scholarly journals Edge Detection Method for Determining Boundary Layer Height Based on Doppler Lidar

Atmosphere ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1103
Author(s):  
Ya’ni Pan ◽  
Zhili Jin ◽  
Pengfei Tong ◽  
Weiwei Xu ◽  
Wei Wang
Keyword(s):  
Boundary Layer ◽  
Edge Detection ◽  
Critical Role ◽  
Pollution Prevention ◽  
Doppler Lidar ◽  
Atmospheric Conditions ◽  
Layer Height ◽  
Variance Method ◽  
Boundary Layer Height ◽  
The Mean

The top of the boundary layer, referred to as the planetary boundary layer height (BLH), is an important physical parameter in atmospheric numerical models, which has a critical role in atmospheric simulation, air pollution prevention, and climate prediction. The traditional methods for determining BLHs using Doppler lidar vertical velocity variance (σw2) can be classified into the variance and peak methods, which depend on atmospheric conditions due to their use of a single threshold, hence limiting their ability to estimate diurnal BLHs. Edge detection (ED) was later introduced in BLH estimation due to its ability to identify the 2D gradient of an image. A key step in ED is automatically identifying the edge of BLHs based on the peaks of the profile, hence avoiding the influence of extreme atmospheric conditions. Two cases in the diurnal cycle on 4 March 2019 and 8 July 2019 reveal that ED outperforms both the variance and peak methods in nighttime and extreme atmospheric conditions. The retrieved BLHs from 2018 to 2020 were compared with radiosonde (RS) measurements for the same time at the neutral, stable, and convective boundary layers. The correlation coefficient (R: 0.4 vs. 0.05, 0.14; 0.26 vs. −0.10, −0.16; 0.35 vs. 0.01, 0.16) and root mean square error (RMSE (km): 0.58 vs. 0.82, 0.90; 0.37 vs. 1.01, 0.50; 0.66 vs. 0.98, 0.82) obtained by the ED method were higher and lower than those obtained by the variance and peak methods, respectively. The mean absolute error (MAE) of the ED method under the NBL, SBL, and CBL conditions are lower than the variance and peak methods (MAE (km): 0.44, 0.14, 0.50 vs. 0.62, 0.34, 0.64; 0.59, 0.75, 0.74), respectively. The mean relative error (MRE) of the ED method is lower than the variance and peak methods under the NBL condition (MRE: −8.88% vs. −18.39%, 13.91%). Under the SBL, the MRE of the ED method is lower than the variance method and higher than the peak method (−38.64%, vs. −152.23%; 14.02%). Under the CBL, the MRE of the ED method is lower than the variance method and higher than the peak method (−15.07% vs. 2.24%; 5.64%). In addition, the comparison between ED and wavelet covariance transform (WCT) method and RS measurements showed that the ED method has a similar performance with the WCT method and is even better. In the long-term analysis, the hourly and monthly BLHs in the diurnal and annual cycles, respectively, as obtained by ED, were highly consistent with the RS measurements and obtained the lowest standard error. In the annual cycle, the retrieved BLHs in summer and autumn were higher than those retrieved in spring and winter.

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 TransCom continuous experiment: comparison of <sup>222</sup>Rn transport at hourly time scales at three stations in Germany

2011 ◽  
Vol 11 (19) ◽  
pp. 10071-10084 ◽  
Author(s):  
S. Taguchi ◽  
R. M. Law ◽  
C. Rödenbeck ◽  
P. K. Patra ◽  
S. Maksyutov ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Atmospheric Transport ◽  
Inversion Layer ◽  
Temporal Variations ◽  
Transport Models ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Diurnal Amplitude ◽  
Local Inversion ◽  
The Mean

Abstract. Fourteen global atmospheric transport models were evaluated by comparing the simulation of 222Rn against measurements at three continental stations in Germany: Heidelberg, Freiburg and Schauinsland. Hourly concentrations simulated by the models using a common 222Rn-flux without temporal variations were investigated for 2002 and 2003. We found that the mean simulated concentrations in Heidelberg are related to the diurnal amplitude of boundary layer height in each model. Summer mean concentrations simulated by individual models were negatively correlated with the seasonal mean of diurnal amplitude of boundary layer height, while in winter the correlation was positive. We also found that the correlations between simulated and measured concentrations at Schauinsland were higher when the simulated concentrations were interpolated to the station altitude in most models. Temporal variations of the mismatch between simulated and measured concentrations suggest that there are significant interannual variations in the 222Rn exhalation rate in this region. We found that the local inversion layer during daytime in summer in Freiburg has a significant effect on 222Rn concentrations. We recommend Freiburg concentrations for validation of models that resolve local stable layers and those at Heidelberg for models without this capability.

scholarly journals The potential for geostationary remote sensing of NO<sub>2</sub> to improve weather prediction

2020 ◽  
Author(s):  
Xueling Liu ◽  
Arthur P. Mizzi ◽  
Jeffrey L. Anderson ◽  
Inez Fung ◽  
Ronald C. Cohen
Keyword(s):  
Remote Sensing ◽  
Boundary Layer ◽  
Air Quality ◽  
Data Assimilation ◽  
Weather Prediction ◽  
Urban Air ◽  
Atmospheric Conditions ◽  
Wind Fields ◽  
Layer Height ◽  
Boundary Layer Height

Abstract. Observations of winds in the planetary boundary layer remain sparse making it challenging to simulate and predict atmospheric conditions that are most important for describing and predicting urban air quality. Short-lived chemicals are observed as plumes whose location is affected by boundary layer winds and with a lifetime affected by boundary layer height and mixing. Here we investigate the application of data assimilation of NO2 columns as will be observed from geostationary orbit to improve predictions and retrospective analysis of wind fields in the boundary layer.

