青藏高原东南部昌都地区近地层湍流输送的观测研究
TURBULENT MEASUREMENT OVER THE SOUTHEASTERN TIBETAN PLATEAU
-
摘要: 利用我国1998年第2次青藏高原气象科学试验 (TIPEX) 昌都的湍流观测资料, 初步分析了三维风速、温度和湿度湍流谱、归一化方差与稳定度的关系、湍流通量和整体输送系数.结果表明, 白天标准化的湍流谱大多数满足2/3次方定律.风速方差与稳定度的关系在不稳定条件下基本服从1/3次方定律, 但水平风速方差比垂直速度方差与稳定度的关系离散.中性层结下的A、B值比平原地区大, 与起伏地形的值接近, C值与平原地区和起伏地区的差异不大.温度和湿度方差与不稳定层结的关系基本满足1/3次方定律, 而在稳定层结下的关系均无明显规律.湍流通量在干湿期转换中有突变现象, 干期的动量和热量通量均大于湿期, 热源强度以感热为主, 占80%.湿期热源强度明显增大, 其中以潜热为主, 占热源强度的60%.整体输送系数与稳定度的关系明显, 拟合得到的中性层结条件下的CDN和CHN分别为4.40×10-3和4.70×10-3, 其结果大于高原中、西部的同期观测值.
-
关键词:
- 第2次青藏高原气象科学试验 (TIPEX);
- 涡旋相关法;
- 湍流结构;
- 整体输送系数
Abstract: Based on the second Tibetan Plateau Meteorological Experiment (TIPEX) turbulent data from Changdu, the turbulent structure and transportation characteristics in the near-surface layer for summer time are analyzed by using the eddy correlation technique. The main results show that the relation between the normalized variance of 3D winds and z/L satisfies the similarity law under both unstable and stable stratification. The relations of normalized variances of temperature and specific humidity to z/L obey the law of 1/3 fractional power only under the unstable condition. In the case of stable stratification, their relations to z/L are disperse. The sensible heat dominates in the dry period, making up 80% of the total heating; while in the wet period the heating is intensified to great degree, in which latent (sensible) heat constitutes 60% (40%). The relations of drag coefficients (Cd and Ch) to z/L are quite close and the fitted Cdn (4.40×10-3) Chn (4.70×10-3) are obtained in a neutral case, which are bigger than those for the middle and western parts of the plateau in the same period.-
Key words:
- TIPEX;
- Eddy correlation;
- Turbulent structure;
- Drag coefficient
-
表 1 湍流测量系统传感器的主要技术指标
表 2 近中性条件无因次风速方差值
表 3 昌都的平均热源强度
-
[1] 章基嘉, 朱抱真, 朱福康, 等.青藏高原气象学进展.北京:科学出版社, 1988.1~268. [2] Tsukamoto O, Sahashi K, Wang J.Heat budget and evapotranspiration at an Oasis surface surroundinged by desert.J.Met.Soc.Japan, 1995, 73(5):925~935. [3] 周秀骥, 陶善昌, 姚克亚.高等大气物理学.北京:气象出版社, 1991.206~236. [4] Panafsky H A, Larko D, Lipschutz R, et al.Spectra of velocity components and complex terrain.Quart J.R.Meteor Soc., 1982, 108:215~230. doi: 10.1002/(ISSN)1477-870X [5] Kaimal J C, Wyngaard J C, Izumi Y, et al.Spectral characteristics of surface layer turblence.Quart J.R.Meteor.Soc., 1972, 98:563~589. doi: 10.1002/(ISSN)1477-870X [6] Panafsky H A, Dutton J A.Atomspheric Turbulence.New York:John Willy and Sons, 1984.10~50. [7] Hedde T, Darand P.Turbulence intensities and bulk coefficients in the surface layer above sea.Boundary Layer Meteorology, 1994, 71:415~432. doi: 10.1007/BF00712178 [8] Wyngaard J C, Cote O R.Volution of a convective planetary bound rylayer-a high-order-closure model study.Boundary Layer Meteorology, 1974, 7:290~307. [9] 祁永强, 王介民.青藏高原五道梁地区湍流输送特征的研究.高原气象, 1996, 15(2):172~177. http://www.cnki.com.cn/Article/CJFDTOTAL-GYQX602.005.htm [10] Panafsky H A, Tenekes H, Lenschow D H, et al.The characteristics of turbulent velocity components in the surface layer under convective conditions.Boundary Layer Meteorology, 1977, 21:356~360. doi: 10.1007/BF00121926?no-access=true [11] Hirohiko I, Taichi H, Kenji T, et al.Summary of planetary boundary Layer observation in GAME/TIBET.Proceedings of the 1st international workshop on GAME/Tibet, Xian, China, 11~13, Jan.1999, 69~76. [12] 王介民, 刘晓虎, 马耀民.HEIFE戈壁地区近地层大气湍流结构和输送特征.气象学报, 1993, 51(3):343~349. http://www.cnki.com.cn/Article/CJFDTOTAL-QXXB199303009.htm [13] Hogstrom U, Semdman-Hogstrom A S.Turbulence mechanics at an agricultural site.Boundary layer Meteorology, 1974, 7:374~388. [14] 朱福康, 赵卫.青藏高原地面净辐射对大气环流作用的一些观测事实.青藏高原气象科学实验文集 (三).北京:科学出版社, 1987.54~61. [15] 李家伦, 洪钟祥, 罗卫东, 等.青藏高原改则地区近地层通量观测研究.大气科学, 1999, 23(2):142~151. http://www.cnki.com.cn/Article/CJFDTOTAL-DQXK199902001.htm [16] Mitsuta Y, Tsukamoto O.Drag coefficients in light wind, Bull.Disaster prevention Res.Inst., Kyoto Univ., 1978, 28(2):25~32. [17] 李月洪, 李维亮, 丁晓蓉, 等.1993年7~9月拉萨近地层湍流输送特征的分析.亚洲季风研究的新进展.北京:气象出版社, 1996.26~27. [18] 陈万隆, 翁笃鸣.关于青藏高原感热和潜热旬总量计算方法的初步研究.青藏高原气象科学实验文集 (二).北京:科学出版社, 1984.38~39.