The observation and study on the turbulent flux and transport of CO2 and H2O over suburban areas at the northern part of Qinling Mountains of China
Based on the data obtained on April 2021 to March 2023 from eddy covariance measurements at aerosol and cloud microphysical characteristics field station over Qinling Mountains,CMA,the characteristics of CO2 and H2O concentration,evaporation,and flux of CO2 and H2O were studied and compared with some urban and suburban sites.The influence of temperature,soil temperature at 5cm depth,relative humidity,wind speed and wind direction on CO2 flux were discussed.Furthermore,the total annual CO2 emission/absorption at the northern part of Qinling Mountains was estimated.The result showed that annual mean concentration of CO2 was(404.4±27.9) ×10-6,which was significantly lower than those obtained at urban and suburban areas in East China while compared to the values observed at the global atmospheric background stations and the Chinese atmospheric background stations(Waliguan,Qinghai).The monthly mean concentration of CO2 showed bimodal variation with one peak values in February and the other in October,and the minimum concentration of CO2 was observed in June.The diurnal variation of CO2 concentration showed higher in the early morning and midnight,while lower in the midday during four seasons.The annual mean concentration of H2O was 9.44g/m3.And the total annual evaporation was about 1321.5mm with higher values in summer(598.1mm)and lower values in winter(84.7mm).The CO2 flux observed at Chang'an Station showed obviously diurnal and monthly variation.And it showed strong absorption during daytime in four seasons with the maximum values appearing in June(-11.95 μmol/(m2·s)),and lowest values in January(-4.06 μmol/(m2·s)).For the nighttime it showed net emissions with higher values in July and lower in January.The water vapor flux showed relative higher during daytime and close to zero at night.The total CO2 absorption at daytime was about-3047g/m2,and the total emission of CO2 at night was about 2631g/m2 during the observation period.The diurnal and seasonal variation of CO2 flux was associate with solar radiation,air temperature,soil temperature at 5cm depth,wind speed fluctuations and relative humidity.The result showed that the absorption and emission rate of CO2 at Chang'an station were both increased with temperature,and the respiration of plants was more sensitive to the increased of temperature during nighttime.The negative values of CO2 flux appeared mostly under westerly wind directions during the daytime,which mainly from the area with large coverage of farmland and vegetation.The positive values of CO2 flux at night were both higher under southwesterly and easterly wind directions,which indicating that respiration of plants and anthropogenic emissions were both important to the emission of CO2.In general,the ecosystem of the suburban area with high vegetation coverage in the northern part of the Qinling Mountains was an obvious carbon sink,and the net absorption of CO2 during the study period was about-416g/m2.
CO2 fluxthe northern part of Qinling Mountainssuburban areaeddy covariance methodmeteorological factors
万方数据
