Knowledge Resource Center for Ecological Environment in Arid Area
| 中国西北区西部夏半年强降水若干统计及其干、湿年形成的对比分析 | |
| 其他题名 | Some Statistics of Intense Precipitation and Comparative Analysis of the Formation of Strong Wet and Dry years in the West Part of Northwestern China during Summer Half years |
| 栾晨 | |
| 出版年 | 2012 |
| 学位类型 | 硕士 |
| 导师 | 蔡英 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 本文利用美国NCEP/NCAR 1961-2007年月平均比湿、风速、高度等的再分析值格点资料，分辨率为 2.5°×2.5°Lat./Lon.，和我国同期日降水实测资料，对强降水日进行了详细的普查统计，项目包括各站夏半年出现强降水日的频数及其变化趋势、各站的日最大降水量、各站强降水日出现的最早、最晚及平均日期、强降水日频数的变化趋势等统计量。考虑到西北区西部不同区域在地理、气候方面自成一体，把西北区西部划分为南疆区、北疆区、青海区、河西及阿拉善区四个分区，分别对各分区夏季干、湿月间水汽输送，大气环流及高原大气加热强度的差异进行对比分析，并讨论这些差异对形成西北区西部夏季干、湿差别的贡献。\n（一）对该区强降水事实的分析，有如下结论：（1）西北区西部强降水日数东多西少。最多出现在半湿润的青海高原东缘，次多出现在半干旱区的天山及祁连山区，位于干旱区的南、北疆盆地四周及河西阿拉善区，很少或从未出现过强降水日。（2）更干旱的该区西部比青海高原似更易出现降水极大值，特别是位于峡谷、山口及冷空气通道的巴仑台、乌鲁木齐、阿合奇、若羌及阿左旗等。（3）该区强降水日出现的最早及最迟时间受东、西两侧降水气候影响大。（4）该区强降水日出现频数虽呈增长态势（特别是中天山地区），但增长趋势并不显著。\n（二）对该区干、湿年形成的对比分析，有如下结论：（1）青海及南疆区干、湿月时，高原中、北部的大气加热强度的差异比较明显；而对北疆区及河西阿拉善区的干、湿月，高原中、北部的大气加热场差别不明显。强干月西北区西部对流层中、高层一般盛行“上高下高”的环流形势，强湿月则为“上高下低”的环流形势。（2）南疆强湿月在高原北侧有一个较小的经向环流圈，环流圈较小，到300hPa，但很深厚，伸展至地面，带来了大量南部的水汽，强干月的干冷空气。（3）西北区西部虽然同样地处我国的干旱区，但影响其强降水的水汽输送却并不相同，水汽来源各有各的特点和侧重性。南疆强降水的水汽主要经由孟加拉湾，在四川盆地东侧汇合，再通过低空偏东风急流输送到南疆腹地；而北疆强降水的水汽则主要来自于中亚西风急流；河西阿拉善地区从典型强降水过程的分析中可看出，西太副高西伸带来了东南暖湿气流，在四川盆地东侧汇合，再通过低空偏东风急流输送到河西走廊。 |
| 英文摘要 | Using NCEP/NCAR 1961- 2007 mean monthly specific humidity, wind speed, height and many such 2.5 ° x 2.5 ° Lat. / Lon. reanalyzed grid data and the daily precipitation data in the same period, analyze the temporal and spatial distribution and change tendency of intense rainfall during summer half year of nearly 47 years. The statistics include that the frequency of intense rainfall day over W-NWC, the maximum daily precipitationearliest, the latest and average date of intense rainfall day occurrence, the change tendency of intense rainfall days, etc. Considering the difference of geography, climate in each area, dividing the west part of Northwestern China into Southern Xinjiang, Northern Xinjiang, Qinghai and Hexi and Alxa such four divisions, compare respectively the differences of vapor transmission, atmospheric circulation and atmospheric heating intensity and discuss contributions of the differences on forming wet and dry events. , the \nThe main results of some statistics of intense precipitation in the west part of northwestern China show that:\n(1) Intense rainfall frequency is more in the East than that in the West. The most intense rainfall occurs in the east of Qinghai plateau which belongs to sub-humid areas, and the second one occurs in Tianshan Mountains and Qilian Mountains which belongs to semiarid region, and it rarely occurs and even has never occurred in the arid and extreme arid regions including the edge of South and North Xinjiang Basin and the west of QaidamBasin.（2）It seems to be easier for maximum precipitation to appear in the west of this region which is more arid than Qinghai plateau, especially Balguntay, Urumqi, Akqi, Charkhlik and Alxa Left Banner. (3) The earliest date of intense rainfall day occurrence in this region presents that it is earlier in the East and the West and later in the middle, while the latest one is opposite. (4) Intense rainfall frequency in this region (especially Tianshan Mountains) has a growing trend, but increasing intensity is not obvious. \nThe main results of intense precipitation in the west part of northwestern China show that:\n(1) On the strong wet and dry months of Southern Xinjiang and Qinghai province, the difference of atmospheric heating strength of the northern and middle plateau is great, while the one of Northern Xinjiang and hexi and Alxa is small. On the strong wet month of Southern Xinjiang, Northern Xinjiang and Qinghai province, atmospheric heating strength of the eastern plateau is greater on wet months