雪过程的发生、发展机制,对今后分析大雪过程具有一定指导意义。