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Profiling the atmospheric boundary layer (ABL): from harmonised measurement networks to multidisciplinary applications

The EU COST action PROBE (Profiling the atmospheric boundary layer at European scale) would like to promote recent advances in profiling the atmospheric boundary layer (ABL) using ground-based remote sensing and instrument networks to facilitate knowledge exchange between all actors concerned with ABL profiling.
We aim at highlighting new developments in measurement technology and advanced products and discussing how new profiling observations will impact various applications like weather, hydrology, climate, air quality, transportations, renewable energy, agriculture, and environmental hazards.
Contributions are welcome from people working with individual ABL profilers (incl. wind, cloud, aerosol, temperature, and humidity) as well as from networks. The session accepts also contributions on advanced products and tools (e.g. clouds and precipitation, forecast indices, fog and icing alerts, aerosols and air quality, wind and turbulence/gusts and ABL characterization) and applications for model assessment, data assimilation, nowcasting, climate simulations, and satellite data validation. Special interest is placed on work reporting on the ABL in specific environments, such as complex terrain, coastal locations, or cities.

Public information:

Dear conference participants, 

The EGU conference is about to start and the PROBE session on Monday afternoon as well!!

We are very excited to hear about your research and exchange nice discussions :) 

With these instructions, we hope to make your time at the conference enjoyable and fruitful. We thought of setting up some additional tools for making the interaction during the session easier and for also extending the discussion time beyond the session time slot, if needed. You can find below all the information.


Session program: https://bit.ly/38ww1gB 


In-person session logistic information

Mon, 23 May, 15:10–18:30 (CEST), Room M2
Austria Center, Bruno-Kreisky-Platz 1, 1220 Wien, Austria



Online session on Zoom:

All sessions will be run as Zoom meetings. We encourage all participants to download and use the Zoom app rather than accessing the meeting via a browser; 
Sessions can be accessed via the online programme. Please note that the respective "Enter Zoom Meeting" button will only appear approx. 15 min before the start of the session; 
Alternatively, sessions can be accessed from the Virtual Conference Centre on the landing page; 


Additional online tools

Discussion pad: https://yopad.eu/p/EGU_PROBE_session

The discussion pad is a link where you can write your questions during the session, and get answered by the authors. We will also read those questions in the short discussion time at the end of the presentation slots. We invite authors to add in the discussion pad also a link to their material, either their presentation or additional material they would like to make available to foster the discussion on their research. 


Gather town space: https://bit.ly/3yIYOJh 

This space is thought to meet your peers online, either in pairs or in larger groups if you like, to go on with the discussions when the time of the conference is over. We invite you to use this tool after the conference session is over or during coffee breaks, not to steal time for the session discussion. On Gather, you will find an object holding the discussion pad, so you can easily find there the links to the material or the questions that were asked. 






Convener: Claudia AcquistapaceECSECS | Co-conveners: Klara Jurcakova, Juan Antonio Bravo ArandaECSECS, Ekaterina Batchvarova, Maria Jose Granados-MuñozECSECS
| Mon, 23 May, 15:10–18:30 (CEST)
Room M2
Public information:

Dear conference participants, 

The EGU conference is about to start and the PROBE session on Monday afternoon as well!!

We are very excited to hear about your research and exchange nice discussions :) 

With these instructions, we hope to make your time at the conference enjoyable and fruitful. We thought of setting up some additional tools for making the interaction during the session easier and for also extending the discussion time beyond the session time slot, if needed. You can find below all the information.


Session program: https://bit.ly/38ww1gB 


In-person session logistic information

Mon, 23 May, 15:10–18:30 (CEST), Room M2
Austria Center, Bruno-Kreisky-Platz 1, 1220 Wien, Austria



Online session on Zoom:

All sessions will be run as Zoom meetings. We encourage all participants to download and use the Zoom app rather than accessing the meeting via a browser; 
Sessions can be accessed via the online programme. Please note that the respective "Enter Zoom Meeting" button will only appear approx. 15 min before the start of the session; 
Alternatively, sessions can be accessed from the Virtual Conference Centre on the landing page; 


Additional online tools

Discussion pad: https://yopad.eu/p/EGU_PROBE_session

The discussion pad is a link where you can write your questions during the session, and get answered by the authors. We will also read those questions in the short discussion time at the end of the presentation slots. We invite authors to add in the discussion pad also a link to their material, either their presentation or additional material they would like to make available to foster the discussion on their research. 


Gather town space: https://bit.ly/3yIYOJh 

This space is thought to meet your peers online, either in pairs or in larger groups if you like, to go on with the discussions when the time of the conference is over. We invite you to use this tool after the conference session is over or during coffee breaks, not to steal time for the session discussion. On Gather, you will find an object holding the discussion pad, so you can easily find there the links to the material or the questions that were asked. 






Mon, 23 May, 15:10–16:40

Chairpersons: Claudia Acquistapace, Klara Jurcakova, Juan Antonio Bravo Aranda

General introduction

Martial Haeffelin and DomeNico Cimini and the PROBE COST action core group

Meteorological and air quality surface sensor networks sample atmospheric variables close to the ground while satellite observations provide global spatial coverage of the upper atmosphere. There is however, an observation gap on the temporal variability and vertical structure of atmospheric parameters in the atmospheric boundary layer (ABL). The ABL is the lowest 2 – 3 km of atmosphere above ground where the vertical structure is driven by surface-atmosphere exchanges, ABL-to-free-troposphere exchanges, in addition to larger-scale processes. Most human activities take place in the ABL, it is hence very important to improve our ability to characterize those processes that affect weather conditions, air quality, transport and energy provision systems, and longer-term issues such as climate change adaptation and mitigation, of particular importance in urban settings.

Motivated by the overarching objective to support the efficient exploitation of ABL data and to maximize their societal impact, the PROBE COST action is creating a cooperation hub where a wide range of stakeholders from Academia, Research structures, Industry, Operational agencies, and general end-users can share advances and expertise on ABL profiling.

In the first two years of the action, the PROBE partners were able to attract a diverse community of more than 200 users that share information through webinars (on instruments, networks, and high-quality observations) and working group meetings (on ABL profiling in complex terrain and urban environments), and engage the community in a wide range of activities through efficient multi-media communication (http://www.probe-cost.eu/, newsletters, videos, social channels). No less than 5 working groups on thermodynamics, clouds, ABL height, wind and turbulence, and aerosol profiling reported on key ABL parameters, their applications and end-user requirements. A comprehensive document is being compiled that gives insights on “overview, access and benefits” of existing ABL profiling networks (e.g. E-PROFILE, ACTRIS, ICOS, …). Also less known (“hidden”) networks were identified. 5 specific instrument task groups (on microwave radiometers, cloud radars, doppler lidars, automatic lidars and ceilometers, and drones) are developing recommendations for configuration, operation, calibration, and quality control procedures.

