Results of a CLM4 Land Surface Simulation over China Using a Multisource Integrated Land Cover Dataset

In this study, the high-accuracy multisource integrated Chinese land cover(MICLCover) dataset was used in version 4 of the Community Land Model(CLM4) to assess how the new land cover information affected land surface simulation over China. Compared to the default land cover dataset in CLM4, the MICL data indicated lower values for bare soil(14.6% reduction), needleleaf tree(3.6%), and broadleaf tree(1.9%); higher values for shrub cover(1.8% increase), grassland(9.9%), cropland(5.0%), glaciers(0.5%), lakes(1.6%), and wetland(1.1%); and unchanged for urban areas. Two comparative CLM4 simulations were conducted for the 33-yr period from 1972 to 2004, one using the MICL dataset and the other using the default dataset. The results revealed that the MICL data produced a 0.3% lower mean annual surface albedo over China than the original data. The largest contributor to the reduced value was semiarid regions(2.1% reduction). The MICL-data albedo value agreed more closely with observations(MODIS broadband black-sky albedo products) over arid and semiarid regions than for the original data to some extent. The simulated average sensible heat flux over China increased by only 0.1 W m–2 owing to the reduced values in arid and semiarid regions, as opposed to increases in humid and semihumid regions, while an increased latent heat flux of 1 W m–2 was reflected in almost identical changes over the whole region. In addition, the mean annual runoff simulated by CLM4 using MICL data decreased by 6.8 mm yr–1, primarily due to large simulated decreases in humid regions.

基于中国植被数据的陆面覆盖及其对陆面过程模拟的影响

本文基于中国1:100万植被图、马里兰大学AVHRR森林覆盖资料和中国753个气象站点40年的降水气温资料,发展了一套用于气候模拟的中国陆面覆盖资料(Chinese land cover derived fromvegetation map,简称CLCV)。该套资料与CLM(Community Land Model)原来所用的MODIS(Moderate Resolution I maging Spectro-radiometer)陆面覆盖资料相比有较大不同:其中裸土比例减少了14.5%,森林、灌木、草原和农作物比例分别增加了3.3%、4.8%、4.4%和0.3%,冰川、湖泊和湿地比例分别增加了0.4%、0.8%和0.6%。将CLCV和MO-DIS资料分别与全国土地资源概查汇总结果分省统计资料和基于中国1km土地利用图的土地利用资料比较表明,CLCV与两者较为接近。最后,利用CLM模式分别采用CLCV与MODIS陆面覆盖资料在中国区域内进行数值模拟,结果显示,使用CLCV资料所模拟的蒸散增加了约7.7mm/a;地表反照率、感热和径流分别减小了约0.7%、0.3W/m2和7.6mm/a;与MODIS卫星反演地表反照率和GRDC(Global Runoff Data Centre)径流资料比较表明,利用CLCV资料所模拟的地表反照率有一定改进,并能基本模拟出径流分布趋势。