scholarly journals PathfinderTURB: an automatic boundary layer algorithm. Development, validation and application to study the impact on in-situ measurements at the Jungfraujoch

2017 ◽  
Author(s):  
Yann Poltera ◽  
Giovanni Martucci ◽  
Martine Collaud Coen ◽  
Maxime Hervo ◽  
Lukas Emmenegger ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Vertical Structure ◽  
Reference Method ◽  
Swiss Alps ◽  
Aerosol Layer ◽  
Reference Methods ◽  
Spatial Coverage ◽  
The Impact

Abstract. Continuous observations of the vertical structure of the planetary boundary layer are invaluable for the validation of atmospheric transport models on the micro and meso scale. Lidar and ceilometer backscatter observations offer a robust technique with growing spatial coverage, but the obtained backscatter profiles need to be carefully translated into boundary layer parameters. Here we present the development of the PathfinderTURB algorithm for the analysis of ceilometer backscatter data and the real-time detection of the vertical structure of the planetary boundary layer. Two typical aerosol layer heights are retrieved by PathfinderTURB: the Convective Boundary Layer (CBL) and the Continuous Aerosol Layer (CAL). PathfinderTURB combines the strengths of gradient- and variance-based methods and addresses the layer attribution problem by adopting a geodesic approach. The algorithm has been applied to one year of data measured by two CHM15k ceilometers operated at the Aerological Observatory of Payerne (491 m, a.s.l.) on the Swiss plateau, and at the Kleine Scheidegg (2061 m, a.s.l.) in the Swiss Alps. The retrieval of the CBL has been validated at Payerne using two reference methods: (1) manual detections of the CBL height performed by independent human experts using the ceilometer backscatter data of the year 2014; (2) values of CBL heights calculated using the Richardson's method from co-located radio sounding data. We found average biases as small as 27 m (53 m) with respect to reference method 1 (2). Based on the excellent agreement with the two reference methods, PathfinderTURB has been applied to the ceilometer data at the mountainous site of the Kleine Scheidegg for the period September 2014 till November 2015. At this site, the CHM15k is operated in a novel, tilted configuration at 71° zenith angle to probe the air next to the Sphinx Observatory (3580 m, a.s.l.) on the Jungfraujoch (JFJ). The analysis of the retrieved layers led to the following results: the CAL reaches the JFJ during 41 % of the time in summer and during 21 % of the time in winter for a total of 97 days during the two seasons. The season-averaged daily cycles show that the CBL height reaches the JFJ only during short periods (4 % of the time) on 20 individual days in summer and never during winter. Especially during summer the CBL and the CAL modify the air sampled in-situ at JFJ, resulting in an unequivocal dependence of the measured absorption coefficient on the height of both layers. This highlights the relevance of retrieving the height of CAL and CBL in mountainous regions.

scholarly journals PathfinderTURB: an automatic boundary layer algorithm. Development, validation and application to study the impact on in situ measurements at the Jungfraujoch

2017 ◽  
Vol 17 (16) ◽  
pp. 10051-10070 ◽  
Author(s):  
Yann Poltera ◽  
Giovanni Martucci ◽  
Martine Collaud Coen ◽  
Maxime Hervo ◽  
Lukas Emmenegger ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Reference Method ◽  
Swiss Alps ◽  
Aerosol Layer ◽  
Convective Boundary ◽  
Reference Methods ◽  
Measured Absorption ◽  
Swiss Plateau ◽  
The Impact

Abstract. We present the development of the PathfinderTURB algorithm for the analysis of ceilometer backscatter data and the real-time detection of the vertical structure of the planetary boundary layer. Two aerosol layer heights are retrieved by PathfinderTURB: the convective boundary layer (CBL) and the continuous aerosol layer (CAL). PathfinderTURB combines the strengths of gradient- and variance-based methods and addresses the layer attribution problem by adopting a geodesic approach. The algorithm has been applied to 1 year of data measured by two ceilometers of type CHM15k, one operated at the Aerological Observatory of Payerne (491 m a.s.l.) on the Swiss plateau and one at the Kleine Scheidegg (2061 m a.s.l.) in the Swiss Alps. The retrieval of the CBL has been validated at Payerne using two reference methods: (1) manual detections of the CBL height performed by human experts using the ceilometer backscatter data; (2) values of CBL heights calculated using the Richardson's method from co-located radio sounding data. We found average biases as small as 27 m (53 m) with respect to reference method 1 (method 2). Based on the excellent agreement between the two reference methods, PathfinderTURB has been applied to the ceilometer data at the mountainous site of the Kleine Scheidegg for the period September 2014 to November 2015. At this site, the CHM15k is operated in a tilted configuration at 71° zenith angle to probe the atmosphere next to the Sphinx Observatory (3580 m a.s.l.) on the Jungfraujoch (JFJ). The analysis of the retrieved layers led to the following results: the CAL reaches the JFJ 41 % of the time in summer and 21 % of the time in winter for a total of 97 days during the two seasons. The season-averaged daily cycles show that the CBL height reaches the JFJ only during short periods (4 % of the time), but on 20 individual days in summer and never during winter. During summer in particular, the CBL and the CAL modify the air sampled in situ at JFJ, resulting in an unequivocal dependence of the measured absorption coefficient on the height of both layers. This highlights the relevance of retrieving the height of CAL and CBL automatically at the JFJ.

