光腔衰荡光谱(CRDS)法观测我国4个本底站大气CO2

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风山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、龙风山和上甸子站CO2平均体积...

Measurement of atmospheric CO2 mixing ratio by cavity ring-down spectroscopy (CRDS) at the 4 background stations in China

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.