scholarly journals Atmosphere Boundary Layer Height (ABLH) Determination under Multiple-Layer Conditions Using Micro-Pulse Lidar

2019 ◽  
Vol 11 (3) ◽  
pp. 263 ◽  
Author(s):  
Ruijun Dang ◽  
Yi Yang ◽  
Hong Li ◽  
Xiao-Ming Hu ◽  
Zhiting Wang ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Correlation Coefficient ◽  
Cloud Layer ◽  
Horizontal Wind ◽  
Cloud Base ◽  
Accurate Estimation ◽  
Lidar Measurement ◽  
Height Distribution ◽  
Layer Height ◽  
Boundary Layer Height

Accurate estimation of the atmospheric boundary layer height (ABLH) is critically important and it mainly relies on the detection of the vertical profiles of atmosphere variables (temperature, humidity,’ and horizontal wind speed) or aerosols. Aerosol Lidar is a powerful remote sensing instrument frequently used to retrieve ABLH through the detection of the vertical distribution of aerosol concentration. A challenge is that cloud, residual layer (RL), and local signal structure seriously interfere with the lidar measurement of ABLH. A new objective technique presenting as giving a top limiter altitude is introduced to reduce the interference of RL and cloud layer on ABLH determination. Cloud layers are identified by looking for the rapid increase and sharp attenuation of the signal combined with the relative increase in the signal. The cloud layers weather overlay are classified or are decoupled from the ABL by analyzing the continuity of the signal below the cloud base. For cloud layer capping of the ABL, the limiter is determined to be the altitude where a positive signal gradient first occurs above the cloud upper edge. For a cloud that is decoupled from the ABL, the cloud base is considered to be the altitude limiter. For RL in the morning, the altitude limiter is the greatest positive gradient altitude below the RL top. The ABLH will be determined below the top limiter altitude using Haar wavelet (HM) and the curve fitting method (CFM). Besides, the interference of local signal noise is eliminated through consideration of the temporal continuity. While comparing the lidar-determined ABLH by HM (or CFM) and nearby radiosonde measurements of the ABLH, a reasonable concordance is found with a correlation coefficient of 0.94 (or 0.96) and 0.79 (or 0.74), presenting a mean of the relative absolute differences with respect to radiosonde measurements of 10.5% (or 12.3%) and 22.3% (or 17.2%) for cloud-free and cloudy situations, respectively. The diurnal variations in the ABLH determined from HM and CFM on four selected cases show good agreement with a mean correlation coefficient higher than 0.99 and a mean absolute bias of 0.22 km. Also, the determined diurnal ABLH are consistent with surface turbulent kinetic energy (TKE) combined with the time-height distribution of the equivalent potential temperature.

scholarly journals Turbulent and boundary layer characteristics during VOCALS-REx

2021 ◽  
Vol 21 (3) ◽  
pp. 1937-1961
Author(s):  
Dillon S. Dodson ◽  
Jennifer D. Small Griswold
Keyword(s):  
Boundary Layer ◽  
Heat Flux ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Sensible Heat Flux ◽  
Cloud Layer ◽  
Cloud Base ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Turbulent Characteristics

