scholarly journals Improved mixing height estimates from atmospheric LiDAR measurements

2021 ◽  
Vol 2145 (1) ◽  
pp. 012053
Author(s):  
Ronald Macatangay ◽  
Worapop Thongsame ◽  
Raman Solanki ◽  
Ying-Jen Wu ◽  
Sheng-Hsiang Wang ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Haar Wavelet ◽  
Early Morning ◽  
Time Dependent ◽  
Light Detection And Ranging ◽  
Atmospheric Conditions ◽  
Mixing Height ◽  
Lidar Measurements ◽  
Atmospheric Light

Abstract In this study, an improvement in the estimation of the mixing height is carried out by introducing a time-dependent maximum and minimum analysis altitude (TDMMAA) in the Haar wavelet covariance transform (WCT) technique applied to atmospheric light detection and ranging (LiDAR) measurements generally used in mixing height estimations. Results showed that the standard method usually overestimates the mixing height and that the proposed algorithm is more robust against clouds and residual layers in the boundary layer that generally occur in the nighttime and early morning. The TDMMAA method does have a bit of subjectivity especially in defining the analysis periods as well as the top and bottom of the analysis altitudes as it needs user experience and guidance. Moreover, the algorithm needs to be further objectively refined for automation and operational use, validated with in-situ profile measurements, and tested during different atmospheric conditions.

scholarly journals Improved mixing height monitoring through a combination of lidar and radon measurements

2012 ◽  
Vol 5 (5) ◽  
pp. 6835-6866 ◽  
Author(s):  
A. D. Griffiths ◽  
S. D. Parkes ◽  
S. D. Chambers ◽  
M. F. McCabe ◽  
A. G. Williams
Keyword(s):  
Boundary Layer ◽  
Time Series ◽  
Radon Concentration ◽  
Quantitative Measure ◽  
Potential Method ◽  
Length Scale ◽  
Mixing Length ◽  
Mixing Height ◽  
Lidar Measurements ◽  
Radon Measurements

Abstract. Surface-based radon (222Rn) measurements can be combined with lidar backscatter to obtain a higher quality time series of mixing height within the Planetary Boundary-Layer (PBL) than is possible from lidar alone, and a more quantitative measure of mixing height than is possible from only radon. The lidar measurements benefit because even when aerosol layers are detected, reliably attributing the mixing height to the correct layer presents a challenge. By combining lidar with a mixing length scale derived from a time series of radon concentration, automated and robust attribution is possible during the morning transition. Radon measurements also provide mixing information during the night and with the addition of lidar these measurements become insensitive to night-to-night changes in radon emissions. After calibration with lidar, the radon-derived equivalent mixing height agrees with other measures of mixing on daily and hourly time scales and is a potential method for studying intermittent mixing in nocturnal boundary layers.

scholarly journals Columnar modelling of nucleation burst evolution in the convective boundary layer – first results from a feasibility study Part II: Meteorological characterisation

2006 ◽  
Vol 6 (12) ◽  
pp. 4215-4230 ◽  
Author(s):  
O. Hellmuth
Keyword(s):  
Boundary Layer ◽  
Convective Boundary Layer ◽  
Third Order ◽  
Convective Boundary ◽  
Large Eddy ◽  
Previous Hypothesis ◽  
Lidar Measurements ◽  
First Results ◽  
Model Setup

Abstract. While in Paper I of four papers a revised columnar high-order modelling approach to investigate gas-aerosol-turbulence interactions in the convective boundary layer (CBL) was deduced, in the present Paper II the model capability to predict the evolution of meteorological CBL parameters is demonstrated. Based on a model setup to simulate typical CBL conditions, predicted first-, second- and third-order moments were shown to agree very well with those obtained from in situ and remote sensing turbulence measurements such as aircraft, SODAR and LIDAR measurements as well as with those derived from ensemble-averaged large eddy simulations and wind tunnel experiments. The results show, that the model is able to predict the meteorological CBL parameters, required to verify or falsify, respectively, previous hypothesis on the interaction between CBL turbulence and new particle formation.

