摘要:利用那曲地区的微脉冲激光雷达探测资料，采用梯度法获取了那曲地区白天混合层高度随时间的演变信息及混合层特征参数，结果表明混合层在上午发展缓慢，中午以后发展迅速，14：00（北京时）前后达到稳定；强烈的对流热泡活动导致混合层高度起伏较大，参数化反演得到的卷夹层厚度达到0.4~0.5 km，卷夹比在0.2左右。利用探空资料结合日最大位温资料，采用气块法得到了高原地区7个站点的每日最大混合层高度数据集。通过对由激光雷达和探空资料得到的最大混合层高度结果进行对比，发现二者有很好的一致性（相关系数0.85，均值偏差0.11 km，均方根误差0.30 km，并通过0.05显著性水平的t检验）。最大混合层高度在7个站点均有明显的逐日变化特征。从年均值看，最大混合层高度与海拔高度之间没有明显相关关系。从季节均值看，格尔木与都兰站表现出明显的春高冬低的分布特征，而其它五个站点则表现为春高夏低，表明高原地区的盆地地形和山地地形对混合层高度有显著而不同的影响。通过定义热力稳定度和确定特征气压层高度，利用热力稳定度与最大混合层高度之间良好的线性关系，获取了一种简便地获取最大混合层高度的统计方法。
关键词:青藏高原/
混合层高度/
微脉冲激光雷达(MPL)/
探空资料
Abstract:The time series of mixing layer height and other characteristic variables in Naqu area are retrieved from Micro-Pulse Lidar (MPL, the same below) data by using the gradient method. Results show that the development of the mixing layer is slow in the morning and rapid in the afternoon, reaching a stable status at around 1400 BT (Beijing time). The fluctuation of the mixing layer height in the afternoon indicates that there exist frequent and strong convective activities over the Tibetan Plateau. An estimation of 400-500 m for the entrainment ozone depth and about 0.2 for the entrainment rate can be obtained by a parameterization method. Based on radiosonde data collected at 0800 BT and the daily highest surface potential temperature, the maximum mixing height (MMH) at 7 stations in the Tibetan Plateau can be obtained using the parcel method. The MMHs from MPL data and from radiosonde data show a good agreement with each other with the correlation coefficient of 0.85, mean bias of 0.11 km, root-mean-square error of 0.30 km, and the correlation passes the t test at the significance level of 0.05. The MMHs at the 7 stations all show an obvious daily variation. The annual mean of MMH indicates that there is no significant correlation between the MMH and the site altitude. The MMHs at Golmud and Dulan stations show different seasonal characteristics from those at other 5 stations. The former reaches their peaks in spring and monotonically decrease to low values in winter, while the latter reach their highest values in spring and the lowest values occur in summer. The above results show that terrain features of basin and mountain in the Tibetan Plateau have significant but different effects on the mixing layer height. With the definitions of thermal stability and characteristic pressure level, a statistical approach that can be used to easily obtain MMH is proposed based on the good linear relationship between thermal stability and MMH.
Key words:Tibetan Plateau/
Mixing layer height/
Micro-Pulse Lidar (MPL)/
Radiaosonde
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http://www.iapjournals.ac.cn/dqkx/article/exportPdf?id=20180514