Over the remaining period of the PROBE COST action (until fall 2023), the partners will continue to develop a solid literature (technical reports and scientific publications) on the topic of ABL profiling, improving content through short term scientific visits (either in person or virtual) and focused working groups (mostly virtual). Some partners will participate in a large international effort to better characterize the ABL in urban environments through an intensive measurement campaign to be held in the Paris region (France) in summer 2022 while others are involved in the TEAMx collaboration initiative observing the mountain boundary layer. Finally, the PROBE community is launching an inter-journal special issue, offering an opportunity for the advances in ABL profile observations and applications to gain visibility. For example, a very detailed review paper on ABL height retrievals from ground-based remote sensing was just submitted, resulting from several years of intense review work.

The presentation will provide an overview of recent achievements and upcoming activities.

How to cite: Haeffelin, M. and Cimini, D. and the PROBE COST action core group: Recent achievements of the “PROBE” COST Action: Towards profiling of the atmospheric boundary layer at European scale, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11570, https://doi.org/10.5194/egusphere-egu22-11570, 2022.

Simone Kotthaus et al.

A detailed understanding of atmospheric boundary layer (ABL) processes is key to improve forecasting of pollution dispersion and cloud dynamics in the context of future climate scenarios. International networks of automatic lidars and ceilometers (ALC) are gathering valuable data that allow for ABL layers to be derived in near real time. A new generation of advanced methods to automatically detect the ABL heights now exist. However, diversity in ALC models means these algorithms need to be tailored to instrument-specific capabilities.

In the framework of the ABL testbed project (funded by ICOS, ACTRIS and EUMETNET E-PROFILE), two advanced algorithms for the detection of ABL heights are being assessed for application in an operational network setting. A prime example of collaborations within the EU COST action PROBE on profiling the atmospheric boundary layer, the ABL testbed is a crucial step towards harmonised ABL height products at the European scale. A subset of 11 E-PROFILE sites in diverse geographical and land cover settings across Europe are selected where data from different ALC are available covering multiple years. Automatic layer detection is implemented, including instrument-specific corrections and calibrations. Algorithm performance for layer height detection is being evaluated via comparison of results from different ALC. Recommendations are formulated for implementation of automatic ABL height retrievals across a diverse sensor network. First results are very promising, revealing consistent temporal and spatial variations in ABL layer heights across the network.

How to cite: Kotthaus, S., Van Hove, M., Haeffelin, M., Drouin, M.-A., Laplace, C., Bouffies-Cloche, S., Dupont, J.-C., Ruefenacht, R., Hervo, M., Haefele, A., Collaud Coen, M., and Rivier, L. and the PROBE ABL testbed team: Automatic detection of atmospheric boundary layer heights at the European scale (ABL testbed), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7378, https://doi.org/10.5194/egusphere-egu22-7378, 2022.

Kristina Lundgren et al.

The field campaign FESSTVaL (Field Experiment on sub-mesoscale spatio-temporal variability in Lindenberg) was carried out by 16 institutions from May to August 2021 in the surroundings of the Meteorological Observatory Lindenberg – Richard-Aßmann-Observatory of the German Meteorological Service (DWD). The project aims at an improved understanding of the initiation and interaction of cold pools and wind gusts in the summertime convective boundary layer. Such weather phenomena can cause great damage, but are, however, difficult to capture by conventional surface networks due to their small-scale nature. Unique to this campaign is the deployment of a high-density near-surface measurement network made of over 100 ground-level stations for measurements of temperature and pressure, complemented by 20 automatic weather stations as well as a dense network of soil moisture measurements. An X-band radar and several energy balance stations were also used. The surface network was augmented by a network of vertical profiling instruments including nine Doppler LiDAR systems for measurements of the wind profile and turbulence variables up to an altitude of several kilometers, four microwave radiometers, and measurement flights with unmanned and remotely-controlled aircraft. As a supplement to these measurements, the project investigates the gain of a citizen science measurement network.

This presentation will shed light on the 4D structure and evolution of cold pools associated with a strong convective event as viewed by the different sensors. The cold pool observations will be compared to forecasts and to large-eddy simulations conducted for that particular case. Overall, the results of the project will serve to improve the representation of such small-scale processes in numerical weather prediction and to define new measurement strategies. The data products of the campaign are treated under the FAIR principle and are made available via a platform at the Integrated Climate Data Center of the University of Hamburg. 

How to cite: Lundgren, K., Hohenegger, C., Ament, F., Beyrich, F., Löhnert, U., Göber, M., Rust, H., Sakradzija, M., Bastak-Duran, I., Masbou, M., and Jahnke-Bornemann, A.: FESSTVaL: Field Experiment on sub-mesoscale spatio-temporal variability in Lindenberg – the campaign, first results and data availability, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8889, https://doi.org/10.5194/egusphere-egu22-8889, 2022.

Domenico Cimini et al.

Atmospheric stability is a measure of atmospheric status which determines whether thermodynamically perturbed air will rise, sink, or be neutral. Atmospheric stability has a major impact on the evolution of wind turbine wakes and thus on the yield and performance of offshore wind parks. For estimations of wind park power output and for improving analyses of offshore wind park wakes, a crucial parameter was found to be profiles of atmospheric temperature and stability metrics. Atmospheric temperature profiles can be measured in-situ by balloon-borne sensors, but also estimated from the ground using radiometric observations. This presentation reviews the stability metrics useful for monitoring wind park performances and provides a quantitative assessment of the value of microwave radiometer (MWR) observations to estimate these stability metrics from near surface, either over land or ocean. Results from three different MWR instruments, representing the most common available on the market, and at least three field experiments will be presented.


This work has been funded by Carbon Trust and the partner companies of the Off-shore Wind Accelerator program: (in alphabetical order) EnBW, Equinor, Orsted, RWE, Scottish Power Renewables, Shell, SSE Renewables, Total Energies, Vattenfall.

How to cite: Cimini, D., Gandoin, R., Fiedler, S., Wilson, H., Pospichal, B., Martinet, P., Balotti, A., Gentile, S., and Romano, F.: Assessment of atmospheric stability measurements from microwave radiometer observations for offshore wind energy applications, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12954, https://doi.org/10.5194/egusphere-egu22-12954, 2022.


Tatiana Nomokonova et al.

