SEAPLANE

SIMULATION AND MODELLING OF INTERFACE FLUXES IN WIND-WAVE FLOWS FOR AN IMPROVED CLIMATE SCIENCE

The interactions of a turbulent wind with a water surface represents a very fundamental problem for many atmospheric processes. The momentum and heat exchanges across the interface with oceans abruptly affects the atmosphere and the understanding of the driving mechanisms would certainly improve weather predictions capabilities. However, after decades of research efforts, the wind-wave problem is still recognized as extremely elusive. The reason is the multiscale and multiphysical nature of the phenomena involved. Indeed, the scales of the turbulent wind are significantly affected by the smaller scales of the water waves which in turn are influenced by the structure of the turbulent wind itself thus forming a complex multiscale coupling phenomenon. The SEAPLANE project aims to address these issues by using innovative statistical tools and advanced modeling approaches. The scale- and position-dependent wind-wave mechanisms will be studied by means of the Kolmogorov and Yaglom equations applied to a two-phase fully coupled DNS simulation, first of its kind. The theoretical framework enables unprecedented details on the scale-by-scale cascade mechanisms of momentum and heat in a turbulent wind interacting with water waves. The formalism is strictly connected with the filtering approach to the Navier-Stokes equations and will be used to develop an advanced LES practice. This will be used to produce a high-fidelity database for the momentum and heat exchanges at the air-sea surface from low to high wind speeds. Such information is of overwhelming importance for forecasting systems where these surface fluxes are parametrized using rough assumptions. The SEAPLANE project will also address this issue that, more generally, is related to the rough approximation of several multiphysical processes determining the atmosphere dynamics at mesoscale. The state-of-art tool WRF-Chem for the simulation of the atmosphere dynamics will be improved by the fundamental insights gained on LES and on the heat and momentum exchanges. Furthermore, an advanced parametrization of the mechanisms generating the sea spray aerosol will be also introduced. Aerosol particles are widely recognized to have a strong impact on the Earth’s climate and the developed model will have a strong impact on the quality of forecasting systems. Overall, the unprecedented details on the cascade phenomena, the production of high-fidelity LES data bases and the improved parameterizations of the atmosphere-ocean exchanges will have significant impact on climate science and in the prediction capabilities of climate and weather forecasting systems at all timescales.

 

RESEARCH UNITS AND PEOPLE INVOLVED

The SEAPLANE project involves the collaboration of three qualified units, with a long-standing and demonstrated experience in fluid dynamics and in environmental flows:

- University of Modena and Reggio Emilia (UNIMORE): Prof. Andrea Cimarelli, Dr. Lorenzo Silvestri
- University of Padova (UNIPD): Prof. Federico Dalla Barba
- National Research Council - Institute of Anthropic impact and Sustainability in marine environment (CNR-IAS) - Institute of Atmospheric Sciences and Climate (CNR-ISAC): Dr. Elisa Canepa, Dr. Umberto Rizza

 

RESEARCH ACTIVITY

The research activities are organized into 3 work packages. A fourth WP is in charge of coordination, knowledge transfer among units and dissemination of the results. The next sections describe the expertise, role and interrelation of the different units. The feasibility of the project in terms of timing and costs is also addressed.

WP1: Turbulent wind and water waves interactions: multiscale analysis and modelling

This WP is led by UNIMORE and focuses on the study of the scale-by-scale physics of the heat and momentum transfer occurring at the wind-wave interface region. In the first phase, the DNS of the two-phase open channel will be designed and then runned by means of the open-source code Basilisk. Thereafter, the DNS data will be analyzed first through classical single-point statistics and then by computing the Kolmogorov and Yaglom equations. Finally, the best LES closures and LES resolutions for the simulation of the wind-wave multiscale phenomena emerging from the scale-by-scale analysis will be studied.

WP2: Wall-modeled LES of wind-wave flows at high-wind conditions

This WP is led by UNIPD and aims at developing an high-fidelity WM-LES approach for the study of the wind-wave interface phenomena from low to high wind speed. The capabilities of the code CaNS equipped with IBM and WM-LES modules will be extended to take into account the High-Order Spectral Method (HOSM) for the generation of the nonlinear gravity waves. Validation tests will be performed in order to identify the best practice for high-fidelity WM-LESs of the wind blowing over the ocean surface. An high-fidelity WM-LES database will be then produced in order to identify correlation functions between wave height, wave steepness, wave age, wind friction Reynolds number and the heat and momentum exchanged between the ocean and the atmosphere under moderate and high wind conditions.

WP3: Mesoscale simulations of the atmosphere dynamics over oceans with sea spray effects

This WP is led by CNR-IAS-ISAC and is devoted to the development of advanced parameterizations for improved mesoscale simulations of the atmosphere dynamics over ocean. An advanced parametrization of the sea-spray generation will be formulated and implemented in the open-source forecasting system WRF-Chem. A campaign of simulations will be performed to test and refine the new sea-spray source. The created database will be analyzed in order to study the complex effects of the emission of sea-spray aerosols on the marine boundary layer dynamics and on meteorological forecasts. Finally, a further improvement of the WRF-Chem forecast capabilities will be performed by implementing new roughness lengths as a parametrization of the air-sea momentum and heat fluxes provided by WP2 and by updating WRF-Chem with more reliable LES closures identified by WP1.

 

FUNDING

PIANO NAZIONALE DI RIPRESA E RESILIENZA (PNRR) – Missione 4 – Componente 2. Dalla Ricerca all’Impresa -Investimento 1.1 Fondo per il Programma Nazionale della Ricerca (PNR) e Progetti di Ricerca di Rilevante Interesse Nazionale (PRIN)”, finanziato dall’Unione europea – NextGenerationEU - rif. D.D. N. 1409 MUR 14/09/2022.

 

NEWS

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