than on dry months, while the one of the western plateau is smaller on wet months than the dry months. The eastern atmospheric heat source produces and maintains rise gas on high-level, and there is negative vorticity in the top of the column, making high pressure center increasing, while the western atmospheric heat source makes high pressure decrease.Then 200 hPa high-pressure center moves from the west to the east, changing from the western type into eastern type, that it is the eastern type on the strong wet months, while it is the western type on the strong dry months. In addition, the circulation situation of the middle-high-level of troposphere in the west part of Northwestern China on strong dry months is “high on the high-level, high on the low-level”; while is “high on the high-level, low on the low-level” and “high in the east, low in the west" on strong wet months. The influence of thermal action of Tibetan plateau of Qinghai and Southern Xinjiang is the most one; the next one is the Northern Xinjiang; the influence of the hexi and Alxa is not significant. (2) When the strong dry and wet events happen in each division, the subprime longitude circle circulation in the north of the plateau has different complex flow type. On wet months of Southern Xinjiang, the circle is small but deep, stretching from 300 hPa to the ground, providing a lot of southern moisture, While dry months have not that kind of circulation. Sinking airflow from north and less water vapor content on strong dry months cause dry weather. While the circulation situation on wet months of hexi and Alxa is different with Southern Xinjiang, rising motion is obvious in hexi and Alxa on wet months, and there is a reverse circulation in the north of the plateau on dry months, not only making the area be a sinking motor one, but also bringing the cold dry air. (3) The west part of Northwestern China is almost located in the arid areas in our country, but the vapor transmission which affect the strong rainfall is not the same, the steam source of each divisions have each characteristics and focus. The vapor forming southern strong rainfall are mainly from the Bay of Bengal, then converging in east of Sichuan basin and sending to the southern hinterland through lower-level easterly jet, in addition, there is stronger southerly wind vapor transmission from plateau in wet months than dry months; While the vapor forming northern strong rainfall are mainly from Central Asia upper-level westerly jet; As Alxa and Hexi area is located in the joint zone of highland, basin and the Qilian mountain, and is the transition zone of west and east part of Northwestern China, climate here is relatively complex, the impact factor is much, and the vapor transmission difference is not obvious, but though the analysis of strong rainfall process, we can see that the vapor forming Alxa and Hexi strong rainfall are mainly from the southerly wind vapor transmission of the west pacific subtropical high, then converging in east of Sichuan basin and sending to Alxa and Hexi through lower-level easterly jet; When it happens strong rainfall in Qinghai, on the low-level, the vapor from all directions focus on the plateau, especially the southerly wind vapor transmission from the Arabian sea, the Bay of Bengal and the east of Sichuan basin, and on the high-level, the southerly wind vapor transmission of southern plateau is more obvious on wet months than dry months. |
| 中文关键词 | 西北区西部 ; 强降水 ; 干 ; 湿年 ; 影响因子 |
| 英文关键词 | W-NWC Intense precipitation Strong dry and wet months factor of influence |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 气象学 |
| 来源机构 | 中国科学院西北生态环境资源研究院 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287094 |
| 推荐引用方式 GB/T 7714 | 栾晨. 中国西北区西部夏半年强降水若干统计及其干、湿年形成的对比分析[D]. 中国科学院大学,2012. |
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