Over the last years, climate monitoring and operational weather forecasts have become an important topic for the renewable energy sector. An effective operation of national, and in the case of EU international, power generation aims to find the right balance between the minimization of CO2 emission and reduction of energy costs. In Germany a considerable part of the electricity generation comes from wind. Therefore, an accurate forecast of low-level wind is essential to predict the generation of electrical power produced by wind parks. This enables timely adjustments of the conventional power plants. Currently, short-term low-level wind forecasts have considerable uncertainties. One of the cost-effective solutions to improve low-level wind forecasts is an assimilation of new observations into numerical weather prediction models. Even though in the last decade, the number of remote-sensing sites has been continuously growing, the coverage is far from being optimal to achieve significant improvement of the short-term wind forecast. However, before building new large networks of ground-based instruments it is important to estimate in advance which instruments to install, what effect to expect, and what spatial density of the distributed instruments should be.


One of the ground-based instruments that can provide valuable information for low-level wind forecasts are Doppler lidars. In this study we focus on the estimation of the potential impact of a network of Doppler lidars for short-term low-level wind forecasts essential for sustainable energy applications. The potential impact is analyzed using the ensemble sensitivity analysis (ESA) [1, 3]. ESA is based on the Ensemble Transform Kalman Filter and allows us to investigate how the assimilation of hypothetical Doppler lidars can reduce the wind forecast variance. The impact a Doppler lidar network was analyzed with respect to surface measurements operationally assimilated by national weather services. We investigated the sensitivity of the obtained results to ESA settings such as number of Doppler lidars in the network, number of altitude layers observed by Doppler lidars, and forecast lead time. Our analysis is based on a 1000-member ensemble simulation for the urban and highly populated Rhein-Ruhr area and surrounding regions [2]. The simulation uses a full-physics non-hydrostatic regional model SCALE-RM and covers a two-week time period in May/June 2016.


This work has been conducted in the framework of the Hans-Ertel-Centre for Weather Research funded by the German Federal Ministry for Transportation and Digital Infrastructure (grant number BMVI/DWD 4818DWDP5A). This online publication is based upon work within the COST Action CA18235 supported by COST (European Cooperation in Science and Technology), funding agency for research and innovation networks, weblink: www.cost.eu. We acknowledge RIKEN for providing the SCALE-RM model data.



[1] Ancell, B., and G. J. Hakim, 2007: Comparing adjoint-and ensemble-sensitivity analysis with applications to observation targeting, Mon. Wea. Rev., doi.org/10.1175/2007MWR1904.1.

[2] Necker., T., S. et al, 2020: A convective-scale 1000-member ensemble simulation and potential applications. Quarterly Journal of the Royal Meteorological Society, doi.org/10.1002/qj.3744.

[3] Torn, R. D., 2014: The Impact of Targeted Dropwindsonde Observations on Tropical Cyclone Intensity Forecasts of Four Weak Systems during PREDICT. Mon. Wea. Rev., doi.org/10.1175/MWR-D-13-00284.1.

How to cite: Nomokonova, T., Griewank, P., Löhnert, U., Necker, T., and Weissmann, M.: Benefits of Doppler wind lidars to improve short-term low-level wind forecasts, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3864, https://doi.org/10.5194/egusphere-egu22-3864, 2022.

Steven Knoop

The Ruisdael Observatory [1] is a national initiative, a nationwide observatory for measurements of the atmosphere. It is set up to enable more concrete, detailed forecasts of the weather and air quality. The Ruisdael Observatory, named after the 17th century painter Jacob van Ruisdael, famous for his cloudy skies, will be modelling the entire Dutch atmosphere with a high resolution of only 100m.  At the Cabauw site, which fulfils the role of main station within the Ruisdael Observatory, a large set of instruments is operated to study the atmosphere and its interaction with the land surface. Doppler wind lidars, which are laser-based remote sensing instruments, will provide detailed measurements of the wind field, aerosols and clouds around the Cabauw site.

We have installed a scanning long-range Doppler lidar Windcube 200S (Leosphere/Vaisala) at the Cabauw site at April 6th, 2021. This instrument operates at a laser wavelength of 1.5 µm and retrieves return signals mainly from aerosol backscatter. Therefore the wind measurements are typically limited to the boundary layer, although higher lying clouds up to 14km can also provide data. The instrument has full semi-hemisphere scanning capabilities and the principle measurands are the radial wind speed, i. e. the wind component along the line-of-sight, and the relative attenuated backscatter coefficient. Wind profiles of horizontal wind speed and wind direction are retrieved from specific scan modes.

During its first year at Cabauw the Doppler lidar has operated continuously, alternating between different scan modes and instrument parameters, This included all standard Windcube scan modes: RHI (Range Height Indicator) for elevation scans at fixed azimuth angle, PPI (Plan Position Indicator) for azimuth scans at a fixed elevation angle, DBS (Digital Beam Swing) to retrieve wind profiles, and vertical staring. In addition, the six-beam method for retrieving wind and turbulence profiles [2] have been applied. During two campaign periods the Doppler lidar was co-located with Doppler cloud radars to investigate possible synergy between the retrieved wind profiles. Also a co-located ceilometer (Lufft CHM15K) is present, being part of the automatic weather station at Cabauw, which can be helpful in interpreting the Doppler lidar data.

Among the topics that are investigated:

  • intercomparison with the in situ wind measurements in the tall meteorological tower at 200m
  • comparison DBS and six-beam wind profiling scan modes
  • presence of range ambiguity and its consequences on the chosen resolution
  • vertical velocity information from DBS and continuous vertical staring scan modes
  • PPI and RHI scans for (LES-)model evaluation

Here we will present some results of those studies, and our plans towards a long-term operational measuring program.

[1] https://ruisdael-observatory.nl/

[2] A six-beam method to measure turbulence statistics using ground-based wind lidars, Sathe, Mann, Vasiljevic, and Lea, Atmos. Meas. Tech., 8, 729 (2015)

How to cite: Knoop, S.: Scanning Doppler wind lidar at Ruisdael Observatory, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11985, https://doi.org/10.5194/egusphere-egu22-11985, 2022.

Cristina Benzo and Ludovic Thobois

Accurate measurement of the wind is essential in many applications. From improving the efficiency of wind farms to identifying wind hazards at ports, airports, or industrial plants, precise knowledge of the wind is critical. Wind Lidars are widely used to provide detailed information on wind, and Scanning Wind Lidars provide further measurements in full hemisphere around its location with multiple scanning patterns (azimuthal scans, elevation scans, etc.).

