Helicopter-borne observations with portable microwave radiometer in the Southern Ocean and the Sea of Okhotsk

Accurately measuring and monitoring the thickness distribution of thin ice is crucial for accurate estimation of ocean–atmosphere heat fluxes and rates of ice production and salt flux in ice-affected oceans. Here we present results from helicopter-borne brightness temperature (TB) measurements in th...

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Bibliographic Details
Published in:Annals of Glaciology
Main Authors: Tamura, Takeshi, Ohshima, Kay I., Lieser, Jan L., Toyota, Takenobu, Tateyama, Kazutaka, Nomura, Daiki, Nakata, Kazuki, Fraser, Alexander D., Jansen, Peter W., Newbery, Kym B., Massom, Robert A., Ushio, Shuki
Format: Article in Journal/Newspaper
Language:English
Published: Cambridge University Press
Subjects:
remote sensing
sea ice
660
Antarctic
Okhotsk
Southern Ocean
Annals of Glaciology
Antarc*
Iceberg*
Sea ice
Online Access:http://hdl.handle.net/2115/70591
https://doi.org/10.3189/2015AoG69A621
Description
Summary:Accurately measuring and monitoring the thickness distribution of thin ice is crucial for accurate estimation of ocean–atmosphere heat fluxes and rates of ice production and salt flux in ice-affected oceans. Here we present results from helicopter-borne brightness temperature (TB) measurements in the Southern Ocean in October 2012 and in the Sea of Okhotsk in February 2009 carried out with a portable passive microwave (PMW) radiometer operating at a frequency of 36 GHz. The goal of these measurements is to aid evaluation of a satellite thin-ice thickness algorithm which uses data from the spaceborne Advanced Microwave Scanning Radiometer–Earth Observing System AMSR-E) or the Advanced Microwave Scanning Radiometer-II (AMSR-II). AMSR-E and AMSR-II TB agree with the spatially collocated mean TB from the helicopter-borne measurements within the radiometers’ precision. In the Sea of Okhotsk in February 2009, the AMSR-E 36GHz TB values are closer to the mean than the modal TB values measured by the helicopter-borne radiometer. In an Antarctic coastal polynya in October 2012, the polarization ratio of 36GHz vertical and horizontal TB is estimated to be 0.137 on average. Our measurements of the TB at 36 GHz over an iceberg tongue suggest a way to discriminate it from sea ice by its unique PMW signature.

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