Abstract. Boundary layer and turbulent characteristics (surface fluxes, turbulent kinetic energy – TKE, turbulent kinetic energy dissipation rate – ϵ), along with synoptic-scale changes in these properties over time, are examined using data collected from 18 research flights made with the CIRPAS Twin Otter Aircraft. Data were collected during the Variability of the American Monsoon Systems (VAMOS) Ocean–Cloud–Atmosphere–Land Study Regional Experiment (VOCALS-REx) at Point Alpha (20∘ S, 72∘ W) in October and November 2008 off the coast of South America. The average boundary layer depth is found to be 1148 m, with 28 % of the boundary layer profiles analyzed displaying decoupling. Analysis of correlation coefficients indicates that as atmospheric pressure decreases, the boundary layer height (zi) increases. As has been shown previously, the increase in zi is accompanied by a decrease in turbulence within the boundary layer. As zi increases, cooling near cloud top cannot sustain mixing over the entire depth of the boundary layer, resulting in less turbulence and boundary layer decoupling. As the latent heat flux (LHF) and sensible heat flux (SHF) increase, zi increases, along with the cloud thickness decreasing with increasing LHF. This suggests that an enhanced LHF results in enhanced entrainment, which acts to thin the cloud layer while deepening the boundary layer. A maximum in TKE on 1 November (both overall average and largest single value measured) is due to sub-cloud precipitation acting to destabilize the sub-cloud layer while acting to stabilize the cloud layer (through evaporation occurring away from the surface, primarily confined between a normalized boundary layer height, z/zi, of 0.40 to 0.60). Enhanced moisture above cloud top from a passing synoptic system also acts to reduce cloud-top cooling, reducing the potential for mixing of the cloud layer. This is observed in both the vertical profiles of the TKE and ϵ, in which it is found that the distributions of turbulence for the sub-cloud and in-cloud layer are completely offset from one another (i.e., the range of turbulent values measured have slight or no overlap for the in-cloud and sub-cloud regions), with the TKE in the sub-cloud layer maximizing for the analysis period, while the TKE in the in-cloud layer is below the average in-cloud value for the analysis period. Measures of vertical velocity variance, TKE, and the buoyancy flux averaged over all 18 flights display a maximum near cloud middle (between normalized in-cloud height, Z*, values of 0.25 and 0.75). A total of 10 of the 18 flights display two peaks in TKE within the cloud layer, one near cloud base and another near cloud top, signifying evaporative and radiational cooling near cloud top and latent heating near cloud base. Decoupled boundary layers tend to have a maximum in turbulence in the sub-cloud layer, with only a single peak in turbulence within the cloud layer.

scholarly journals Turbulent and Boundary Layer Characteristics during VOCALS-REx

2020 ◽  
Author(s):  
Dillon S. Dodson ◽  
Jennifer D. Small Griswold
Keyword(s):  
Boundary Layer ◽  
Mixed Boundary ◽  
Turbulent Energy ◽  
Cloud Layer ◽  
Cloud Base ◽  
Small Scale ◽  
Synoptic Scale ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Turbulent Characteristics

Abstract. Stratocumulus clouds have a significant impact on climate due to their large spatial extent, with areas of enhanced coverage termed stratocumulus decks. How turbulence evolves with time and influences the stratocumulus deck properties however, in particular throughout the vertical profile of the boundary layer, is still lacking through model parameterizations of the small-scale flow. Collecting in situ data to better understand the turbulence and physical processes occuring within the stratocumu- lus deck therefore key to better model parameterizations. Boundary layer and turbulent characteristics, along with synoptic scale changes in these properties over time, are examined using data collected from 14 research flights made with the CIR- PAS Twin Otter Aircraft. Data was collected during the VOMOS Ocean-Cloud-Atmosphere-Land Study-Regional Experiment (VOCALS-REx) at Point Alpha in October and November of 2008 off the cost of South America (20°S, 72°W). Findings show that the influence of a synoptic system on Nov 1st and 2nd brings in a moist layer above the boundary layer, leading to a deepening cloud layer and precipitation during passage, and a large increase in boundary layer height and cloud thinning after passage. The maximum value in turbulent kinetic energy (TKE) was measured on Nov. 1st due to precipitation destabilizing the sub-cloud layer while a minimum occurred on Nov. 2nd after precipitation had ceased due to turbulent mixing overturning the boundary layer and depleting the initial turbulent energy produced from the evaporation of precipitation below cloud base. Turbulent properties averaged over all 14 flights reach a maximum near cloud middle (between normalized in- cloud values of 0.25–0.75), with well mixed boundary layers experiencing two peaks in TKE, one near cloud base due to latent heat release and another near cloud top due to evaporational cooling. Overall, it appears that turbulence measured at Point Alpha is weaker than that measured over the open ocean to the west of Point Alpha, and that measured during other scientific campaigns. Synoptic scale analysis suggests that as the geopotential height decreases, the boundary layer height and entrainment zone thickness increases, accompanied by a decrease of in-cloud and below-cloud turbulence, and vice versa.

