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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >A Vertical Diffusion Scheme to estimate the atmospheric rectifier effect - art. no. D04306
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A Vertical Diffusion Scheme to estimate the atmospheric rectifier effect - art. no. D04306

机译：用于估计大气整流器效果的垂直扩散方案-艺术没有。 D04306

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The magnitude and spatial distribution of the carbon sink in the extratropical Northern Hemisphere remain uncertain in spite of much progress made in recent decades. Vertical CO2 diffusion in the planetary boundary layer (PBL) is an integral part of atmospheric CO2 transport and is important in understanding the global CO2 distribution pattern, in particular, the rectifier effect on the distribution [Keeling et al., 1989; Denning et al., 1995]. Attempts to constrain carbon fluxes using surface measurements and inversion models are limited by large uncertainties in this effect governed by different processes. In this study, we developed a Vertical Diffusion Scheme (VDS) to investigate the vertical CO2 transport in the PBL and to evaluate CO2 vertical rectification. The VDS was driven by the net ecosystem carbon flux and the surface sensible heat flux, simulated using the Boreal Ecosystem Productivity Simulator (BEPS) and a land surface scheme. The VDS model was validated against half-hourly CO2 concentration measurements at 20 m and 40 m heights above a boreal forest, at Fraserdale (49degrees52'29.9"N, 81degrees34'12.3"W), Ontario, Canada. The amplitude and phase of the diurnal/seasonal cycles of simulated CO2 concentration during the growing season agreed closely with the measurements (linear correlation coefficient (R) equals 0.81). Simulated vertical and temporal distribution patterns of CO2 concentration were comparable to those measured at the North Carolina tower. The rectifier effect, in terms of an annual-mean vertical gradient of CO2 concentration in the atmosphere that decreases from the surface to the top of PBL, was found at Fraserdale to be about 3.56 ppmv. Positive covariance between the seasonal cycles of plant growth and PBL vertical diffusion was responsible for about 75% of the effect, and the rest was caused by covariance between their diurnal cycles. The rectifier effect exhibited strong seasonal variations, and the contribution from the diurnal cycle was mostly confined to the surface layer ( less than 300 m). [References: 67]
机译：尽管近几十年来取得了很大进展，但温带北半球碳汇的规模和空间分布仍不确定。二氧化碳在行星边界层（PBL）中的垂直扩散是大气中CO2传输不可或缺的一部分，对于理解全球CO2的分布模式，特别是整流器对分布的影响，具有重要意义[Keeling等，1989; N.C。等。 Denning等，1995]。使用表面测量和反演模型来限制碳通量的尝试受到这种不确定性的巨大不确定性的限制，这种不确定性受不同过程的制约。在这项研究中，我们开发了一种垂直扩散方案（VDS），以研究PBL中的垂直CO2传输并评估CO2垂直精馏。 VDS是由生态系统净碳通量和表面感热通量驱动的，使用北方生态系统生产力模拟器（BEPS）和陆地表面方案进行了模拟。在加拿大安大略省的弗雷泽代尔（Fraserdale）（北纬49度52'29.9英寸，北纬81度34'12.3英寸），在北方森林上方20 m和40 m高度处，半小时的CO2浓度测量值对VDS模型进行了验证。生长季节内模拟的CO2浓度的昼夜/季节周期的振幅和相位与测量值非常吻合（线性相关系数（R）等于0.81）。模拟的CO2浓度垂直和时间分布模式与在北卡罗莱纳州塔测得的模式相当。在弗雷泽代尔（Fraserdale）发现，根据大气中CO2浓度的年平均垂直梯度（从PBL的表面到顶部的递减），整流器效应约为3.56 ppmv。植物生长的季节性周期与PBL垂直扩散之间的正协方差约占效应的75％，其余的则由它们昼夜周期之间的协方差引起。整流器效应表现出强烈的季节性变化，并且昼夜周期的贡献主要局限于表层（小于300 m）。 [参考：67]

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