黄土高原干旱半干旱区陆面特征参数敏感性分析及优化

The exchange of energy, water, and matter between land and air is the main way to achieve surface-atmosphere interactions. Land surface feature parameters play an important role in the simulation of land surface processes, and their representativeness and accuracy can affect the simulation effects of land surface models in some extent. The weather forecast in the area of complex underlying surface is the difficulty of model forecasting, and it was also the focus of the forecaster and model researchers. The expression of the land-atmosphere interaction process in this area is extremely important in the weather model. The optimization of parameters in the land surface process model and the combination of different parameters before and after optimization have different effects on the simulation results. This project is aimed at the complex underlying surface area in the arid and semi-arid region of northwestern China, using the extended Fourier amplitude sensitivity test (EFAST) method to identify the surface sensible heat and latent heat flux from the land surface parameters of the Noah_MP land surface process model. The key parameters that have a great influence are optimized by using the shuffled complex evolution algorithm (SCE-UA) to obtain the optimal values of the parameters. Design control and sensitivity tests to evaluate the improve effect of land surface parameters optimization to the land surface mode. The aim is to improve the simulation effect of the land surface process model on the complex underlying surface area in arid and semi-arid areas.

地气之间的能量、水分和物质交换是实现地表-大气相互作用的主要途径。陆面特征参数在陆面过程模拟中扮演着重要的角色，其代表性和准确性在一定程度上能够影响陆面模式的模拟效果。复杂下垫面区域的天气预报是模式预报的难点所在，也是预报员及模式研究人员重点关注区域，而该区域陆气相互作用过程的表述在天气模式中极其重要。陆面过程模型中参数的优化选取，以及不同参数在优化前后的组合方式对模拟结果均有不同程度的影响。本项目针对西北干旱半干旱区复杂下垫面区域，采用扩展的傅里叶振幅敏感性分析（EFAST）方法从Noah_MP陆面过程模式众多的陆面参数中甄别出对地表感热和潜热通量影响较大的关键参数，使用洗牌算法（SCE-UA）对其进行优化得到参数最优化值，设计控制试验和敏感性试验评估陆面参数优化对陆面模式的改进效果，可望有效地提高陆面过程模式对干旱半干旱区复杂下垫面区域的模拟效果。

陆面特征参数的设置在陆面过程及陆气相互作用中有重要作用，陆面参数设置的准确性直接影响到陆面过程是否能够准确表述本地陆面特征，进而影响到陆气相互作用。本项目开展了黄土高原半干旱半湿润区陆面特征参数的敏感性分析，得到该区域的关键敏感陆面参数有粗糙度Z0、土壤饱和含水量MAXSMC、土壤石英含量QUARTZ、土壤参数“b”BEXP。对以上关键敏感陆面参数的敏感性特征进行分析，发现陆面特征参数敏感性存在季节分布的差异性。对黄土高原陆面参数敏感性分析得到三个关键陆面参数Z0、MAXSMC、QUARTZ进行优化，得到该地区关键参数的最优化值。评估黄土高原关键陆面特征参数优化效果，参数优化对半湿润区感热通量的模拟效果优于半干旱区，而对潜热通量的模拟效果反之。从模式模拟性能的整体评估效果看，参数优化有效提高了模式在半湿润区的模拟效果。将黄土高原陆面特征参数优化结果应用到西北区域中尺度高分辨率数值预报系统中，有效提高了该预报系统对黄土高原近地面气象要素的预报效果，而且对对流降水的预报效果也有改进。