User feedback has always played a vital role in developing this technology. In the most recent round of development, two key areas were identified for improvement, resulting in the development of a new version of the WindCube Scan:

  • Reducing range ambiguities that occur when clouds or obstacles are located further than the maximum acquisition distance.
  • Adding more flexibility between the different modes of measurement to optimize both measurement range and resolution.

The new WindCube Scan addresses these points with the introduction of new resolutions, mitigated ambiguities, and greater ranges.

This paper will describe the metrological validation performed over the last year both in the field and in a factory setting.

A field validation was conducted in collaboration with two leading meteorological organizations in Europe, pioneers in the PROBE European project for large-scale atmospheric boundary layer remote-sensing deployment and data-sharing. Both organizations received the new version of WindCube Scan for a beta test. They gathered wind data at their sites and compared to other remote sensing devices such as radiosondes and radar wind profilers to verify the performances of different resolutions and overall performance of data retrieval and wind speed precision.

A factory validation, which was conducted at the Vaisala France site, near Paris, consisted of both an indoor and outdoor test. The indoor verification test was aimed at testing radial wind speed precision with intrinsic lidar parameters such as pulse shape, energy, etc. The outdoor validation followed guidelines set by the ISO 28902-2 regarding remote sensing measurement verification with other in-situ devices. The lidar was pointed to an ultrasonic anemometer on a meteorological tower about 2km away. The wind speed measurements from both devices were then compared for precision and accuracy with proper filtering of unsuitable weather conditions. 

The results of the validation testing thus far show positive performance and noticeable improvements of the new version of the WindCube Scan. Additionally, the external validation collaboration with other PROBE members highlights the importance of fortifying and understanding remote sensing device precision and data collection methods if they are to be integrated into large, observational networks.

How to cite: Benzo, C. and Thobois, L.: Validation of a New Version of the WindCube Scan Lidar , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12644, https://doi.org/10.5194/egusphere-egu22-12644, 2022.


Joelle Buxmann et al.

Raman lidars are often used to gain quantitative aerosol profile information in the atmosphere including the atmospheric boundary layer. While ceilometers are less powerful  and show some technological disadvantages compared to lidars, their lower cost and low maintenance needs may be useful to fill geographical and temporal gaps between advanced lidar stations.

The Met Office operates a ground based operational network of nine dual-polarisation Raman lidars  and co-located sun photometers (column integrated information), as well as  more than 40 ceilometers across the United Kingdom. In this study we present a comparison between attenuated backscatter profiles, extinction profiles and mass concentration retrieved from the Raman lidars as well as selected ceilometer stations. The AERONET data from the sun photometers are used as an additional input parameter in the retrieval, and for validating the integrated extinction profiles. Aerosol optical properties from the Raman lidars are calculated from glued analogue and photon-counting signals using a data analysis package developed at the Met Office. A-Profiles, which is a python library dedicated to the analysis of atmospheric profilers, is used for the Ceilometer data. The calibration constant of the ceilometer in particular, is shown to impact the quality of the retrieval and will be investigated in detail. The Raman LR111-300s lidars (manufacturer: Raymetrics) emit at 355 nm and have polar and cross-polar depolarisation detection channels at 355 nm and a N2 Raman detection channel at 387 nm. The Ceilometer network consists of a mix of Vaisala CL31 and CL61 operating at 910.5nm, as well as Lufft CHM15K with an emitting wavelength at 1064nm. The CL31 and CHM15K ceilometers are part of the E-PROFILE network. In this study, we focus on several pollution events in the boundary layer, as well as aerosol transported from the Canadian wild fires in September 2020. The aerosol information at different wavelengths is used to inform the origin and type of the aerosols in conjunction with satellite images and dispersion model outputs using the Met Office Numerical Atmospheric-dispersion Modelling Environment (NAME).

Ceilometers show a good potential for aerosol profiling, especially in synergy with lidars and sun photometers. The higher spatial resolution of the ceilometer network in conjunction with the better sensitivity and accuracy of the lidar, improves the  knowledge of the vertical aerosol distributions and transport in near real time. This is needed to complement in situ surface measurements especially for monitoring air pollution and related health impacts.

How to cite: Buxmann, J., Osborne, M., Mortier, A., Ruefenacht, R., Turp, M., and O'Sullivan, D.: Intercomparison of Ceilometer aerosol profiling versus Raman lidar including  pollution events and transported biomass burning aerosols across the United Kingdom, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8213, https://doi.org/10.5194/egusphere-egu22-8213, 2022.

Henri Diémoz et al.

ALICEnet is a network of Automated Lidar Ceilometers (ALCs) operating across Italy. The geographical distribution of the measuring stations, extending from the north to the south of the country, allows monitoring of aerosol vertical profiles over a wide range of environmental and atmospheric conditions, dominated, for example, by anthropogenic particle production, Saharan dust transport or volcanic ash advections. The network, coordinated by CNR-ISAC and involving different institutions, is also a contributor of E-PROFILE, a EUMETNET program for surface-based profile observations.

The ALICEnet infrastructure and data processing flow (including signal correction and automatic calibration procedures) are here described, together with the inversion and retrieval algorithms. These latter allow to retrieve the aerosol properties over the vertical profile, to identify different layers, and to assess the atmospheric boundary layer (ABL) characteristics, such as the ABL and mixing layer height. Based on this setup, both use of near-real time data (e.g., to monitor aerosol transport events) and long-term studies (e.g., evaluation of aerosol climatological, site-dependent characteristics) will be possible.

In the present contribution, we focus on two examples of application: a case of long-range transport of Saharan dust and smoke, occurred over Rome in July 2017 during the EMERGE campaign, and the analysis of the climatological features of the mesoscale circulation between the Po Valley and the Alps. For both cases the ALICEnet retrieval procedure is validated based on independent measurements from the ground. Benefits from coupling with other remote sensing instruments, satellite radiometers, and atmospheric dispersion models are discussed.

How to cite: Diémoz, H., Bellini, A., Barnaba, F., Di Liberto, L., and Gobbi, G. P.: The Italian Automated Lidar-Ceilometer Network (ALICEnet): infrastructure, algorithms and applications, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6118, https://doi.org/10.5194/egusphere-egu22-6118, 2022.

Aurélie Riandet et al.

