摘要
利用中国陆地生态系统通量观测网络(ChinaFLUX)西双版纳热带森林通量观测站涡度相关方法测定的热带季节雨林林冠上方三维方向风速(u,v,w)以及CO2浓度、H2O浓度、气温等变量的10 Hz观测资料,选取1、4、7和10月4个代表性月份晴好天气,在全天5个不同时段内(8:00—11:30,12:00—15:00,15:30—19:00,19:30—23:30,0:00—7:30)求算了各要素的功率谱和与垂直风速的协谱,探讨了热带季节雨林林冠上方数据的高低频响应问题。结果表明:在热带季节雨林林冠上方,晴好天气且湍流条件良好状况下,6个变量的功率谱点阵曲线斜率在惯性副区内均满足-2/3定律;并且各要素与垂直风速的协谱点阵曲线斜率在惯性副区内满足-4/3定律。说明大尺度运动对物质和能量传输的贡献在高频率和中等强度频率信号范围内的响应能力能够满足观测所需要求,可以认为在复杂地形条件下西双版纳热带季节雨林进行通量测定的采样频率合理,所获得数据可以用来作为实际通量的结果加以使用。
By using eddy covariance method and a open-path CO2 analyzer placed on a tower in a tropical seasonal rain forest in Xishuangbanna （ChinaFLUX）, the 10 Hz observation data of six microclimate variables including three dimensional direction wind speed （u, v, w） , CO2 concentration, H20 concentration, and air temperature above the canopy of the forest were Obtained, and the clear days in four typical months （January, April, July, and October） were selected to calculate the power spectrum and cospectrum of the variables to vertical velocity （w） at five periods of time in a day （ morning, 08：00-11：30 ; noon, 12：00-15：00 ; afternoon, 15：30-19：00 ; night, 19：30-23：30; before dawn, 0：00-07：30）, aimed to approach the high/low frequency responsivity of the variables above the canopy of tropical seasonal rain forest. Under the conditions of clear weather and good turbulence above the canopy in the tropical seasonal rain forest, the power spectrum slopes of the six variables in their inertial subrange followed -2/3 power law, and their cospectral slopes in inertial subrange followed to -4/3 power law, indicating that the contribution of large-scale motions to matter and energy transference above the canopy could satisfy the requirement of observing the responsivity in high and middle frequency signal areas. It was inferred that our sampling frequency of flux observation was reasonable, and our data obtained from the complicated topographical condition were valid and could be used as the actual flux figures in the further study.
出处
《生态学杂志》
CAS
CSCD
北大核心
2009年第9期1779-1786,共8页
Chinese Journal of Ecology
基金
国家自然科学基金项目(40571163)
中国科学院知识创新工程重要方向项目(KJCX2-YW-432-1和KZCX2-YW-Q1-05-04)
国家重点基础研究发展计划项目(2002CB412501)
中国科学院创新工程重大资助项目(KZCX1-SW-01-01A)
关键词
谱分析
涡度相关
通量测定
热带季节雨林
西双版纳
spectrum analysis
eddy covariance
flux observation
tropical seasonal rain forest
Xishuangbanna.
