A Comparison of Lossless Compression Algorithms for Altimeter Data

Satellite data transmission is usually limited between hundreds of kilobits-per-second (kb/s) and several megabits-per-second (Mb/s) while the space-to-ground data volume is becoming larger as the resolution of the instruments increases while the bandwidth remains limited, typically. The Surface Water and Ocean Topography (SWOT) altimetry mission is a partnership between the National Aeronautics and Space Administration (NASA) and the Centre National des &Eacute;tudes Spatiales (CNES) which uses the innovative KaRin instrument, a Ka band (35.75 GHz) synthetic aperture radar combined with an interforemeter. Its launch is expected for 2022 for oceanographic and hydrological levels measurement and it will generate 7 TeraBytes-per-day, for a lifetime total of 20 PetaBytes. That is why data compression needs to be implemented at both ends of satellite communications. This study compares the compression results obtained with 672 algorithms, mostly based on the Huff- man coding approach which constitute the state-of-the-art for scientific data manipulation, including Computational Fluid Dynamics (CFD). We also have incorporated data preprocessing such as shuffle and bitshuffle, and a novel algorithm named SL6.</p