Downscaling of wind fields on the east coast of India using deep convolutional neural networks and their applications in storm surge computations

Abstract

Downscaling is reconstructing data from low to high resolution, capturing local effects and magnitudes. Widely employed methods for downscaling are dynamic and statistical methods with pros and cons. With ample data, machine learning (ML) and deep learning (DL) techniques can be employed to learn mapping from low to high resolution. This article investigates convolutional neural network capabilities for downscaling winds. The speed and direction of the wind are guided by a complex relation among pressure, Coriolis force, friction, and temperature, which leads to highly nonlinear wind patterns and poses a significant challenge for downscaling. The problem can be formulated as a super-resolution technique called a super-resolution convolutional neural network (SRCNN) for data reconstruction. Few variations of SRCNN are studied for wind downscaling. Six years of European Centre for Medium-Range Weather Forecasts (ECMWF) wind datasets along the east coast of India are used in the current study and are downscaled up to four times. Downscaled winds provide better results than traditional interpolation methods. Simulations for an extreme event are conducted with SRCNN downscaled winds and are compared against interpolation methods and original data. The numerical simulation results show that DL-based methods provide results closer to the ground truth than interpolation methods. HIGHLIGHTS The application of machine learning (ML) for downscaling winds is explored.; Three different ML techniques are employed to downscale winds.; The performance of ML methods over traditional interpolation methods is compared by plotting probability density functions and by coupled ADCIRC + SWAN model simulations with winds as atmospheric forcing.; Computed storm surge with ML winds as forcing is superior to interpolation methods.;

Keywords

• convolutional neural networks
• deep learning
• downscaling
• storm surge
• super-resolution
• wind