scholarly journals Relationship analysis of PM<sub>2.5</sub> and boundary layer height using an aerosol and turbulence detection lidar

2019 ◽  
Vol 12 (6) ◽  
pp. 3303-3315 ◽  
Author(s):  
Chong Wang ◽  
Mingjiao Jia ◽  
Haiyun Xia ◽  
Yunbin Wu ◽  
Tianwen Wei ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Weather Forecasting ◽  
Direct Detection ◽  
Vertical Wind ◽  
Precipitation Event ◽  
Cloud Base ◽  
Convective Boundary ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Relationship Analysis

Abstract. The atmospheric boundary layer height (BLH) is a key parameter in weather forecasting and air quality prediction. To investigate the relationship between BLH and air pollution under different conditions, a compact micro-pulse lidar integrating both direct-detection lidar (DDL) and coherent Doppler wind lidar (CDWL) has been built. This hybrid lidar is operated at 1.5 µm, which is eye-safe and made of all-fibre components. The BLH can be determined from aerosol density and vertical wind independently. During a 45 h continuous observation in June 2018, the stable boundary layer, residual layer and convective boundary layer are identified. The fine structure of the aerosol layers, drizzles and vertical wind near the cloud base are also detected. In comparison, the standard deviation between BLH values derived from DDL and CDWL is 0.06 km, indicating the accuracy of this work. The retrieved convective BLH is a little higher than that from ERA5 reanalysis due to different retrieval methods. Correlation between different BLH and PM2.5 is strongly negative before a precipitation event and becomes much weaker after the precipitation. Different relationships between PM2.5 and BLH may result from different BLH retrieval methods, pollutant sources and meteorological conditions.

scholarly journals A Review of Techniques for Diagnosing the Atmospheric Boundary Layer Height (ABLH) Using Aerosol Lidar Data

2019 ◽  
Vol 11 (13) ◽  
pp. 1590 ◽  
Author(s):  
Ruijun Dang ◽  
Yi Yang ◽  
Xiao-Ming Hu ◽  
Zhiting Wang ◽  
Shuwen Zhang
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
Atmospheric Boundary Layer ◽  
Weather Prediction ◽  
Mixing Layer ◽  
Accurate Estimation ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Vertical Distributions ◽  
Multi Wavelength

The height of the atmospheric boundary layer (ABLH) or the mixing layer height (MLH) is a key parameter characterizing the planetary boundary layer, and the accurate estimation of that is critically important for boundary layer related studies, which include air quality forecasts and numerical weather prediction. Aerosol lidar is a powerful remote sensing instrument frequently used to retrieve the ABLH through detecting the vertical distributions of aerosol concentration. Presently available methods for ABLH determination from aerosol lidar are summarized in this review, including a lot of classical methodologies as well as some improved versions of them. Some new recently developed methods applying advanced techniques such as image edge detection, as well as some new methods based on multi-wavelength lidar systems, are also summarized. Although a lot of techniques have been proposed and have already given reasonable results in several studies, it is impossible to recommend a technique which is suitable in all atmospheric scenarios. More accurate instantaneous ABLH from robust techniques is required, which can be used to estimate or improve the boundary layer parameterization in the numerical model, or maybe possible to be assimilated into the weather and environment models to improve the simulation or forecast of weather and air quality in the future.

scholarly journals Random Sample Fitting Method to Determine the Planetary Boundary Layer Height Using Satellite-Based Lidar Backscatter Profiles

