Numerical analysis of ground temperature in Qinghai-Tibet Plateau

On the basis of the existing theories such as permafrost, thermodynamics and fluid mechanics, as well as the climate features on the Qinghai-Tibet Plateau and the data collected from both laboratory and the on-the-spot test, this paper puts forward a set of analytical methods and a numerical module for ground thermal regime with consideration of engineering surface features and various natural elements such as wind speed, radiation, evaporation. This paper also probes into the defining method for physical thermal parameter of the silty clay and gravelly sand soil, which widely pervades on the Qinghai-Tibet Plateau. The numerical analysis indicates that the ground thermal regime is a comprehensive reflection of various external elements. It is suggested that the variation of external elements should be fully taken into consideration in engineering design. Furthermore, the analysis of the frozen soil subgrade indicates that the transverse thermal difference in subgrade, which affects the subgrade stability     

西藏羊八井Ka&W双频毫米波云雷达性能及观测分析

介绍了西藏羊八井全大气层观象台最新架设的Ka&W双频毫米波云雷达（以下简称YBJ-DFDR,W波段94GHz,波长3.2 mm,Ka波段35 GHz,波长8.6 mm）的基本性能,并选择该地区不同类型云的观测数据,对其探测能力开展了分析和对比研究。分析结果显示,该双频云雷达系统具有较高的探测能力,其中W波段雷达和Ka波段雷达在10 km距离处的探测灵敏度分别达为-39.2 dBZ和-33 dBZ。对比研究表明Ka和W波段雷达所测等效反射率因子值因云物理属性不同亦呈现不同的特征。发生降雨时,由于液态雨和云粒子对雷达信号的吸收和散射作用,造成回波信号出现衰减,此时Ka和W波段雷达二者之间的衰减程度明显不同,W波段雷达信号衰减较严重,甚至出现衰减后低于探测灵敏度而无法获得回波的情况（严重时二者之差可达30 dB）。而当云中粒子多为冰相时,回波信号的衰减程度显著减弱,W波段雷达相比Ka波段雷达展示出更佳的探测能力,其所测反射率因子值普遍高于Ka波段雷达。研究亦发现Ka波段雷达对于云层边缘区域,如云顶、云底部分,容易出现漏测的情况,从而导致云顶高度的低估和云底高度的高估,其主要原因是这些...     

复垦土地土壤有机碳空间插值方法研究——以平朔露天煤矿为例

通过优化空间插值方法获取矿区重构土壤有机碳含量对于复垦农用地监测与评价具有重要的理论和实际应用价值。采用多元线性回归法、反距离加权法、普通克里金法及回归克里金法对平朔煤矿复垦区土壤有机碳含量进行空间插值分析,插值精度通过Pearson相关系数、均方根误差、平均预测误差以及准确度进行评价。研究结果表明：① 露天煤矿排土场复垦土地土壤有机碳空间变异性较大,变异系数最高达到145.408%,属于强变异性;② 预测精度上,回归克里金法的预测精度最高,Pearson相关系数达到0.984,均方根误差、平均预测误差以及准确度分别为-0.012,0.211,0.991,多元线性回归法的的预测精度次之,预测精度最差的为反距离加权法及普通克里金法;③ 局部细节表达上,回归克里金法的预测表达较为精细,能够较好地刻画出数据的跳动性和不确定性,反距离插值法与普通克里金法预测具有明显的平滑作用,空间变化较为连续。回归克里金法相较其他方法在露天煤矿排土场复垦土地土壤有机碳插值预测具有较大优势。     

黄土高原水土流失区薪炭林发展问题探讨

从阐述黄土高原水土流失区发薪炭林的必要性入手，分析了影响薪炭林发展的原因，认为薪炭林自身经济效益低是主要制约因素，因此，薪炭林在发挥水土保持功能的基础上，如何达到兼有薪用的多种经济目的是关键，优良薪炭草也应当纳入薪炭林的发展计划，进一步分析表明，多用途薪炭树种的开发利用及植物间的混合种植是促进薪炭林发民菜的有效技术措施。本文提出了薪炭林发展的主要类型，认为林草间作及农地薪炭林草植被建设更为突出的措     

若尔盖泥炭小流域地下水水位的时空变化规律

若尔盖泥炭湿地是黄河上游重要的水源涵养地,发挥着蓄水、固碳和生态的重要功能。近几十年来若尔盖泥炭湿地面积持续萎缩,其地下水水位的变化对湿地萎缩发挥着关键性作用。选取若尔盖高原的黑河上游泥炭湿地典型小流域,采用HOBO自记水位计布设5个靠近沟道和3个远离沟道的地下水水位观测点,结合2017年5-9月地下水水位观测数据以及红原站气象资料,分析该小流域内地下水水位的时空变化规律。结果表明：沟道可为周边泥炭层提供更加长效的补水时间,而且能够更快汇集地表水流;远离沟道的地下水水位变化与降雨过程趋于同步,其与降雨量的相关系数达到0.8;洼地的地下水水位变化比坡地受降雨影响小;地下水水位变化对降雨过程具有滞后响应,即随着降雨强度增大,滞后时长逐渐减小,且远离沟道比靠近沟道的观测点的滞后时长要短约18 min。     

Permafrost and cold-region environmental problems of the oil product pipeline from Golmud to Lhasa on the Qinghai-Tibet Plateau and their mitigation

The 1076-km-long Golmud-Lhasa oil product pipeline is located closely parallel to the highway constructed 20 years earlier within the relatively narrow north-south engineering corridor crossing the treeless central area of the Qinghai-Tibet Plateau. Much of the corridor is at elevations exceeding 4500 m and high-elevation, generally warm permafrost is encountered in more than one-half of the length. The pipeline, transporting mostly diesel, motor and aviation fuels at ambient temperatures, is 159 mm in diameter, has a wall thickness of 6 mm and was buried in a trench at a nominal depth of between 1.2 and 1.4 m. The soils encountered, mostly periglacial sands, silts and gravels, often have elevated saline contents and are subject to severe wind erosion and occasional monsoon flash flooding conditions. During its first quarter century of operation, the pipeline suffered at least 30 significant leaks and four pipeline ruptures. About 337 km of the pipeline was extensively rehabilitated, including relocations or replacements in major problem areas and, where feasible for an existing pipeline, improvements in pipeline protection during 2001-2004. It was supposed to safely operate for another 30 years with proper checks and needed repairs. This paper provides a review on the history of the permafrost and cold regions environmental problems of the pipeline, and their major rehabilitation, repairs and problems in the future, which might have useful implications for similar oil product pipeline at high elevations or permafrost regions.     

青藏高原湖泊动态变化的地球卫星遥感监测及地球动力学分析

利用遥感数据对观测对象的可逆及追踪的记录特性，对青藏高原腹地苟鲁措湖泊进行了20余年(1985—2005年)的连续监测，建立了长时相观测记录及连续变化序列，破译了湖水自然演化过程的自组织耗散结构及运动现象，采用系统吸引子及分形分维演绎刻划了湖泊随机演化过程及运动轨迹，从而阐明了青藏高原湖泊动态变化的地球动力学机制及运动过程，为科学认识大陆湖泊记录的气候环境响应事件及全球变化分析提供客观自然的变化信息。