Impacts of the near-surface urban boundary layer structure on PM2.5 concentrations in Beijing during winter

2019 ◽  
Vol 669 ◽  
pp. 493-504 ◽  
Author(s):  
Linlin Wang ◽  
Hong Wang ◽  
Junkai Liu ◽  
Zhiqiu Gao ◽  
Yuanjian Yang ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Layer Structure ◽  
Urban Boundary Layer ◽  
Near Surface ◽  
Boundary Layer Structure

scholarly journals Integrated System for Atmospheric Boundary Layer Height Estimation (ISABLE) using a ceilometer and microwave radiometer

2020 ◽  
Vol 13 (12) ◽  
pp. 6965-6987
Author(s):  
Jae-Sik Min ◽  
Moon-Soo Park ◽  
Jung-Hoon Chae ◽  
Minsoo Kang
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Layer Structure ◽  
Microwave Radiometer ◽  
Accurate Determination ◽  
Integrated System ◽  
Lapse Rate ◽  
High Temporal Resolution ◽  
Near Surface ◽  
Boundary Layer Structure

Abstract. Accurate boundary layer structure and height are critical in the analysis of the features of air pollutants and local circulation. Although surface-based remote sensing instruments provide a high temporal resolution of the boundary layer structure, there are numerous uncertainties in terms of the accurate determination of the atmospheric boundary layer heights (ABLHs). In this study, an algorithm for an integrated system for ABLH estimation (ISABLE) was developed and applied to the vertical profile data obtained using a ceilometer and a microwave radiometer in Seoul city, Korea. A maximum of 19 ABLHs were estimated via the conventional time-variance, gradient, wavelet, and clustering methods using the backscatter coefficient from the ceilometer. Meanwhile, several stable boundary layer heights were extracted through near-surface inversion and environmental lapse rate methods using the potential temperature from the microwave radiometer. The ISABLE algorithm can find an optimal ABLH from post-processing, such as k-means clustering and density-based spatial clustering of applications with noise (DBSCAN) techniques. It was found that the ABLH determined using ISABLE exhibited more significant correlation coefficients and smaller mean bias and root mean square error between the radiosonde-derived ABLHs than those obtained using the most conventional methods. Clear skies exhibited higher daytime ABLH than cloudy skies, and the daily maximum ABLH was recorded in summer because of the more intense radiation. The ABLHs estimated by ISABLE are expected to contribute to the parameterization of vertical diffusion in the atmospheric boundary layer.

scholarly journals The Development of Boundary Layer Structure Index (BLSI) and Its Relationship with Ground Air Quality

Atmosphere ◽  
2018 ◽  
Vol 10 (1) ◽  
pp. 3 ◽  
Author(s):  
Xiang Zheng ◽  
Jun Qin ◽  
Shengwen Liang ◽  
Zhengxuan Yuan ◽  
Yassin Mbululo
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
Layer Structure ◽  
Ambient Air ◽  
Air Quality Monitoring ◽  
Ambient Air Quality ◽  
Vertical Diffusion ◽  
Near Surface ◽  
Boundary Layer Structure ◽  
Structure Index

Ambient air quality monitoring data and radar tracking sonde data were used to study the atmospheric boundary layer structure (ABLS) and its changing characteristics over Wuhan. The boundary layer structure index (BLSI), which can effectively describe the ABLS, was accordingly developed and its ability to describe the near-surface air quality was analyzed. The results can be summarized as follows. (1) An analysis of the ABLS during seriously polluted cases revealed that the ABLS was usually dry and warm with a small ventilation index (VI); meanwhile, the ABLS during clean cases was usually wet and cold with a large VI. (2) The correlation between the air quality and BLSI at 100~300 m was good and passed the confidence level limit at 99%. Moreover, the correlation coefficient increased with the altitude at 10~250 m and showed a downward trend at 250~500 m. The correlation between the BLSI at 250 m and the ground air quality was the most significant (r = 0.312), indicating that the layer ranging from 0 to 250 m is essential for determining the ground air quality. (3) The BLSI considers both the vertical diffusion capability and horizontal removal capability of the atmosphere. Therefore, it is highly capable of describing the ABLS and the ground air quality.

