European Facility For Airborne Research

EriSMA

investigating the Effects of Satellite assimilation of dust in NMM-DREAM Model over SW Africa

Scientific project

TA-011. Applications of atmospheric in-situ measurements.

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AMIRIDIS Vassilis

BSc in Physics, Aristotle University of Thessaloniki, MSc and PhD in Atmospheric Physics, Aristotle University of Thessaloniki (Laboratory of Atmospheric Research).

Vassilis Amiridis (VA) is a member of ISARS-NOA since 2006. His main academic and professional qualifications include: (i) Ground-based and Satellite Remote sensing measurements of the atmospheric composition using lidar and sunphotometric techniques, (ii) Optical and Microphysical properties of aerosols, and (iii) Studies of radiation transfer in the atmosphere. He has participated in several national, European and international projects and experimental campaigns. He has more than 40 publications in peer-reviewed scientific journals, more than 110 in conference proceedings, various scientific and technical reports and more than 300 third party citations. VA is responsible for the Aerosol Remote Sensing Station (ARSS) of ISARS in Athens, Greece.

VA considers himself to be inexperienced in use of research aircraft. However, he has been participated in several projects and experimental campaigns where airborne aerosol measurements were acquired and used in his research (e.g. “THERMOPOLIS 2009 Campaign”, 2009-2010; “UV / Tropospheric Aerosol Campaign” in the framework of “Stratospheric-Climate Links with Emphasis on the Upper Troposphere and Lower Stratosphere (SCOUT-O3)”, 2004-2009; “Liquid hydrogen fuelled aircraft - system analysis (CRYOPLANE)”, 2000-2002 ; “Photochemical Activity in the Ultraviolet Spectral Region - PAUR-II”, 1998-2000)

Namib desert extents along the west coast of Namibia and dust plumes originating from these coastal dust sources have often been identified by satellite images to extend hundreds of kilometers over the ocean off the west African coast. Moreover, the dry lake of Etosha Pan is an additional inland source of fine dust in this area and dust plumes from this source are also often blown towards the sea. The collocation of airborne dust originating from sources with such different mineralogy provides an ideal opportunity to test remote sensing methodologies for characterizing these particles and examining their particular optical and microphysical properties. To our knowledge, dust in this area has not been widely examined neither by in-situ experiments nor by remote sensing or modeling studies.
This project aims in improving the description of the dust plumes in the area provided by the NMM-DREAM model, by assimilating satellite dust retrievals in it, as the MSG-SEVIRI dust optical depth and the CALIPSO and CATS dust vertical profiling. The results will be compared with dust microphysical and optical property retrievals, utilizing aircraft lidar profiles, airborne polarimeter measurements, as well as in-situ observations from airborne sizers and collecting filters (if available).

FA20 - SAFIRE

The airborne polarimeter on-board this aircraft will provide measurements which we consider valuable for our analysis

The main objectives of this research are the following :
1. Examine the optical and microphysical properties of airborne dust particles over the greater area of South-West Africa and South-East Atlantic.
2. Improve the description of these plumes in numerical dust models by assimilating satellite dust retrievals in NMM-DREAM model. More specifically the advances in modeled dust will be investigated first with the assimilation of the MSG-SEVIRI dust optical depth retrieval as provided by the UK Met Office algorithm (Brindley et al., 2009) and second with the assimilation of vertical profiling from CALIPSO and CATS measurements.
3. Assessment on the representation of dust emission in NMM-DREAM model and validation against airborne observations of an ongoing emission event. The examination will illustrate the capability of the model to represent the location of the source, the atmospheric conditions during emission and the dispersion of entrained dust in terms of transport pathways. This will help for quantifying the ability of the NMM-DREAM in its novel setup including assimilation of satellite dust retrievals.

The analysis will be mainly based on observations of mineral dust plumes from both Namib desert and Etosha lake. The methodology proposed to carry out the proposed experiments includes the assimilation of the satellite measurements in the NMM-DREAM model and the validation of the new model results with the dust properties retrieved with a combination of airborne remote sensing and in-situ measurements. For the first part, a source-receptor analysis for each flight leg will be performed for the identification of the dust particle origin. Backwards Lagrangian simulations with FLEXPART-WRF will be carried out with the use of high resolution atmospheric fields from the WRF model. Additionally, all collocated CALIPSO and/or CATS overpasses will be analyzed and lidar retrievals will be compared to the aircraft 3-wavelength lidar measurements. MSG-SEVIRI dust retrievals at this area often indicate AOD values comparable to Saharan AODs. We will investigate the effects of assimilating these fields in NMM-DREAM model and also examine the possibility to assimilate CALIPSO and CATS dust retrievals in the model.
For the second part, the interpretation and assessment of the modeling results will be performed using retrievals of the dust microphysical and optical properties, utilizing aircraft lidar profiles, airborne polarimeter measurements, as well as in-situ observations from airborne sizers and collecting filters (if available) and ground-based sizers and chemical analyzers. More specifically, we plan to develop and implement a novel inversion scheme that will take as input the remote sensing and in-situ measurements and calculate the ambient microphysical properties of dust particles at different heights of the atmospheric column, in terms of their concentration, size distribution and refractive index.

The anticipated outputs from this work include the improvement of our knowledge on dust processes over an almost unexplored area and the validation of satellite retrievals and dust modeling results that will increase our confident on these products over this particular area. Scientific results from the analysis and interpretation of campaign measurements will be published in peer-review journals at the fields of remote sensing, atmospheric physics and numerical modeling (e.g. Atmospheric Chemistry and Physics, Journal of Geophysical Research, Atmospheric Environment, Atmospheric Measurements and Techniques etc.)

