Have you ever been to the Solomon Islands or the Republic of Vanuatu? They are both remote islands located in the southwestern Pacific Ocean, relatively close in proximity to Australia and Papau New Guinea. There is a tropical cyclone that is a-brewing in this area of the world….her name is tropical cyclone ‘Donna’. As of Friday morning, 5 May 2017, Donna is a Category 2 hurricane and is expected to reach a Category 3 on the Saffir-Simpson Scale.
Donna is unique in that it is considered an ‘out of season’ tropical cyclone where tropical cyclones are normally produced between the months of November and May in the Southern Hemisphere. Flooding, high winds and heavy rains are expected for islands that are in the path of Donna; a tropical cyclone warning has been issued for the effected areas.
To track and monitor Donna, a forecaster or user can utilize the Day/Night Band (DNB) which is a sensor, and is one of 22 channels on the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument which is on-board the Suomi-National Polar-orbiting Partnership (S-NPP) satellite. The DNB uses a sun/moon reflectance model that illuminates atmospheric features, senses emitted natural and anthropogenic lights, and assists with cloud monitoring during the night-time hours; consider it as a night-time visible channel. A DNB image of tropical cyclone Donna, provided from the CIRA TC Real-Time web-page at 1432Z, 5 May 2017, is seen below.
Users can see the high-resolution (750-meters) and the detailed cloud structures that the DNB provides during the night-time as Donna moves through the area. Users can also assess the magnitude of Donna, inferring how many islands are or will be impacted by the storm.