scholarly journals Investigation of the Planetary Boundary Layer in the Swiss Alps Using Remote Sensing and In Situ Measurements

2014 ◽  
Vol 151 (2) ◽  
pp. 317-334 ◽  
Author(s):  
C. Ketterer ◽  
P. Zieger ◽  
N. Bukowiecki ◽  
M. Collaud Coen ◽  
O. Maier ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
In Situ Measurements ◽  
Swiss Alps

scholarly journals Air quality observations onboard commercial and targeted Zeppelin flights in Germany – a platform for high-resolution trace-gas and aerosol measurements within the planetary boundary layer

2021 ◽  
Author(s):  
Ralf Tillmannn ◽  
Georgios I. Gkatzelis ◽  
Franz Rohrer ◽  
Benjamin Winter ◽  
Christian Wesolek ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Power Plant ◽  
Greenhouse Gases ◽  
Planetary Boundary Layer ◽  
Air Pollutants ◽  
Vertical Profiles ◽  
Diurnal Variability ◽  
The Impact ◽  
German Cities

Abstract. A Zeppelin airship was used as a platform for in-situ measurements of greenhouse gases and short-lived air pollutants within the planetary boundary layer in Germany. A novel quantum cascade laser-based multi-compound gas analyzer (MIRO Analytical AG) was deployed to simultaneously measure in-situ concentrations of greenhouse gases (CO2, N2O, H2O, and CH4) and air pollutants (CO, NO, NO2, O3, SO2, and NH3) with high precision at a measurement rate of 1 Hz. These measurements were complemented by electrochemical sensors for NO, NO2, Ox (NO2+O3), and CO, an optical particle counter, temperature, humidity, altitude, and position monitoring. Instruments were operated remotely without the need for on-site interactions. Three two-week campaigns were conducted in 2020 comprising commercial passenger as well as targeted flights over multiple German cities including Cologne, Mönchengladbach, Düsseldorf, Aachen, Frankfurt, but also over industrial areas and highways. Vertical profiles of trace gases were obtained during the airship landing and take-off. Diurnal variability of the Zeppelin vertical profiles was compared to measurements from ground-based monitoring stations with a focus on nitrogen oxides and ozone. We find that their variability can be explained by the increasing nocturnal boundary layer height from early morning towards midday, an increase in emissions during rush hour traffic, and the rapid photochemical activity midday. Higher altitude (250–450 m) NOX to CO ratios are further compared to the 2015 EDGAR emission inventory to find that pollutant concentrations are influenced by transportation and residential emissions as well as manufacturing industries and construction activity. Finally, we report NOx and CO concentrations from one plume transect originating from a coal power plant and compare it to the EURAD-IM model to find agreement within 15 %. However, due to the increased contribution of solar and wind energy and/or the impact of lockdown measures the power plant was operated at max. 50 % capacity; therefore, possible overestimation of emissions by the model cannot be excluded.

scholarly journals Dome effect of black carbon and its key influencing factors: A one-dimensional modelling study

2017 ◽  
Author(s):  
Zilin Wang ◽  
Xin Huang ◽  
Aijun Ding
Keyword(s):  
Boundary Layer ◽  
Air Pollution ◽  
Black Carbon ◽  
Rural Areas ◽  
Land Surface ◽  
Critical Role ◽  
Aerosol Layer ◽  
Near Surface ◽  
Haze Pollution ◽  
The Impact

