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| 中亚气候变化的动力降尺度研究 | |
| 其他题名 | Dynamical Downscaling of Climate Change in Central Asia |
| 邱源 | |
| 出版年 | 2018 |
| 学位类型 | 博士 |
| 导师 | 张弛 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 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。 |
| 英文摘要 | Central Asia is the region of five countries, Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan and Uzbekistan, and the Xinjiang province of China. Along with the diverse climate is a suite of ecosystems from the desert to the alpine mountains, which are sensitive to climate change. Central Asia has shown dramatic changes, with the surface air temperature fast rising and annual precipitation increasing, which have accelerated retreating of the glaciers in the Tien Shan Mountains and caused substantial losses of surface biomass in western Central Asia. These strong sensitivities elevate the importance for acquiring well understanding of future precipitation and temperature changes in Central Asia. This study applied the high-resolution (20km) Weather Research and Forecasting (WRF) Model to simulate the regional climate in Central Central during three 10-year periods (1996-2005, 2045-2054, and 2091-2100). The forcing data is NCAR CCSM4 and the scenario RCP8.5 is selected.Differences between the current and future simulated precipitation show no monotonic trend in precipitation from the current to the future decades. In the middle decade (2045-2054), annual precipitation shows increase from the current amount in eastern half of Central Asia and decrease in the western half. The last decade is featured with less precipitation in the central portion of Central Asia and substantially more in surrounding areas. Meanwhile, extremely intense events are suggested to increase significantly but the light events to decrease, particularly in the last decade. Because the total precipitation remains nearly stable, the increase in intense precipitation events stretches the dry period between them. The precipitable water in the atmosphere will increase over Central Asia in the future two decades. However, precipitation will not increase in the entire region due to the lack of dynamic mechanism to convert precipitable water into precipitation. Further analysis found that the changes in precipitation are related to 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 in the spring and over the desert areas, which is consistent with the study on temperature changes in the past. It’s found that surface air temperature has been increasing at larger rate in winter than other seasons during most of the last century. This situation has changed in the recent 30 years during which the largest increase in seasonal temperature has been found 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 to changes in climate system in Arctic and its surrounding areas. In addition, the regions with faster warming are dominated by deserts, such as southwestern Central Asia, southern Xinjiang, and southern Kazakhstan. Because the specific heat capacity of the desert is relatively low, it is easier to be heated than other land covers. Therefore, the surface temperature will rise faster in the deserts under the scenario of increasing atmospheric radiation.The results in this study have implication for understanding the possible climate changes in Central Asia under the RCP8.5 scenario. The high-resolution downscaled data from this study have been used in ecological and hydrological studies. The validated WRF model can be applied as a tool for weather and climate research in Central Asia. |
| 中文关键词 | 气候变化 ; WRF ; 降尺度 ; 区域气候 ; 中亚 |
| 英文关键词 | Climate Change WRF Downscaling Regional Climate Central Asia |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 地图学与地理信息系统 |
| 来源机构 | 中国科学院新疆生态与地理研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/288184 |
| 推荐引用方式 GB/T 7714 | 邱源. 中亚气候变化的动力降尺度研究[D]. 中国科学院大学,2018. |
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