陆气相互作用机理的多参数化方案集合模拟研究

Land-atmosphere (LA) interaction has profound impacts on regional weather and climate. The mechanisms underlying the LA interaction have long been investigated in the literature but remain largely unresolved. Recently some new understanding has been obtained regarding the LA coupling strength and its role in shaping climate variabilities at the seasonal to inter-annual scales. However, further progresses are in need at these aspects: methodological development; understanding key physical processes that govern the coupling strength; quantifying the impacts of LA coupling on seasonal climate predication. Built upon the traditional approaches of simulating the LA coupling, the current project would fully account for the influence of land surface processes on LA coupling system, and take an ensemble approach with vast sample size to represent the joint impacts from multiple key parameterizations associated with LA coupled system. The proposed approach is geared toward observational datasets comparison, integrated analyses of key processes and their parameterizations that significantly affect the simulation of LA coupling, and optimal selection of these parameterizations. The resultant framework can be used to interpret the coupling strength and associated "hot-spots", quantitatively access the role of LA coupling in seasonal and interannual climate predication and evaluate the related uncertainty. Further, it can help characterize and understand the mechanism underlying LA interaction. The results can also provide reliable decision support for ecological and environmental management, risk mitigation, and sustainable development under the scenario of climate change.

陆气相互作用是影响区域天气、气候特征的关键过程，陆气耦合机理是长期以来备受关注的难题。对于陆气耦合强度，及其在季节、年际尺度气候变化中的作用近年来有了新的认识。但陆气相互作用研究方法，及控制陆气耦合强度的关键物理过程，陆气耦合影响季节尺度气候预报预测的定量表达等目前仍需进一步发展。本项目拟在传统大气耦合模拟研究的思路上，充分考虑陆面过程对陆气系统的影响，通过大气、陆面两者关键物理过程多参数化方案同时参与的大样本量集合模拟实验,对比观测数据，集成分析影响陆气耦合模拟的关键过程和参数化方案，优化组合参数化方案。进而解答陆气相互作用中耦合强度、"热点"区域等问题，定量评估陆气在季节、年际气候预报预测中的作用和不确定性,剖析和描绘陆气相互作用的机理。为气候变化背景下的生态环境建设、防灾减灾和可持续发展的有效决策提供科学依据。

陆面过程是影响区域天气、气候特征的关键过程，陆面过程模式的不确定性影响了对陆地水循环和陆气相互作用的研究。本项目使用Noah-MP陆面过程模式开展大尺度水文过程模拟，充分检验了Noah-MP对蒸散发、径流、陆地水储量、土壤湿度的模拟性能，并通过比较发现，Noah-MP对土壤湿度的模拟能力优于CLM；在此基础上，进一步开展了多参数化方案集合模拟，发展了基于方差分解的参数化方案敏感性计算方案，定量研究了模式对叶孔导度、湍流、土壤湿度阻抗因子、径流参数化方案的敏感性，表明在湿润区，模式对叶孔导度方案最为敏感，在干旱区对径流方案最为敏感。该研究表明，多参数化方案陆面过程模型能够显著加深对陆面过程模拟不确定性的认识，定量评估不同过程对模拟不确定性的贡献，从而指出未来模式研发的主要方向。