Study Of The Formation Conditions Of Cirrus Clouds And Aircraft Contrails (M/W)

Universities and Institutes of France
December 09, 2022
Offerd Salary:Negotiation
Working address:N/A
Contract Type:Temporary
Working Time:Full time
Working type:N/A
Job Ref.:N/A
  • Organisation/Company: CNRS
  • Research Field: Environmental science › Earth science Environmental science › Global change
  • Researcher Profile: First Stage Researcher (R1)
  • Application Deadline: 09/12/2022 23:59 - Europe/Brussels
  • Location: France › GUYANCOURT
  • Type Of Contract: Temporary
  • Job Status: Full-time
  • Hours Per Week: 35
  • Offer Starting Date: 01/01/2023
  • • Processing of lidar data • Analysis of data according to the context • Field Campaign Organization (OHP) • Participation in project meetings • Presentation and publication of results

    Context Water in the upper troposphere, both in the form of water vapor and ice (cirrus) plays an important role in the climate because of its major contribution to the radiation balance, and remains one of the strong uncertainties concerning the climate feedbacks. Air traffic injects a surplus of water vapor into the upper troposphere which, depending on atmospheric conditions, can also lead to the formation of white trails behind aircraft, themselves composed of ice crystals which can, depending on the concentration of ambient water vapor and thermodynamic conditions extend spatially and generate “cirrus-contrails” with a lifetime of several hours. The exact conditions of formation and extension are not perfectly determined because these are phenomena initiated on a local scale with fluctuations in water vapor also showing high spatial variability. It is necessary to accumulate more observations with good spatial resolution. The ANR project "CONTRAILS" proposes to implement visible and infrared imagers from the ground in order to better identify these signatures of emerging contrails and characterize their evolutions. These instruments will be deployed at the Observatory of Haute- Provence (OHP), which provides additional observations describing local thermodynamic conditions. This information is obtained from lidar giving the altitude and the vertical structure of the contrail as well as the water vapor concentration. It is also possible to supplement these observations with meteorological balloon probes. Tasks The work will focus on the analysis of lidar data (Cadet et al., 2005, Larroza et al., 2013) and the identification of aircraft contrail signatures among the cloud set and to analyze the local thermodynamic conditions associated. The objective will be to determine under what conditions aircraft contrails grow and transform into large-scale cirrus clouds. In addition to backscatter lidar, water vapor lidar (Hoareau et al;, 2009) and meteorological soundings will be used. Lidar data will also be used to interpret wide-field camera data obtained at the site. Evolutions of the instruments will be performed and will have to be supervised. This study will focus on case studies and statistical approaches, but also on field campaigns to be organized. Statistical analysis (Keckhut et al., 2006) will be based on a clustering approach (Artificial Intelligence) making it possible, by coupling all the information, to better separate the classes of cirrus (whether or not from aircraft contrails) and to better identify the training conditions from one class to another. Finally, the intensive observation campaigns will make it possible to follow trails to inform their speed of expansion and to carry out continuous lidar measurements coupled with balloon soundings. These local characteristics can be compared with the information available in the numerical models of the German meteorology involved in this bilateral project (CONTRAILS) in order to assess their ability to predict conditions for the appearance of contrails. Spatial data of the MODIS (passive multi-channel remote sensing) or CALIPSO (lidar) type will complement the detection of cirrus clouds from the ground and will make it possible to assess the conditions of detectability from space (Hoareau et al., 2013). Bibliography Cadet, B., V. Giraud, M. Haeffelin, P. Keckhut, A. Rechou, and S. Baldy, IMPROVED RETRIEVALS OF THE OPTICAL PROPERTIES OF CIRRUS CLOUDS BY A COMBINATION OF LIDAR METHODS, Appl. Opt., 44 (9), 1726-1734, 2005 Keckhut, P., F. Borchi, S. Bekki, A. Hauchecorne, and M. SiLaouina, CIRRUS CLASSIFICATION AT MID-LATITUDE FROM SYSTEMATIC LIDAR OBSERVATIONS, Journal of Applied Meteorology and Climatology: Vol. 45, No. 2, pp. 249-258, doi: 10.1175/JAM2348.1, 2006 Hoareau, C., P. Keckhut, A. Sarkissian, J-L. Baray, And G. Durry, METHODOLOGY FOR WATER MONITORING IN UPPER TROPOSPHERE WITH RAMAN LIDAR AT OBSERVATORY OF HAUTE-PROVENCE, Journal of Atmospheric and Oceanic Technology, 26(10), 2149-2160, 2009, DOI: 10.1175/2009JTECHA1287.1 Hoareau, C., P. Keckhut, V. Noël, H. Chepfer and J.-L. Baray, A DECADAL CIRRUS CLOUDS CLIMATOLOGY FROM GROUND-BASED AND SPACEBORNE LIDAR ABOVE SOUTH OF FRANCE (43.9°N – 5.7°E), Atmos. Chem. Phys., 13, 6951-6963, doi:10.5194/acp-13-6951-2013, 2013. Larroza, E.G., W. M. Nakaema, R. Bourayou, C. Hoareau, E. Landulfo and P. Keckhut, TOWARDS AN AUTOMATIC LIDAR CIRRUS CLOUD RETRIEVAL FOR CLIMATE STUDIES, Atmos. Meas. Tech., 6, 3197-3210, doi:10.5194/amt-6-3197-2013, 2013.

    The work will be done in Guyancourt under the responsibility of Philippe Keckhut Physicist at UVSQ, researcher at LATMOS and in collaboration with researchers and engineers from the laboratory working on lidar data and from the Observatory de Haute-Provence Frequent missions of a week in the south of France at the OHP are to be expected. There will also be many interactions with the project partners.

    Eligibility criteria

    • Holder of a doctorate in cloud microphysics, meteorology or lidar techniques • Expertise in signal processing and possibly with experience in geophysical data processing • Knowledge of instrumentation and, possible field campaign experience

    Web site for additional job details

    https: //

    Required Research Experiences
  • Environmental science

  • None

  • Environmental science › Earth science

  • None

  • Environmental science › Global change

  • None

    Offer Requirements
  • Environmental science: Master Degree or equivalent

  • FRENCH: Basic

    Contact Information
  • Organisation/Company: CNRS
  • Department: Laboratoire "Atmosphères et Observations Spatiales"
  • Organisation Type: Public Research Institution
  • Website: https:// www.
  • Country: France
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