MODIS Sea Ice Thickness and Open Water–Sea Ice Charts over the Barents and Kara Seas for Development and Validation of Sea Ice Products from Microwave Sensor Data

Marko Mäkynen,Juha Karvonen

doi:10.3390/rs9121324

Marko Mäkynen, Juha Karvonen

Open Access

https://doi.org/10.3390/rs9121324

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Journal: Remote Sensing	Publication Date: Dec 16, 2017
Citations: 14	License type: CC BY 4.0

Affiliation: Finnish Meteorological Institute

Abstract

We have developed algorithms and procedures for calculating daily sea ice thickness (SIT) and open water–sea ice (OWSI) charts, based on the Moderate Resolution Imaging Spectroradiometer (MODIS), ice surface temperature (IST) (night-time only), and reflectance ( R ) swath data, respectively. The resolution of the SIT chart is 1 km and that of the OWSI chart is 250 m. The charts are targeted to be used in development and validation of sea ice products from microwave sensor data. We improve the original MODIS cloud masks for the IST and R data, with a focus on identifying larger cloud-free areas in the data. The SIT estimation from the MODIS IST swath data follows previous studies. The daily SIT chart is composed from available swath charts by assigning daily median SIT to a pixel. The OWSI classification is simply conducted by a fixed threshold for the MODIS band 1 R . This was based on manually selected R data for various ice types in late winter, early melt, and advanced melt conditions. The composition procedures for the daily SIT and OWSI charts somewhat compensates for errors due to the undetected clouds. The SIT and OWSI charts were compared against manual ice charts by Arctic and Antarctic Research Institute in Russia and by Norwegian Meteorological Institute, respectively, and on average, a good relationship between the charts was found. Pixel-wise comparison of the SIT and OWSI charts showed very good agreement in open water vs. sea ice classification, which gives further confidence on the reliability of our algorithms. We also demonstrate usage of the MODIS OWSI and SIT charts for validation of sea ice concentration charts based on the SENTINEL-1 SAR and AMSR2 radiometer data and two different algorithms.

Highlights

For operational sea ice monitoring microwave sensors; such as synthetic aperture radar (SAR), scatterometer, and microwave radiometer, are mainly used as they can image sea ice through clouds and regardless of daylight conditions
We concluded that manual quality control is needed for selecting the good quality charts for comparison with other sea ice products
We have developed algorithms and procedures for calculating daily sea ice thickness (SIT) and open water–sea ice (OWSI) charts based on the Moderate Resolution Imaging Spectroradiometer (MODIS) ice surface temperature (IST) and reflectance swath data, respectively

Summary

Introduction

For operational sea ice monitoring microwave sensors; such as synthetic aperture radar (SAR), scatterometer, and microwave radiometer, are mainly used as they can image sea ice through clouds and regardless of daylight conditions. SAR images are typically analysed visually by expert ice analysts or classified automatically into different ice types and open water, or sea ice parameters, such as sea ice concentration (SIC), stage of development, degree of ice deformation, etc. The main usage of the microwave radiometer data has been the mapping of SIC, e.g., [4,5]. Scatterometer data has been used for mapping of sea ice extent and ice edge location, and for sea ice typing [12]. All of the sensors have been used for estimation of beginnings and endings of different sea ice thermodynamic regimes, e.g., [12,13,14], and sea ice drift based on tracking of temporal changes in the imagery, e.g., [12,15,16,17]

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