A unique eye into the world’s most extreme weather
When major weather tightens its grip, the world turns to Raytheon tech for insight
Early in the morning of Sept. 14, the tiny island of Itbayat in the Philippines was consumed by what has been called the worst storm of 2016 — and one of the worst ever on record.
As the world watched in horror, a pair of images showed in stark detail just how perilous the moment was for Itbayat. Satellite imagery showed Super Typhoon Meranti completely surrounding the 32-square-mile island, with a view of the island through the eye of the storm.
That’s bad news for any area caught in a typhoon. The eye wall — the part of the storm centered around the eye — has the most intense winds and rain. And it was doubly bad for Filipinos, as they had found themselves in a similar situation just three years ago when 6,300 lives were lost during Super Typhoon Haiyan.
While the damage to the Philippines from Typhoon Meranti is still being assessed, the import of that image goes beyond just the awe factor. Weather satellites, equipped with infrared, low-light and other advanced sensors, provide critical information needed to enhance the prediction of the intensity and path of major storms with ever-increasing fidelity. And that provides the ability to better protect people and property caught in their paths.
Here, Raytheon’s Dr. Jeff Puschell, chief scientist for the Visible Infrared Imaging Radiometer Suite which captured the Typhoon Meranti images, answers questions about the unique capabilities infrared and low-light imaging sensors bring to the weather monitoring community.
What can infrared data tell us about a storm that we can’t get through a simple visual reconnaissance?
Puschell: IR data measures temperature of cloud tops and the Earth’s surface. With that and other satellite data, cloud top heights and thicknesses can be derived along with quantitative estimates of precipitation expected from these clouds. This data is critical for putting together an accurate weather forecast, for civilian as well as military meteorologists.
How do scientists read IR data like what we saw with Typhoon Meranti?
Puschell: The color codes refer to the apparent temperature of the phenomenon being monitored, whether it is a cloud, sea surface, land, or some combination thereof. The blues and greens you see around the eye represent relatively warmer temperatures, while things get significantly cooler moving out through yellow, orange and eventually dark red and black. Again, scientists rely on a whole host of data to make these kinds of determinations, but that is typically where the clouds are thickest.
How is IR data collected? How is the process different from other data collection capabilities, like true color?
Puschell: IR data is collected using special detectors that are sensitive to heat – from sources at great distances. In the case of satellites, this can mean several hundred miles. The VIIRS instrument that took the images of Super Typhoon Meranti flies 512 miles above Earth on the Suomi-NPP satellite.
IR detectors are cooled to a very low temperature to reduce interference from other heat sources. Maintaining the detectors at such a cold temperature, and reducing the amount of heat radiated by the instrument itself, are the main challenges with collecting IR data from space.
What are the benefits of low light imagery when it comes to monitoring the weather?
Puschell: One of the sensors on our Visible Infrared Imaging Radiometer Suite is the Day/Night Band, which can capture visible imagery in very low light — moonlight or even simply airglow, ambient light from the stars and Earth itself. This can generate information on cloud structure and particle size at night that is not available in any other way. Under very cold conditions in the Arctic and elsewhere, the Day/Night Band can provide higher contrast imagery than IR data to show, for instance, where snow has fallen.
What do you see when you view the images of Itbayat island in the midst of Typhoon Marenti?
Puschell: Those are just remarkable images — an extraordinary moment in time where you can see this tiny island right in the center of this enormous typhoon. The eye is so clearly defined both in the IR image where you can see the rapidly cooling temperatures as you move from the center out, and then with the benefit of the Day/Night Band you can see the cloud formation itself in such great detail. It really offers a lesson in what’s going on in a massive weather system like Meranti.
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