• 关键词：光腔衰荡光谱(CRDS)  大气CO  本底站  体积分数  后向轨迹

• 基金项目：公益性行业科研专项(No.GYHY200806026);国家自然科学基金(No.40775078);国际科技合作重点项目(No.2007DFA20650)

• 方双喜
• 中国气象科学研究院, 中国气象局大气成分观测与服务中心, 中国气象局大气化学重点开放实验室, 北京 100081

• 周凌晞
• 中国气象科学研究院, 中国气象局大气成分观测与服务中心, 中国气象局大气化学重点开放实验室, 北京 100081

• 臧昆鹏
• 中国气象科学研究院, 中国气象局大气成分观测与服务中心, 中国气象局大气化学重点开放实验室, 北京 100081

• 汪巍
• 中国气象科学研究院, 中国气象局大气成分观测与服务中心, 中国气象局大气化学重点开放实验室, 北京 100081

• 许林
• 中国气象科学研究院, 中国气象局大气成分观测与服务中心, 中国气象局大气化学重点开放实验室, 北京 100081

• 张芳
• 中国气象科学研究院, 中国气象局大气成分观测与服务中心, 中国气象局大气化学重点开放实验室, 北京 100081

• 姚波
• 中国气象科学研究院, 中国气象局大气成分观测与服务中心, 中国气象局大气化学重点开放实验室, 北京 100081

• 刘立新
• 中国气象科学研究院, 中国气象局大气成分观测与服务中心, 中国气象局大气化学重点开放实验室, 北京 100081

• 温民
• 中国气象科学研究院, 中国气象局大气成分观测与服务中心, 中国气象局大气化学重点开放实验室, 北京 100081

• 摘要：利用基于光腔衰荡光谱(CRDS)技术自组装的大气CO₂在线观测系统,于2009年在青海瓦里关、浙江临安、北京上甸子和黑龙江龙凤山4个世界气象组织全球大气观测网(WMO/GAW)大气本底站对大气CO₂进行了在线观测.初步分析结果表明,4站全年大气CO₂体积分数最低值出现在7～8月,夏季临安、龙凤山和上甸子站CO₂平均体积分数日变化趋势较接近,每日最低值出现在16:00～18:00(北京时间);临安站CO₂月平均值较高,月均值振幅为10.52×10^-6;龙凤山站月均值振幅在4站中最高,达到28.19×10^-6,主要是由8月较低的CO₂体积分数(平均值373.51×10^-6)引起,同时该站夏季小时平均值的日变化振幅也最高(50.27×10^-6);夏季瓦里关、临安、上甸子和龙凤山站非本底值分别占有效观测数据的50.1%、54.1%、44.6%和56.0%,对夏季0:00、6:00、12:00、18:00(世界时)370多条3日后向轨迹聚类分析结果表明,4站夏季来自污染方向的气团分别占总数的53.4%、45.4%、68.6%和85.0%,可能贡献大量非本底观测数据.

• Abstract：Background mixing ratios of atmospheric CO₂ were continuously measured by cavity ringdown spectroscopy at the 4 World Meteorological Organization/Global Atmosphere Watch (WMO/GAW) stations (Waliguan in Qinghai,Lin'an in Zhejiang,Shangdianzi in Beijing and Longfengshan in Heilongjiang) in 2009. Seasonal variations of CO₂ mixing ratios were observed at the four stations,with the lowest values occurring in summer (July and August) and the highest values in winter or early spring. The diurnal variation patterns at the Lin'an,Longfengshan and Shangdianzi stations in the summer were similar,and the lowest values occurred at about 16:00 (Beijing time). The monthly average CO₂ mixing ratio in Lin'an was the highest with a variation amplitude of only 10.52×10^-6. The variation amplitude of the monthly average at Longfengshan was the highest at 28.19×10^-6,which was mainly ascribed to the relatively low value (373.51×10^-6) in August. Additionally,the diurnal variation amplitude of the hourly average at Longfengshan reached 50.27×10^-6,which was the highest among the 4 stations. Statistical analysis indicated that non-background data for Waliguan,Lin'an,Shangdianzi and Longfengshan accounted for about 50.1%,54.1%,44.6% and 56.0%,respectively of the total valid data. Cluster analysis from 3-day backward trajectories (ca. 370 routes) ending at 0:00,6:00,12:00 and 18:00 (Universal Time Coordinate) showed that air parcels from polluted areas accounted for 53.4%,45.4%,68.6% and 85.0%,respectively of the total data at the four stations. It is evident that the non-background data at the four background stations accounted for a large proportion of the observed data,which should be rationally eliminated when analyzing the long-term trend of background CO₂.

• Key words：CRDS  CO₂  background station  mixing ratio  backward trajectory

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