The boundary layer is the main dilution factor of gas and aerosol sources but high uncertainties remain on its variability, in particular in southeastern France. Atmospheric dynamics that take place there are complex due to the presence of the sea in the west and the south and by hills in the north and the east. This study is based on a field campaign performed in this area from November 7th, 2019 to January 27th, 2020. Four sites were selected : an urban site equipped with a CIMEL CE376 lidar in the city center of Marseille, two suburban sites (Nîmes and Marignane) equipped with a radiosounding facility and a Vaisala CL31 ceilometer respectively, and a rural site (Observatoire de Haute-Provence – OHP) equipped with radioundings and a CIMEL CE376 lidar, unfortunately encountering many issues during that period. Wind measurements are available for each site. The boundary layer height was retrieved with both the Richardson method and the wavelet transform one. Due to the complexity of aerosol layers encountered above Marseille, the boundary layer height temporal variability is investigated through 2 typical meteorological situations encountered in Marseille, e.g. sea/land breezes and Mistral (regional-northwestward-colder wind blowing over southeastern France from Rhône valley). To better trace the origin of the air masses, the depolarisation ratio from lidar is used. Comparisons between the four sites contribute to describe the spatial variability of the boundary layer height in south-eastern France.

How to cite: Riandet, A., Xueref-Remy, I., Blanc, P.-E., Popovici, I., Goloub, P., Lelandais, L., and Armengaud, A.: Boundary layer height variability in winter in southeastern France for typical meteorological situations, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7326, https://doi.org/10.5194/egusphere-egu22-7326, 2022.

Ozge Eren

Ambient air pollution (AAP) is one of the greatest environmental risk for human health and well-being   for both cities and rural areas. According to the World Health Organization (WHO), AAP levels exceed recommended limits almost 92% of the world’s population. The Air Quality Index (AQI) is a simple, unitless index divided into six categories corresponding to a different level of health concern with a specific a specific color. There are lots of calculations to measure AAP and one of them, widely used in the world, is provided from EPA (U.S. Environmental Protection Agency).  EPA establishes an AQI for five major air pollutants ( ground-level ozone particle pollution (PM2.5 and PM10), carbon monoxide, sulfur dioxide nitrogen dioxide) regulated by the Clean Air Act. In this calculation, the highest AQI calculated for each pollutant constitutes the AQI value for that day. This calculation also brings sensitivity problems. This situation causes us to question the precision of the measurement. The main aim of this study is to show some calculation examples of concentration levels of the pollutants with the different cases. Thanks to these scenarios, the necessity of a much more precise measurement will be revealed.

How to cite: Eren, O.: Sensitivity Analysis on Air Quality Index Calculation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11394, https://doi.org/10.5194/egusphere-egu22-11394, 2022.

Discussion and wrap up

Mon, 23 May, 17:00–18:30

Chairpersons: Claudia Acquistapace, Maria Jose Granados-Muñoz, Juan Antonio Bravo Aranda

David Turner et al.

Ground-based remote sensing instruments provide a unique and powerful view of the thermodynamic structure and evolution of the atmospheric boundary layer.  A range of different technologies have been developed over the past 40 years to observe profiles of temperature and humidity from the ground.  These methods include passive techniques, such as single- and multi-channel microwave radiometers (MWRs) and infrared spectrometers (IRS), and active approaches, such as Raman lidars (RLID), differential absorption lidars (DIALs), and radio acoustic sounding systems (RASS).  All of these techniques have strengths and weaknesses, and it can be challenging to evaluate the relative differences in their information content in a consistent way.  Furthermore, this leads to questions on how to combine observations from multiple instruments synergistically.  Additionally, the profiles derived from many remote sensors have correlated errors between different height levels, and thus the covariance of the profile needs to be understood if the profiles are to be properly assimilated into a weather forecast model.


To address these questions, we have developed the TROPoe retrieval software package.  TROPoe is a 1-dimensional variational algorithm, based upon optimal estimation, that incorporates forward models for all of these instruments to allow an iterative solution to be determined.  A climatology, usually of historical radiosondes launched near the instrumented site, is used to provide a constraint to the retrieved solution. Uncertainties from the observations, the sensitivity of the forward models, and the uncertainty in the prior are all propagated to provide a full error covariance matrix for each retrieved thermodynamic profile. Retrievals using single instrument configurations (e.g., MWR-only, IRS-only, DIAL-only) as well as multi-instrument retrievals (e.g., MWR+IRS, MWR+DIAL, IRS+RLID, MWR+IRS+DIAL) have been performed.  Since the same retrieval framework and prior dataset was used, the uncertainties and information content for each instrument complement can be directly compared.  We will present some examples in the differences in the information content among these different instrument combinations.


The TROPoe software is being packaged into a Docker container, which will facilitate the use of the software easily by a wide range of users.  We will present our vision for how TROPoe could be used to provide consistent retrievals for the ground-based remote sensing community, including how to assimilate these data, regardless of the actual instrument datasets used in the analysis.

How to cite: Turner, D., Löhnert, U., Gebauer, J., Bell, T., and Blumberg, G.: TROPoe: Tropospheric Remotely Observed Profiling via Optimal Estimation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10512, https://doi.org/10.5194/egusphere-egu22-10512, 2022.

Min Seong Kim et al.

In the atmospheric boundary layer (ABL), the humidity profile was retrieved by combining the data of the radiometer and the wind profiler, and was compared with that of the GPS radiosonde. The variation of the amount of precipitable water (PW) was analyzed in sea breeze, typhoon, and precipitation cases. High-frequency electromagnetic waves emitted from the wind profiler are affected by atmospheric thermodynamic factors (temperature, humidity, and atmospheric pressure). An algorithm was developed to determine the optimal vertical gradient of refractivity (M) which plays important role in the vertical variation of humidity. M was corrected in consideration of the boundary layer height estimated by the wind profiler and the humidity characteristics in the mixed layer. The root mean square error (RMSE) of the retrieved specific humidity was 1.72 g/kg, which was twice as low as the RMSE 3.42 g/kg of radiometer specific humidity. The variation of PW is essential for understanding the structure of the ABL. As the sea breeze blows, the PW increased in the lower layer. As the typhoon approaches the Korean Peninsula, the lower level PW increased rapidly. The PW before and after precipitation showed clear increase and decrease, respectively except for summer season when there is enough water vapor

How to cite: Kim, M. S., Kwon, B. H., Kim, S., Lee, K., and Kim, Y.: Retrieval of Humidity Profile Using Refractive Index of UHF Wind Profiler Radar , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8970, https://doi.org/10.5194/egusphere-egu22-8970, 2022.

Pauline Martinet et al.

