Impact of nocturnal planetary boundary layer on urban air pollutants: Measurements from a 250-m tower over Tianjin, China

Si, Han; Hai, Bian; Tie, Xuexi; Xie, Yuantao; Sun, Min; Liu, Aixia

doi:10.1016/j.jhazmat.2008.05.056

Cited by 94 publications

(33 citation statements)

References 15 publications

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“…On a clear day, pollutants would be diluted when mixing layer rises during the daytime and be limited to inside the NPBL during the nighttime. The average NPBL height during this period in Tianjin was 132 m (Han et al, 2009), which is similar to that in Beijing (130 km from Tianjin) (Liu et al, 2002). Emitted pollutants such as NO are kept beneath this inversion, which may cause the hourly NO x concentration to increase during the night.…”

Section: Hourly Variation Of O 3 No No 2 and No X Concentrationssupporting

confidence: 70%

“…For example, Hai Bian (Bian et al, 2007;Han et al, 2009;Li et al, 2009;Gu et al, 2010) presented evidence that aerosol particles have a strong effect on the surface ozone concentration in Tianjin. However, O 3 concentration and its precursors were not systemically measured and the relationship between O 3 and its precursors was not analyzed.…”

Section: Introductionmentioning

confidence: 99%

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Analysis of the Relationship between O3, NO and NO2 in Tianjin, China

Hai

Feng

et al. 2011

Aerosol Air Qual. Res.

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272

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The continuous measurement of nitric oxide (NO), nitrogen dioxide (NO 2) , nitrogen oxides (NO x ) and ozone (O 3 ) was conducted in Tianjin from September 8 to October 15, 2006. The data were used to investigate the relationship between the O 3 distribution and its association with ambient concentrations of NO, NO 2 and NO x (NO and NO 2 ). The measured concentrations of the pollutants in the study area varied as a function of time, while peaks in NO, NO 2 and O 3 all occurred in succession in the daytime. The diurnal cycle of ground-level ozone concentration showed a mid-day peak and lower nighttime concentrations. Furthermore, an inverse relationship was found between O 3 NO, NO 2 and NO x . In addition, a linear relationship between NO 2 and NO x , as well as NO and NO x , and a polynomial relationship between O 3 and NO 2 /NO was found.The variation in the level of oxidant (O 3 and NO 2 ) with NO 2 was also obtained. It can be seen that OX concentration at a given location is made up of two parts: one independent and the other dependent on NO 2 concentration. The independent part can be considered as a regional contribution and is about 20 ppb in Tianjin.An obvious difference in NO, NO x and O 3 concentrations between weekdays and weekends was also found, but this difference did not appear in NO 2 .Lastly, the diurnal variation of O 3 concentration under different meteorological conditions was demonstrated and analyzed.

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Section: Hourly Variation Of O 3 No No 2 and No X Concentrationssupporting

confidence: 70%

Section: Introductionmentioning

confidence: 99%

Analysis of the Relationship between O3, NO and NO2 in Tianjin, China

Hai

Feng

et al. 2011

Aerosol Air Qual. Res.

Self Cite

272

183

View full text Add to dashboard Cite

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“…Wood et al (2010) found similar behaviour, but also estimated boundary layer height using turbulence measurements on the 190m BT Tower in London to test mixed layer scaling. Han et al (2009) used a 250 m Tower in Tianjin to relate nocturnal pollutant levels to mixing height (MH) dynamics. Despite the micrometeorological advantage of such high level measurements to assess large-scale urban footprints, simultaneous observation of all heights of the UBL is generally lacking -and given the potential complexities of UBL structure, this is particularly desirable.…”

