Sea Ice Concentration and Sea Ice Extent Mapping with L-Band Microwave Radiometry and GNSS-R Data from the FFSCat Mission Using Neural Networks

David Llaveria,Hyuk Park,Miriam Pablos,Juan Francesc Munoz-Martin,Christoph Herbert,Adriano Camps

doi:10.3390/rs13061139

Abstract

CubeSat-based Earth Observation missions have emerged in recent times, achieving scientifically valuable data at a moderate cost. FSSCat is a two 6U CubeSats mission, winner of the ESA S3 challenge and overall winner of the 2017 Copernicus Masters Competition, that was launched in September 2020. The first satellite, 3Cat-5/A, carries the FMPL-2 instrument, an L-band microwave radiometer and a GNSS-Reflectometer. This work presents a neural network approach for retrieving sea ice concentration and sea ice extent maps on the Arctic and the Antarctic oceans using FMPL-2 data. The results from the first months of operations are presented and analyzed, and the quality of the retrieved maps is assessed by comparing them with other existing sea ice concentration maps. As compared to OSI SAF products, the overall accuracy for the sea ice extent maps is greater than 97% using MWR data, and up to 99% when using combined GNSS-R and MWR data. In the case of Sea ice concentration, the absolute errors are lower than 5%, with MWR and lower than 3% combining it with the GNSS-R. The total extent area computed using this methodology is close, with 2.5% difference, to those computed by other well consolidated algorithms, such as OSI SAF or NSIDC. The approach presented for estimating sea ice extent and concentration maps is a cost-effective alternative, and using a constellation of CubeSats, it can be further improved.

Highlights

Global warming is having a big impact on polar sea ice, notably in the Arctic ocean.Satellite observations make it possible to monitor the sea area covered by ice, i.e., Sea IceExtent (SIE), which has been decreasing in recent years at a rate of 13.1% per decade [1].While this has ecological implications, it opens new commercial opportunities, such as the opening of the North route joining Asia, Europe and North America in a faster way
In the Arctic, the ST by itself possesses most of the information required for generating Sea Ice Concentration (SIC) and Sea IceExtent (SIE) maps, while the Flexible Microwave Payload-2 (FMPL-2) Microwave Radiometers (MWR) by itself does not
SIC and SIE maps are currently generated by large satellite missions, carrying microwave radiometers

Summary

Introduction

Global warming is having a big impact on polar sea ice, notably in the Arctic ocean.Satellite observations make it possible to monitor the sea area covered by ice, i.e., Sea IceExtent (SIE), which has been decreasing in recent years at a rate of 13.1% per decade [1].While this has ecological implications, it opens new commercial opportunities, such as the opening of the North route joining Asia, Europe and North America in a faster way. Global warming is having a big impact on polar sea ice, notably in the Arctic ocean. Satellite observations make it possible to monitor the sea area covered by ice, i.e., Sea Ice. Extent (SIE), which has been decreasing in recent years at a rate of 13.1% per decade [1]. SIE algorithms are based on microwave radiometry observations at ~19 and 37 GHz frequencies [2]. These frequencies can discriminate between sea water and sea ice, which makes it possible to define the sea ice margin and the associated sea ice extent. SIE monitoring at Arctic scale has been possible since 1978 using large satellites embarking

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