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Earth Observatory of Singapore Accepted into JAXA’s Sentinel Asia Group

13 Nov 2017

On 12 September 2017, the Earth Observatory of Singapore (EOS) was accepted as a Data Analysis Node by unanimous consent of the members in Sentinel Asia.

Sentinel Asia is an initiative to support disaster management activity in the Asia-Pacific region through WEB-GIS technology and space-based technology (Source: Sentinel Asia)

This new membership demonstrates EOS’ determination and active involvement in disaster management through international cooperation, and strengthens the connection between EOS and other space technology agencies in the Asia-Pacific region.

Sentinel Asia is an initiative led by the Asia-Pacific Regional Space Agency Forum (APRSAF) to support disaster management activity in the Asia-Pacific region through WEB-GIS technology and space-based technology, such as earth observation satellite data.

The initiative was first proposed in November 2004, a testament to the rapid technological advances in the region. Soon after, the basic organisational infrastructure was established in response to the Indian Ocean earthquake and tsunami event in December of the same year.

Earthquake scientists used a Damage Proxy Map to detect landslides triggered by the 2015 Mount Kinabalu earthquake (Source: Yvonne Soon)

In just 13 years, Sentinel Asia has grown to include multiple space agencies such as JAXA (Japan), ISRO (India), GISTDA (Thailand) and KARI (South Korea). Current Sentinel Asia members come from 92 organisations in 28 countries.

Sentinel Asia compiles requests for observation data made by member organisations, and coordinates emergency observation operations to provide rapid information for disaster management. They focus primarily on wildfires, typhoon floods, glacier lake outburst floods, landslides, and earthquakes.

EOS will contribute to the Sentinel Asia community by applying synthetic aperture radar (SAR) interferometry technologies to gather data that will be useful for disaster management. These technologies are unique in that they can detect changes on the ground regardless of weather conditions. In Asia, where skies are often cloudy, this is particularly beneficial.

(Left) An ALOS-2 Damage Proxy Map shows potential coseismic slope failures on Mount Kinabalu (Right) A Landsat 8 image of Mount Kinabalu acquired in August 2016 overlaid by the mapped landslides, denoted by green polygons (Source: Adapted from Wang et al. (2017))

The SAR interferograms are useful for detecting ground displacement and for delineating earthquake faults on the ground surface. With this data, EOS is fully capable of modelling the source of an earthquake, which can then be used by geo-engineers.

Besides SAR interferograms, EOS will also be contributing to Sentinel Asia by producing Damage Proxy Maps (DPM), which can be used to identify areas of possible damage to built infrastructure. Damage Proxy Maps are created by using SAR images of a disaster area before and after a hazard event. Earthquake scientists at EOS have successfully used a DPM to detect landslides triggered by the 2015 Mount Kinabalu earthquake.

Finally, EOS will be providing Sentinel Asia with Flood Proxy Maps (FPM). These maps can be produced by estimating the change in amplitude of the SAR signal. In the presence of water, the SAR signal will reflect off the water’s surface in the direction away from the satellite, resulting in a darker image pixel compared to areas with no water.

Flood Proxy Map of Texas flooding caused by Hurricane Harvey in August 2017. The map was derived from ALOS-2 SAR amplitude images; blue pixels indicate open flood water (Source: Advanced Rapid Imaging and Analysis (ARIA) team in JPL/Caltech)

EOS’ collaboration with the Jet Propulsion Laboratory (JPL) will eventually allow the production of SAR interferograms, Damage Proxy Maps, and Flood Proxy Maps to become fully automatic. Together, EOS and JPL will work to develop an ARIA (Advanced Rapid Imaging and Analysis) system.

This technology, along with many others provided by Sentinel Asia, are valuable tools for disaster management and mitigation.