Seasonal variations of acetone in the upper troposphere-lower stratosphere of the northern midlatitudes as observed by ACE-FTS
Seasonal variations of acetone in the upper troposphere-lower stratosphere of the northern midlatitudes as observed by ACE-FTS
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ACE-FTS观测的北半球中纬度对流层上层-平流层下层丙酮的季节变化
DOI：
10.1016/j.jms.2016.02.006
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发表时间：
2016
影响因子：
1.4
通讯作者：
Dufour G
中科院分区：
文献类型：
--
作者：
Dufour G
本研究报告了北方中纬度地区对流层上部和平流层下部的气候学丙酮分布和季节变化，这些数据来自SCISAT卫星上的大气化学实验傅里叶变换光谱仪（ACE-FTS）的观测。从5到2020公里处检索的丙酮剖面涵盖2004年1月至2010年9月期间。1σ统计拟合误差在对流层上部（UT）通常为105 -20%，在平流层下部（LS）随着丙酮的减少而增加。系统误差在15%~ 20%之间。夏季在北方中高纬度观测到最大的UT丙酮混合比（西伯利亚7月平均1200 ppt）。大陆区域的混合比大于海洋区域。与空气中的测量结果在文献中的比较指向一个可能的低估丙酮从ACE-FTS检索。最大的差异主要发生在冬季和背景值。这种低估归因于用于检索的光谱区域的复杂性。30-70°N中纬带丙酮的年循环在夏季有一个极大值，反映了丙酮主要陆源生物源的年循环。与ACE-FTS相比，LMDz-INCA全球气候化学模式系统性地高估了低于400 ppt的丙酮混合比。因此，这种高估是普遍的平流层下部，热带和70°N以上的对流层上部。相比之下，在对流层上层30-70°N区域，丙酮浓度最高（平均>450 ppt），模式-观测差异在观测不确定度范围内。然而，在这一地区，该模型未能捕捉到丙酮的年度循环，在7月达到顶峰。只有考虑到高生物源排放量才能得出季节性周期，但这一周期向秋季转移，可能表明低估了北方高纬度地区的化学破坏。
This study reports on the climatological acetone distribution and seasonal variations in the upper troposphere and lower stratosphere of the northern midlatitudes, derived from observations by the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) onboard SCISAT. The acetone profiles retrieved from 5 to ∼20 km cover the period from January 2004 to September 2010. The 1σstatistical fitting errors are typically ∼5–20% within the upper troposphere (UT), increasing in the lower stratosphere (LS) with decreasing acetone. The systematic errors range between 15% and 20%. The largest UT acetone mixing ratios (∼1200 ppt on average in July over Siberia) are observed in summer in the northern mid- and high latitudes. Mixing ratios are larger over continental regions than over the ocean. Comparisons with airborne measurements available in the literature point toward a possible underestimation in acetone retrieved from ACE-FTS. The largest differences occur primarily in winter and for the background values. This underestimation is attributed to the complexity of the spectral region used for the retrieval. The annual cycle of acetone for the 30–70°N midlatitude band shows a maximum during summer, reflecting the annual cycle of the primary terrestrial biogenic source of acetone. By comparison with ACE-FTS, the LMDz-INCA global climate-chemistry model systematically overestimates acetone mixing ratios lower than 400 ppt. This overestimation is thus generalized for the lower stratosphere, the Tropics and beyond 70°N for the upper troposphere. In contrast, in the upper troposphere of the 30–70°N region, where the acetone levels are the highest (>450 ppt on average), the model-observation differences are in the range of the observation uncertainty. However, in this region, the model fails to capture the annual cycle of acetone, culminating in July. A seasonal cycle can only be obtained by considering high biogenic emissions but this cycle is shifted toward autumn, likely indicating an underestimation of the chemical destruction in the northern high latitudes.