2020 ◽  
Vol 12 (23) ◽  
pp. 4006
Author(s):  
Lin Du ◽  
Ya’ni Pan ◽  
Wei Wang
Keyword(s):  
Boundary Layer ◽  
Random Sample ◽  
Planetary Boundary Layer ◽  
Weather Forecasting ◽  
Cloud Layer ◽  
Superior Performance ◽  
Planetary Boundary Layer Height ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Fitting Method

The planetary boundary layer height (PBLH) is the atmospheric region closest to the earth’s surface and has important implications on weather forecasting, air quality, and climate research. However, lidar-based methods traditionally used to determine PBLH—such as the ideal profile fitting method (IPF), maximum gradient method, and wavelet covariance transform—are not only heavily influenced by cloud layers, but also rely heavily on a low signal-to-noise ratio (SNR). Therefore, a random sample fitting (RANSAF) method was proposed for PBLH detection based on combining the random sampling consensus and IPF methods. According to radiosonde measurements, the testing of simulated and satellite-based signals shows that the proposed RANSAF method can reduce the effects of the cloud layer and significantly fluctuating noise on lidar-based PBLH detection better than traditional algorithms. The low PBLH bias derived by the RANSAF method indicates that the improved algorithm has a superior performance in measuring PBLH under a low SNR or when a cloud layer exists where the traditional methods are mostly ineffective. The RANSAF method has the potential to determine regional PBLH on the basis of satellite-based lidar backscatter profiles.

scholarly journals Lidar measurement of planetary boundary layer height and comparison with microwave profiling radiometer observation

2012 ◽  
Vol 5 (1) ◽  
pp. 1233-1251 ◽  
Author(s):  
Z. Wang ◽  
X. Cao ◽  
L. Zhang ◽  
J. Notholt ◽  
B. Zhou ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Data Sets ◽  
Lidar Measurement ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Lidar Measurements ◽  
Theoretical Predictions ◽  
Entrainment Zone ◽  
The City ◽  
Atmospheric Boundary Layer Height

Abstract. Using the wavelet technology method and lidar measurements the atmospheric boundary layer height was derived above the city of Lanzhou (China) and its suburb rural area – Yuzhong. Furthermore, at Yuzhong, the average boundary layer height and entrainment zone thickness was derived in convective situations. Simultaneously the boundary layer height was derived from the microwave observations using a profiling radiometer and the parcel method. The results show that both data sets agree in strong convective situations. However, for weak convective situations the lidar measurements reveal boundary layer heights that are higher compared to the microwave observations, because a decrease of the thermal boundary layer height does not directly lead to a drop of aerosols in that altitude layer. Finally, the entrainment zone thicknesses are compared with theoretical predictions, and the results show some consistence between both data sets.

scholarly journals Lidar measurement of planetary boundary layer height and comparison with microwave profiling radiometer observation

2012 ◽  
Vol 5 (8) ◽  
pp. 1965-1972 ◽  
Author(s):  
Z. Wang ◽  
X. Cao ◽  
L. Zhang ◽  
J. Notholt ◽  
B. Zhou ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Microwave Radiometer ◽  
Theoretical Models ◽  
Lidar Measurement ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Lidar Measurements ◽  
Theoretical Predictions ◽  
Entrainment Zone ◽  
The City

Abstract. The atmospheric boundary layer height was derived at two locations in the city of Lanzhou (China) and its suburb rural area Yuzhong. The aerosol backscatter lidar measurements were analysed using a wavelet technology and the parcel method was applied to profiling microwave radiometer observations. For a few occasions the average boundary layer height and entrainment zone thickness was derived in convective situations at Yuzhong. Results from selected observation days show that both datasets agree in strong convective situations. However, for weak convective situations the lidar measurements reveal boundary layer heights that are higher compared to the microwave observations, because a decrease of the thermal boundary layer height does not directly lead to a change of aerosols in that altitude layer. Finally, the entrainment zone thicknesses are compared with theoretical predictions, and the results show that the measurements are compatible with theoretical models.

