冰川下垫面对夏季云结构和云水含量的影响--以祁连山区疏勒南山为例

云水含量和云结构参量是天气预报、高山区水循环过程分析的基础。基于2012-2015年夏季CloudSat卫星遥感资料的2B-CLDCLASS、2B-GEOPROF和2B-GEOPROF-LIDAR,结合中国第二次冰川编目数据及气象资料,对祁连山地区疏勒南山冰川区与非冰川区云水含量和云类型特征进行分析。结果表明:(1)云水含量的垂直分布受下垫面和云类型的影响,主要表现为有冰川覆盖的高山上空降水云类型以深对流云为主,无冰川覆盖的高山上空降水云类型以雨层云为主。(2)疏勒南山地区高含水量主要分布在5 km以下的中低层云中,且冰川区气流垂直运动较非冰川区活跃。(3)疏勒南山冰川区云水含量平均值为0.07 g·m^-3,非冰川区云水含量平均值为0.17 g·m^-3,云水的空间变化在一定程度上能够反映降水和水汽的分布状况。

天山北坡奎屯河流域径流模拟及对气候变化的敏感性分析

利用乌苏气象站和将军庙水文站1964—2009年气象与水文数据,将月径流分为消融期和非消融期进行研究,并结合第一和第二次冰川编目数据以及1979—2009年分辨率为0.1°×0.1°的CMFD数据,基于BP人工神经网络模型对新疆天山北麓奎屯河流域消融期月径流进行模拟及气候变化的敏感性分析,结果表明:(1)奎屯河流域年径流量总体呈上升趋势,消融期径流增速与年径流增速十分接近,非消融期径流变化不甚显著。(2)通过对比分析,发现将气温、降水、日照时数、风速和相对湿度等五种气象要素作为输入的神经网络模型性能最佳。根据两次冰川编目的冰川储量变化值确定的5-7-1结构的BP人工神经网络模拟结果较好,可用于奎屯河流域径流模拟。(3)奎屯河流域消融期径流对气温、降水和日照时数的敏感性较高,对相对湿度和风速的敏感性较低,除风速其他四个要素对径流均起促进作用。降水不变,气温升高0.5℃、1℃和2℃时,径流分别较2000—2009年消融期月径流平均值增加4.62%、9.13%和18.30%;气温不变,降水增加10%时,径流将增加9.78%。气温和降水同时作用时,径流增加幅度明显高于仅气温或仅降水作用下的情景。

基于TRMM降水订正数据的祁连山地区最大降水高度带研究

采用TRMM卫星反演月降水数据和气象台站实测降水数据,通过误差评估等数理统计方法验证数据,并结合Kriging法对TRMM降水数据进行订正,以此研究了祁连山地区最大降水高度带的时空变化。结果表明:(1)TRMM降水数据在祁连山地区的整体适用性较好。其中TRMM降水数据与台站实测值的年均降水量相关系数达0.94;季节平均降水量的相关系数分别为春季(0.87)、夏季(0.89)、秋季(0.88)、冬季(0.70)。(2)祁连山地区27个气象台站实测值与TRMM降水数据的相关性较好,但在个别台站误差较大且存在低值高估、高值低估的现象。(3)祁连山地区年均降水量自东向西呈减少趋势。东、中、西三段最大降水高度带分别为4100 m、4500 m、4700 m,年均降水量的垂直变化率分别为16.6 mm/100 m、10.8 mm/100 m、9.8 mm/100 m。(4)1998-2016年祁连山地区东、中、西三段降水量均呈波动增加,最大降水高度带也呈波动上升趋势,祁连山地区年内各季节最大降水高度带按夏、春、秋、冬的次序降低。