In general clear skies (in terms of clouds) and dusty conditions are preferable. Generation of dust episodes from low level jets (LLJ) or haboobs might give an additional opportunity to study such processes.

Due to the episodic nature of dust advection the flights should be scheduled according to dust forecasts. Optimal flight legs should be collocated with CATS and/or CALIPSO overpasses. CALIPSO overpasses over Namibia (ascending and descending) occur around 00 and 12 UTC (+/- 1h). CATS overpasses (onboard ISS - International Space Station) are roughly once per day.

Namibia and the greater SW Africa - SE Atlantic region is an almost unexplored area regarding mineral dust processes in the atmosphere. The existence of both desert dust sources and dry lake sediment sources provides a unique opportunity to investigate the possible different properties (mineralogical, optical and microphysical) of airborne dust in this area and assess also their representation in numerical modeling simulations and satellite retrievals.

In order to obtain the maximum information for the characterization of dust layers the aircraft should under-fly CALIPSO or CATS overpasses during episodes of dust advection at the greater area of SW Africa. In total a minimum of 10 flight hours are requested (approximately 2 missions).

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The combination of the 3-wavelength lidar with the polarimeter measurements from the FA20-SAFIRE aircraft, along with the airborne and ground in-situ measurements of size and chemical composition will be used for the characterization of dust particles and for the evaluation of the assimilated model results. Moreover, dropsonde measurements will provide the thermodynamical structure (moisture and temperature) of the dust plumes. The key measurements required for this campaign are the following:

- Basic meteorological fields (temperature, wind, humidity, turbulence, etc.).
- Active remote sensing measurements including aerosol attenuated backscatter and depolarization ratio profiles from the 3-wavelength lidar.
- Multi-wavelegth polarized radiances from the polarimeter.
- Dropsonde profiles to obtain the thermodynamical profile of the atmosphere above-inside-and below the dust clouds.
- Airborne and ground in-situ measurements of dust particles (chemical, optical, size, hygroscopicity , etc.)

• Basic meteorological fields(temperature, wind, humidity,turbulence, etc.).
• Active remote sensing measurements including aerosol attenuated backscatter and depolarization ratio profiles from the 3-wavelength lidar.
• Dropsonde profiles to obtain the thermodynamical profile of the atmosphere above-inside-and below the dust clouds.
• Multi-wavelegth polarized radiances from the polarimeter.
• Ground analysis of dust samples (chemical, optical, size, hygroscopicity , etc.)

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Except the basic aircraft instrumentation for this campaign we would also need:
1. 3-wavelength lidar
2. polarimeter

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3

The airborne measurements will be performed by the aircraft and instrument operators. NOA will be responsible for the satellite (MSG-SEVIRI, CALIPSO-CALIOP and ISS-CATS) data collection and processing and for the modeling activities (NMM-DREAM, WRF, FLEXPART). Archiving of all in-situ, remote sensing and modeling data will be ensured by NOA. Data processing includes the analysis and interpretation of observations (in-situ and remote sensing) for the determination of dust properties (concentration, size distribution, CCN activation, etc.). This data will be compared with model dust fields for various options of satellite assimilation in order to evaluate the model performance and improve the representation of dust in modeling results.

The PI will be actively participating in the field campaign contributing in flight planning, and post-flight analysis. 3 senior researchers, 1 Post-Doc and 1 PhD student will form the post-possessing data analysis team. They will be responsible for aircraft, satellite and ground-based data analysis. The participating personnel is composed by experienced tenured research staff and project-funded researchers. ERiSMA campaign is scientifically related with the ACTRIS-2 (Aerosols, Clouds and Trace gases Research InfraStructure network) EU project. It is anticipated that the campaign results will contribute to ACTRIS-2 efforts “to develop new integration tools to fully exploit the use of multiple atmospheric techniques in particular for the calibration/validation/integration of satellite sensors and for the improvement of the parameterizations used in global and regional-scale climate and air quality models”. The campaign will be followed by experienced researchers acting as consultants. These are Dr. Slobodan Nickovic and Dr. Kerstin Schepanki, both consulting on the assimilation of the NMM-DREAM model.

15 August 2016 to 15 October 2016

Yes

Most of the participants have experience on airborne campaigns gained within the framework of several projects (e.g. MINOS, 2001 - http://luna.tau.ac.il/~peter/MEIDEX/Reports/Minos/minos.htm; SCOUT-O3, 2006 - http://www.ozone-sec.ch.cam.ac.uk/scout_o3/field_campaigns/uv_campaign/index.html; THERMOPOLIS, 2009 -http://www.esa.int/esaCP/SEMVNMH7KYF_index_0.html, ACEMED -Evaluation of CALIPSO’s aerosol classification scheme over Eastern Mediterranean, 2011). The proposed work provides excellent training opportunities to new students and postdoctoral researchers involved. They will gain experience in the planning and execution of a major aircraft experiment and the understanding of aircraft observation techniques. Through this experiment, all the members involved will gain expertise on aerosol monitoring with in-situ and remote sensing methods. In addition, three group members from NOA wish to participate in the flights preparation and if possible in the flights.

Lucas Alabos Arboledas
Group of Atmospheric Physics, University of Granada, Spain
Email: alados@ugr.es

Nikolaos Mihalopoulos
Institute for Environmental Research and Sustainable Development, NOA, Greece
Email: nmihalo@meteo.noa.gr

Eleni Athanasopoulou
Karlsruhe Institute of Technology, Germany
Email: eleni.athanasopoulou@imk.fzk.de

Most of the team members are funded by the participating Institutes, thus they will support this project merely for scientific reasons.

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