scholarly journals Planetary boundary layer height from CALIOP compared to radiosonde over China

2016 ◽  
Vol 16 (15) ◽  
pp. 9951-9963 ◽  
Author(s):  
Wanchun Zhang ◽  
Jianping Guo ◽  
Yucong Miao ◽  
Huan Liu ◽  
Yong Zhang ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Large Scale ◽  
Accurate Estimation ◽  
Orthogonal Polarization ◽  
Planetary Boundary Layer Height ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Spatial Coverage ◽  
Ground Based Lidar

Abstract. Accurate estimation of planetary boundary layer height (PBLH) is key to air quality prediction, weather forecast, and assessment of regional climate change. The PBLH retrieval from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) is expected to complement ground-based measurements due to the broad spatial coverage of satellites. In this study, CALIOP PBLHs are derived from combination of Haar wavelet and maximum variance techniques, and are further validated against PBLHs estimated from ground-based lidar at Beijing and Jinhua. Correlation coefficients between PBLHs from ground- and satellite-based lidars are 0.59 at Beijing and 0.65 at Jinhua. Also, the PBLH climatology from CALIOP and radiosonde are compiled over China during the period from 2011 to 2014. Maximum CALIOP-derived PBLH can be seen in summer as compared to lower values in other seasons. Three matchup scenarios are proposed according to the position of each radiosonde site relative to its closest CALIPSO ground tracks. For each scenario, intercomparisons were performed between CALIOP- and radiosonde-derived PBLHs, and scenario 2 is found to be better than other scenarios using difference as the criteria. In early summer afternoon over 70 % of the total radiosonde sites have PBLH values ranging from 1.6 to 2.0 km. Overall, CALIOP-derived PBLHs are well consistent with radiosonde-derived PBLHs. To our knowledge, this study is the first intercomparison of PBLH on a large scale using the radiosonde network of China, shedding important light on the data quality of initial CALIOP-derived PBLH results.

scholarly journals Planetary boundary layer height from CALIOP compared to radiosonde over China

2016 ◽  
Author(s):  
Wanchun Zhang ◽  
Jianping Guo ◽  
Yucong Miao ◽  
Huan Liu ◽  
Zhengqiang Li ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Large Scale ◽  
Early Summer ◽  
Accurate Estimation ◽  
Planetary Boundary Layer Height ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Spatial Coverage ◽  
Ground Based Lidar

Abstract. The accurate estimation of boundary layer height is key to air quality prediction, weather forecast and so on. The planetary boundary layer height (PBLH) retrieval from CALIOP is expected to complement the ground-based site measurement due to its large spatial coverage. To such end, we estimated PBLHs from CALIOP, using the combination of Haar wavelet and maximum variance techniques, which was validated against PBLHs from ground-based lidar at Beijing and Jinhua. Comparison between ground-based and satellite lidar shows good agreement with a correlation coefficient of 0.59 in Beijing and 0.65 in Jinhua. The PBLH climatology from CALIOP was compiled over China during 2011 to 2014. Maximum PBLH was seen in summer as compared to lower value in other seasons. Prior to intercomparisons between CALIOP- and radiosonde-derived PBLHs, three matchup scenarios were proposed according to the position of each radiosonde site relative to its closest CALIPSO ground tracks. The CALIOP observations belonging to Scenario 2 were found to be better for comparison with radiosonde-derived PBLH, owing to smaller difference between them. The PBLHs at early summer afternoon range from 1.6 km to 2.0 km, accounting for over 70 % of the total radiosonde sites. Overall, CALIOP-derived PBLHs seem to be well consistent with radiosonde-derived PBLHs. To our knowledge, this study is the first intercomparison study of PBLH over large scale using the radiosonde network of China, shedding important light on the data quality of initial CALIOP-derived PBLH results.

Sign in / Sign up

Export Citation Format

Share Document