基于CoLM模型的根分布对陆-气水热交换的影响研究:以玉米农田为例

Study of the effects of the root distribution on land-atmosphere water and heat flux exchanges based on CoLM:Corn field as a case

利用2007—2008年辽宁锦州玉米农田生态系统野外观测站资料,基于CoLM模型对玉米根分布在陆-气水热通量模拟中的影响进行研究,结果表明:模型模拟性能随年际气象条件的差异而不同,与2007年相比,2008年生长季内降水偏多,感热和潜热模拟精度明显提高;决定根分布形态的50%和95%根总量土层深度(d50和d95)两个参数中,d50比d95敏感;根分布对土壤湿度的影响在极端干旱条件下很小,在一定土壤湿度范围内随土壤湿度及土层深度的增大而减小;在水汽通量各分量中,植物蒸腾受根分布影响最大,其次是土壤蒸发,而叶片蒸发不受影响;根分布对潜热和感热模拟的影响随土壤湿度增大而减小。

Using the observations from the Jinzhou agricultural ecosystem research station during 2007-2008,the effects of the maize root distribution on land-atmosphere flux exchanges were investigated with the Common Land Model （CoLM）.The results showed that there were differences in simulation performance of CoLM for the different annual meteorological condi-tions,that is,for the case with more precipitation in the growing season of maize in 2008,the simulation accuracies of sensible and latent heat fluxes were higher than that in 2007 with less precipitation.The two parameters,d50 and d95 ,were used to in-dicate the shape root distribution profile for 50%and 90%of the total root soil depth,respectively.The simulations of sensible and latent heat fluxes were more sensitive to the former than the latter.The effect of the root distribution on the soil water con-tent （SWC）was increasing with the decreasing SWC and the soil depth within the certain realms and was inappreciable under the condition of extreme drought.In addition,the effects of the root distribution were the most obvious on the simulation of transpiration and next on the simulation of soil evaporation,but ignorable on the simulation of leaf evaporation.On the other hand,it was decreasing on the simulations of sensible and latent heat fluxes with SWC increasing.