稻麦轮作农田近地层湍流通量计算方案对比研究

Comparative Study of Near-Surface Turbulent Flux Calculation Schemes in Rice-Wheat Crop Rotation Farmland

稻麦轮作农田是我国典型农田类型,其模拟效果对我国农田气候模拟具有重要参考价值。气候中尺度模拟结果对近地层通量极为敏感,选择合适的通量计算方案对模拟效果至关重要。因此,对比分析稻麦轮作农田下不同的通量计算方案具有重要意义。本文选取了8种具有代表性的近地层湍流通量计算方案,采用寿县国家气候观象台实测资料对比分析了各方案在稻麦轮作农田的计算特征和差异。结果表明,在不同稳定度和不同风速情况下,各方案的误差特征各异。本文基于归一化标准差综合评价了各方案的准确度,总体而言,所有方案的动量通量总体平均归一化平均差为0.536,其中SS14(Sharan和Srivastava, 2014年)方案最大为0.575,SS20(Sharan和Srivastava等,2020年)方案最小为0.517;所有方案的感热通量总体平均归一化标准差为0.638,其中GLGS20(Gryanik等,2020年)方案最大为0.871,SS14方案最小为0.476。此外,本研究还给出了稻麦轮作农田不同稳定层结和不同风速情况下各通量计算方案的误差特征。本文的研究结论,可为准确计算近地层湍流通量提供支撑。

Rice-wheat rotation farmland is a typical type of farmland understory in China,and its simulation effect has important reference value for climate modelling of agricultural fields in our country.The results of mesoscale climate simulation are highly sensitive to the calculation schemes of surface fluxes,and selecting appropriate flux calculation schemes is crucial for simulation accuracy.Therefore,it is of great significance to compare and analyse different flux calculation schemes under the rice-wheat crop rotation system.In this paper,eight representative near-surface turbulent flux calculation schemes are selected,and the measured data from the Shouxian National Climatological Observatory are used to compare and analyse the calculation characteristics and differences of the schemes in the underlay of rice-wheat rotation farmland using the method of normalised standard deviation.The results show that the error characteristics of the schemes are different under different stabilised stratification conditions and wind speed conditions.In general,the overall average normalised mean difference of momentum flux of all schemes is 0.536,of which the maximum is 0.575 for the Sharan and Srivastava,2014 scheme(SS14 scheme)and the minimum is 0.517 for the Sharan and Srivastava et al.,2020 scheme;and the overall average normalised standard deviation of sensible heat flux of all schemes is 0.638,of which the maximum is 0.871 for the Gryanik et al.,2020 scheme and the minimum is 0.476 for the SS14 scheme.In addition,this study is also giving the error characteristics of each flux calculation scheme under different stratification conditions and wind speed conditions under the rice-wheat rotation farmland,and finally,this paper is giving recommendations for the selection of turbulent flux calculation schemes for the rice-wheat rotation farmland,for the momentum fluxes,under the unstable stratification conditions,it is recommended to use the SS14 or Li et al.,2014&2015 schemes(Li1415 scheme),the Businger,1971 scheme is recommended for weakly stabilised stratification,and Wang et al.,2002 scheme(Wa02 scheme)is recommended for strongly stabilised stratification;for heat flux calculation,Li et al.,2010 scheme(Li10 scheme)is recommended for unstable and weakly stabilised stratification and Li1415 scheme is recommended for strongly stabilised stratification.Under low wind conditions,it is recommended to use SS14 or Li1415 scheme to calculate the momentum flux and Li10 scheme to calculate the sensible heat flux;under strong wind conditions,it is recommended to use Li1415 scheme to calculate the momentum flux and Gryanik and Lüpkes,2018 scheme or Wa02 scheme to calculate the sensible heat flux.These findings of this paper support the accurate calculation of near-surface layer turbulent flux.