scholarly journals Seasonal Variability in the Diurnal Evolution of the Boundary Layer in a Near-Coastal Urban Environment

2012 ◽  
Vol 29 (5) ◽  
pp. 697-710 ◽  
Author(s):  
Christine L. Haman ◽  
Barry Lefer ◽  
Gary A. Morris
Keyword(s):  
Boundary Layer ◽  
Surface Layer ◽  
Vertical Profiles ◽  
High Wind ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Wind Speeds ◽  
Early Evening ◽  
Stable Surface Layer

Abstract Boundary layer height is estimated during a 21-month period in Houston, Texas, using continuous ceilometer observations and the minimum-gradient method. A comparison with over 60 radiosondes indicates overall agreement between ceilometer- and radiosonde-estimated PBL and residual layer heights. Additionally, the ceilometer-estimated PBL heights agree well with 31 vertical profiles of ozone. Difficulty detecting the PBL height occurs immediately following a frontal system with precipitation, during periods with high wind speeds, and in the early evening when convection is weakening, a new stable surface layer is forming, and the lofted aerosols detected by the lidar do not represent the PBL. Long-term diurnal observations of the PBL height indicate nocturnal PBL heights range from approximately 100 to 300 m throughout the year, while the convective PBL displays more seasonal and daily variability typically ranging from 1100 m in the winter to 2000 m in the summer.

scholarly journals Micro-Pulse Lidar Cruising Measurements in Northern South China Sea

2020 ◽  
Vol 12 (10) ◽  
pp. 1695
Author(s):  
Yuan Li ◽  
Baomin Wang ◽  
Shao-Yi Lee ◽  
Zhijie Zhang ◽  
Ye Wang ◽  
...  
Keyword(s):  
Boundary Layer ◽  
South China Sea ◽  
South China ◽  
Vertical Profiles ◽  
Depolarization Ratio ◽  
Layer Height ◽  
Boundary Layer Height ◽  
The Mean ◽  
Micro Pulse Lidar ◽  
Atmospheric Boundary Layer Height

A shipborne micro-pulse lidar (Sigma Space Mini-MPL) was used to measure aerosol extinction coefficient over the northern region of the South China Sea from 9 August to 7 September 2016, the first time a mini-MPL was used for aerosol observation over the cruise region. The goal of the experiment was to investigate if the compact and affordable mini-MPL was usable for aerosol observation over this region. The measurements were used to calculate vertical profiles of volume extinction coefficient, depolarization ratio, and atmospheric boundary layer height. Aerosol optical depth (AOD) was lower over the southwest side of the cruise region, compared to the northeast side. Most attenuation occurred below 3.5 km, and maximum extinction values over coastal areas were generally about double of values offshore. The extinction coefficients at 532 nm (aerosol and molecular combined) over coastal and offshore areas were on average 0.04 km−1 and 0.02 km−1, respectively. Maximum values reached 0.2 km−1 and 0.14 km−1, respectively. Vertical profiles and back-trajectory calculations indicated vertical and horizontal layering of aerosols from different terrestrial sources. The mean volume depolarization ratio of the aerosols along the cruise was 0.04. The mean atmospheric boundary layer height along the cruise was 653 m, with a diurnal cycle reaching its mean maximum of 1041 m at 12:00 local time, and its mean minimum of 450 m at 20:00 local time. Unfortunately, only 11% of the measurements were usable. This was due to ship instability in rough cruise conditions, lack of stabilization rig, water condensation attached to the eye lens, and high humidity attenuating the echo signal. We recommend against the use of the mini-MPL in this cruise region unless substantial improvements are made to the default setup, e.g., instrument stabilization, instrument protection cover, and more theoretical work taking into account atmospheric gas scattering or absorption.

scholarly journals Shift in the Temporal Trend of Boundary Layer Height in China Using Long‐Term (1979–2016) Radiosonde Data

2019 ◽  
Vol 46 (11) ◽  
pp. 6080-6089 ◽  
Author(s):  
Jianping Guo ◽  
Yuan Li ◽  
Jason Blake Cohen ◽  
Jian Li ◽  
Dandan Chen ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Temporal Trend ◽  
Radiosonde Data ◽  
Layer Height ◽  
Boundary Layer Height

Long-term variation of boundary layer height and possible contribution factors: A global analysis

2021 ◽  
pp. 148950
Author(s):  
Yarong Li ◽  
Jiming Li ◽  
Yuxin Zhao ◽  
Miao Lei ◽  
Yang Zhao ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Global Analysis ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Term Variation

Long-term measurements of planetary boundary layer height and interactions with PM2.5 in Shanghai, China

2019 ◽  
Vol 10 (3) ◽  
pp. 989-996 ◽  
Author(s):  
Liang Pan ◽  
Jianming Xu ◽  
Xuexi Tie ◽  
Xiaoqing Mao ◽  
Wei Gao ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Planetary Boundary Layer Height ◽  
Layer Height ◽  
Boundary Layer Height

scholarly journals Potential Approach for Single-Peak Extinction Fitting of Aerosol Profiles Based on In Situ Measurements for the Improvement of Surface PM2.5 Retrieval from Satellite AOD Product

