Knowledge Resource Center for Ecological Environment in Arid Area
| 基于WRF气候模式的天山北坡山地 - 绿洲 - 荒漠系统水热格局与局地气候研究 | |
| 其他题名 | A study on water - heat patterns and regional climate of mountain - oasis - desert system in north Tianshan Mountains based on WRF model |
| 张苗 | |
| 出版年 | 2018 |
| 学位类型 | 博士 |
| 导师 | 罗格平 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 天山北坡是亚洲中部干旱区气候与地形的缩影。该区域地形复杂，孕育了欧亚大陆腹地典型的山地 - 绿洲 - 荒漠复合生态系统（Mountain - Oasis - Desert System，MODS），气候变化敏感，近60年气温与降水呈现显著增长的趋势，并且较其它亚洲干旱区域变化幅度更加剧烈。具体来说，天山北坡降水呈现11.3% 的增长趋势，增加幅度为22% - 33%；且温度以0.8 ° C /10 年速率变暖，而亚洲干旱区和全球陆地的变暖速率分别为 0.39 ° C/10 年和0.27 - 0.31 ° C/10 年。这个区域经的人类活动主要表现为绿洲大规模的灌溉和急剧的扩张。绿洲是这个区域的精华，决定着这个区域人类生存与发展的命脉。这种发展于有限水土资源下和复杂山盆之间的灌溉绿洲及其扩张对区域气候的影响是怎样的还不清楚，需要深入的研究。从绿洲 - 荒漠交互和山盆之间交互的角度分析，认识这个问题对干旱区人类活动与气候变化的相互作用机理具有重要的科学意义，也对发展于有限水土资源下的绿洲稳定与可持续发展有着现实的指导意义。基于Land Use/Cover Change（LUCC）与气候变化关系的大科学问题背景，本毕业设计通过使用区域气候模式Weather Research and Forcasting（WRF），从能量、温度、湿度、降水、大气结构、风速与风向等要素分析复杂的天山北坡MODS的水热格局与局地气候特征，重点从绿洲与荒漠交互作用，山盆交互作用方面探讨灌溉绿洲对整个MODS的水热格局的影响及机制。研究内容主要包括以下几个方面：WRF对陆面地理 - 生态参数的敏感性：由于WRF内嵌的基础地理数据集陈旧过时，且在这种复杂缺资料区域利用真实遥感陆面参数替换所有内嵌地理数据耗时、耗力、不具操作性的问题，我们探讨了WRF对于Land Use（LU），Albedo，Leaf Area Index（LAI）和 Green Vegetation Fraction（GVF）的敏感性，旨在寻找决定WRF模拟局地/区域气候研究的关键参数。结果表明，WRF对于真实的GVF陆面地理数据最为敏感，GVF对模式模拟温度、湿度和潜热误差校正贡献率分别为62%，87% 和92%。LU数据作为模式一级参数对二级参数有决定作用，在模拟过程中也不可忽视。耦合滴灌过程：针对WRF缺乏对干旱区典型的绿洲滴灌过程的有效表征，限制了模式数值模拟客观反映绿洲的水热状态，我们在前人研究基础上，新发展一个符合干旱区灌溉模式的滴灌框架，并将其与WRF耦合，以提高模型对区域水热格局和局地气候的数值模拟精度。结果表明：改进的WRF现实地模拟了灌溉绿洲的水热状态，模拟的灌溉量与区域灌溉定额和气候预测一致；并且结果表明：灌溉不仅加强了灌溉季绿洲的冷湿岛效应和绿洲 - 荒漠局地环流，也增加了上游山区高程大约为1000 - 2000米的降水量。绿洲效应，与山盆交互作用的关系： MODS的气温总体上呈现从山地到绿洲到荒漠条带性增长的格局，而比湿在1 km - 2 km高程左右区域显著的高于同高度盆地区域，10 - m环流在盛行西风控制下，展示了典型的区域山谷风格局。在这种水热格局特征下，我们观测到北部绿洲 - 荒漠边界一条明显温湿梯度及白天绿洲上空气温（比湿）显著低于（高于）同高程的外围荒漠区域，这是典型的绿洲冷湿岛效应特征，这种效应强度在近地面可以达到?0.61 ° C（1.56 g kg?1），可以影响到绿洲上空大约1.5 km 的高度。由于强劲山谷风的存在隐匿了由绿洲荒漠水热差异产生的绿洲 - 荒漠局地环流，使得前人提出的理论“绿洲自我维持机制”对天山北坡的绿洲的生态稳定不能发挥有效作用。而且，白天谷风使得绿洲的冷湿气团向山区移动，在高程大约1000 - 2000 米山区成云致雨；晚上，山风将绿洲上空的冷湿气团携带进入部分荒漠区域，有益于绿洲 - 荒漠过渡带的植被生长；但山谷风破坏了绿洲的自我维持机制，使得其不能在当前MODS中发挥作用，并且加速了天山北坡内陆流域水文循环过程。 |
| 英文摘要 | The Northern Tianshan Mountains(NTM), which are located in the hinterland of Central Asia（CA），is a microcosm of the terrain and climate of CA and consists of a great number of complex mountains and basins in the world. The NTM has been experiencing distinct intense human activities in the recent 60 years. Based on limited runoff from snow - and glacial - melt in mountainous region and unrestrained extraction of groundwater for irrigation，oases with high primary productivity have developed between mountains and basins，thus the NTM can be consisting of mountain，oasis，and desert areas，named as Mountain - Oasis - Desert ecosystem (MODS) . The total area of oasis has expanded 4 times more than the original size. Meanwhile，recent studies indicate that annual mean air temperature in the NTM has been increasing at an average rate of 0.8 ° C decade?1，which is far larger than the average rate for CA(i.e.,0.39 ° C decade?1 from 1979 to 2011) and for global land areas (i.e.,0.27 - 0.31 ° C decade?1 from 1979 to 2005). Precipitation and frequency of extreme precipitation have an obvious increasing tendency in NTM at an increase rate of 11.3%. How does the abnormal regional temperature and precipitation change in NTM respond to irrigated oasis and its expansion in complex mountain and basin systems ? The answer is not yet clear. Answering the scientific question is essential，both theoretically and practically，to the sustainable development and ecological stability of oases and will provide useful information for further investigating the impact of oasis expansion on regional climate changes under global warming.In this study，the sensible heat，latent heat，temperature，humidity，atmospheric structure and circulation patterns of the complex MODS in the NTM were simulated using the Weather Research and Forecasting (WRF) model. The main contents of this study included the following: Because of the use of outdated terrestrial datasets，including