Subjects: Geosciences >> Geography submitted time 2024-03-01 Cooperative journals: 《干旱区研究》
Abstract： Precipitation acts as a crucial supply for mountain glaciers, and its water vapor source closely correlates to the amount of precipitation. This study focuses on the modern glacier distribution area of Ulugh Muztagh in the eastern Kunlun Mountains, analyzing water vapor sources in the region from 2005 to 2022 using the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model and the Global Data Assimilation System (GDAS). Employing backward trajectory analysis, we reveal the source and regularity of water vapor in the Ulugh Muztagh region and discuss its seasonal changes. The results show that the water vapor source in the Ulugh Muztagh area mainly extends to the Eurasian interior along the midlatitude westerly belt and is divided into three routes entering the Qinghai-Tibet Plateau from the Tianshan Mountains, the Pamir Plateau, and over the high-altitude stratosphere. On the Qinghai-Tibet Plateau, water vapor from the Indian Ocean either moves northward over the Himalayas or turns northwestward to merge with the westerly circulation into the plateau’s hinterland. Land-source water vapor, entering from the Pamir Plateau and Tianshan Mountains, accounts for 62.52% of the total water vapor in the Ulugh Muztagh area. Meanwhile, sea source water vapor, comprising high-altitude water vapor from the westerly belt (Atlantic water vapor) and the Indian Ocean, accounts for 37.48% of the total water vapor. Notably, we find that the proportion of water vapor from the sea source has increased steadily over recent decades. Analyzing multiyear seasonal averages for water vapor, we find a notably high proportion of locally recycled water vapor in the summer, comprising 22.64% of the total. This study’s outcomes offer valuable insights into the water cycle dynamics of the Ulugh Muztagh area in the East Kunlun Mountains.
Subjects: Geosciences >> Geography submitted time 2023-12-16 Cooperative journals: 《干旱区研究》
Abstract： Based on precipitation and soil water isotope data at different elevations in the north and south mountains of Lanzhou from April to October 2018, the lc-excess method and the lc-excess equilibrium equation were used to qualitatively and quantitatively analyze the soil water infiltration process in this area. The infiltration process of soil water, indicated by the soil water lc-excess value, was verified by correlation analysis and single factor analysis. The results showed that there are obvious variations in soil water content in the study area on a monthly scale and at different depths, with loss dominating from April to June and accumulation dominating from July to September. The soil water content in the high altitude areas was found to be greater than that in the low altitude areas, and the soil water content in the north mountains was found to be greater than that in the south mountains. Stable isotopes of soil water at each sampling site we found to be most depleted from August to September. At increasing soil depth, soil water isotopes showed a trend of gradual depletion and stabilization. The soil water lc-excess results showed that the piston flow mode and the priority flow mode coexist in the infiltration and recharge process of soil water in the study area. The priority flow signal appeared at all sampling sites from July to August. The contribution of the preferred flow pattern to deep soil water was higher at the low elevation sampling sites than at the high elevation sampling sites. The soil water content and soil water lc-excess were found to be positively correlated. The monthly scale and depth of soil water lc-excess were not significantly different between the north and south mountain, indicating that the infiltration and recharge patterns of soil water in the north and south mountains are the same, and that both are dominated by the piston flow infiltration pattern of precipitation recharge. However, in the south mountains, where there is greater vegetation cover, the preferential flow pattern signal appeared more often, especially in July and August, when precipitation is concentrated. Based on the soil water infiltration and replenishment processes in the north and south mountains, it the selection of salt- and drought- tolerant, shallow- rooted shrubs and perennial grasses is recommended for the north mountains, while reasonable irrigation is recommended in the south mountains during the plant growing season (from April to June). The results of this study provide a theoretical reference for understanding the hydrological process in the north and south mountains of Lanzhou.
