【摘要】 城市是人类居住和活动最集中地区，其CO₂排放量占世界总排放量的71%,城市碳排放规律研究对全球碳减排工作具有重要意义。利用涡动相关技术观测了北京市某街区2015年至2016年的CO₂通量，重点研究了不同时间尺度和气象条件下的CO₂通量的日变化规律，分析了影响城市CO₂通量的社会及自然因素。结果表明，CO₂通量日变化特征具有（1）明显的早晚“双峰型”特征，早晚高峰分别出现在早上7:30—9:30和晚上17:30—20:30;（2）周末特征：周末早高峰时间延迟，晚于工作日约1.5h,且峰值低了约10.8%,但晚高峰时间提前，且峰值高于工作日约10.6%;（3）季节特征：冬季CO₂通量均值和早高峰值明显高于其他季节，夏季中午具有明显低峰区；（4）风向特征：在不同来风方向上，CO₂通量的日变化峰值差异很大；（5）天气特征：阴天双峰特征比晴天明显。研究表明CO₂通量日变化主要与交通流量动态变化关系最为密切，其次要受到植被的影响。因此，交通减排和植被增汇对于控制城市碳排放具有重要意义。更多还原

【Abstract】 Cities are the most concentrated area of human habitation and activities, and their CO₂ emissions account for 71% of the world′s total emissions. The study on the law of urban carbon emission has great significance for the reduction of the global carbon emission. In this study, we used the eddy covariance（EC） to measure CO₂ fluxes of a block in Beijing, China in 2015—2016, and analyzed the patterns of diurnal variations in CO₂ fluxes over different timescales. The diurnal variations in CO₂ fluxes exhibited（1） the obvious “bimodal” pattern: peaks of CO₂ fluxes appeared at 7:30—9:30 and 17:30—20:30 in the morning and the evening, respectively.（2） The weekend phenomona: Compared with weekday, the peak in the morning on weekends appeared about 1.5 hours later and 10.8% lower, while the peak in the evening was about 10.6% higher.（3） The seasonal dependence: The mean and daily peak values of CO₂ fluxes in winter were significantly higher than those in other seasons. There was an obvious valley in CO₂ fluxes at noon in summer.（4） Differences among wind direction: In the two main wind directions, the peaks varied greatly.（5） The weather influence: The “bimodal” pattern on cloudy days was more obvious than that on sunny days. Our research suggested that the diurnal variation of CO₂ fluxes in cities was mainly related to traffic volume, and was secondarily affected by vegetation. Therefore, the reduction in traffic emission and enhancement in vegetation sink play an important role in reducing carbon emissions in cities.更多还原