The fog lifecyle and more especially formation and dissipation times are still poorly represented in even the highest resolution operational numerical weather prediction (NWP) models, causing large economic costs in the aviation industry. A new, continuous transmission, 95 GHz cloud radar (CR), sensitive to cloud and fog droplets, opens up the possibility of retrieving vertical profiles of fog microphysical properties with unprecedented capabilities. Additionally, well-know ground-based microwave radiometers (MWR) can provide detailed information on the fog thermodynamics and total liquid water path. This work aims at combining ground-based MWR and CR measurements constrained with short-term-forecasts (called background profiles) from the high-resolution operational model AROME into a one dimensional variational approach (1DVAR) in order to retrieve physically consistent temperature, humidity and liquid water content profiles within fog conditions. Firstly, background and forward model errors during fog conditions are investigated and a methodology of improving the background profile is proposed. Then, a first evaluation of the algorithm using a synthetic dataset will be presented. This evaluation aims at quantifying the capabilities of the algorithm on idealized conditions, providing an upper limit on the performance that could be reached by the algorithm. The algorithm is then applied to real observations from the SOFOG3D (SOuth FOGs 3D experiment for fog processes study) field experiment led by Météo-France during the winter 2019/2020 where the 95 GHz BASTA cloud radar has been collocated with the HATPRO MWR together with in-situ observations. The capability of the algorithm to retrieve liquid water contents with an approximate error of 0.05 g.m-3  but also temperature and humidity profiles with an accuracy better than 1 K and 1 g.kg-1 respectively thanks to comparison with in-situ measurements (radiosondes and cloud droplet probe measurements) has been demonstrated. A sensitivity study will also be presented to identify the major sources of uncertainties in the algorithm (microphysics assumption and 1D-Var background-error-covariance matrix). These developments open new capabilities for future assimilation of the retrieved profiles in the new AROME ensemble data assimilation scheme and to better understand physical processes taking part in the fog lifecycle.

How to cite: Martinet, P., Bell, A., Caumont, O., Vié, B., Burnet, F., and Delanoë, J.: Optimal estimation of thermodynamic and microphysical profiles within fog events from ground-based microwave radiometer and cloud radar synergy., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12410, https://doi.org/10.5194/egusphere-egu22-12410, 2022.

Guillaume Thomas et al.

While fog can severely affect human activities (air, land and marine transportation), its forecast with current numerical weather prediction (NWP) models stays challenging, especially due to the lack of observations in the atmospheric boundary layer and the misrepresentation of non linear small scale processes. To improve knowledge on fog formation, evolution and dissipation, several instruments have been deployed during the SOFOG3D (SOuth west FOGs 3D experiment for processes study) experimental campaign to provide an unprecedent database of detailed 3D observations. In that context, a network of 8 ground-based microwave radiometers (MWR) provided continuous temperature profiling as well as integrated water vapor and liquid water path measurements during a 6 month period. Additionally, Martinet et al (2020) highlighted large temperature errors in the AROME-France (Application of Research to Operations at Mesoscale) NWP model background profiles during fog forecasts, leading to temperature differences up to 6 K when compared to tower measurements. Nevertheless, this study also demonstrate that the assimilation of MWR observations with a one dimensional variational data assimilation scheme could leads to improved initial conditions. To go further in that direction, MWR temperature profile observations from the SOFOG3D experiment have been added in the AROME-France operational data assimilation system, which uses a three dimensional variational algorithm (3D-Var) and climatological and homogeneous background error covariances (B matrix), to quantify the benefit on operational analyses and forecasts of several fog events. Then, the recently developped ensemble variational (EnVar) data assimilation system has been used to conduct new assimilation experiments. The main advantage of such method is to prescribe a fully flow dependent B matrix which is spatially and temporally coherent with the forecasted meteorological conditions. In consequences, it leads to more realistic increments. The results obtained with the different assimilation experiments will be presented. Firstly, a statistical analysis of the impact on the AROME-France analyses and short-range forecasts against conventional observations will be discussed. Secondly, specific SOFOG3D observations will be used to investigate the benefit on dedicated fog case studies.

How to cite: Thomas, G., Martinet, P., Brousseau, P., Chambon, P., and Burnet, F.: Data assimilation experiments of a ground-based microwave radiometer network for fog forecast improvement., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7025, https://doi.org/10.5194/egusphere-egu22-7025, 2022.

Jonnathan Cespedes et al.

Air quality and meteorology in urban environments are strongly affected by dynamical and turbulent processes occurring in the atmospheric boundary layer. These are largely driven by the interaction between the surface and the atmosphere, including the exchange of momentum, heat, moisture, and various gases and aerosols. Vertical ventilation, horizontal advection, and atmospheric stratification are key processes.

To improve the understanding of the exchange processes in the urban atmosphere and to assess the implications of spatial variations in surface roughness, spatially resolved vertical profiles of the horizontal wind are required. In this work, we are implementing a novel “volume wind processing” approach to retrieve horizontal wind information on a 3D spatial grid from observations of a scanning Doppler wind lidar (Vaisala Windcube 400s). Deployed on the rooftop of a tall building in downtown Paris, France, the Doppler lidar is operated with a series of scan strategies to monitor the vertical and horizontal variations of the mean wind field across the city center.

In order to quantify the performance of the volume wind processing, an evaluation measurement campaign was performed combining measurements at the Vaisala measurement site and the SIRTA atmospheric observatory (Paris-Saclay) located 3.5 km from each other. The Windcube 400s, located on the Vaisala site, gathered measurements based on different scan patterns (full or sector (>30°) Plan-position Indicator (PPI)), from which wind profiles were retrieved using the volume wind processing. These retrievals were then compared to vertical wind profiles obtained from a previously validated and calibrated Doppler lidar (WLS70) running in a vertical profiling mode located at SIRTA. The comparison is performed over a 30-days period. We found a mean difference (Volume Wind – Vertical Stare) of -0.69 m/s and a standard deviation of 1.32 m/s for 10-min averaged profiles.

The ongoing work consists of identifying the sources of uncertainty in the volume wind processing and improving the quality of the retrievals by improving quality control procedures. High-quality wind profile products will then be available for research on the spatial variability of the wind speed profiles, in order to determine the influence of the surface roughness on exchange processes in the Paris urban atmosphere.

How to cite: Cespedes, J., Kotthaus, S., Thobois, L., and Haeffelin, M.: Retrieving wind profiles over the Paris (France) urban area from a single Doppler Lidar measurements, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11471, https://doi.org/10.5194/egusphere-egu22-11471, 2022.


