High-Resolution Polar-Low Winds Obtained from Unsupervised SAR-Wind Retrieval

Abstract

<p>High-resolution sea surface observations by spaceborne synthetic aperture radar (SAR) instruments are sorely neglected resources for meteorological applications in polar regions. Such radar observations provide information about wind speed and direction based on wind-induced roughness of the sea surface. The increasing coverage of SAR observations in polar regions calls for the development of SAR-specific applications that make use of the full information content of this valuable resource. Here we provide examples of the potential of SAR observations to provide details of the complex, mesoscale wind structure during polar low events, and examine the performance of two current wind retrieval methods. Furthermore, we suggest a new approach towards accurate wind vector retrieval of complex wind fields from SAR observations that does not require a priori wind direction input that the most common retrieval methods are dependent on. This approach has the potential to be particularly beneficial for numerical forecasting of weather systems with strong wind gradients, such as polar lows.</p>

Recognition of polar lows in Sentinel-1 SAR images with deep learning

“…Synthetic aperture radars (SARs) are light agnostic and provide imagery at very high spatial resolution (typically a few to tens of metres). Researchers have already indicated that SAR data adds value for monitoring polar lows [12]- [14]. Assimilation of SAR data into NWP models is however challenging, since the exact relationships between radar measurement and geophysical parameters are not trivial, especially at high wind speeds [14]- [16].…”

“…Researchers have already indicated that SAR data adds value for monitoring polar lows [12]- [14]. Assimilation of SAR data into NWP models is however challenging, since the exact relationships between radar measurement and geophysical parameters are not trivial, especially at high wind speeds [14]- [16]. An alternative approach to make use of SAR data is to rely on data driven techniques, such as deep learning.…”