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Status: Confirmed |
Open to sharing: Yes |
Confidential: No |
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Transnational Access: Yes |
Open to training: No |
Grounded / Maintenance: No |
Aircraft name: FA20 - DLR
Airport: The area of Crete is a natural laboratory for dust research. It is located at a crossroad of aerosol transport paths from Africa and European sources and the abrupt topography of the island favors the development of convective clouds that are more susceptible to IN variations. Moreover, the station of Finokalia is a fully equipped ACTRIS station heavily assisting the dust research activities in the area.
Project theme: TA-021. Applications of atmospheric in-situ measurement
Project abstract: Dust is the most abundant aerosol at the greater Mediterranean region. Apart from the air quality implications, dust is also a significant climate and weather modulator. Dust aerosols are very efficient ice nuclei (IN), and they play an important role in heterogeneous cloud glaciation. Introducing a dust based ice nucleation parameterization in NMM-DREAM model allows the calculation of dust IN activation and the related impacts in cloud properties. However, in order to properly assess the modification of cloud properties due to dust contamination one should first evaluate the model performance with regards to the basic parameters that participate in these processes. The model IN parameterization takes into account two different mechanisms: 1. Immersion ice nucleation (DeMott et al., 2015) that is dominant for high cloud temperatures (-5 ; -36 C) and 2. Deposition ice nucleation (Steinke et al., 2015) that takes place at lower cloud temperatures (-36; -55 C). Both modeling schemes rely on atmospheric parameters (temperature and relative humidity) and on dust concentration. More specifically, immersion nucleation requires the number concentration of dust particles with a diameter larger than 0.5 μm. Evaluation of these model processes over the Mediterranean is very important for the quantification of dust impact in cloud formation and evolution. A correct representation of these processes in the model will allow the accurate description of aerosol radiative forcing due to the dust cloud interactions (indirect aerosol effect). Furthermore, weather forecast and precipitation estimations will benefit from the more realistic representation of dust interactions in cold clouds.
Measurements to be made by aircraft: Dust is always present in the Mediterranean and especially during transition seasons (e.g. April-May) huge dust amounts are transported from the Saharan sources towards SE Europe with significant implications for weather and climate. Crete is the ideal natural laboratory to investigate the aerosol – cloud interactions by taking advantage of the in-situ and remote sensing instrumentation in Finokalia ACTRIS core station in cooperation with aircraft measurements and modeling simulations. The main objectives of this research are the following: 1. Measure temperature and humidity profiles inside the elevated dust layers 2. Examine the concentration of airborne dust particles and their size distribution (fine to coarse ratio) over the greater E Mediterranean region. 3. Assess the accuracy of dust concentration forecasting in NMM-DREAM and investigate the ice glaciation capabilities of the model. The methodology proposed to carry out the experiment is mainly based on observations of Saharan mineral dust plumes. During spring, these plumes are usually accompanied by cloud formations often leading to stormy weather and severe precipitations including wet deposition of dust. These clouds are affected by dust and their properties are altered depending on dust concentration and sizes. Aircraft measurements of the meteorological and aerosol parameters inside the dust layers will be used to evaluate the performance of NMM-DREAM forecast fields. Model interpretation and assessment of the simulations will be performed together with space-borne and aircraft lidar profiles, ground photometers and ground chemical/size characterization of dust. The anticipated outputs from this work include the improvement of our knowledge on dust processes and the validation of 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.) References DeMott, P. J., Prenni, A. J., McMeeking, G. R., Sullivan, R. C., Petters, M. D., Tobo, Y., Niemand, M., Möhler, O., Snider, J. R., Wang, Z., and Kreidenweis, S. M.: Integrating laboratory and field data to quantify the immersion freezing ice nucleation activity of mineral dust particles, Atmos. Chem. Phys., 15, 393–409, doi:10.5194/acp-15-393-2015, 2015. Steinke, I., Hoose, C., Möhler, O., Connolly, P., and Leisner, T.: A new temperature- and humidity-dependent surface site density approach for deposition ice nucleation, Atmos. Chem. Phys., 15, 3703–3717, doi:10.5194/acp-15-3703-2015, 2015.
Season: April 2017
Weather constraints: Transport of Saharan dust towards Crete is the most important requirement for the evaluation of the relevant parameters in the model.
Time constraints: Periods of Saharan dust advection over Crete are targeted. April is the month of highest frequency for Saharan dust episodes in Eastern Mediterranean, thus, the preferred time window of the campaign is 01/04/2016 – 30/04/2016. The proposed project is clustered with the ClIMa and SEAMAN EUFAR projects, which have been scheduled for the same time period. 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 A-Train overpasses (CALIPSO, CLOUDSAT) and flight heights should allow the measurement of dust properties at areas permitting cold cloud formation. Model dust forecasts will be routinely used during the campaign to assist the scheduling of aircraft operations.
Flights (number and patterns): In order to obtain the maximum information for the characterization of dust layers the aircraft should fly during episodes of dust advection of various properties (e.g. no cloud conditions, dust contaminated cyclone, and dust affected orographic clouds). In total, two flights are requested that correspond to 2 aircraft missions. The duration of each flight is approximately 04:00 hr. The flights pattern is illustrated in Figure 2. After take-off in Paphos, the Falcon aircraft will climb to 12 km altitude and fly westwards towards Crete thereby characterizing the dust layer with the airborne lidar instrument. Over Finokalia, the Falcon will descend with a stepped profile containing 4 steps at different altitudes between 0.3 km and the dust layer top, each of 7 minutes duration. Before landing at Paphos, a vertical profile with 4 steps at different altitudes in the dust layer will be flown over the ground-based lidar at Limassol, Cyprus.
Instruments: None
Project website: http://pre-tect.space.noa.gr/
Name: NICKOVIC Slobodan
PI email: nickovic@gmail.com