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坐标旋转对东北山地森林涡动通量的影响
引用本文:王兴昌,王传宽.坐标旋转对东北山地森林涡动通量的影响[J].生态学杂志,2016,27(9):2779-2788.
作者姓名:王兴昌  王传宽
作者单位:东北林业大学生态研究中心, 哈尔滨 150040
基金项目:国家自然科学基金项目(41503071)和教育部长江学者和创新团队发展计划项目(IRT_15R09)资助
摘    要:坐标旋转是复杂地形条件下涡动协方差(EC)通量观测的必要步骤,系统评价不同坐标旋转方法的影响有助于提高EC通量观测的精度.以处于山谷坡面的帽儿山温带落叶阔叶林为例,采用标准主轴法探讨了复杂地形条件下不同倾斜校正方法对感热通量(H)、潜热通量(LE)、CO2通量(Fc)、能量平衡、摩擦风速(u*)和垂直速度(w)的影响.结果表明: 与校正前的通量相比,二次旋转(DR)、平面拟合(PF)、垂直速度无偏平面拟合(NBPF)、月尺度平面拟合(MPF)、三次旋转(TR)和月尺度分风向区平面拟合(MSWPF)得到的H变幅依次为+1.5%、+3.8%、+3.1%、+3.3%、-1.3%和-7.1%.对LE来说,NBPF和DR分别升高1.0%和0.4%,PF增加0.671 W·m-2,MPF降低0.4%,但截距增加0.747 W·m-2,MSWPF和TR则分别降低4.5%和15.1%.坐标旋转后Fc降幅为6.0%(DR)~12.1%(TR).不同倾斜校正方法中,PF使能量平衡闭合平均提高约2%,TR却降低约6%.从校正后的u*w看,TR和NBPF不宜用于风速仪倾斜校正.考虑到EC观测精度和应用,帽儿山站坐标系统应优先选择PF,其次为DR.此结果为复杂地形条件下EC通量观测的风速仪倾斜校正提供参考.

关 键 词:涡动协方差  倾斜校正  二次旋转  三次旋转  平面拟合  能量平衡
收稿时间:2016-04-18

Effects of coordinate rotations on eddy fluxes over a forest on a mountainous terrain in Northeast China.
WANG Xing-chang,WANG Chuan-kuan.Effects of coordinate rotations on eddy fluxes over a forest on a mountainous terrain in Northeast China.[J].Chinese Journal of Ecology,2016,27(9):2779-2788.
Authors:WANG Xing-chang  WANG Chuan-kuan
Institution:Center for Ecological Research, Northeast Forestry University, Harbin 150040, China
Abstract:Coordinate rotation is an essential step in eddy covariance (EC) flux measurements particularly on complex terrains. Systematically assessing impacts of coordinate rotation methods can improve the accuracy in EC flux estimations. Taking the Maoershan flux tower in a temperate deci-duous forest on valley slopes as a case, we comprehensively examined the effects of various tilt-correction methods on sensible heat flux (H), latent heat flux (LE), CO2 fluxes (Fc), energy ba-lance, friction velocity (u*), and vertical velocity (w) using the standardized major axis method. Compared with the unrotated fluxes, the double rotation (DR), planar fit (PF), vertical velocity unbiased planar fit (NBPF), monthly planar fit (MPF), triple rotation (TR) and monthly sector-wist planar fit (MSWPF) changed the H by +1.5%, +3.8%, +3.1%, +3.3%, -1.3% and -7.1%, respectively. The NBPF and DR increased LE by 1.0% and 0.4%, respectively. The PF also increased LE by 0.671 W·m-2, and the MPF decreased LE by 0.4%, but increased the intercept by 0.747 W·m-2. In contrast, the MSWPF and TR decreased the LE by 4.5% and 15.1%, respectively. The coordinate rotation reduced the Fc by 6.0% (DR)-12.1% (TR). Among the studied methods, the PF increased the energy balance closure by about 2%, whereas the TR decreased it by about 6%. In the light of u* and w, the TR and NBPF were inappropriate for anemometer tilt correction. Considering the precision and practical application of EC measurements, we recommend the PF as the first choice for the Maoershan flux tower site, followed by the DR. These findings are useful for tilt correction of anemometer in EC flux observations over complex terrains.
Keywords:eddy covariance  tilt correction  double rotation  triple rotation  planar fit  energy balance
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