地形对民勤沙尘暴发生发展影响的模拟研究——以一次特强沙尘暴为例

doi:10.7522/j.issn.1000-694X.2013.00385

摘要/Abstract

摘要： 河西走廊是中国西北路径冷空气的必经之地，其狭管地形加之丰富的沙尘源地，使其成为中国沙尘暴多发区；民勤位于走廊中段，地处巴丹吉林和腾格里两大沙漠的接壤地带，正好位于雅布赖山和龙首山形成的山口下游方。河西走廊加上民勤周边这种双狭管的特殊地形，使得民勤又成为河西走廊沙尘暴的多发区以及中国的生态环境极度脆弱区。本文以2010年4月24日河西走廊一次特强沙尘暴（部分时段能见度为0，达到了黑风标准）为例，利用GRAPES_SDM沙尘模式对这次沙尘暴进行了数值模拟，并重点对民勤周边山地采取改变高度和范围等方式，模拟研究了地形对过境民勤的风速、地面起沙通量、沙尘浓度以及沙尘输送的影响。结果表明：（1）民勤周边地形高度降低的情况下，地面风速减弱，携沙气流遇到地形阻挡，沿着坡地爬升，部分沙尘可以翻越地形到背风坡，此时的地形特征将减弱沙尘扩散强度；（2）民勤周边地形高度增高，风速小于地形不变时的风速，气流发生明显的绕流，改变沙尘扩散方向；（3）改变民勤周边山体地形位置，狭管效应减弱，地面风速明显减小，沙尘影响范围较控制试验向南及东南方向扩展；（4）河西走廊南部祁连山高度改变对沙尘的影响程度大于民勤北部雅布赖山的改变，这与祁连山的山体面积和高度明显大于雅布赖山有关，说明河西走廊“狭管”地形是民勤沙尘暴之所以多发的重要原因，民勤周边的小型“狭管”地形又使得民勤成为走廊中沙尘暴最为严重的区域。（5）地形改变将减小地表起沙量，从而减小沙尘浓度，也即减弱沙尘暴的发生发展。

关键词: 民勤, 沙尘暴, 地形作用, 模拟

Abstract: Hexi Corridor is the only way of cold air from northwest, its funnelling terrain and abundant sand source made it became sand storm prone area. Minqin of Gansu is located in the middle of the corridor, where the Badain Jaran Desert borders the Tengger Desert, and is a wind outlet area of Yabrai Mountain and Longshou Mountain. The corridor terrain and the funnelling terrain made Minqin become the sand storm prone area with extremely vulnerable ecological environment. By data during a heavy sandstorm (the visibility reach to 0 m sometime, and reach to black storm standard) in the Hexi corridor on April 24 of 2010, We use GRAPES-SDM sandstorm model to imitate this sandstorm process, and simulate the effect of terrain on the wind speed, sand flux from the ground, concentration of sand and sand transport by experiment change of the mountain height and range. The results show that: (1) When decrease of the height of the mountain around Minqin, the surface wind speed weakens. The air with sand meets the resist of the mountain, some sand reaches to the leeward slope. The terrain characteristic would weaken the diffusion intensity of sand. (2) The wind speed decreases when increase of height of the mountain around Minqin, the airflow obviously turn and the direction of dust spreading is changed. (3) The surface wind speed obviously decreases when the position of mountain around Minqin changes, and the dust influence area extends to southward and southeast compared with the initial condition because of the weaken of the funneling effect. (4) The height change of Qilian Mountain to the south of the Hexi Corridor affects more significantly compared with the same change of the Yabrai Mountain to the north of Minqin because the area and the height of the Qilian Mountain was larger than the Yabrai Mountain. It indicates that the "funnelling" terrain of Hexi Corridor is an important reason of the high frequency of sandstorm in Minqin, the small "funnelling" terrain around Minqin made Minqin area became the most serious area of sandstorm in the Hexi Corridor. (5) The change of terrain would reduce the amount of sand from the surface, thus reduce the concentration of dust, and reduce the development of sandstorm.

Key words: Minqin, sand storm, terrain effect, simulation

中图分类号:

P425.55

李耀辉, 沈洁, 赵建华, 胡田田, 尹晗. 地形对民勤沙尘暴发生发展影响的模拟研究——以一次特强沙尘暴为例[J]. 中国沙漠, 2014, 34(3): 849-860.

Li Yaohui, Shen Jie, Zhao Jianhua, Hu Tiantian, Yin Han. Simulation of Terrain Effect to the Development of Sandstorm in Minqin——Take a Heavy Sandstorm for Example[J]. JOURNAL OF DESERT RESEARCH, 2014, 34(3): 849-860.

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