Abstract
Leads with a length on the order of 1000 km occurred in the Beaufort Sea in February 2013. These leads can be observed in Moderate Resolution Imaging Spectroradiometer (MODIS) images under predominantly clear sky conditions. Sea ice concentrations (SIC) derived from the Advanced Microwave Scanning Radiometer 2 (AMSR2) using the Bootstrap (BST) algorithm fail to show the lead occurrences, as is visible in the MODIS images. In contrast, SIC derived from AMSR2 using the Arctic Radiation and Turbulence Interaction Study (ARTIST) sea ice algorithm (ASI) reveal the lead structure, due to the higher spatial resolution possible when using 89-GHz channel data. The ASI SIC are calculated from brightness temperatures interpolated on three different grids with resolutions of 3.125 km (ASI-3k), 6.25 km (ASI-6k) and 12.5 km (ASI-12k) to investigate the effect of the spatial resolution. Single-swath data is used to study the effect of temporal sampling in comparison to daily averages. For a region of interest in the Beaufort Sea, BST and ASI-3k show area-averaged SIC of 97%±0.7% and 93%±7.0%, respectively. For ASI-6k, the area-averaged SIC are similar to ASI-3k, while ASI-12k data show more agreement with BST. Visual comparison with MODIS True Color imagery exhibits good agreement with ASI-3k. In particular, ASI-3k are able to reproduce lead structure and size in the sea ice cover, which are not or are less visible in the other SIC data. The results will be valuable for selecting a SIC data product for studies of the interaction between ocean, ice, and atmosphere in the polar regions.
Highlights
The polar regions are essential components of the global climate system
We presented a case study using a new 3.125-km passive-microwave sea ice concentration (SIC) data set that is calculated based on Advanced Microwave Scanning Radiometer 2 (AMSR2) Level-1R brightness temperature (Tb) measurements
We present a new high-resolution sea ice concentration data set based on satellite microwave radiometry that is able to provide more details of a fractured sea ice cover than sea ice concentration data at lower spatial resolutions
Summary
The polar regions are essential components of the global climate system. The Arctic and Antarctic sea ice cover have considerable effects on ocean-atmosphere heat transfer [1] and on the formation of deep water masses [2]. Since the 1970s, numerous satellite missions have been launched and a considerable number of algorithms has been developed to derive SIC from passive-microwave (PM) data. In the course of the “Arctic Radiation and Turbulence Interaction Study” (ARTIST), the ARTIST sea ice algorithm (ASI) was developed using the 85-GHz channels of the Special Sensor Microwave/Imager (SSM/I) to provide high spatial resolution SIC [9]. SIC has even further improved, due to both scans available from the feedhorns measuring at 89-GHz. This work studies the effect of spatial resolution and temporal sampling in ASI SIC on the ability to resolve local structures, like leads within the sea ice cover. The AMSR2 on-board the Global Change Observation Mission 1st-Water (GCOM-W1) satellite is the successor instrument of AMSR-E [17] It was launched in May 2012 and placed into the Afternoon. A redundant momentum wheel has been added to the system to increase reliability
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