KMS XINJIANG INSTITUTE OF ECOLOGY AND GEOGRAPHY，CAS
| 全球变暖背景下 1960-2014 年中国降水时空变化特征 | |
| 宋世凯 | |
| Subtype | 博士 |
| Thesis Advisor | 李龙辉 ; 丁建丽 |
| 2017-05-01 | |
| Degree Grantor | 中国科学院大学 |
| Place of Conferral | 新疆乌鲁木齐 |
| Degree Discipline | 理学博士 |
| Keyword | 气候变暖 中国 小雨 极端降水 时空变化 Climate Warming China Light Rain Extreme Precipitation Spatio-temporal Trends |
| Abstract | 降水是水循环过程中最基本的环节，是地表径流的本源，也是地下水的主要补给来源，降水在时空分布上的不均匀是引起洪涝和旱灾的直接原因。降水的过程伴随着能量的转换过程，雨滴的凝结是吸热过程，而地表降水的蒸发又是散热过程。总之，降水是连接天气、气候和水循环等方面的关键物理过程，也是生态系统清洁水的最终来源，是关系到国计民生的重要气象要素之一。中国降水量的分布极不均匀，且洪涝干旱灾害频发。IPCC 第五次评估报告指出，近百年来全球气候变暖毋庸置疑，气温升高使得大气中水汽增多，水循环加快，极端降水事件增加，在此背景下，开展中国降水变化趋势的研究，有助于理解中国降水变化的特征和机制，并对提高相应地区水资源管理和调控能力，对洪涝干旱的防灾减灾具有借鉴意义。本文以中国大陆为研究区，并划分了西部、北方、青藏和南方四个区域，以国家气象局发布的气象站台逐日降水观测数据为主要研究数据，采用自定义和国家气象局的通用标准分别将降水划分为小、中和大雨。本文重点分析了在气候变暖背景下1960-2014 年间不同强度降水的时空变化趋势和特征，最后通过综合比较，总结出了降水的时空变化规律，并深入探究了影响小雨降水频率的因素以及大雨（极端降水）与局地气温的关系，比较了不同强度降水与总降水量的相关性，量化了不同强度降水量、频率和强度在总降水变化中的贡献，以及不同强度降水频率和强度在降水量变化中贡献，展示了小雨和大雨降水量在总降水量中比例的变化特征，分析了降水量变化与地形的关系，本文的主要结论如下：（1）1960-2014 年间，总降水、小、中和大雨的降水量、频率和强度的空间分布和时空变化趋势因地而异，区域性差异明显。全国平均降水量没有表现出显著变化趋势，降水频率显著减少而强度显著增强，且强降水事件明显增多，而小雨降水事件显著减少。（2）小雨降水频率减少量在总降水频率的减少趋势中起主要作用，而且，小雨降水频率的减少是整个中国小雨降水量减少的主要原因。低空大气的气温和比湿和夏半年小雨降水频率的减少有着密切关系。气温的升高被认为是对整个中国小雨降水频率有减少作用，而比湿变化的地域性差异决定了小雨降水频率变化的地域性差异，这也导致了在中国西部地区小雨降水频率呈显著增加趋势，而在东部地区呈显著减少趋势。（3）只有南方地区的大雨降水量、频率和强度均呈显著增加和增强趋势，而且局地气温的升高对大雨（极端降水）降水有一定的增强作用，包括降水量、频率和强度三个方面，而且，大雨阈值越高，气温的增强作用越明显，在其他地区没有发现该特征。（4）在全国和区域尺度上，总降水量的增加趋势中，大雨降水量的增加量最多，起主要作用；总降水频率的减少趋势中，小雨降水频率的减少量最大，起主要作用。同时，降水量和频率有从小雨、中雨转移到大雨的趋势，并且，小雨的降水量在总降水量中所占比例显著减少，而大雨的降水量在总降水量中所占比例显著增大。（5）降水频率和强度的变化均对降水量的变化起作用，在中国以及各区域中，降水频率的变化在总降水、小、中和大雨降水量的变化均起主要作用。（6）关于降水量与海拔的关系，在西北地区，年均降水量、频率和强度均随着海拔的升高而逐渐增大，而且大雨变化量在总降水量变化量中的比例随着海拔的升高而增加。 |
| Other Abstract | Precipitation is the most basic link in water cycle, source of surface runoff and groundwater. Unbalance spatial and temporal distribution of precipitation is the direct cause of floods and droughts. And energy conversion process is with rainfall. Endothermic process happens when raindrops condenses, while exothermic process happens when precipitation evaporates. Precipitation also is the key physical process to connect weather,climate and water cycle, and the ultimate source of clean water in ecosystem, to be one of the important meteorological elements related to the national economy and people's livelihood. In China, precipitation distributes unevenly with frequent floods and droughts.IPCC fifth assessment report pointed out that global temperature increased over the past century. Global warming has been estimated to increase the content of atmospheric water vapor, to accelerate the hydrological cycle, and to increase the extreme precipitation events.In the context of global warming, a good understanding of precipitation variations over China is beneficial to effective management and control of water resource.The area of study is mainland China, and we divided mainland China into four regions (northwestern of China, northern of China, Tibetan plateau and northern of China).The data employed in this study is observational data of meteorological stations obtained from the China Meteorological Administration. We divided the precipitation intensity into three groups (light, moderate, and heavy precipitation) according to the custom method and widely used China Meteorological Administration standards. In this study, spatial and temporal trends for different groups of