Multiaxis differential absorption spectroscopy(MAX-DOAS)is a newly developed advanced vertical profile detection method,but the vertical nitrogen dioxide(NO_(2))profiles measured by MAX-DOAS have not yet been fully ve...Multiaxis differential absorption spectroscopy(MAX-DOAS)is a newly developed advanced vertical profile detection method,but the vertical nitrogen dioxide(NO_(2))profiles measured by MAX-DOAS have not yet been fully verified.In this study,we perform MAX-DOAS and tower gradient observations to simultaneously acquire tropospheric NO_(2)observations in the Beijing urban area from 1 April to 31 May 2019.The average values of the tropospheric NO_(2)vertical column densities measured by MAX-DOAS and the tropospheric monitoring instrument are 15.8×1015 and 12.4×1015 molecules cm−2,respectively,and the correlation coefficient R reaches 0.87.The MAX-DOAS measurements are highly consistent with the tower-based in situ measurements,and the correlation coefficients R from the ground to the upper air are 0.89(60 m),0.87(160 m),and 0.76(280 m).MAX-DOAS accurately measures the trend of NO_(2)vertical profile changes,although a large underestimation occurs by a factor of two.By analyzing the NO_(2)vertical profile,the NO_(2)concentration reveals an exponential decrease with height.The NO_(2)vertical profile also coincides with the evolution of the boundary layer height.The study shows that the NO_(2)over Beijing mainly originates from local sources and occurs in the boundary layer,and its vertical evolution pattern has an important guiding significance to better understand nitrate production and ozone pollution.展开更多
Air-sea heat flux intensifies during cold airs and other strong weather events.However,due to the lack of long-term observations during such cold air processes,the quantitative enhancement of air-sea heat flux and its...Air-sea heat flux intensifies during cold airs and other strong weather events.However,due to the lack of long-term observations during such cold air processes,the quantitative enhancement of air-sea heat flux and its underlying mechanisms remain poorly understood.To address this issue,based on a tower-based platform in the southern Bohai Sea,a high-frequency turbulence measurement system was implemented to conduct a two-year air-sea flux measurement,collecting air-sea heat flux data covering 20 cold air outbreak events.This study quantitatively analyzes and reveals the pronounced variations in air-sea sensible heat flux of SHF and latent heat flux of LHF during cold air events,as well as the distinct roles of wind speed,air-sea temperature difference and specific humidity difference.The enhancement of SHF and LHF is further quantified.Our results show that the significant increases in wind speed and air-sea temperature difference are the primary drivers of the enhanced heat flux.Although LHF exhibits higher magnitude than SHF during cold air processes,LHF is predominantly controlled by increased wind speed,whereas SHF is mainly influenced by both wind speed and the air-sea temperature difference,with its enhancement being substantially greater than that of LHF.Compared to calm weather conditions,SHF and LHF under cold air conditions increased by an average of 12.8 and 1.6 times,respectively,while the total heat flux increased by 2.6 times on average.The increasement of heat flux can exceed 10 times during cold waves,even can reach the magnitude comparable to that observed during tropical cyclones.展开更多
Due to the long-standing lack of understanding the role of wind waves on wind stress at moderate to high wind speeds,a high-frequency turbulence observation system is used in this study to obtain air-sea momentum flux...Due to the long-standing lack of understanding the role of wind waves on wind stress at moderate to high wind speeds,a high-frequency turbulence observation system is used in this study to obtain air-sea momentum flux data under pure wind wave conditions based on the tower-based marine meteorological observation platform in the southern Bohai Sea.Moreover,the modulation of wind waves on wind stress under wind speeds greater than 10 m s^(–1)is analyzed.The results indicated that the wind wave states caused by winds from the northwest and northeast are different under the influence of cold air,resulting in different wind stresses and drag coefficients.The wind stress increases with an increasing wind speed,reaching its maximum value when the northwest wind is nearly 20 m s^(–1),while the extreme value of the drag coefficient is basically the same when the northwest wind speed is the maximum and the northeast wind wave significant wave height is the maximum.The drag coefficient increases with an increasing wind speed within the range of 10–15 m s^(–1),reaching saturation at 15 m s^(–1).The critical wind speed is smaller than other observed results.Further analysis showed that wind-induced turbulent stress deviates from the observed values,and the degree of deviation depends on the wind speed and wave state,with a greater deviation caused by strong winds and waves.The wave-induced stress can correct the negative deviation between wind-induced turbulent stress and the observed value,and the drag coefficient calculated based on the modified wind stress tends to be close to the observed value overall.展开更多
基金This work was supported by the National Key R&D Program of China(Grant No.2017YFC0210000)the National Natural Science Foundation of China(Grant Nos.41705113,41877312)+1 种基金the National Research Program for Key Issues in Air Pollution Control(Grant No.DGQQ202004)the Beijing Major Science and Technology Project(Grant No.Z181100005418014).
