不同土壤类型的热通量变化特征

利用2004—2007年中国科学院中国生态系统研究网络(CERN)生态站实测土壤热通量、辐射等资料,分析了不同土壤类型表层热通量的日变化和季节变化,以及不同土壤类型的热通量与总辐射、净辐射的关系。结果表明,由于导热率越大,热量传输就越快;热容量越小,热量传输也越快,造成土壤热通量的日较差和年较差较大,所以黄绵土和紫色土的表层热通量日较差最大(220～280 W.m-2),高寒草甸土和水稻土最小(55W.m-2);季节变化中土壤表层热通量的年较差变化范围在12～28W.m-2之间,灰漠土最大,为28W.m-2,热通量年较差从大到小依次为灰漠土、黄绵土、盐碱潮土、红壤土、紫色土、沼泽土、水稻土和高寒潮土,高寒潮土最小,为12W.m-2。不同土壤类型的热通量与总辐射、净辐射呈正相关关系,但不同土壤类型的土壤热通量在12:00(地方时)所占净辐射的比例各不相同,高寒草甸土最小,约为8%;黄绵土最大,为38%,多数土壤的热通量占净辐射的比例在15%～20%之间,这充分表明不同土壤类型表层热通量的传输存在很大差异。

Characteristics of Soil Heat Flux in Different Soil Types in China

Utilizing the observed soil heat flux,global radiation and net radiation data during 2004—2007 from the Ecosystem Research Network(CERN) built by the Chinese Academy Sciences,the diurnal and seasonal variation characteristics of surface soil heat flux for different soil types and their relationship with the global radiation and net radiation are studied.The results show that the soil heat fluxes of cultivated loessial and purplish soils have the largest diurnal ranges of 220~280 W·m-2,while tableland meadow and paddy soils correspond to the least values of 55 W·m-2.The seasonal difference of the soil surface heat flux in different soil types vary from 12 to 28 W·m-2.The sequence from the largest to the least is gray desert soil,cultivated loessial soils,saline soil,red soil,purple soil and swamp soil and soils.Soil heat flux has obvious positive correlation with global radiation and net radiation.The ratio of the soil heat flux to the net radiation at 12:00(local solar time) is different in different soil types.The tableland meadow soil has the least value of about 8%,while cultivated loessial soil has the largest value of 38%.The ratios of most of soil types are between 15%~20%,which fully shows that the transmission of soil surface heat flux for different soil types is very different.