全球植被年际尺度动态过程的数值模拟及其评估

Numerical Simulation and Assessment of Interannual Variation in Vegetation at Global Scale

动态植被模型(Interactive Canopy Model,ICM)中考虑了生态系统碳氮循环过程,能够描述较短时间尺度上的植被与大气之间相互作用过程。利用21 a的GIMMS卫星观测LAI资料,与ICM模拟结果进行年际变率对比分析,评估模型对植被年际变化的模拟性能。结果表明,ICM能在一定程度上反映植被年际变率的空间分布特征,但模拟的热带部分地区植被的年际变率偏小,除此之外大部分地区模拟的年际变率偏大;模拟能够反映出全球植被年际变化的主要空间分布型,同时低纬度地区植被的时间演变特征要好于高纬度地区;ICM对寒带灌丛、北非稀树大草原、落叶针叶林的年际变化模拟较好,但对中国东部农作物的模拟表现出了明显的周期振荡现象,与实际情况差距较大。

The dynamic vegetation model,ICM,including the carbon and nitrogen cycles in the ecosystem,has an ability to describe the vegetation-atmosphere interactive process on short time scale.By using 21-yr LAI from GIMMS（Global Inventory Modeling and Mapping Studies）,the interannual variability simulated by ICM is analyzed and compared in order to assess the performance of the dynamic vegetation model.Results support that ICM is competent enough to simulate the spatial characteristics of LAI（leaf area index） interannual variation.In this context,also one disadvantage is found that the simulated patches of LAI interannual variabilities are larger than the observed in most areas except in some tropical areas.The large LAI interannual varibilities are represented in most regions of the world,with better results in low-latitudes than those in high-latitudes.The model depicts better results in case of boreal shrubs,savanna in North Africa and deciduous needleleaf trees than other types of vegetation.The simulated crops in eastern China have an obvious biennial oscillation,which does not comply with the observed one.