Subjects: Environmental Sciences, Resource Sciences >> Basic Disciplines of Environmental Science and Technology submitted time 2020-11-19 Cooperative journals: 《干旱区地理》
Abstract：基于中国绿洲喜温作物分布区67个地面气象站1960—2016年逐日平均气温数据，运用线性 趋势法、反距离加权（IDW）、Morlet小波分析法、Mann-Kendall检验等方法，分析了中国绿洲喜温作物气候生长期生长初、终日及生长期的时空变化对全球变暖停滞（globe warming hiatus）的响应。结果表明：1998—2012年中国绿洲喜温作物气候生长期生长初、终日及生长期变化倾向率分别为：-2.15d·（10 a）－1、2.76 d·（10 a）－1、4.91 d·（10 a）－1，与1960—2016年和1960—1998年相比呈现出初日提前、终日推迟、生长期延长的态势，没有出现对全球变暖停滞的响应；空间变化方面，仅有超过22%的站点有对全球变暖停滞的响应，整体响应不显著；但各绿洲对全球变暖停滞的响应却不尽相同，柴达木 绿洲喜温作物气候生长期对全球变暖停滞的响应最为显著，其余绿洲则反之，也反映了青藏高原是气候变化的驱动器与放大镜。突变分析显示，研究区喜温作物生长初日、终日及生长期分别在2008年、2001年、2006年发生突变，突变年份多集中于变暖停滞期，之后的变化趋势显示对全球变暖停滞没有响应。Morlet小波分析表明其周期存在2.4～3.8 a的优势短周期，与2～4 a大气环流和厄尔尼诺事件2～7 a的周期相吻合，表明喜温作物气候生长期主要受大气环流与厄尔尼诺活动的影响。
Subjects: Geosciences >> Geography submitted time 2020-06-02 Cooperative journals: 《干旱区地理》
Abstract： 基于2012年6-8月的实测水汽同位素数据及相关气象数据，对黑河中游夏季昼夜的同位素基本特征、水汽来源方向及潜在蒸发源地进行了研究。结果表明:空气水汽线斜率白天大于夜晚和水汽过量氖值白天大于夜晚，综合说明白天局地蒸发较夜晚强烈;夏季受西风水汽影响显著。其中，6月主要受西风水汽和北冰洋水汽影响，大8月主要受西风水汽和东南方向水汽影响，且8月受东南方向水汽影响最为明显;水汽运移路径上下垫面地形和气压带移动会影响水汽后向轨迹高度，西北方向上水汽输送通道较顺畅，风速较大，有利于水汽的输送;水汽蒸发源地主要集中在研究区周围及以东、以北部，其次是西北部。绿洲是主要的水汽蒸发源地，其次是城市和河流，白天较夜晚局地蒸发强烈且面积大。
Subjects: Geosciences >> Other Disciplines of Geosciences submitted time 2019-09-10 Cooperative journals: 《干旱区研究》
Abstract：基于中国地面气象站逐小时观测资料、GDAS气象数据及2016—2017年NCEP/NCAR再分析资料，利用拉格朗日后向轨迹模型，结合比湿变化对新疆短时强降水的水汽来源进行订正。结果表明：① 新疆的水汽主要来源于包括里海、黑海、地中海、大西洋、北冰洋和附近的内陆地区；新疆常年受西风影响，偏南西风影响较大；② 阿尔泰-塔城森林草原自然区和准噶尔盆地荒漠自然区水汽路径总体偏北，伊犁-巴音布鲁克（中天山）自然区和哈密-吐鲁番荒漠自然区受陆地水汽源的影响更大，而塔里木盆地极端干旱荒漠自然区水汽路径总体偏南。聚类分析结果显示，阿尔泰-塔城森林草原自然区的水汽来自于欧洲，准噶尔盆地荒漠自然区的水汽主要来自于中亚、里海和蒙古高原，塔里木盆地极端干旱荒漠自然区水汽主要来自塔里木盆地、西亚、中亚和黑海；③ 经过比湿判断水汽补给情况后，气团回溯路径普遍变短，水汽主要来自中亚、黑海、里海和附近的陆地；从主要水汽源地的传输水汽平均需要3.5 d左右，季节上表现为夏季的水汽源地最近，秋季的水汽源地较远，区域上阿尔泰-塔城森林草原自然区水汽源地最远，哈密-吐鲁番荒漠自然区水汽源地最近；④ 新疆各起始高度上的降水主要受偏北和偏南的西向气流影响，且从对水汽的贡献来看，偏北的西向气流大于偏南的。
Subjects: Geosciences >> Other Disciplines of Geosciences submitted time 2019-09-09 Cooperative journals: 《干旱区研究》
Abstract： 局地水汽再循环是陆地水循环过程的重要环节。在我国西北干旱区水汽再循环的绝对量虽然有限，但对区域降水的贡献（即水汽再循环率）却不容忽视。本文基于嵌套同位素模块的LMDZ模式模拟数据，运用同位素混合模型，对西北干旱区1979—2007年水汽再循环率的时空特征及其作用机制进行了分析。结果表明：研究时段内，外来水汽对降水的月尺度和年尺度贡献率都明显高于再循环水汽，季节上呈夏高冬低，年际上呈逐渐上升的态势；而再循环水汽的贡献率较低，呈夏季低冬季高且逐年下降（冬半年植物蒸腾水汽的贡献率在年际上呈上升趋势）的特点。外来水汽对降水的贡献率存在空间差异，山区附近的值往往较高，荒漠平原区的值则较低。就地表蒸发与植物蒸腾而言，地表蒸发对降水的贡献率整体低于植物蒸腾，但在小范围地区也有相反的规律。外来水汽和地表蒸发水汽的贡献量与其贡献率的空间分布特征基本一致，而植物蒸腾水汽在山区的贡献量高于荒漠平原区。