Retrieve of Planetary Boundary Layer Height Based on Image Edge Detection

2016 ◽  
Vol 43 (7) ◽  
pp. 0704003 ◽  
Author(s):  
项衍 Xiang Yan ◽  
叶擎昊 Ye Qinghao ◽  
刘建国 Liu Jianguo ◽  
张天舒 Zhang Tianshu ◽  
范广强 Fan Guangqiang ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Edge Detection ◽  
Planetary Boundary Layer ◽  
Planetary Boundary Layer Height ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Image Edge Detection ◽  
Image Edge

scholarly journals Convective boundary-layer height estimation from combined radar and Doppler lidar observations in VORTEX-SE

2020 ◽  
Author(s):  
Joan Villalonga ◽  
Susan L. Beveridge ◽  
Marcos Paulo Araujo Da Silva ◽  
Robin L. Tanamachi ◽  
Francesc Rocadenbosch ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Convective Boundary Layer ◽  
Doppler Lidar ◽  
Convective Boundary ◽  
Height Estimation ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Lidar Observations

scholarly journals Planetary boundary layer height variability over athens, greece, based on the synergy of raman lidar and radiosonde data: Application of the kalman filter and other techniques (2011-2016)

2018 ◽  
Vol 176 ◽  
pp. 06007 ◽  
Author(s):  
Dimitrios Alexiou ◽  
Panagiotis Kokkalis ◽  
Alexandros Papayannis ◽  
Francesc Rocadenbosch ◽  
Athina Argyrouli ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Radiosonde Data ◽  
Lidar Data ◽  
Planetary Boundary Layer Height ◽  
Raman Lidar ◽  
Extended Kalman Filtering ◽  
Layer Height ◽  
Boundary Layer Height ◽  
The Mean

In this paper we studied the temporal evolution of the Planetary Boundary Layer height (PBLH) over the basin of Athens, Greece during a 5-year period (2011-2016) using data from the EOLE Raman lidar system. The lidar data (range-corrected lidar signals-RCS) were selected around 12:00 UTC and 00:00 UTC for a total of 332 cases: 165 days and 167 nights. Extended Kalman filtering techniques were used for the determination of the PBLH. Moreover, several well established techniques for the PBLH estimation based on lidar data were also tested for a total of 35 cases. Comparisons with the PBLH values derived from radiosonde data were also performed. The mean PBLH over Athens was found to be of the order of 1617±324 m at 12:00 UTC and of 892±130 m at 00:00 UTC, for the period examined. The mean PBLH growth rate was found to be about 170±64 m h-1 and 90±17 m h-1, during daytime and nighttime, respectively.

scholarly journals Estimating the planetary boundary layer height from radiosonde and doppler lidar measurements in the city of São Paulo - Brazil

2018 ◽  
Vol 176 ◽  
pp. 06015 ◽  
Author(s):  
Márcia T. A. Marques ◽  
Gregori de A. Moreira ◽  
Maciel Pinero ◽  
Amauri P. Oliveira ◽  
Eduardo Landulfo
Keyword(s):  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Sao Paulo ◽  
São Paulo ◽  
Doppler Lidar ◽  
Planetary Boundary Layer Height ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Lidar Measurements ◽  
The City

This study aims to compare the planetary boundary layer height (PBLH) values estimated by radiosonde data through the bulk Richardson number (BRN) method and by Doppler lidar measurements through the Carrier to Noise Ratio (CNR) method, which corresponds to the maximum of the variance of CNR profile. The measurement campaign was carried during the summer of 2015/2016 in the city of São Paulo. Despite the conceptual difference between these methods, the results show great agreement between them.

scholarly journals The potential for geostationary remote sensing of NO<sub>2</sub> to improve weather prediction

2021 ◽  
Vol 21 (12) ◽  
pp. 9573-9583
Author(s):  
Xueling Liu ◽  
Arthur P. Mizzi ◽  
Jeffrey L. Anderson ◽  
Inez Fung ◽  
Ronald C. Cohen
Keyword(s):  
Remote Sensing ◽  
Boundary Layer ◽  
Air Quality ◽  
Data Assimilation ◽  
Weather Prediction ◽  
Urban Air ◽  
Atmospheric Conditions ◽  
Wind Fields ◽  
Layer Height ◽  
Boundary Layer Height

Abstract. Observations of winds in the planetary boundary layer remain sparse making it challenging to simulate and predict atmospheric conditions that are most important for describing and predicting urban air quality. Short-lived chemicals are observed as plumes whose location is affected by boundary layer winds and whose lifetime is affected by boundary layer height and mixing. Here we investigate the application of data assimilation of NO2 columns as will be observed from geostationary orbit to improve predictions and retrospective analysis of wind fields in the boundary layer.

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