scholarly journals Comparison of lidar-derived PM<sub>10</sub> with regional modeling and ground-based observations in the frame of MEGAPOLI experiment

2011 ◽  
Vol 11 (20) ◽  
pp. 10705-10726 ◽  
Author(s):  
P. Royer ◽  
P. Chazette ◽  
K. Sartelet ◽  
Q. J. Zhang ◽  
M. Beekmann ◽  
...  
Keyword(s):  
Mixed Boundary ◽  
Ground Level ◽  
In Situ Measurements ◽  
Percentage Error ◽  
Atmospheric Conditions ◽  
Transport Models ◽  
Near Surface ◽  
Lidar Measurements ◽  
Surface Measurements

Abstract. An innovative approach using mobile lidar measurements was implemented to test the performances of chemistry-transport models in simulating mass concentrations (PM10) predicted by chemistry-transport models. A ground-based mobile lidar (GBML) was deployed around Paris onboard a van during the MEGAPOLI (Megacities: Emissions, urban, regional and Global Atmospheric POLlution and climate effects, and Integrated tools for assessment and mitigation) summer experiment in July 2009. The measurements performed with this Rayleigh-Mie lidar are converted into PM10 profiles using optical-to-mass relationships previously established from in situ measurements performed around Paris for urban and peri-urban aerosols. The method is described here and applied to the 10 measurements days (MD). MD of 1, 15, 16 and 26 July 2009, corresponding to different levels of pollution and atmospheric conditions, are analyzed here in more details. Lidar-derived PM10 are compared with results of simulations from POLYPHEMUS and CHIMERE chemistry-transport models (CTM) and with ground-based observations from the AIRPARIF network. GBML-derived and AIRPARIF in situ measurements have been found to be in good agreement with a mean Root Mean Square Error RMSE (and a Mean Absolute Percentage Error MAPE) of 7.2 μg m−3 (26.0%) and 8.8 μg m−3 (25.2%) with relationships assuming peri-urban and urban-type particles, respectively. The comparisons between CTMs and lidar at ~200 m height have shown that CTMs tend to underestimate wet PM10 concentrations as revealed by the mean wet PM10 observed during the 10 MD of 22.4, 20.0 and 17.5 μg m−3 for lidar with peri-urban relationship, and POLYPHEMUS and CHIMERE models, respectively. This leads to a RMSE (and a MAPE) of 6.4 μg m−3 (29.6%) and 6.4 μg m−3 (27.6%) when considering POLYPHEMUS and CHIMERE CTMs, respectively. Wet integrated PM10 computed (between the ground and 1 km above the ground level) from lidar, POLYPHEMUS and CHIMERE results have been compared and have shown similar results with a RMSE (and MAPE) of 6.3 mg m−2 (30.1%) and 5.2 mg m−2 (22.3%) with POLYPHEMUS and CHIMERE when comparing with lidar-derived PM10 with periurban relationship. The values are of the same order of magnitude than other comparisons realized in previous studies. The discrepancies observed between models and measured PM10 can be explained by difficulties to accurately model the background conditions, the positions and strengths of the plume, the vertical turbulent diffusion (as well as the limited vertical model resolutions) and chemical processes as the formation of secondary aerosols. The major advantage of using vertically resolved lidar observations in addition to surface concentrations is to overcome the problem of limited spatial representativity of surface measurements. Even for the case of a well-mixed boundary layer, vertical mixing is not complete, especially in the surface layer and near source regions. Also a bad estimation of the mixing layer height would introduce errors in simulated surface concentrations, which can be detected using lidar measurements. In addition, horizontal spatial representativity is larger for altitude integrated measurements than for surface measurements, because horizontal inhomogeneities occurring near surface sources are dampened.

scholarly journals Doppler Lidar Estimation of Mixing Height Using Turbulence, Shear, and Aerosol Profiles

