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 Monitoring Ocean Environment

Ocean Environment Monitoring

The oceans play an enormously important role in global climate change in terms of energy and water cycle, including atmospheric circulation. It is also pointed out that the global warming significantly affects the ocean environment changes. Since the oceans cover some 70% of the Earth’s surface, they deeply connect to our lives through fishing industry, marine transport, and/or marine resource management. Therefore, ocean observations by satellites are widely used not only in climate change researches but also in other fields, including meteorology and fishery. EORC utilizes satellite data from both microwave radiometers, which can observe the ocean surface even through clouds, and infrared radiometers, which can observe even the coastal area with fine spatial resolution, to produce and distribute information related to ocean environment, including sea surface temperature (SST) and wind speeds.


▲SST anomalies from climatology at during El Niño (upper: 5-day averaged SST from Nov. 16 to 20, 2015 observed by GCOM-W/AMSR2) and La Niña (lower: same as upper but in 2007 observed by Aqua/AMSR-E). Since microwave radiometers are able to observe status of ocean surface through clouds, it is suitable for frequent monitoring of the ocean environment over broad areas.


Sea Ice Monitoring

Sea ice covering the North and South Poles provides a useful index for measuring the pace of global warming. In the Arctic Ocean, the sea ice cover has shrunk in recent years. This trend reduces the time and cost required to transport goods by ship, raising the attraction of the Arctic as a shipping channel. EORC uses microwave sensors (GCOM-W), which are little affected by differences in weather, and optical sensors (GCOM-C), which offer powerful resolution, to provide frequent monitoring of the polar sea ice covers. This figure is an image of the Arctic Ocean on September 21, 2018, as observed by GCOM-W. We can see that the shrinking trend in the sea ice until about 2012 has slowed in recent years. Also, the synthetic-aperture radar (SAR) mounted on the ALOS Series satellites can observe the extent of sea ice to a resolution within several meters to 100m. EORC will continue to monitor the sea ice from both a scientific and a practical perspective.


▲Image of the Arctic sea ice on September 21, 2018 based on observation data from GCOM-W


Ocean-Color Monitoring

Sea color is a useful indicator of conditions at the ocean surface. The color of the sea can vary by the type and quantity of photosynthetic pigments such as chlorophyll a, a component of marine phytoplankton. Along the coasts, sea color varies according to the quantity of suspended solids supplied from the land, such as organic matter and soil. By observing the ocean’s color from satellites, researchers can discern the distribution of phytoplankton worldwide and the ways in which it is changing, or the flow of matter from the coasts into the ocean.Phytoplankton plays a role in carbon fixing through photosynthesis and as a primary producer in the ocean ecosystem. Researchers expect to find applications for phytoplankton in observing how climate change transforms ocean ecosystems, determining the on distribution of fisheries and predicting changes in that distribution, among others.


▲Image of chlorophyll a density around Japan as observed by Shikisai on April 16, 2019. Values can be found in the scale at right. Phytoplankton propagation (the spring bloom) can be seen occurring from the coasts of Hokkaido to the seas around Tohoku (northeastern Honshu).


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