Aircraft-based CH4 flux estimates for validation of emissions from an agriculturally dominated area in Switzerland
Aircraft-based CH4 flux estimates for validation of emissions from an agriculturally dominated area in Switzerland
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DOI：
10.1002/2013jd020918
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发表时间：
2014-04-27
影响因子：
4.4
通讯作者：
Eugster, Werner
中科院分区：
文献类型：
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作者：
Hiller, Rebecca V.;Neininger, Bruno;Eugster, Werner
对于区域尺度的温室气体收支调查，需要当地排放源的空间明确信息，然后可以与通量测量进行比较。在这里，我们提出了一个空间明确的CH 4排放清单瑞士的一部分的第一次验证。使用低空飞行的飞机（离地面50-500米）的测量结果对农业为主的罗伊斯山谷进行了验证。我们使用现有的地质统计数据将国家排放量估计分布到一个500米单元格大小的网格中。验证通量测量获得涡度相关（EC）技术和边界层预算（BLB）的方法，只使用相同的飞机断面的平均浓度。飞机测量的通量足迹的清单估计值最低（中位数为0.40 g CH（4）m（-2）s（-1）），罗伊斯河谷的BLB通量最高（1.02 g CH（4）m（-2）s（-1）），EC通量介于两者之间（0.62 g CH（4）m（-2）s（-1））。从测量和清单的通量估计是在同一数量级，但测量的通量明显大于清单的排放量估计。这些差异大于与粪肥储存、排放的温度依赖性、牛肠道发酵的昼夜周期以及仅涵盖所有预期甲烷排放量的90%的清单的局限性相关的不确定性。由此我们推断，瑞士的CH 4排放清单估计数可能过低。
For regional-scale investigations of greenhouse gas budgets the spatially explicit information from local emission sources is needed, which then can be compared with flux measurements. Here we present the first validation of a section of a spatially explicit CH4 emission inventory of Switzerland. The validation was done for the agriculturally dominated Reuss Valley using measurements from a low-flying aircraft (50-500 m above ground level). We distributed national emission estimates to a grid with 500 m cell size using available geostatistical data. Validation flux measurements were obtained using the eddy covariance (EC) technique and the boundary layer budgeting (BLB) approach that only uses the mean concentrations of the same aircraft transects. Inventory estimates for the flux footprint of the aircraft measurements were lowest (median 0.40 g CH(4)m(-2)s(-1)), and BLB fluxes were highest (1.02 g CH(4)m(-2)s(-1)) for the Reuss Valley, with EC fluxes in between (0.62 g CH(4)m(-2)s(-1)). Flux estimates from measurements and inventory are within the same order of magnitude, but measured fluxes were significantly larger than the inventory emission estimates. The differences are larger than the uncertainties associated with storage of manure, temperature dependence of emissions, diurnal cycle of enteric fermentation by cattle, and the limitations of the inventory that only covers 90% of all expected methane emissions. From this we deduce that it is not unlikely that the Swiss CH4 emission inventory estimates are too low.