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A Particle-in-Cell wave model for efficient sea-state and swell estimates in Earth System Models - PiCLES
  • Momme Hell,
  • Bertrand Chapron,
  • Baylor Fox-Kemper
Momme Hell
National Center for Atmospheric Research

Corresponding Author:[email protected]

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Bertrand Chapron
IFREMER
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Baylor Fox-Kemper
Brown University
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Abstract

Ocean surface waves have been demonstrated to be an important component of coupled Earth System Models (ESMs), influencing atmosphere-ocean momentum transfer, ice floe breakage, CFC, carbon and energy uptake, and mixed-layer depth. Modest errors in sea state properties do not strongly affect the impacts of these parameterizations. The minimal data and accuracy needed contrast sharply with the computational costs of spectral wave models in next-generation ESMs. We establish an alternative, cost-efficient wave modeling framework for air-sea and ice-ocean interactions that enables the routine use of sea state-dependent air-sea coupling in ESMs. In contrast to spectral models, the Particle-in-Cell for Efficient Swell (PiCLES) wave model is constructed for coupled atmosphere-ocean-sea ice modeling. Combining Lagrangian wave growth solutions with the Particle-In-Cell method leads to a model that periodically projects onto any convenient grid and scales in an embarrassingly parallel manner. The set of equations solves for the growth and propagation of a parametric wave spectrum’s peak wavenumber and total wave energy, which reduces the state vector size by a factor of 50-200 compared to spectral models. We estimate PiCLES’s computational costs about 1-4 orders of magnitude faster than established wave models with sufficient accuracy for ESMs – rivaling that of spectral models in the open ocean. We evaluate PiCLES against WAVEWATCH III in efficiency and accuracy and discuss the advantages of future performance and planned extensions of its capability in ESMs.