2021年10月山西一次罕见持续性强降水过程物理机制分析

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。     

地浸采铀浸出液氧化沉淀法除铁研究

在氧化沉淀法去除铁的过程中,氧化反应分别在自然曝气、充气和除钙的条件下进行,对照结果进行分析,得出最佳的除铁配方,同时还着重对氧化反应速率及其影响因素（pH,Eh等）进行了探索性研究,为以后试验提供了一定的依据。     

攀枝花龙洞煤矿地下水运移的同位素研究

攀枝花市西区龙洞煤矿经过十余年的生产,不但在地下形成了较大范围的采空区,而且通过影响地下水形成了较大范围的疏干,致使矿区内大部分泉点断流.因而,为确定矿山地下水长期疏干对龙洞泉流域的影响程度,笔者通过比较水库水、大气降水、地下水与渗漏水之间的同位素特征,区分出了地下水的补给来源,并为查明本区的水文地质条件及确定矿坑地下水疏干的影响范围提供科学依据.     

SOME NEW UNDERSTANDINGS OF LAND-SURFACE PROCESSES IN ARID AREA FROM THE HEIFE*

The survey for the HEIFE(Atmosphere-Land Surface Processes Experiment at Heihe River Basin,Western China) is given in the paper.The following basic subjects for land-surface processes in arid areas are studied:(1) the general characteristics of the energy budget on ground surface in arid areas;(2) the parameterization of the land surface processes;(3) the interaction between oasis and its desert circumstances,a special phenomenon in arid areas.The analysis shows that the sensible heat flux in the surface energy budget is in the majority,and the latent heat flux may be neglected.The influence of atmospheric stratification stability on the turbulent transfer of energy and substance must be considered in parameterization of land surface processes in arid areas.The "cold island effect" phenomenon in oasis and the "humidity inversion" phenomenon in desert near oasis are the result of the interaction between them.The results would improve the understanding of land surface processes in arid areas.     

“雅安天漏”研究 III：特征、物理量结构及其形成机制

本文的这一部分首先进一步分析了第二部分的预报结果,结果发现,在本文第二部分所建立的模式,不仅较好地预报出了24小时总降水量,而且也较好地预报出了“雅安天漏”的降水特征和降水中的物理结构。模式基本上抓住了形成雅安降水的主要影响因子。然后通过一系列精心设计的数值模拟试验得到了形成雅安降水的可能机制。     

东北漫岗黑土区春季冻融期浅沟侵蚀

浅沟侵蚀是东北漫岗黑土区农耕地上常见的水蚀类型,往往对坡耕地造成严重的破坏。2005年春季,通过对两个小流域浅沟侵蚀的调查测量,发现该区浅沟侵蚀相当严重,两流域分别形成浅沟14条、16条,浅沟总长度分别达3 269 m、2 146 m,浅沟密度分别为908 m/km2、766 m/km2,侵蚀深度分别为0.17 mm、0.16 mm,侵蚀模数分别达181.8 t/km2、173.6 t/km2。2005年春季两流域浅沟侵蚀期的径流深分别是6.8 mm、7.7 mm。分析表明,研究区在春季表层土壤解冻、地表裸露和存在季节性冻土层的条件下,春季融雪及强降水易造成强烈的浅沟侵蚀。在分布上,浅沟一般位于坡面的中下部,而且多发育在瓦背状坡面的集流水路上。另外,耕作措施对浅沟的形成和发展也有重要影响。     

Deformation-induced garnet zoning

Compositional zoning patterns in garnet porphyroblasts from kyanite-bearing samples of the Devonian Littleton Formation, north-central Massachusetts, reveal complex patterns of growth that are related to multiple deformation and metamorphic events. Garnet porphyroblasts exhibit asymmetrical and irregular zoning patterns in X_Mn, X_Ca and Fe/(Fe + Mg). Zoning reversals in Mn and Fe/(Fe + Mg) and patch distribution in Ca appear to occur around the boundaries of the textural zones. Also, the compositions of the garnet at the textural boundaries are variable for all traverses. These observations suggest that the garnet zoning was not only modified from diffusion processes, but was also influenced by pre-existing microfabrics through the effects of preferential dissolution and resorption in partial disequilibrium. Relationships between chemical and textural truncations indicate that the zoning patterns of garnet were strongly modified from preferential dissolution and precipitation during the development of successive foliations that occurred in zones of high strain/stress (cleavage seams) and zones of low strain/stress, respectively.     

Climate change in Mt. Qomolangma region since 1971

Using monthly average, maximum, minimum air temperature and monthly precipitation data from 5 weather stations in Mt. Qomolangma region in China from 1971 to 2004, climatic linear trend, moving average, low-pass filter and accumulated variance analysis methods, the spatial and temporal patterns of the climatic change in this region were analyzed. The main findings can be summarized as follows: (1) There is obvious ascending tendency for the interannual change of air temperature in Mt. Qomolangma region and the ascending tendency of Tingri, the highest station, is the most significant. The rate of increasing air temperature is 0.234 oC/decade in Mt. Qomolangma region, 0.302 oC/decade in Tingri. The air temperature increases more strongly in non-growing season. (2) Compared with China and the global average, the warming of Mt. Qomolangma region occurred early. The linear rates of temperature increase in Mt. Qomolangma region exceed those for China and the global average in the same period. This is attributed to the sensitivity of mountainous regions to climate change. (3) The southern and northern parts of Mt. Qomolangma region are quite different in precipitation changes. Stations in the northern part show increasing trends but are not statistically significant. Nyalam in the southern part shows a decreasing trend and the sudden decreasing of precipitation occurred in the early 1990s. (4) Compared with the previous studies, we find that the warming of Mt. Qomolangma high-elevation region is most significant in China in the same period. The highest automatic meteorological comprehensive observation station in the world set up at the base camp of Mt. Qomolangma with a height of 5032 m a.s.l will play an important role in monitoring the global climate change.     

Diurnal Variations of Hydrochemistry in a Travertine-depositing Stream at Baishuitai, Yunnan, SW China

Diurnal variations of hydrochemistry were monitored at a spring and two pools in a travertine-depositing stream at Baishuitai, Yunnan, SW China. Water temperature, pH and specific conductivity were measured in intervals of 5 and 30 min for periods of 1 to 2 days. From these data the concentrations of Ca²⁺, HCO₃⁻, calcite saturation index, and CO₂ partial pressure were derived. The measurements in the spring of the stream did not show any diurnal variations in the chemical composition of the water. Diurnal variations, however, were observed in the water of the two travertine pools downstream. In one of them, a rise in temperature (thus more CO₂ degassing) during day time and consumption of CO₂ due to photosynthesis of submerged aquatic plants accelerated deposition of calcite, whereas in the other pool, where aquatic plants flourished and grew out of the water (so photosynthesis was taking place in the atmosphere), the authors suggest that temperature-dependent root respiration underwater took place, which dominated until noon. Consequently, due to the release of CO₂ by the root respiration into water, which dominated CO₂ production by degassing induced by temperature increase, the increased dissolution of calcite was observed. This is the first time anywhere at least in China that the effect of root respiration on diurnal hydrochemical variations has been observed. The finding has implications for sampling strategy within travertine-depositing streams and other similar environments with stagnant water bodies such as estuaries, lakes, reservoirs, pools and wetlands, where aquatic plants may flourish and grow out of water.