Section: Introductionmentioning

confidence: 99%

Boundary layer dynamics over London, UK, as observed using Doppler lidar during REPARTEE-II

et al. 2011

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Abstract. Urban boundary layers (UBLs) can be highly complex due to the heterogeneous roughness and heating of the surface, particularly at night. Due to a general lack of observations, it is not clear whether canonical models of boundary layer mixing are appropriate in modelling air quality in urban areas. This paper reports Doppler lidar observations of turbulence profiles in the centre of London, UK, as part of the second REPARTEE campaign in autumn 2007. Lidar-measured standard deviation of vertical velocity averaged over 30 min intervals generally compared well with in situ sonic anemometer measurements at 190 m on the BT telecommunications Tower. During calm, nocturnal periods, the lidar underestimated turbulent mixing due mainly to limited sampling rate. Mixing height derived from the turbulence, and aerosol layer height from the backscatter profiles, showed similar diurnal cycles ranging from c. 300 to 800 m, increasing to c. 200 to 850 m under clear skies. The aerosol layer height was sometimes significantly different to the mixing height, particularly at night under clear skies. For convective and neutral cases, the scaled turbulence profiles resembled canonical results; this was less clear for the stable case. Lidar observations clearly showed enhanced mixing beneath stratocumulus clouds reaching down on occasion to approximately half daytime boundary layer depth. OnCorrespondence to: J. F. Barlow (j.f.barlow@reading.ac.uk) one occasion the nocturnal turbulent structure was consistent with a nocturnal jet, suggesting a stable layer. Given the general agreement between observations and canonical turbulence profiles, mixing timescales were calculated for passive scalars released at street level to reach the BT Tower using existing models of turbulent mixing. It was estimated to take c. 10 min to diffuse up to 190 m, rising to between 20 and 50 min at night, depending on stability. Determination of mixing timescales is important when comparing to physicochemical processes acting on pollutant species measured simultaneously at both the ground and at the BT Tower during the campaign. From the 3 week autumnal data-set there is evidence for occasional stable layers in central London, effectively decoupling surface emissions from air aloft.

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“…NCP is one of the most populated and polluted regions in China. During the recent years, the rapid economical development has resulted in heavy atmospheric aerosol loadings in this region (Bian et al, 2007;Han et al, 2009;Tie et al, 2009;). The high aerosol concentrations induce severely environmental and climate problems.…”

Section: Introductionmentioning

confidence: 99%

Analysis of the formation of fog and haze in North China Plain (NCP)

et al. 2011

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Abstract. North China Plain (NCP) is one of the most populated and polluted regions in China. During the recent years, haze and fog occur frequently and cause severely low visibility in this region. In order to better understand the impact of aerosol particles on the formation of haze and fog, a long-term record of haze and fog occurrences in the past 56 yr (from 1954-2009) over NCP is analyzed. The results show that there are rapid changes in the occurrences of haze and fog over NCP. The occurrences of haze and fog were low during 1970-1980, and reached a maximum during 1981-1998. After 1999, the occurrences of haze and fog slightly decreased. There was a nonlinear relationship between the occurrences of haze and fog. When the occurrence of haze was lower than 40 days yr −1 , the occurrence of fog was strongly proportional to the occurrence of haze. However, when the occurrence of haze was high (larger than 75 days yr −1 ), the occurrence of fog was not sensitive to the occurrence of haze. In order to better understand the relationship between the occurrences of haze and fog as well as the effect of aerosol particles on the formation of haze and fog, an in-situ field experiment was conducted during a period with a mixed occurrence of haze and fog. The analysis of the experiment suggests that there were considerably high aerosol concentrations during the measurement period with an averaged aerosol number concentration of 24 000 cm −3 . The measurement also shows that a large amount of aerosol particles can act as condensation nuclei to enhance the formation of fog droplets. As a result, a large amount of fog droplets (>1000 cm −3 ) with small size (5-6 µm) were observed during the fog period, resulting in extremely low visibility (less than 100 m).

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Impact of nocturnal planetary boundary layer on urban air pollutants: Measurements from a 250-m tower over Tianjin, China

Cited by 94 publications

References 15 publications

Analysis of the Relationship between O3, NO and NO2 in Tianjin, China

Analysis of the Relationship between O3, NO and NO2 in Tianjin, China

Boundary layer dynamics over London, UK, as observed using Doppler lidar during REPARTEE-II

Analysis of the formation of fog and haze in North China Plain (NCP)

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