北京大学陆面过程模式PKULM(Peking University Land Model)介绍及检验  

Description and evaluation of the Peking University Land Model(PKULM)

作　　者：郑辉[1] 刘树华[1] Prabhakar Clement 刘振鑫[3] 候旭宏[4] 王姝[1] 赵靖川[1] 李源[1] 缪育聪[1] 郑亦佳[1] 盛黎[5] 朱琳[6] 

机构地区：[1]北京大学物理学院大气与海洋科学系,北京100871 [2]Department of Civil Engineering,Auburn University,Auburn,AL 36849 [3]中国科学院大气物理研究所,北京100029 [4]中国科学院寒区旱区环境与工程研究所,兰州730000 [5]中国气象局国家气象中心,北京100081 [6]中国气象局卫星气象中心,北京100081

出　　处：《地球物理学报》2016年第1期79-92,共14页Chinese Journal of Geophysics

基　　金：国家科技支撑计划(2012BAH29B03)资助

摘　　要：陆面过程模式是气候模式和天气模式的核心组成部分之一.在土壤—植被—大气耦合模式(Soil-PlantAtmosphere Model,SPAM)的基础上,发展了新一代北京大学陆面过程模式PKULM(Peking University Land Model).本文首先介绍了PKULM的辐射传输、湍流输送、光合作用、土壤水热输送等过程的参数化方案;采用隐式迭代计算框架,发展并应用了一个快速的线性方程组求解算法,提高了模式计算稳定性;提出并使用了二分搜索算法计算气孔阻抗,避免了CLM(Community Land Model)等使用的迭代方法在干旱区不稳定的情况,提高了模式的适用性;采用水势为基础的土壤水分扩散方程,使模式能够模拟土壤饱和区的水分输送过程,为进一步与水文过程模式耦合奠定了基础;还发展了一个地表积水与径流过程的机理模型,提高了模式对地表水分平衡过程的模拟能力;最后,使用"中国西北干旱区陆—气相互作用观测试验"平凉站的资料对模式进行了检验并与NOAH(National Center for Environmental Prediction,Oregon State University,Air Force,and Hydrology Lab model)陆面过程模式的模拟结果进行了比较,结果表明PKULM能够较好地模拟西北半干旱区农田下垫面地气交换过程.The land surface model is a key component of climate and weather models.It isintractable to accurate modeling land-atmosphere interaction in arid and semi-arid regions.Evolved from the Soil-Plant-Atmosphere Model（SPAM）,a new Peking University Land Model（PKULM）has been developed with several augments in physical processes and numerical solution for application in arid and semi-arid environments.The model included five modules：radiation transfer,turbulence,photosynthesis,soil heat diffusion and soil water transport.PKULM has augmented biophysical and hydrological processes over SPAM and introduced a new numerical solution for coupled nonlinear equation set of land surface processes：（1）Radiation transfer process within canopy is introduced into the model.The two-stream approximation is used to simulate this process.（2）We use the photosynthesis-based Ball-Berry stomatal resistance scheme instead of the Jarvis algorithm for modeling transpiration,which controls canopy carbon and water fluxes consistently and simultaneously.（3）The original algorithm used in Community Land Model（CLM）for solving coupled photosynthesis and stomatal resistance model does not converge in a dry environment.We propose a new and efficient bisection method that can ensure convergence with ambient low environmental vapor pressure.（4）We update the numerical solution of Richards equation from a saturation-based form to a head-based form.It is apt for modeling soil water movement either in the vadose zone or saturated zone.（5）A new mechanism runoff model is adopted to replace the parameterized model.（6）We adapt the traditional Thomas algorithm and use an implicit iterative method for solving the coupled energy balance and water balance equations of soil,canopy and land surface.With the data obtained in NWC-ALIEX（Northwest China Atmosphere-Land Interaction Experiment）,we evaluated the performance of PKULM over cropland in Pingliang and compared it with the Noah land surface model.PKULM outperforms Noah in

关 键 词：陆面过程模式 地表能量平衡 土壤湿度 气孔导度 

分 类 号：P404[天文地球—大气科学及气象学]