珠江三角洲地区大气CO2浓度特征及地面风的作用

CHARACTERISTICS OF ATMOSPHERIC CO2 CONCENTRATION AND THEIR CORRELATIONS WITH SURFACE WIND IN THE PEARL RIVER DELTA

关键词:  珠三角城市群  大气CO2  浓度  地面风

Key words:  Pearl River Delta  atmospheric CO2  concentration  surface wind

摘要:

利用光腔衰荡光谱(CRDS)技术在线观测了广州番禺大气成分站(GPACS)的大气CO2浓度特征，分析了地面风对CO2的作用。结果表明：(1) 大气CO2在珠江三角洲地区存在明显的地域不均匀特征，2014—2016年期间GPACS的年均本底浓度比全球背景地区平均增加了22.5×10-6(22.5 ppm)；(2) 大气CO2浓度在春季最高，冬、秋季次之，夏季最低，年均值为426.64±15.76 ppm；(3) CO2的日变化为双峰结构，峰值分别在05:00—07:00和21:00—22:00，谷值在13:00—15:00，表明受到了自然过程以及人为排放源的复合影响；(4) 风场显著影响CO2的浓度分布，春、夏季CO2浓度距平日变化与地面风速为显著负相关，秋、冬季则为显著正相关。在春、夏季，S-WSW和NNE-N风向上CO2浓度较低，在秋、冬季，SSE-S和N方向均导致CO2浓度下降。NW和NE-ENE风向在四季中均能提升CO2浓度，其中NW-NNW和NNE-ENE为弱的CO2源区，分别贡献了0.42 ppm 和0.32 ppm 的CO2浓度。

Abstract:

By using cavity ring-down spectroscopy (CRDS) technology, the present study measured the CO2 mole fraction (1×10-6, ppm) for the period 2014—2016 in the Guangzhou Panyu Atmospheric Composition Site (GPACS), a suburban site in the Pearl River Delta (PRD) region of China, and the correlations of CO2 concentration with surface wind were also investigated. Results show that: (1) Atmospheric CO2 has obvious geographical inhomogeneity in the PRD region, and the annual average value of background concentration in GPACS is 22.5 ppm higher than the value in the global background area. (2) The CO2 concentration is the highest in spring, moderate in winter and autumn, and the lowest in summer, with the annual average value being 426.64 ± 15.76 ppm. The diurnal CO2 shows two peaks: one peak at 05:00—07:00 and the other at 21:00—22:00 Local Standard Time, and the minimum value appears at 13:00—15:00. Together, these patterns indicate that the CO2 is affected by the combined effects of anthropogenic and biogenic processes. (3) The diurnal CO2 anomaly and wind speed show a significant negative correlation (p<0.01) during spring and summer, but they show a significant positive correlation (p<0.01) during autumn and winter. In spring and summer, winds from the directions of S-WSW and NNE-N result in lower CO2 concentrations. By contrast, in autumn and winter, winds from the directions of SSE-S and N substantially lower the CO2. Winds from the directions of NW and NE-ENE significantly increase the CO2 concentration throughout the year, and furthermore, winds from the directions of NW-NNW, and NNE-ENE contribute 0.42 ppm and 0.32 ppm to the corresponding CO2 concentration, which indicates that the CO2 may have a potential source in these sectors.