2009 ◽  
Vol 26 (4) ◽  
pp. 673-688 ◽  
Author(s):  
Sara C. Tucker ◽  
Christoph J. Senff ◽  
Ann M. Weickmann ◽  
W. Alan Brewer ◽  
Robert M. Banta ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
Potential Temperature ◽  
Lidar Data ◽  
Doppler Lidar ◽  
Mixing Height ◽  
Coherent Doppler Lidar ◽  
Lidar Measurements ◽  
Comparison Of The Results ◽  
Humidity Profiles

Abstract The concept of boundary layer mixing height for meteorology and air quality applications using lidar data is reviewed, and new algorithms for estimation of mixing heights from various types of lower-tropospheric coherent Doppler lidar measurements are presented. Velocity variance profiles derived from Doppler lidar data demonstrate direct application to mixing height estimation, while other types of lidar profiles demonstrate relationships to the variance profiles and thus may also be used in the mixing height estimate. The algorithms are applied to ship-based, high-resolution Doppler lidar (HRDL) velocity and backscattered-signal measurements acquired on the R/V Ronald H. Brown during Texas Air Quality Study (TexAQS) 2006 to demonstrate the method and to produce mixing height estimates for that experiment. These combinations of Doppler lidar–derived velocity measurements have not previously been applied to analysis of boundary layer mixing height—over the water or elsewhere. A comparison of the results to those derived from ship-launched, balloon-radiosonde potential temperature and relative humidity profiles is presented.

Upper-Level Atmospheric Circulation Patterns and Ground-Level Ozone in the Atlanta Metropolitan Area

2010 ◽  
Vol 49 (11) ◽  
pp. 2185-2196 ◽  
Author(s):  
Jeremy E. Diem ◽  
Melissa A. Hursey ◽  
Imani R. Morris ◽  
Amanda C. Murray ◽  
Ricardo A. Rodriguez
Keyword(s):  
Ozone Production ◽  
Back Trajectory ◽  
Metropolitan Statistical Area ◽  
Atmospheric Conditions ◽  
Mixing Height ◽  
Ozone Concentrations ◽  
Circulation Patterns ◽  
The Mean ◽  
Western Side

Abstract The purpose of this paper is to identify middle-troposphere circulation patterns associated with high ozone concentrations during June–August of 2000–07 in the Atlanta, Georgia, metropolitan statistical area (MSA), which is located in the southeastern United States. The methods involved classifying daily 500-hPa geopotential height fields into synoptic types, determining the mean atmospheric conditions (i.e., daytime temperature, daytime relative humidity, daytime cloud cover, morning mixing height, and afternoon mixing height) for the types, determining the mean daily maximum 8-h average ozone concentrations for the types, and performing back-trajectory analyses for high-ozone types. There were a total of 12 synoptic types, and significantly high ozone concentrations across the MSA coincided with the three following types: Atlanta under a continental anticyclone, Atlanta to the east of a continental anticyclone and west of a trough, and Atlanta under the western side of a trough. The continental-anticyclone type was much more prevalent than the other two types. When the MSA was under or just to the east of a continental anticyclone, atmospheric conditions were conducive to increased in situ ozone production and pollutant carryover from the previous day. Between 45% and 60% of the days with those circulation patterns had ozone concentrations exceeding the federal standard. When the Atlanta MSA was under the western side of a trough, not only did the potential for in situ ozone production and pollutant carryover contribute to high ozone concentrations, but there also was a high potential for pollutant transport from the Ohio River valley into the Atlanta MSA.

scholarly journals Wavelet Correlation Transform Method and Gradient Method to Determine Aerosol Layering from Lidar Returns: Some Comments

2013 ◽  
Vol 30 (6) ◽  
pp. 1189-1193 ◽  
Author(s):  
Adolfo Comerón ◽  
Michaël Sicard ◽  
Francesc Rocadenbosch
Keyword(s):  
Boundary Layer ◽  
Gradient Method ◽  
Haar Wavelet ◽  
Transform Method ◽  
Boundary Layer Height ◽  
Aerosol Distribution ◽  
Lidar Measurements ◽  
Low Pass ◽  
Signal Profile ◽  
Aerosol Properties