Subjects: Environmental Sciences, Resource Sciences >> Basic Disciplines of Environmental Science and Technology submitted time 2019-08-02 Cooperative journals: 《干旱区地理》
Abstract：雨滴从云底降落到地面过程的云下二次蒸发现象会影响雨滴中的同位素比率，明确降水过程中稳定同位素的变化对研究流域水循环具有重要意义。基于全球降水同位素网络（GNIP）、相关文献同位素数据以及气象数据，首先建立局地大气水线（LMWL）定性分析了黄河流域云下二次蒸发与各气象要素间的关系，其次运用改进的Stewart模型定量计算了蒸发剩余比（f）和云底降水与地面降水的D-excess之差（Δd）。结果表明：（1） 黄河流域LMWL方程为：δ2H=7.01δ18O+1.25（n=293，R2=0.92），斜率和截距相比GMWL均较小，说明雨滴在下落过程中受到云下二次蒸发的影响。其中0～10 mm的降雨事件对云下二次蒸发影响显著；气温越高，或者水汽压、相对湿度越小，云下二次蒸发越强烈。（2） 季节变化上，从春季到冬季， f和Δd逐渐增大，云下二次蒸发逐渐减小。空间变化上，蒙甘区、蒙中区、晋陕甘区和渭河区的西安，年际间云下二次蒸发变化较大，而青南区、祁连-青海湖区、渭河区的平凉、长武、华山和鲁淮区年际差异较小。（3） 降水中Δd和f之间的线性关系在不同气象要素范围内有不同的数值，由于不同区域各气象条件存在差异，因此在应用经验公式时需考虑研究区的具体气象条件。
Subjects: Environmental Sciences, Resource Sciences >> Basic Disciplines of Environmental Science and Technology submitted time 2019-08-02 Cooperative journals: 《干旱区地理》
Abstract：基于中国0.5°×0.5°逐月与逐日降水量网格数据集，采用线性趋势、克里金插值（Kriging）、森斜率等方法，分析1961—2015年中国3个自然区的降水量和降水面积的变化特征。结果表明：（1） 中国1961—2015年年均和季节平均降水量呈现由东南沿海向西北内陆递减的空间分布特征，中国一半以上的地区年均和四季降水量呈增加趋势。（2） 日变化特征上，东部季风区、西北干旱区和青藏高寒区均以小雨和中雨为主，其日降水面积多年平均值分别为：1 112.75×103 km2、52.65×103 km2，1 380.57×103 km2、92.83×103 km2，1 253.9×103 km2、34.3×103 km2，暴雨和大暴雨占的面积较小；三个区域不同等级日降水面积年内变化均符合二次函数曲线，三个区小雨日平均降水面积年际变化均呈略微减少趋势，青藏高寒区和西北干旱区大雨、暴雨和大暴雨均呈略微增加趋势，大暴雨整体波动较大。（3） 季节变化特征上，三个区四季均以小雨为主，暴雨和大暴雨所占面积较少。春季和秋季三个区小雨降水面积均呈减少趋势，春季和夏季三个区暴雨降水面积均呈增加趋势，冬季三个区中雨和大雨降水面积呈增加趋势。（4） 东部季风区春季和秋季，西北干旱区年均和四季，青藏高寒区春季、秋季和冬季不同等级降水量对应的降水面积均符合负指数分布规律。
Subjects: Environmental Sciences, Resource Sciences >> Basic Disciplines of Environmental Science and Technology submitted time 2018-06-28 Cooperative journals: 《干旱区研究》
Abstract： 利用TrajStat软件中的后向轨迹计算模块与浓度权重轨迹（CWT）方法，对中国西部（新疆乌鲁木齐、青海祁连和玛多）和东部（湖南长沙和广东广州）事件尺度的夏季降水水汽来源进行分析，并结合水汽通量进行补充分析。结果发现:①乌鲁木齐、祁连、玛多夏季降水受西风水汽影响显著，而长沙夏季降水受西太平洋水汽影响显著，广州夏季降水受印度洋水汽影响显著。②5个站点夏季降水均有局地再循环水汽参与。在西部，影响夏季降水的循环水汽主要分布在相对湿度较大的山区、盆地以及蒸发量较大的地区。而在东部，影响夏季降水的循环水汽主要分布在一些地表水体集中的地方。③在西部，由于水汽在运移过程中，下垫面起伏大，空气团水汽d值变化除受地表蒸发水汽影响外，还受下垫面地势起伏的影响。在东部，由于水汽在运移过程中，下垫面起伏小，空气团水汽d值变化一般只受地表蒸发水汽影响。
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