precipitation from 1960-2014 over China were determined and compared finally to get the spatio-temporal characteristics. The goals of this work were to: 1) determine the primary cause for changes in light rain days; 2) analyze the relationship between heavy or extreme precipitation and local temperature; 3) compare the correlation between different groups of precipitation and mean annual precipitation; 4)compare the contributing proportions of light, moderate, and heavy precipitation to the changes in annual precipitation; 5) calculate the contributions of frequency and intensity to changes in precipitation amount; and 6) detect trends of precipitation amount and latitude.The main conclusions were as follows:(1) During 1960-2014, there were obvious regional differences in the spatial distributions and trends in the precipitation amount, frequency, and intensity of total, light,moderate, and heavy precipitation. Annual precipitation amount over China did not show significant trend, while frequency decreased and intensity strengthened significantly.Events of extreme precipitation displayed significant increase and opposite trends for the light rain.(2) The decrease in light rain frequency precipitation intensity was mainly the result of decrease of light rain amount in China, and dominated the change of total precipitation frequency. Lower-tropospheric warming and the water vapor content in warm season were responsible for light rain reduction. Increases in lower-tropospheric temperature reduced light rain days over the entire China, while variations in water vapor content dominated regional trend differences in light rain days, which resulted in the increase over western China while decrease over eastern China for light rain days.(3) Heavy (extreme) precipitation amount, frequency, and intensity in the southern China exhibited significant increasing trends, and local warming climate partly explained these trends. In addition, more effect of warming was along with higher threshold of heavy precipitation. And, these findings were only determined in southern China.(4) Over China and four regions, heavy precipitation contributed the most to increase in total precipitation amount, while light precipitation dominated the decreasing trend in total precipitation frequency. Furthermore, there were less amount and frequency of light and moderate precipitation, and more in heavy precipitation. As a result, proportion of light precipitation in total precipitation amount decreased, while heavy precipitation increased.(5) Both precipitation frequency and precipitation intensity have important effects on trends of precipitation amounts. And we found that variations in precipitation amount were mainly contributed by precipitation frequency for total, light, moderate, and heavy precipitation over China and four regions.(6) In northwestern of China, we found that annual precipitation amount, frequency,and intensity increased with altitude, and the same as proportion of heavy precipitation contributing to total precipitation amount changes. |
| Subject Area | 地图学与地理信息系统 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://ir.xjlas.org/handle/365004/14790 |
| Collection | 研究系统_荒漠环境研究室 研究系统_空间对地观测与系统模拟研究室 |
| Affiliation | 中国科学院新疆生态与地理研究所 |
| Recommended Citation GB/T 7714 | 宋世凯. 全球变暖背景下 1960-2014 年中国降水时空变化特征[D]. 新疆乌鲁木齐. 中国科学院大学,2017. |
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