基于体制转换的乡村转型时空格局及演变机理--以甘肃省榆中县为例

乡村转型是乡村振兴的关键,也是“三农”转型的重要抓手。论文以黄土高原沟壑区甘肃省榆中县为例,从人口转型、土地转型和产业转型3个维度构建乡村转型指标体系,基于2002—2018年统计数据、农户调研数据、遥感数据等多源数据,运用熵值法、层次分析法、乡村转型度模型和空间分析方法,从县域和农户视角,量化与分析榆中县乡村转型及其时空演变格局,刻画农户生计转型路径;在此基础上,引入体制转换理论阐释乡村转型过程机理,并运用逐步回归分析方法识别驱动乡村转型的关键因素。结果表明:①2002—2018年榆中县乡村转型度、产业转型度和人口转型度明显上升,而土地转型度稳中有降,乡村转型度和产业转型差异明显且变化较大,在中部川区最为突出。②乡村转型、人口转型、产业转型均呈现“中部川区较高速和高速转型、北部山区低速转型、南部山区由低速转型向较高速过渡转型的空间格局”,并伴有逐级式和跨级式的变化特点,土地转型空间分布较为分散;乡村转型、人口转型、产业转型和土地转型的热点区主要集聚在中部川区,冷点区主要集聚于北部山区。③农户生计表现出多路径转型特征,北部山区为综合型生计转型路径,中部川区和南部山区为兼农型生计转型路径。④中部川区实现乡村体制转换,南部山区乡村发展明显升级转型,但未形成新的乡村体制,而北部山区乡村转型不够显著。⑤固定资产投资是决定榆中县乡村转型的关键因素。研究结果可为乡村转型提供新的研究视角,也为黄土高原沟壑区乡村振兴与乡村高质量发展提供理论依据。

Definition and classification system of glacial lake for inventory and hazards study

Glacial lakes are not only the important refresh water resources in alpine region, but also act as a trigger of many glacial hazards such as glacial lake outburst flood （GLOF） and debris flow. Therefore, glacial lakes play an important role on the cryosphere, climate change and alpine hazards. In this paper, the issues of glacial lake were systematically discussed, then from the view of glacial lake inventory and glacial lake hazards study, the glacial lake was defined as natural water mainly supplied by modern glacial meltwater or formed in glacier moraine＇s depression. Furthermore, a complete classification system of glacial lake was proposed based on its formation mechanism, topographic feature and geographical position. Glacial lakes were classified as 6 classes and 8 subclasses, i.e., glacial erosion lake （including cirque lake, gla- cial valley lake and other glacial erosion lake）, moraine-dammed lake （including end mo- raine-dammed lake, lateral moraine-dammed lake and moraine thaw lake）, ice-blocked lake （including advancing glacier-blocked lake and other glacier-blocked lake）, supraglacial lake, subglacial lake and other glacial lake. Meanwhile, some corresponding features exhibiting on remote sensing image and quantitative indices for identifying different glacial lake types were proposed in order to build a universal and operational classification system of glacial lake.

Evaluation and spatiotemporal characteristics of glacier service value in the Qilian Mountains

Glaciers provide essential resources and services for human well-being and socio-economic development in arid regions.It is of great significance for regional socioeconomic sustainable development and environmental protection to conduct a glacier service value assessment and to analyze its spatiotemporal characteristics.Based on the first and second Chinese glacier inventories of the Qilian Mountains,a glacier service value evaluation system was established.Then the glacier service value and its spatiotemporal variation were assessed by combining the methods of unit area service price,value equivalent factor,and the glacier service value change index(GSCI).Three key results were obtained.(1)The total service value of glaciers in the Qilian Mountains for 2016 was 24.354 billion yuan.The main services provided were climate regulation and runoff regulation,which accounted for 60.58%and 33.14%of the total service value,respectively.Minor services were freshwater supply and hydropower,which accounted for 3.47%and 1.75%of the total value,respectively.The value of other types of services was about 0.259 billion yuan.(2)Among the various river systems in the Qilian Mountains,the Shule River basin had the highest glacier service value(7.771 billion yuan,31.91%),followed by the Haltang River basin(4.321 billion yuan,17.74%)and the Beida River basin(3.281 billion yuan,13.47%).In terms of administrative divisions,the glacier service value of the Qilian Mountains in Qinghai Province was 1.138 billion yuan higher than that of Gansu Province at 11.608 billion yuan,of which the services in the Haixi Mongol and Tibetan Autonomous Prefecture and Jiuquan City were valued at 11.124(45.68%)and 7.758(31.86%)billion yuan,respectively.(3)During the period from 1956 to 2010,the service value of glaciers in the Qilian Mountains declined by 435 million yuan,with an acceleration in the decreasing trend from west to east.