KMS XINJIANG INSTITUTE OF ECOLOGY AND GEOGRAPHY，CAS
| 中亚气候变化的动力降尺度研究 | |
| 邱源 | |
| Subtype | 博士 |
| Thesis Advisor | 张弛 |
| 2018-06-05 | |
| 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 | 气候变化 WRF 降尺度 区域气候 中亚 Climate Change WRF Downscaling Regional Climate Central Asia |
| Abstract | 中亚包括哈萨克斯坦、吉尔吉斯斯坦、塔吉克斯坦、土库曼斯坦和乌兹别克斯坦五个国家和中国的新疆。多样的气候条件孕育了从荒漠到高山的一系列生态系统，它们对气候变化异常敏感。在过去，中亚地区气温急剧升高，降水增加，这引起了天山冰川的快速消融和中亚西部地上生物量的大幅减少。故此，理解中亚的未来气温和降水变化有重要的意义。本研究使用高分辨率（20km）的 Weather Research and Forcasting(WRF) 模型模拟了中亚当前和未来三个 10 年（1996-2005、2045-2054 和 2091-2100）的气候，使用的驱动数据是 NCAR CCSM4，选择的排放情景是 RCP8.5。通过比较未来两个 10 年和当前 10 年的模拟降水结果，我们发现未来的降水变化不是单调的。在 21 世纪中期 10 年（2045-2054），年降水在中亚的西部是减少的，在东部是增加的；在 21 世纪远期 10 年（2091-2100），年降水在中亚的中部是减少的，在周边地区是增加的。同时，中亚的极端降水事件是显著增加的，小雨事件是减少的，特别是在本世纪远期 10 年。因为年降水变化不大，所以极端降水的增加意味着未来的干旱天数可能增加。虽然未来的大气可降水量在整个中亚都是增加的，但中亚的降水不是普遍增加的，原因可能是缺少将可降水变为降水的动力机制。进一步对变化机制的分析发现，降水的变化与该地区位势变化引起的相对涡度的变化有关。模拟的气温结果显示，在本世纪中期和远期 10 年，该地区年均温将分别升高 4.0和 6.9℃，春季和荒漠地区增温最快，这与气温历史变化的研究一致。前人发现在上个世纪大部分时间中亚冬季升温最快，但在过去近 30 年，冬季升温变慢，春季取代冬季，成为升温最快的季节。而中亚冬季升温变慢可能与北极升温造成的极地极其周边的气候系统变化有关。此外，升温较快的区域以荒漠为主，如中亚西南部、新疆南部和哈萨克斯坦南部。因为荒漠的比热容较低，相对于其他土地覆被类型，更容易被加热，所以在未来大气辐射增加的情景下，荒漠升温更快。本研究结果对于理解中亚气候在 RCP8.5 情景下的可能变化具有参考意义。生成的高分辨率的历史和未来气候数据已被用于生态和水文研究，得到的 WRF 模拟平台可用于中亚气象和气候研究。 |
| Other Abstract | Central Asia is the region of five countries, Kazakhstan, Kyrgyzstan, Tajikistan,Turkmenistan and Uzbekistan, and the Xinjiang province of China. Along with the diverseclimate is a suite of ecosystems from the desert to the alpine mountains, which aresensitive to climate change. Central Asia has shown dramatic changes, with the surface airtemperature fast rising and annual precipitation increasing, which have acceleratedretreating of the glaciers in the Tien Shan Mountains and caused substantial losses ofsurface biomass in western Central Asia. These strong sensitivities elevate the importancefor acquiring well understanding of future precipitation and temperature changes in CentralAsia. This study applied the high-resolution (20km) Weather Research and Forecasting(WRF) Model to simulate the regional climate in Central Central during three 10-yearperiods (1996-2005, 2045-2054, and 2091-2100). The forcing data is NCAR CCSM4 andthe scenario RCP8.5 is selected.Differences between the current and future simulated precipitation show nomonotonic trend in precipitation from the current to the future decades. In the middledecade (2045-2054), annual precipitation shows increase from the current amount ineastern half of Central Asia and decrease in the western half. The last decade is featuredwith less precipitation in the central portion of Central Asia and substantially more insurrounding areas. Meanwhile, extremely intense events are suggested to increasesignificantly but the light events to decrease, particularly in the last decade. Because thetotal precipitation remains nearly stable, the increase in intense precipitation eventsstretches the dry period between them. The precipitable water in the atmosphere willincrease over Central Asia in the future two decades. However, precipitation will notincrease in the entire region due to the lack of dynamic mechanism to convert precipitablewater into precipitation. Further analysis found that the changes in precipitation are relatedto changes in relative vorticity caused by changes in geopotential in Central Asia.The simulated temperature show that annual daily mean temperature in the region will increase 4.0 and 6.9℃ in the middle and last decade, respectively. Warming is strongest inthe spring and over the desert areas, which is consistent with the study on temperaturechanges in the past. It’s found that surface air temperature has been increasing at larger ratein winter than other seasons during most of the last century. This situation has changed inthe recent 30 years during which the largest increase in seasonal temperature has beenfound in spring months whereas the winter temperature increases has been leveling off.The slowing of the warming in Central Asia during the winter is likely to be related tochanges in climate system in Arctic and its surrounding areas. In addition, the regions withfaster warming are dominated by deserts, such as southwestern Central Asia, southernXinjiang, and southern Kazakhstan. Because the specific heat capacity of the desert isrelatively low, it is easier to be heated than other land covers. Therefore, the surfacetemperature will rise faster in the deserts under the scenario of increasing atmosphericradiation.The results in this study have implication for understanding the possible climatechanges in Central Asia under the RCP8.5 scenario. The high-resolution downscaled datafrom this study have been used in ecological and hydrological studies. The validated WRFmodel can be applied as a tool for weather and climate research in Central Asia. |
| 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/365004/14934 |
| Collection | 研究系统_荒漠环境研究室 |
| Affiliation | 中国科学院新疆生态与地理研究所 |
| First Author Affilication | 中国科学院新疆生态与地理研究所 |
| Recommended Citation GB/T 7714 | 邱源. 中亚气候变化的动力降尺度研究[D]. 新疆乌鲁木齐. 中国科学院大学,2018. |
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