Land Use (LU) , Albedo、Leaf Area Index（LAI）and Green Vegetation Fraction（GVF）, the regional climate model WRF has a limited ability to accurately simulate weather and climate conditions over heterogeneous MODS at such scale. Using actual terrestrial datasets from satellite products is the only possible solution to the limitation; however, it is impractical for long - period simulations due to the extremely time - and labor - consuming processes involved. We used the WRF model with observed estimates of LU, albedo, LAI, and GVF datasets from satellite products to examine which terrestrial datasets have a great impact on simulating water and heat conditions over heterogeneous oasis - desert systems. Using actual GVF data has a much greater effect on the simulation of T2, RH, and LE than the other parameters，accounting for mean error correction 62%, 87%, and 92%, respectively. LU data，which is the primary parameter and strongly influences other secondary land surface parameters in the WRF, is also very important.The ability of WRF to accurately simulate water - heat conditions of irrigated oasis is limited due to lack of typical drip irrigation processes implemented. A drip irrigation scheme was incorporated into the WRF to realistically represent water - heat patterns of oasis and to explore irrigation’s effects on local climate of complex MODS. Model evaluation further reveals that the WRF coupled with the drip irrigation scheme can generate irrigation water amounts that are in close agreement with the observation. Irrigation strengthened cold - wet island effects of oasis and oasis breeze circulation（OBC）in the irrigation season, and increased precipitation amount in upwind mountains areas with elevation approximately 1000 - 2000 m in daytime in the irrigation season. The air temperatures of MODS generally exhibit continuous stripe - like increases from the mountainous areas to the oasis areas and to the desert areas，the specific humidity in the mountainous area is higher than that over the basin area at the same elevation; In the context of the prevailing westerly wind, a typical mountain-valley wind is observed with wind direction of WNW at a wind speed of approximately 3 m/s occurs during the daytime，whereas a wind direction of SW with a wind speed of approximately 4 m/s occurs at night. The typical “cold - wet” island effects of the oasis and OBC are fully described within the context of the MODS，as evidence by an obvious temperature - humidity gradient line along the northern boundary of the oasis. The air temperature (pecific humidity) over the oasis during the day was significantly lower (higher) than the other areas at the same height. The intensity of such cold (wetting) island of the oasis is approximately ?0.61 ° C (1.56 g kg?1) at near surface，and extends to a height of approximately 1.5 km above the oasis surface. The OBC is counteracted by the stronger background circulation. Thus, the self - supporting mechanism of oases originating from the OBC plays a limited role in maintaining the ecological stability of oases MODS. The airflow with increased moisture over irrigated oasis is brought to mountains areas by intense valley wind in daytime and forms precipitation with elevation approximately 1000 - 2000 m due to adiabatic cooling and condensation in this region. Meanwhile intense mountain wind bring increased moisture over irrigated oasis to extend into the surrounding desert area at night，which may produce wet conditions favorable for desert plants in the oasis - desert transition zone. These effects accelerated hydrological process in the NTM. |
| 中文关键词 | 气候模式 ; WRF ; 山体 - 绿洲 - 荒漠复合系统 ; 灌溉绿洲效应 ; 天山北坡 |
| 英文关键词 | Climate model WRF Mountain - Oasis - Desert System Irrigated oasis effects The Northern Tianshan Mountains |
| 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/2XILL650/288151 |
| 推荐引用方式 GB/T 7714 | 张苗. 基于WRF气候模式的天山北坡山地 - 绿洲 - 荒漠系统水热格局与局地气候研究[D]. 中国科学院大学,2018. |
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