Abstract Identification of aerosol layers on lidar measurements is of interest to determine ranges where aerosol properties are likely to be homogeneous and to infer transport phenomena and atmosphere dynamics. For instance, the range-corrected backscattered signal from aerosol measured with lidars has long been used as a proxy to determine the depth of the planetary boundary layer. The method relies on the assumption that in a well-mixed atmosphere, a rather homogenous aerosol distribution will exist within the boundary layer; hence, a sudden drop in the lidar range-corrected signal profile will mark the end of the layer. The most usual methods to detect that drop are the gradient method, which detects a negative maximum in the derivative with respect to range of the lidar range-corrected signal, or of its logarithm, and the wavelet correlation transform method, which detects a maximum in the correlation function of the lidar range-corrected signal and a wavelet, usually the Haar wavelet. These methods are not restricted to determining the boundary layer height but can also be used to locate the edges of lofted aerosol layers. Using fundamentals of linear system theory, this study shows the deep link existing between the gradient method and the wavelet correlation transform method using the Haar wavelet, the latter being equivalent to the gradient method applied to a range-corrected signal profile smoothed by a low-pass spatial filtering, which seems not to have been explicitly noted in the literature so far. Consequences are readily drawn for the wavelet correlation transform method using other wavelets.

scholarly journals On the turbulent structure of the marine atmospheric boundary layer from CBLAST Nantucket measurements

2013 ◽  
Vol 10 (3) ◽  
pp. 210-217
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Land Surface ◽  
Atmospheric Stability ◽  
Heat Fluxes ◽  
Turbulent Structure ◽  
Atmospheric Conditions ◽  
Turbulent Characteristics ◽  
Momentum Fluxes

In this work preliminary results on the characteristics of the turbulent structure of the Marine Atmospheric Boundary Layer (MABL) are presented. Measurements used here were conducted in the framework of the Coupled Boundary Layers Air-Sea Transfer Experiment in Low Wind (CBLAST-Low) project. A number of in situ (fast and slow sensors) and remote sensing (SODAR) instruments were deployed on the coast of Nantucket Island, MA, USA. Measurements of the mean wind, the variances of the three wind components, the atmospheric stability and the momentum fluxes from the acoustic radar (SODAR) revealed the variation of the depth, the turbulent characteristics, and the stability of the MABL in response to the background flow. More specifically, under light south-southwesterly winds, which correspond to the MABL wind directions, the atmosphere was very stable and low values of turbulence were observed. Under moderate to strong southwesterly flow, less stable and neutral atmospheric conditions appeared and the corresponding turbulent quantities were characterized by higher values. The SODAR measurements, with high temporal and spatial resolution, also indicated large magnitude of momentum fluxes at higher levels, presumably associated with the shear forcing near the developed low-level jet. The measurements from the in-situ instrumentation confirmed that the MABL typically has small negative momentum and sensible heat fluxes consistent with stable to neutral stratification while strong diurnal variations were typical for the land surface Atmospheric Boundary Layer (ABL). The developed internal ABL at the experimental site was in general less than 10m during the night and could reach 15m heights during the day, particularly under low-wind conditions.

scholarly journals Estimation of turbulence parameters from scanning lidars and in-situ instrumentation in the Perdigão 2017 campaign

2019 ◽  
Author(s):  
Norman Wildmann ◽  
Nicola Bodini ◽  
Julie K. Lundquist ◽  
Ludovic Bariteau ◽  
Johannes Wagner
Keyword(s):  
Temporal Variability ◽  
Shear Zones ◽  
Spectral Width ◽  
Early Morning ◽  
Spatial And Temporal Variability ◽  
Atmospheric Conditions ◽  
Sonic Anemometers ◽  
Spatio Temporal ◽  
Lifting System