文摘Multiaxis differential absorption spectroscopy(MAX-DOAS)is a newly developed advanced vertical profile detection method,but the vertical nitrogen dioxide(NO_(2))profiles measured by MAX-DOAS have not yet been fully verified.In this study,we perform MAX-DOAS and tower gradient observations to simultaneously acquire tropospheric NO_(2)observations in the Beijing urban area from 1 April to 31 May 2019.The average values of the tropospheric NO_(2)vertical column densities measured by MAX-DOAS and the tropospheric monitoring instrument are 15.8×1015 and 12.4×1015 molecules cm−2,respectively,and the correlation coefficient R reaches 0.87.The MAX-DOAS measurements are highly consistent with the tower-based in situ measurements,and the correlation coefficients R from the ground to the upper air are 0.89(60 m),0.87(160 m),and 0.76(280 m).MAX-DOAS accurately measures the trend of NO_(2)vertical profile changes,although a large underestimation occurs by a factor of two.By analyzing the NO_(2)vertical profile,the NO_(2)concentration reveals an exponential decrease with height.The NO_(2)vertical profile also coincides with the evolution of the boundary layer height.The study shows that the NO_(2)over Beijing mainly originates from local sources and occurs in the boundary layer,and its vertical evolution pattern has an important guiding significance to better understand nitrate production and ozone pollution.
基金the platform support from the Shengli Oilfield Branch Offshore Production Plant,Sinopecsupported by the Basic Scientific Fund for National Public Research Institutes of China(Grant No.2024S02)+1 种基金the National Natural Science Foundation of China(Grant Nos.42276024,42249902)the Science and Technology of Laoshan Laboratory(Grant No.LSKJ202201600)。
文摘Air-sea heat flux intensifies during cold airs and other strong weather events.However,due to the lack of long-term observations during such cold air processes,the quantitative enhancement of air-sea heat flux and its underlying mechanisms remain poorly understood.To address this issue,based on a tower-based platform in the southern Bohai Sea,a high-frequency turbulence measurement system was implemented to conduct a two-year air-sea flux measurement,collecting air-sea heat flux data covering 20 cold air outbreak events.This study quantitatively analyzes and reveals the pronounced variations in air-sea sensible heat flux of SHF and latent heat flux of LHF during cold air events,as well as the distinct roles of wind speed,air-sea temperature difference and specific humidity difference.The enhancement of SHF and LHF is further quantified.Our results show that the significant increases in wind speed and air-sea temperature difference are the primary drivers of the enhanced heat flux.Although LHF exhibits higher magnitude than SHF during cold air processes,LHF is predominantly controlled by increased wind speed,whereas SHF is mainly influenced by both wind speed and the air-sea temperature difference,with its enhancement being substantially greater than that of LHF.Compared to calm weather conditions,SHF and LHF under cold air conditions increased by an average of 12.8 and 1.6 times,respectively,while the total heat flux increased by 2.6 times on average.The increasement of heat flux can exceed 10 times during cold waves,even can reach the magnitude comparable to that observed during tropical cyclones.
基金supported by the National Natural Science Foundation of China (Grant No.42276024)the National Natural Science Foundation of China (Grant No.41821004)+1 种基金the Basic Scientific Fund for National Public Research Institutes of China (Grant No.2022Q01)the Science and Technology of Laoshan Laboratory (Grant No.LSKJ202201600)。
文摘Due to the long-standing lack of understanding the role of wind waves on wind stress at moderate to high wind speeds,a high-frequency turbulence observation system is used in this study to obtain air-sea momentum flux data under pure wind wave conditions based on the tower-based marine meteorological observation platform in the southern Bohai Sea.Moreover,the modulation of wind waves on wind stress under wind speeds greater than 10 m s^(–1)is analyzed.The results indicated that the wind wave states caused by winds from the northwest and northeast are different under the influence of cold air,resulting in different wind stresses and drag coefficients.The wind stress increases with an increasing wind speed,reaching its maximum value when the northwest wind is nearly 20 m s^(–1),while the extreme value of the drag coefficient is basically the same when the northwest wind speed is the maximum and the northeast wind wave significant wave height is the maximum.The drag coefficient increases with an increasing wind speed within the range of 10–15 m s^(–1),reaching saturation at 15 m s^(–1).The critical wind speed is smaller than other observed results.Further analysis showed that wind-induced turbulent stress deviates from the observed values,and the degree of deviation depends on the wind speed and wave state,with a greater deviation caused by strong winds and waves.The wave-induced stress can correct the negative deviation between wind-induced turbulent stress and the observed value,and the drag coefficient calculated based on the modified wind stress tends to be close to the observed value overall.
