WPL校正和坐标轴旋转对稻田湍流通量计算的影响

Influence of WPL Correction and Coordinate Rotation on Turbulent Fluxes Calculation in Paddy Field

利用鄱阳湖流域赣抚平原灌区2011年晚稻种植期间观测的涡度相关通量数据,定量分析了WPL校正与3种坐标轴旋转方法对稻田生态系统摩擦风速和湍流通量计算的影响,结果表明:WPL校正对CO2通量与潜热通量计算结果有显著影响。与未经WPL校正的通量数据计算值相比,WPL校正可使CO2通量计算值减小11%,潜热通量计算值增大5.5%,即通过WPL校正可使稻田能量闭合度提高5%左右。二次坐标轴旋转法对晚稻田摩擦风速值的影响最小,而平面拟合法对其影响最大,但二次坐标轴旋转法、三次坐标轴旋转法以及平面拟合法的计算结果之间的差别并不大(<1%)。倾斜校正使得湍流通量计算结果的绝对值趋于变小,且对动量通量计算值的影响最大。对于下垫面平坦、均质的稻田,推荐采用二次坐标轴旋转法对其观测的通量数据进行倾斜校正。

The eddy covariance technique has been used to measure turbulence fluxes data between rice and the atmosphere in 2011 in Ganfu plain irrigation area of Poyang lake area .This paper analyzed the influence of the WPL correction and three coordinate rotation methods on friction wind speed and turbulence fluxes measured in paddy field ecosystem . The results showed that , the WPL correction has a significant influence on CO2 flux and latent heat flux .Compared with calculation based on the original data ,WPL correction method decreased CO2 flux by about 11% ,while reduced latent heat flux by about 5 .5% ,that is ,WPL correction obvi‐ously increased energy balance closure by about 5% for later season rice .The impact of Double Rotation on friction velocity （u＊ ） was minimal ,while the impact of Planar Fit on u＊ was maximal ,however ,there existed not much difference between Double Rota‐tion ,Triple Rotation and Planar Fit （〈1% ） .The absolute values of turbulent fluxes tended to be smaller because of tilt correction , and the influence of tilt correction on momentum flux was the largest . For paddy fields with flat and homogeneous underlying surface ,Double Rotation was recommended as a normalized measure method of tilt correction .