2020 ◽  
Vol 12 (13) ◽  
pp. 2174
Author(s):  
Tang-Huang Lin ◽  
Kuo-En Chang ◽  
Hai-Po Chan ◽  
Ta-Chih Hsiao ◽  
Neng-Huei Lin ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Surface Layer ◽  
Planetary Boundary Layer ◽  
Regional Scale ◽  
Satellite Observations ◽  
Aerosol Extinction ◽  
Planetary Boundary Layer Height ◽  
Layer Height ◽  
Boundary Layer Height

The vertical distribution of aerosols is important for accurate surface PM2.5 retrieval and initial modeling forecasts of air pollution, but the observation of aerosol profiles on the regional scale is usually limited. Therefore, in this study, an approach to aerosol extinction profile fitting is proposed to improve surface PM2.5 retrieval from satellite observations. Owing to the high similarity of the single-peak extinction profile in the distribution pattern, the log-normal distribution is explored for the fitting model based on a decadal dataset (3248 in total) from Micro Pulse LiDAR (MPL) measurements. The logarithmic mean, standard deviation, and the height of peak extinction near-surface (Mode) are manually derived as the references for model construction. Considering the seasonal impacts on the planetary boundary layer height (PBLH), Mode, and the height of the surface layer, the extinction profile is then constructed in terms of the planetary boundary layer height (PBLH) and the total column aerosol optical depth (AOD). A comparison between fitted profiles and in situ measurements showed a high level of consistency in terms of the correlation coefficient (0.8973) and root-mean-square error (0.0415). The satellite AOD is subsequently applied for three-dimensional aerosol extinction, and the good agreement of the extinction coefficient with the PM2.5 within the surface layer indicates the good performance of the proposed fitting approach and the potential of satellite observations for providing accurate PM2.5 data on a regional scale.

Seasonal and episodic influence of local meteorology on fine particulate matter at a regional background site in North East India.

2021 ◽  
Author(s):  
Adnan Qadri ◽  
Shahadev Rabha ◽  
Binoy Saikia ◽  
Tarun Gupta
Keyword(s):  
Boundary Layer ◽  
Wind Speed ◽  
Ambient Air ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Wind Speeds ◽  
Background Site ◽  
North East ◽  
Regional Background ◽  
Ventilation Coefficient

<p>Climatological parameters like wind speed, temperature, boundary layer height facilitate in dispersion and accumulation of aerosols. Stagnant condition of atmosphere promote accumulation while the pollutants are more likely to get dispersed when non stagnation conditions exist. Sparse studies exist to assess the seasonal and episodic impact of stagnant weather conditions on enhancing aerosol formation in the North-East region of India.PM<sub>2.5 </sub>sampling was carried from January to November 2019 at a regional background site in Jorhat,Assam. Meteorological variables like wind speed, surface ambient temperature and relative humidity were obtained at one-minute resolution from a collocated air weather sensor. Ventilation coefficient was calculated from wind speed and Boundary Layer Height (BLH) ( from ERA5 reanalysis dataset)</p><p>Episodic days were identified as those exceeding permissible values of PM<sub>2.5 </sub>(National Ambient Air Quality Standards) i.e, 60µg/m<sup>3</sup>. Average wind speed on polluted and non-polluted days was 0.58±0.08 and 0.77 ± 0.17 m/s respectively. The average BLH was lower for the polluted days (243±73) than the non-polluted days (316±79). Pearson corelation coefficient of PM<sub>2.5 </sub>and wind speeds on polluted days was low (-0.23) compared to the non-polluted days (-0.54).</p><p>Wind rose plots reveal a seasonality trend with winter and summer winds being mostly between North East and South South-West while in monsoon and autumn it lies predominantly between SSW and South South-East (from the Bay of Bengal).  The Pearson correlation coefficients between PM<sub>2.5 </sub>and wind speeds are -0.66, -0.54 and -0.52 (all p <0.01) in winter, summer and autumn, respectively.Low average BLH persists in Winter and autumn . The seasonal maxima of BLH during winter, summer, monsoon and autumn was 847±167m, 932 ± 271m, 871 ±275m and 814 ± 256m, respectively.  Low night-time BLH (≈ 50m) in winter and autumn contributes to higher aerosol loading. The ventilation coefficient reaches its maxima during daytime around noon with summer season having the maximum daytime VC. High VC (≈270m<sup>2</sup>/s) in summer and monsoon  signify the seasonal effect on the pollutant dispersion and consequent high PM<sub>2.5 </sub>loading. Statistically significant negative correlations were obtained between PM<sub>2.5 </sub>and VC in winter and autumn seasons (-0.75 and -0.43).</p><p>Wind speeds have a strong correlation with PM<sub>2.5 </sub>except for the monsoon season and play a major role in aerosol dispersion.During monsoon, weak dependence of PM<sub>2.5 </sub>with wind speed and ventilation coefficient suggest significance of precipitation  which cause sscavenging of aerosols. Low correlations exist in summer for PM<sub>2.5 </sub>and VC due to possible interference due to regional transport of aerosols. 5-day backward trajectory analysis suggest  transport of air masses across the Thar desert and Indo Gangetic Plains to the site during the March(summer) suggesting transport of dust across the region.</p>

The difference in the boundary layer height between urban and suburban areas in Beijing and its implications for air pollution

2021 ◽  
pp. 118552
Author(s):  
Meng Wang ◽  
Guiqian Tang ◽  
Yusi Liu ◽  
Minjin Ma ◽  
Miao Yu ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Air Pollution ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Suburban Areas ◽  
The Difference
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