Abstract. Black carbon (BC) has been identified to play a critical role in aerosol-planet boundary layer (PBL) interaction and further deterioration of near-surface air pollution in megacities, which has been named as its dome effect. However, the impacts of key factors that influence this effect, such as the vertical distribution and aging processes of BC, and also the underlying land surface, have not been quantitatively explored yet. Here, based on available in-situ measurements of meteorology and atmospheric aerosols together with the meteorology-chemistry online coupled model, WRF-Chem, we conduct a set of parallel simulations to quantify the roles of these factors in influencing the BC's dome effect and surface haze pollution, and discuss the main implications of the results to air pollution mitigation in China. We found that the impact of BC on PBL is very sensitive to the altitude of aerosol layer. The upper level BC, especially those near the capping inversion, is more essential in suppressing the PBL height and weakening the turbulence mixing. The dome effect of BC tends to be significantly intensified as BC aerosol mixed with scattering aerosols during winter haze events, resulting in a decrease of PBL height by more than 25 %. In addition, the dome effect is more substantial (up to 15 %) in rural areas than that in the urban areas with the same BC loading, indicating an unexpected regional impact of such kind of effect to air quality in countryside. This study suggests that China's regional air pollution would greatly benefit from BC emission reductions, especially those from the elevated sources from the chimneys and also the domestic combustions in rural areas, through weakening the aerosol-boundary layer interactions that triggered by BC.

scholarly journals Estudo do ciclo diário da Camada Limite Planetária durante a estação cChuvosa da Amazônia (GOAmazon 2014/15)

2018 ◽  
Vol 40 ◽  
pp. 63 ◽  
Author(s):  
Rayonil Gomes Carneiro ◽  
Alice Henkes ◽  
Gilberto Fisch ◽  
Camilla Kassar Borges
Keyword(s):  
Remote Sensing ◽  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Remote Sensing Data ◽  
Great Depth ◽  
Wet Season ◽  
Daily Cycle ◽  
Convective Boundary ◽  
In Situ Observations

In the present study, the evolution the diurnal cycle of planetary boundary layer in the wet season at Amazon region during a period of intense observations carried out in the GOAmazon Project 2014/2015 (Green Ocean Amazon).The analysis includes radiosonde and remote sensing data. In general case, the results of the daily cycle in the wet season indicate a Nocturnal boundary layer with a small oscillation in its depth and with a tardy erosion. The convective boundary layer did not present great depth, responding to the low values of sensible heat of the wet season. A comparison between the different techniques(in situ observations and remote sensing)  for estimating the planetary boundary layer is also presented.

scholarly journals Analyzing the turbulence in the Planetary Boundary Layer by the synergic use of remote sensing systems: Doppler wind lidar and aerosol elastic lidar

2018 ◽  
Author(s):  
Gregori de Arruda Moreira ◽  
Juan Luís Guerrero-Rascado ◽  
Jose Antonio Benavent-Oltra ◽  
Pablo Ortiz-Amezcua ◽  
Roberto Román ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Weather Forecasting ◽  
Saharan Dust ◽  
Aerosol Layer ◽  
Frequency Distributions ◽  
Sensing Systems ◽  
Turbulent Characteristics ◽  
Remote Sensing Systems

Abstract. The Planetary Boundary Layer (PBL) is the lowermost region of troposphere and endowed with turbulent characteristics, which can have mechanical or thermodynamic origins. Such behavior gives to this layer great importance, mainly in studies about pollutant dispersion and weather forecasting. However, the instruments usually applied in studies about turbulence in the PBL have limitations in spatial resolution (anemometer towers) or temporal resolution (aircrafts). In this study we propose the synergetic use of remote sensing systems (microwave radiometer [MWR], Doppler lidar [DL] and elastic lidar [EL]) to analyze the PBL behavior. Furthermore, we show how some meteorological variables such as air temperature, aerosol number density, vertical wind, relative humidity and net radiation might influence the PBL dynamic. The statistical moments of the high frequency distributions of the vertical velocity, derived from DL and of the backscattered coefficient derived from EL, are corrected by two methodologies, namely first lag and −2/3 correction. The corrected profiles present small differences when compare against the uncorrected profiles, showing low influence of noise and the viability of the proposed methodology. Two case studies were analyzed in detail, one corresponding to a well-defined PBL and another one corresponding to a situation with presence of a Saharan dust lofted aerosol layer and clouds. In both cases the results provided by the different instruments are complementary, thus the synergistic use of the different systems allow us performing a detailed monitoring of the PBL.

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