The 3-D model characteristics of a Cb cloud which moves along a valley

Summary The three-dimensional cloud-resolving mesoscale model is used to simulate an individual Cb cloud in condition of real orography. We have conducted our numerical experiments over an area known as hail bearing clouds source. Once formed such clouds regenerate and propagate along the valley if the shallow layer of strong wind shear exists. The orographic effects on model Cb cloud are recognized through comparison of simulated cloud characteristics with those calculated for the flat terrain. Sensitivity experiments with respect to the wind shear layer depth are also conducted.Our results demonstrate the model capability to simulate well some observational Cb cloud characteristics. It is shown that the river valley is of essential importance for Cb cloud development. The most prominent features of the model cloud in this case are as follows: fast propagation along the river valley; considerable depth of the cold air nose with pronounced pulsation mechanism and intense cell regeneration at the leading edge of cold air outflow. Model and observed radar reflectivities in the vertical cross-section are in agreement. Some characteristics of surface cumulative rain precipitation are also well reproduced by the model. In contrast with the real orography case, the model cloud is more intense and it propagates freely in lateral direction for the flat terrain. The cell regeneration associated with forced updraft above the cold air nose is not pronounced in contrast with earlier considerations. Reflectivity pattern near the ground, having mainly bat-like wings, encircles much larger area with altitude compared to the case of real orography. Finally, the model cloud characteristics depend strongly on shear layer.Received June 2002; revised August 22, 2002; accepted October 1, 2002 Published online: April 10, 2003     

The development of transport infrastructure and attitudes of the local population: a case study from the Republic of Serbia

In the last decades, the development of transport infrastructure has been necessary because of the population increase and expansion of urban centres. Infrastructure development leads to modification and changes in areas characterized by high human population density. The lack of adequate transport infrastructure inhibits local economic and social performance. In the period of economic stability (from 1970 to 1990), important roads that increased the connectedness of the Kolubara District (Western Serbia) with other parts of the country and the surrounding countries were built, but there is still a need for the construction of new roads. In order to examine the attitude of the local population in regard to transport infrastructure, a survey was conducted using a questionnaire consisting of closed questions. This topic is one that has not previously been examined. The data obtained were analyzed statistically and showed that local people have a positive attitude towards the existing infrastructure and towards the construction of new roads. There are statistically significant differences between the attitudes of the local population in different municipalities. The results from this research offer an opportunity to develop guidelines which can influence traffic development in these and similar areas.     

新兴葡萄酒旅游目的地空间网络结构及其影响因素——基于社会网络分析方法（QAP）

以宁夏贺兰山东麓这一新兴葡萄酒旅游目的地为例,构建酒庄和景点之间的空间联系网络,并对影响目的地空间网络结构的因素进行分析。结果表明：热门景点处于贺兰山东麓葡萄酒旅游网络中心,而非酒庄。区域、节点等级、获得等级的时间与可访问性等因素显著影响了新兴葡萄酒目的地的网络结构;在新兴葡萄酒旅游目的地,位于相同区域的酒庄由于地理位置邻近,可以共享客源;酒庄获得类似等级以及获级时间邻近也可共享网络吸引葡萄酒游客。然而,成立时间和景点类型并不是葡萄酒旅游地空间网络的重要影响指标。基于此,提出当地政府应制定促进和发展葡萄酒旅游的战略计划,推动葡萄酒品牌形象提升;酒庄应提升自身星级,加强旅游设施建设、提升接待能力,从而承接更多客流量,获得竞争优势。     

Deriving short-duration rainfall IDF curves from a regional climate model

Natural Hazards - Climate change is expected to exacerbate the extremes in the climate variables. Being prone to harsh climate impacts, it is very crucial to study extreme rainfall-induced flooding...     

Holocene estuarine sediments as a source of arsenic in Pleistocene groundwater in suburbs of Hanoi,Vietnam

Groundwater pollution by arsenic is a major health threat in suburban areas of Hanoi, Vietnam. The present study evaluates the effect of the sedimentary environments of the Pleistocene and Holocene deposits, and the recharge systems, on the groundwater arsenic pollution in Hanoi suburbs distant from the Red River. At two study sites (Linh Dam and Tai Mo communes), undisturbed soil cores identified a Pleistocene confined aquifer (PCA) and Holocene unconfined aquifer (HUA) as major aquifers, and Holocene estuarine and deltaic sediments as an aquitard layer between the two aquifers. The Holocene estuarine sediments (approximately 25–40 m depth, 9.6–4.8 cal ka BP) contained notably high concentrations of arsenic and organic matter, both likely to have been accumulated by mangroves during the Holocene sea-level highstand. The pore waters in these particular sediments exhibited elevated levels of arsenic and dissolved organic carbon. Arsenic in groundwater was higher in the PCA (25–94 μg/L) than in the HUA (5.2–42 μg/L), in both the monitoring wells and neighboring household tubewells. Elevated arsenic concentration in the PCA groundwater was likely due to vertical infiltration through the arsenic-rich and organic-matter-rich overlying Holocene estuarine sediments, caused by massive groundwater abstraction from the PCA. Countermeasures to prevent arsenic pollution of the PCA groundwater may include seeking alternative water resources, reducing water consumption, and/or appropriate choice of aquifers for groundwater supply.