Klemens Hocke and Ruben Beynon

Highlights of the thesis of Ruben Beynon are presented. To our knowledge, snow virga at middle latitudes has not been reported yet. We  investigated data from a Micro Rain Radar (MRR) in Bern, Switzerland, from 2008 to 2013 for snow virga precipitation events. The MRR data were reprocessed with the radar data processing by Garcia-Benardi et al. (2020) which allows the reliable determination of the snow virga precipitation rate. Here, we focus on the long-lasting snow virga event of 17 March 2013. The review of the event is additionally supported by atmospheric reanalysis data and atmospheric back trajectories. In the investigated event, we are able to observe a wind shear during the snow virga precipitation. While the wind shear existed, the situation was  that moist and precipitating air was in the upper air layers while dry air was carried into the lower air layers.  The lowest altitudes reached by the precipitation varied between 300 m and 1500 m above the ground. The duration of the snow virga was  22 hours.  In difference to the MRR observations, ERA5 reanalysis indicated drizzle at the ground over a time segment of  4 hours during the snow virga event.

How to cite: Hocke, K. and Beynon, R.: Snow Virga Above the Swiss Plateau Observed by a Micro Rain Radar, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1909, https://doi.org/10.5194/egusphere-egu22-1909, 2022.

Minttu Tuononen et al.

Ceilometers are robust, standalone, and cost-effective lidar-based remote sensing instruments. Conventionally, ceilometers are used in aviation to detect cloud base heights. Ceilometers can also be used for atmospheric profiling, and the applications using profile information are becoming more common, as well as operative networks of profiling instruments. Development of new ceilometers with additional measurement capabilities enables more thorough sensing of the atmosphere, covering a variety of applications. The focus of this presentation is on the different application possibilities that a new lidar ceilometer with a depolarization measurement capability offers.

High-quality attenuated backscatter profiles are used for cloud, boundary-layer, and elevated aerosol-layer profiling. The further addition of the depolarization ratio profiling allows more straightforward and detailed analysis of the current atmospheric conditions. With these measurements, it is not only possible to increase the public safety operationally, but also to investigate atmospheric phenomena in more detail. The newly developed instrument operates with 910.55 nm wavelength and can measure both attenuated backscatter and depolarization ratio.

The differentiation of liquid cloud droplets and ice crystals and the differentiation of rain/drizzle and snowfall is now more accurate and easier with the depolarization measurement. In addition, the detection of the melting layer and potential icing conditions are easier to identify. The structure of the boundary layer and elevated aerosol layers can be monitored in more detail and for example the detection of volcanic ash is a new and potentially very beneficial application with ceilometer with depolarization. The depolarization ratio measurement using a new wavelength can be also used to investigate other different aerosol characteristics and type, and for example to group different pollen types.

In this presentation, we show how different conditions can be distinguished – from hydrometeor and precipitation type analysis to measurement examples of wildfire smoke and dust. Specifically, we will show results of ceilometer measurements in La Palma, Spain, during the volcanic eruption that occurred in the end of 2021. In addition, more accurate identification of potential icing conditions is discussed.

How to cite: Tuononen, M., Lehtinen, R., and Roininen, R.: Applications with ceilometer with depolarization ratio measurement, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7038, https://doi.org/10.5194/egusphere-egu22-7038, 2022.

José Dias Neto et al.

Convective clouds may be associated with substantial transport of momentum. The process of convective momentum transport is typically investigated using simulations due to a lack of observations. This study exploits the currently available remote sensing techniques to visualize wind structures within clouds and their surroundings and quantify the vertical transport of momentum.

The Tracing Convective Momentum Transport in Complex Cloudy Atmospheres experiment (CMTRACE) took place in the experimental site in Cabauw (The Netherlands) between September 13th and October 3rd 2021, as part of the RUISDAEL project. The goal of CMTRACE was to provide continuous profiles of horizontal and vertical wind components with a temporal resolution of ~1 minute and vertical resolution of ~50 m within the cloud and sub-cloud layers to improve our understanding of the role of momentum transport on different scales. One scanning wind lidar provided the observations in the sub-cloud layer, while in the cloud layer, the observations were obtained by one scanning and one vertically pointing cloud radar. The high-resolution data produced by those instruments across the boundary layer can also benefit data assimilation and model evaluation.

During CMTRACE, we sampled various cloud regimes such as non-precipitating shallow cumulus, deep convective clouds and stratiform clouds. Due to the presence of insects, the radar provided almost identical wind profiles to the lidar up to cloud base, giving us confidence in the quality of the observations. The dataset was also validated against the data from radiosondes and the Cabauw mast tower.

In this presentation, we outline the CMTRACE observational dataset and present statistical analyses and classification of the data into different cloud regimes. The profiles of wind fluctuations and momentum fluxes are used to exemplify correlations between vertical and horizontal wind on both cloud- and mesoscale scales.

How to cite: Dias Neto, J., Nuijens, L., Unal, C., and Knoop, S.: Visualising and quantifying momentum transport in cloudy boundary layers using collocated lidar and cloud radars, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12045, https://doi.org/10.5194/egusphere-egu22-12045, 2022.

Christiane Duscha et al.

Convection is a major contributor to the overturning of heat, moisture, and momentum in the atmospheric boundary layer and is responsible for the formation of convective clouds and precipitation. However, the characteristic properties, the dynamics, and the processes that trigger and shape the development of atmospheric convection are still only sparsely sampled. In this study, we present an approach to probe and characterise atmospheric convection from both the Eulerian and the Lagrangian perspectives, utilising dual-doppler lidar observations combined with velocity estimates from paraglider and sailplane flight trajectories. Some of the evaluated flights involve additional sensors to sample temperature and humidity. The observations are obtained over the mountainous terrain of southwestern Norway. As a proof-of-concept, we demonstrate the capability of the dual-doppler lidar setup to accurately characterise atmospheric convection and to validate the complementing estimates from the flight tracks in complex terrain. The Lidar setup accurately resolves dynamic properties of the convective circulation with high detail, while the flight tracks resolve the dynamic (and static) properties of the convective updrafts.  

How to cite: Duscha, C., Pálenik, J., Kähnert, M., Spengler, T., and Reuder, J.: GLidar - Probing atmospheric convection in complex terrain , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2665, https://doi.org/10.5194/egusphere-egu22-2665, 2022.

Nir Shiloah et al.

Clouds are a severe disturbance in a very wide range of applications, such as aviation, and solar energy, and in ground based, airborne, and satellite observations. The ability to accurately predict cloud-base heights (CBH) using the weather models is of crucial importance

In recent years, information on CBH has been added as an integral part of the output of the European Operational Model, the Integrated Forecasting System (IFS) of the European Center for Medium-Range Weather Forecasts (ECMWF).

