Suivez

la liste

POSTDOCTORAL POSITION
Simulation of gravity waves in the middle atmosphere with the ICON model: improving atmospheric specifications for infrasound propagation modeling

RESEARCH FIELD
middle atmosphere, atmospheric model, HPC, simulation, gravity waves, infrasound propagation, infrasound observations, UA-ICON, International Monitoring System.

CONTEXT
In the last ten years it has become clear that the stratosphere and more generally the middle atmosphere (MA) have important effects on tropospheric weather, as well as climate. To this respect it is critical to assess the ability of numerical models to simulate MA dynamics and to improve their parameterizations accordingly. Additionally, MA small scale disturbances like gravity waves (GW) have been identified as a major impactor of detection capability of the International Monitoring System (IMS) infrasound network of the Comprehensive Nuclear-Test-Ban Treaty (CTBT, http://www.ctbto.org) and their impact needs to be quantified and better understood (Le Pichon et al. 2019). The ICOsahedral Non-hydrostatic (CON) model, jointly developed by the Max Planck Institute for Meteorology and by the German Weather
Service (DWD), is a non-hydrostatic numerical weather prediction and research model that has recently been extended to the upper-atmosphere (UA-ICON; Borchert et al. 2019) allowing to explicitly resolve a large part of the GW spectrum at high resolution in the MA. Additionally, recent work undertaken by the Goethe University Frankfurt (GUF) lead to the development of a GW parameterization (Bölöni et al., 2021; Kim et al. 2021) that accounts for transient non-dissipative interactions between GW and the mean flow, currently overlooked by more traditional parameterizations. ICON is thus a model of high interest to assess atmospheric specifications by comparing infrasound observations to propagation simulations. Through the use of long-term infrasound dataset available in the framework of the CTBT, one can access unique constraints of the MA dynamics where observations are lacking. Previous work has already
demonstrated the benefit of combining infrasound with more traditional means of MA observation over the course of the CEA-led European ARISE project (http://arise-project.eu/) (Blanc et al. 2018; Le Pichon et al. 2015). One innovative way to assess models and calibrate their GW parameterization is by using infrasound technology to perform propagation simulations and compare with infrasound observations.

OBJECTIVE
The work will consist in setting up and performing regional and global simulations with UA-ICON, using the HPC infrastructure available at CEA, by choosing appropriate regions to focus on, based on existing catalogues of infrasound observations from reference events (industrial explosions, volcanic eruptions...). Simulation propagation tools will be used to confront the predicted arrival times and wave parameters to observations at relevant regional and IMS infrasound stations. Errors will be quantified and related to the model biases in the MA, based on the high-resolution observations available from ground-based instruments from previous ARISE campaigns. The ability of the UA-ICON model to rely on the GW parameterization at coarse resolution will be evaluated by comparing propagation simulations performed with coarse (with parametrization) and high-resolution (without parametrization) atmospheric simulation outputs. Comparisons with simulation propagations using analysis and reanalysis products will be performed, in order to quantify the differences between models in the MA, and assess the ability of infrasound observation to provide a diagnostic tool to evaluate models. Attempts to adjust the GW parameterization developed by the Goethe University Frankfurt (Bölöni et al, 2021; Kim et al. 2021) for the ICON model will be undertaken in order to assess the feasibility of relying on infrasound for model improvements. Importantly, the impact of GW on the detection capability of the IMS and the global morphology of infrasound propagation will be studied in order to help refine detection capability maps, in the framework of the CTBT.

QUALIFICATION
PhD in atmospheric science or related field, good skills in numerical modelling (required) and with HPC environment (preferred), experience in atmospheric modelling (preferred), good knowledge of Python/Matlab and Linux environment, interest in multidisciplinary research (atmosphere, acoustic), good English language skills (writing and speaking).
Salary commensurate with experience.

APPLICATION
Please send CV and motivation letter, as well as at least two contact persons as potential referees.

CONTACT PERSON
Constantino Listowski (constantino.listowski@cea.fr)
Phone number : +33 (0)1 69 26 40 00

LOCATION
CEA (French Alternative Energies and Atomic Energy Commission)
Centre DAM Ile de France
F-91297 Arpajon, France

START DATE
2022 - position open until filled - 24 months (possibility for additional 2 years depending on achievements)

REFERENCES
Blanc, E., Ceranna, L., Hauchecorne, A. et al. Toward an Improved Representation of Middle
Atmospheric Dynamics Thanks to the ARISE Project. Surv Geophys 39, 171–225 (2018).

Borchert, S., Zhou, G., Baldauf, M., Schmidt, H., Zängl, G., and Reinert, D. (2019): The upper-
atmosphere extension of the ICON general circulation model (version: ua-icon-1.0), Geosci. Model Dev., 12, 3541–3569

Bölöni, G., Kim, Y., Borchert, S., & Achatz, U. (2021). Toward Transient Subgrid-Scale Gravity
Wave Representation in Atmospheric Models. Part I: Propagation Model Including Nondissipative Wave–Mean-Flow Interactions, Journal of the Atmospheric Sciences, 78(4), 1317-1338

Kim, Y., Bölöni, G., Borchert, S., Chun, H., & Achatz, U. (2021). Toward Transient Subgrid-Scale
Gravity Wave Representation in Atmospheric Models. Part II: Wave Intermittency Simulated with
Convective Sources, Journal of the Atmospheric Sciences, 78(4), 1339-1357

Le Pichon, A., Ceranna, L., Vergoz, J., & Tailpied, D. (2019). Modeling the detection capability of
the global IMS infrasound network. In Infrasound Monitoring for Atmospheric Studies (pp. 593-604) Springer, Cham.

Le Pichon, A., et al. (2015), Comparison of co-located independent ground-based middle
atmospheric wind and temperature measurements with numerical