双月刊

ISSN 1006-9895

CN 11-1768/O4

物理协调大气变分客观分析模型及其在青藏高原的应用(I):方法与评估
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作者单位:

1.中山大学大气科学学院;2.中国气象科学研究院;3.国家气象信息中心

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基金项目:

第二次青藏高原综合科学考察研究项目2019QZKK0105; 国家自然科学基金项目91437221,91837204


Physically Consistent Atmospheric Variational Objective Analysis and Applications over Tibetan Plateau (I): Method and Evaluation
Author:
Affiliation:

1.State Key Laboratory of Severe Weather,Chinese Academy of Meteorological Sciences;2.Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies,School of Atmospheric Sciences,Sun Yat-sen University,Southern Marine Science and Engineering Guangdong Laboratory Zhuhai;3.National Meteorological Information Center

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    摘要:

    本文系统地介绍了基于约束变分客观分析法构建的物理协调大气变分客观分析模型,并将模型首次应用于青藏高原那曲试验区。该模型可融合不同时空分辨率的多来源数据,通过利用地面降水和地面、大气顶部的热通量等大气上下边界的观测资料来约束调整探空观测变量,从而尽可能保证气柱内的质量、热量、水汽和动量收支平衡。对模型及其产生的第三次青藏高原大气科学试验那曲试验区2014年8月期间的大气分析数据集进行评估分析,结果表明模型生成的常规状态量很好地保留了观测特征,模型生成的重要大尺度衍生量(如垂直速度、散度、温度/水汽平流、视热源、视水汽汇等)可以较好地反映试验期内大气柱的动力、热力和水汽结构特征,有利于对大气降水过程的分析研究。分析发现,350~400hPa高度层是该时期那曲试验区的动力、热量和水汽的重要变化中心。从各种观测资料对模型生成的分析场的影响来看,探空观测对高空风场的影响最大,但这种影响的幅度在1m/s以内;降水和上下边界通量观测主要影响大尺度衍生量如垂直速度,其中降水主要影响降水时期的上升运动,通量观测主要影响弱/无降水时期的下沉运动。总体而言,物理协调大气变分客观分析模型具备较好的稳定性和合理性。

    Abstract:

    A physically consistent atmospheric objective analysis model based on the constrained variational analysis (CVA) method was applied to the Tibetan Plateau for large-scale atmospheric structure analysis. This objective analysis model can deal with multi-source measurements with different spatial and temporal resolutions, and satisfy the conservation of column-integrated mass, heat, moisture, and momentum by using surface precipitation and flux data at the surface and top of the atmosphere to constrain the sounding measurements. An experiment during August 2014 around Naqu in the Tibetan Plateau shows that those state variables generated by the model can retain observational characteristics. The analyzed large-scale derivatives such as vertical velocity, divergence, temperature and water vapor advection, apparent heat source and apparent moisture sink by the objective analysis model can reasonably demonstrate dynamic, thermal, and moisture structures during the analysis period, which is conducive to the precipitation process studies. It shows that the layer of 350~400hPa is an important change center of dynamics, heat, and water vapor in the analysis region during August 2014. In this model, different sources of measurements have different impact on the final analysis fields. Sounding measurement has a significant impact on the upper-level wind. However, the amplitude of this impact is small within 1 m/s. Precipitation and flux measurements mainly affect the large-scale derivatives such as vertical velocity, in which precipitation mainly affects the upward movement during precipitation periods, and flux data mainly affect the downward movement during light/no rain periods. In general, the physically consistent atmospheric variational objective analysis model has high stability and strong validity.

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  • 收稿日期:2021-04-20
  • 最后修改日期:2021-06-30
  • 录用日期:2021-07-16
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