In order to examine the quality of the IFS forecasts, a CBH comparison was made in this work for low-level clouds at the eastern basin of the Mediterranean, between the IFS model predictions, observations from different meteorological satellites - VIIRS and CALIPSO, ceilometer observations at two sites in Israel - Beit Dagan (Coastal Plain) and Jerusalem (Mountainous area), and aviation weather report data from airports.

The comparison shows that there is a very good agreement between CBH IFS predictions, and ground observations from ceilometers (in most months the difference is less than 25% of the CBH), and a good agreement in cloud cover between IFS forecast and observations of aviation weather reports.

The comparison also shows that there is a good agreement between CBH IFS predictions, and CALIPSO satellite measurements (the difference is on average less than 35% of the CBH, and an excellent 95% fit if CBH measurements are paired compared. Similar comparison of VIIRS satellite observations with CBH IFS predictions, shows good agreement too (the difference is less than 20% of the CBH).

How to cite: Shiloah, N., Yunker, A., Kunin, P., and Rostkier-Edelstein, D.: Low-level cloud base height in the eastern Mediterranean basin: comparison between ECMWF IFS forecasts, ceilometers observations, satellite observations and aviation-weather reports , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2193, https://doi.org/10.5194/egusphere-egu22-2193, 2022.

Kreso Pandzic and Tanja Likso

Vertical wind and air temperature profile related parameters in the surface layer at the edge of a suburban area of Zagreb Capital in Croatia has been studied.  For that purpose, adopted Monin–Obukhov similarity theory and a comprehensive  Campbell Scientific Inc. observation system  of wind and air temperature at 2 and 10 m above ground, recorded since 2013, have been used. The results confirmed  estimation of effective roughness lengths dependent on eight wind direction sectors indicated before. Gratefully to that achievement,  a representativeness of wind data at standard 10-m height can be clarified more deeply for an area of at least about 1 km in upwind direction from the observation site which can be used in numerical weather prediction or atmospheric pollution modelling.

How to cite: Pandzic, K. and Likso, T.: Determination of surface layer parameters at  a suburban area of Zagreb  in Croatia, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7397, https://doi.org/10.5194/egusphere-egu22-7397, 2022.

Donato Summa et al.

The height of the planetary boundary layer is strongly influenced by the surface of the earth since it is directly in contact with it. In this study  we want to discuss the correlation between global warming and PBL variation. This is addressed using both the boundary layer height and other thermodynamic indices. In this study we want to highlight how the variation in the height of the PBL, together with other thermodynamic indices, represent an indication of climate change. PBL variations are therefore analyzed both in the daytime and in the night case, by means of radiosonding profiles from the Global Integrated Archive (IGRA) at the mid-latitudes in the range [30 °; 50 °] N. Data from the European Center for Medium-Range Weather Forecasting (ECMWF) and all the GRUAN station in the same latitude belt station GCOS Upper-Air Network (GRUAN) are used as a comparison dataset for atmospheric parameter uncertainties. 

The study reports a statistical analysis over 40 years, in order to have an evolution of thermodynamic variables both on monthly,  seasonal averages and also  annual. In general, a good agreement is found for the nighttime data compared between IGRA and ERA5, while during the day, the boundary layer height estimates in Europe with ERA5 are characterized by lower spatial homogeneity than those obtained with IGRA.

Finally, the comparison between the Lindenberg data as processed at high-resolution by GRUAN and as provided to IGRA at a lower resolution, shows the significant impact of using high-resolution data in the determination of the boundary layer height. [1,2]

[1] Madonna, F., Summa, D., Di Girolamo, P., Marra, F., Wang, Y., Rosoldi, M. Assessment of Trends and Uncertainties in the Atmospheric Boundary Layer Height Estimated Using Radiosounding Observations over Europe. Atmosphere 2021, 12, 301. https://doi.org/10.3390/atmos12030301

[2] Vivone G., D’Amico G., Summa D., Lolli S., Amodeo A., Bortoli D., and Pappalardo G. Atmospheric boundary layer height estimation from aerosol lidar: a new approach based on morphological image processing techniques. Atmos. Chem. Phys., 21, 4249–4265, 2021,https://doi.org/10.5194/acp-21-4249-2021

How to cite: Summa, D., Madonna, F., Franco, N., De Rosa, B., Rosoldi, M., and Di Girolamo, P.: The PBL and other thermodynamic indices for the study of climate change, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1258, https://doi.org/10.5194/egusphere-egu22-1258, 2022.

Sigalit Berkovic et al.

The boundary layer (BL) profile over the coastal plain of Israel, Eastern Mediterranean (EM),
varies considerably during winter. Although, in the context of air pollution, the
characteristics of the BL height (BLH) was intensively investigated, a quantitative
classification of the BL profile regimes has not been performed. Here, we seek to reveal the
dominant, recurring regimes of the BL profiles, their quantitative characteristics and links to
regional synoptic-scale patterns.
An objective unsupervised classification of winter BL radiosonde profiles is performed for
the first time by multi-parameter self-organizing map (SOM) analysis. The analysis uses high-
resolution, 12-UTC data of wind, temperature, humidity and pressure measurements during
Dec-Feb 2007-2018, and yields 30 distinct profile regimes.
Composite analysis using ERA5 reanalysis suggests strong association between the profile
regimes and synoptic weather systems and highlights four groups: 1. Deep winter cyclones
with strong westerly wind and precipitation; 2. Strong surface anticyclones and Red Sea
troughs (RST) with a mid-tropospheric ridge, moderate dry easterly wind and extreme
temperatures. 3. Moderate pressure gradients under shallow cyclones, anticyclone to the
west and RST to the east of Israel. 4. Active RSTs, accompanied by upper-tropospheric
trough/cutoff low and heavy precipitation. For the first time, general objective classification
observes the active RST without requiring specific criteria.
Consistent with previous knowledge, the new classification exhibits distinct categories of
thermal stability, BLH and turbulence. Importantly, we show that the automatic objective
classification of profile data from a single station can be a sensitive discriminator of winter
synoptic regimes in the EM, and therefore explains the variability of the BL profile. It
facilitates the study of the interaction between the BL and the free troposphere and may
improve the prediction of air pollution or future BL profile regimes based on long time series
from historical data or climate models.

How to cite: Berkovic, S., Mendelsohn, O. Y., Ilotoviz, E., and Raveh-Rubin, S.: Self-organizing map classification of the boundary layer profile – a refinement of Eastern Mediterranean winter synoptic regimes, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-684, https://doi.org/10.5194/egusphere-egu22-684, 2022.

Discussion and wrap up