Abstract. The understanding of the sources, spatial distribution and temporal variability of turbulence in the atmospheric boundary layer (ABL) and improved simulation of its forcing processes require observations in a broad range of terrain types and atmospheric conditions. In this study, we estimate turbulence kinetic energy (TKE) dissipation rate using multiple techniques, including traditional in-situ measurements of sonic anemometers on meteorological towers, a hot-wire anemometer on a tethered lifting system (TLS), as well as remote-sensing retrievals from a vertically staring lidar and two lidars performing range-height indicator (RHI) scans. For the retrieval of ε from the lidar RHI scans, we introduce a modification of the Doppler Spectral Width (DSW) method. This method uses spatio-temporal averages of the variance of the line-of-sight (LOS) velocity and the turbulent broadening of the Doppler backscatter spectrum. We validate this method against the observations from the other instruments, also including uncertainty estimations for each method. The synthesis of the results from all instruments enables a detailed analysis of the spatial and temporal variability of ε across a valley between two parallel ridges at the Perdigão 2017 campaign. We find that the shear zones above and below nighttime low-level jets (LLJ) experience turbulence enhancements, as does the wake of a wind turbine (WT). We analyze in detail how ε varies in the early morning of 14 June 2017, when the turbulence in the valley, approximately eleven rotor diameters downstream of the WT, is still significantly enhanced by the WT wake.

scholarly journals Lidar-derived PM<sub>10</sub> and comparison with regional modeling in the frame of the MEGAPOLI Paris summer campaign

2011 ◽  
Vol 11 (4) ◽  
pp. 11861-11909 ◽  
Author(s):  
P. Royer ◽  
P. Chazette ◽  
K. S artelet ◽  
Q. J. Zhang ◽  
M. Beekmann ◽  
...  
Keyword(s):  
Ground Level ◽  
In Situ Measurements ◽  
Percentage Error ◽  
Atmospheric Conditions ◽  
Vertical Diffusion ◽  
Transport Models ◽  
Chemical Modeling ◽  
Lidar Measurements ◽  
Order Of Magnitude

Abstract. An original approach using mobile lidar measurements was implemented to validate mass concentrations (PM10) predicted by chemistry-transport models. A ground-based mobile lidar (GBML) was deployed around Paris onboard a van during the MEGAPOLI (Megacities: Emissions, urban, regional and Global Atmospheric POLlution and climate effects, and Integrated tools for assessment and mitigation) summer experiment in July 2009. The measurements performed with this Rayleigh-Mie lidar are converted into PM10 profiles using optical-to-mass relationships previously established from in situ measurements performed around Paris for urban and peri-urban aerosols. The method is described here and applied to the 10 measurements days (MD). MD of 1, 15, 16 and 26 July 2009 correspond to contrasted levels of pollution and atmospheric conditions. They are analyzed here in more details. Lidar-derived PM10 are compared with results of simulations from POLYPHEMUS and CHIMERE chemistry-transport models (CTM) and with ground-based observations from AIRPARIF network. GBML-derived and AIRPARIF in situ measurements have been found to be in good agreement with a mean Root Mean Square Error RMSE (and a Mean Absolute Percentage Error MAPE) of 5.9 μg m−3 (21.0%) with peri-urban and 8.7 μg m−3 (25.4%) with urban relationships, respectively. The comparisons between CTMs and lidar have shown that CTMs tend to underestimate wet PM10 concentrations as revealed by the mean wet PM10 observed during the 10 MD of 22.7, 20.0 and 17.5 μg m−3 for lidar with peri-urban relationship, POLYPHEMUS and CHIMERE models, respectively. This leads to a RMSE (and a MAPE) of 7.2 μg m−3 (33.4%) and 7.4 μg m−3 (32.0%) when considering POLYPHEMUS and CHIMERE CTMs, respectively. Wet integrated PM10 computed (between the ground and 1 km above the ground level) from lidar, POLYPHEMUS and CHIMERE results have been compared and have shown similar results with a RMSE (and MAPE) of 6.7 μg m−2 (30.7%) and 7.1 μg m−2 (28.4%) with POLYPHEMUS and CHIMERE when comparing with lidar-periu-urban parametrization. The values are of the same order of magnitude than other comparisons realized in previous studies. The discrepancies observed between models and measured PM10 can be explained by difficulties to accurately model the background conditions, the positions and strengths of the plume, the vertical diffusion (as well as the limited vertical model resolutions) and the chemical modeling such as the formation of secondary aerosols.

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