摘要
青藏高原(下称高原)区域天气系统变化对其周围及下游区域的数值天气预报质量具有重要影响。然而,高原区域质量偏低且稀少的观测资料严重制约了同化分析效果和预报质量。变分质量控制方案(VarQC)具有合理利用不同质量观测资料改善同化分析性能的良好能力。鉴于此,在对高原区域观测误差非高斯分布特征分析的基础上,构建了适应高原区域观测误差特征的“高斯分布+均匀分布”的变分质量控制方案(Flat-VarQC),优化了其关键参数,使其能更准确地基于同化新息向量调整观测对同化分析的影响权重,从而提高高原区域稀少观测资料的有效同化率,改善高原区域的同化分析质量。试验结果表明:高原区域观测误差具有更明显的“厚尾分布”特征,同化过程中单纯的高斯分布假设将导致观测资料的有效同化率偏低,从而降低了高原区域有限观测资料对同化分析的贡献;适用于高原区域资料特点的变分质量控制关键参数优化是充分发挥高原区域FlatVarQC改善同化分析质量的关键;Flat-VarQC能够明显提升高原区域常规资料的有效同化率,吸收更多“有益”资料信息,剔除“有害”资料信息,从而提高观测资料对同化分析的正贡献。这对于高原区域中、小尺度天气系统的同化分析和强降水预报具有更显著的改善效果。
Changes in regional weather systems in the Qingzang plateau(hereafter referred to as the plateau)have important impactson numerical weather forecast in its surrounding and downstream regions.However,the low quality and scarcity of observations inthe plateau seriously restrict the assimilation analysis and prediction quality.The Variational Quality Control scheme(VarQC)hasthe potential to make full use of scarce observations to improve the quality of assimilation analysis.In view of this,based on theanalysis of the non-Gaussian distribution characteristics of the observation error in the plateau region,this paper constructs a VarQCof"Gaussian distribution plus flat distribution"(Flat-VarQC),which is suitable for the characteristics of the observation error in theplateau region,and optimizes those key parameters,so that it can more accurately adjust the influence weight of the observations onthe assimilation analysis based on the innovation vector and thus improve the effective assimilation rate of the scarce observations inthe plateau region.The quality of assimilation analysis in plateau region is improved.The results show that the observation error inthe plateau region has a more obvious characteristic of"fat-tail distribution",and the simple assumption of Gaussian distribution inthe assimilation process will lead to low effective assimilation rate of observations,which reduces the contribution of limitedobservation data in the plateau region to the assimilation analysis.The key parameter optimization of variational quality controlsuitable for the characteristics of plateau regional data is crucial for the full play of the Flat-VarQC in plateau region to improve thequality of assimilation analysis.Flat-VarQC can significantly improve the effective assimilation rate of conventional data in theplateau region,absorb more useful data information and eliminate harmful data information,and thus can improve positivecontribution of observation data to assimilation analysis.This has a more significant improvement effect
作者
杨嘉瑞
和杰
马旭林
郝冰洁
张彤彤
YANG Jiarui;HE Jie;MA Xulin;HAO Bingjie;ZHANG Tongtong(Key Laboratory of Meteorological Disaster,Ministry of Education(KLME),Nanjing University of Information Science and Technolo-gy,Nanjing 210044,China;Guangzhou Institute of Tropical and Marine Meteorology,China Meteorological Administration,Guangzhou 510640,China)
出处
《气象学报》
CAS
CSCD
北大核心
2024年第4期443-458,共16页
Acta Meteorologica Sinica
基金
国家自然科学基金项目(U2242213、42305172)
国家重点研发计划项目(2021YFC3000902)。
关键词
青藏高原
资料同化
变分质量控制
新息向量
观测误差
Qingzang plateau
Data assimilation
Variational quality control
Innovation vector
Observation error