Impact of Parameterized Boundary Layer Structure on Tropical Cyclone Rapid Intensification Forecasts in HWRF

2017 ◽  
Vol 145 (4) ◽  
pp. 1413-1426 ◽  
Author(s):  
Jun A. Zhang ◽  
Robert F. Rogers ◽  
Vijay Tallapragada
Keyword(s):  
Boundary Layer ◽  
Tropical Cyclone ◽  
Inner Core ◽  
Layer Structure ◽  
Intensity Change ◽  
Rapid Intensification ◽  
Near Surface ◽  
Boundary Layer Structure ◽  
Tangential Wind ◽  
The Impact

Abstract This study evaluates the impact of the modification of the vertical eddy diffusivity (Km) in the boundary layer parameterization of the Hurricane Weather Research and Forecasting (HWRF) Model on forecasts of tropical cyclone (TC) rapid intensification (RI). Composites of HWRF forecasts of Hurricanes Earl (2010) and Karl (2010) were compared for two versions of the planetary boundary layer (PBL) scheme in HWRF. The results show that using a smaller value of Km, in better agreement with observations, improves RI forecasts. The composite-mean, inner-core structures for the two sets of runs at the time of RI onset are compared with observational, theoretical, and modeling studies of RI to determine why the runs with reduced Km are more likely to undergo RI. It is found that the forecasts with reduced Km at the RI onset have a shallower boundary layer with stronger inflow, more unstable near-surface air outside the eyewall, stronger and deeper updrafts in regions farther inward from the radius of maximum wind (RMW), and stronger boundary layer convergence closer to the storm center, although the mean storm intensity (as measured by the 10-m winds) is similar for the two groups. Finally, it is found that the departure of the maximum tangential wind from the gradient wind at the eyewall, and the inward advection of angular momentum outside the eyewall, is much larger in the forecasts with reduced Km. This study emphasizes the important role of the boundary layer structure and dynamics in TC intensity change, supporting recent studies emphasizing boundary layer spinup mechanism, and recommends further improvement to the HWRF PBL physics.

scholarly journals Integrated System for Atmospheric Boundary Layer Height Estimation (ISABLE) using a Ceilometer and Microwave Radiometer

2020 ◽  
Author(s):  
Jae-Sik Min ◽  
Moon-Soo Park ◽  
Jung-Hoon Chae ◽  
Minsoo Kang
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Layer Structure ◽  
Microwave Radiometer ◽  
Integrated System ◽  
Lapse Rate ◽  
High Temporal Resolution ◽  
Near Surface ◽  
Boundary Layer Structure ◽  
Mean Square Errors

Abstract. Accurate boundary-layer structure and height are critical in analyzing the features of air pollutants as well as the local circulation. Although surface-based remote sensing instruments give high temporal resolution of the boundary-layer structure, there were many uncertainties in determining the accurate atmospheric boundary-layer heights (ABLHs). In this study, an algorithm for an integrated system for ABLH estimation (ISABLE) was developed and applied to the vertical profile data obtained by a ceilometer and microwave radiometer in Seoul City, Korea. A maximum of 19 ABLHs were calculated by the conventional time-variance, gradient, wavelet, and clustering methods using the backscatter coefficient data. Meanwhile, several stable boundary layer heights were extracted by the near-surface inversion and environmental lapse rate methods using potential temperature data. The ISABLE algorithm could find an optimal ABLH from post-processing including k-means clustering and density-based spatial clustering of applications with noise (DBSCAN) techniques. It is found that the ABLH determined by ISABLE exhibited larger correlation coefficients and smaller absolute bias and root mean square errors between the radiosonde-derived ABLHs than those obtained by most conventional methods. Clear skies showed higher daytime ABLH than cloudy skies, and the daily maximum ABLH was recorded in spring due to the stronger radiation. The ABLHs estimated by ISABLE are expected to contribute to the parameterization of vertical diffusion in the atmospheric boundary layer and in understanding the severe smog/haze events that arise from by fumigation during the ABL evolution period.

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