Ever since last week, Hurricane Ophelia was meandering in the eastern Atlantic Ocean, not knowing where to go. Ophelia gradually became a tropical storm, then hurricane, as it moved northeastward and past through the Azores. As of this past weekend (14-15 October 2017), Ophelia inched closer and closer to the country of Ireland. Before Ophelia made landfall, the strength of Ophelia decreased slightly and had maximum sustained winds of 85 mph. Hurricane Ophelia made landfall along Ireland’s coast in the early morning hours on 16 October 2017. Ophelia brought heavy rain, flooding and storm surge to Ireland, and with how large the areal extent of Ophelia, it advected smoke from the wildfires that were blazing in Spain and Portugal. Even local European airlines, re-routing around Ophelia, noticed the odor of the fires in their airplanes that day.
Static polar-orbiting satellite images taken of the event are seen below via the Day/Night Band (DNB), and the Imagery Band (I-4) (3.74um) at 0248Z, 16 October 2017. More detailed information about each satellite image is described below.
The DNB utilizes a sun/moon reflectance model that illuminates atmospheric features, senses emitted and reflected light sources, and assists with cloud monitoring during the nighttime. The DNB image below shows Hurricane Ophelia before it made landfall along the coast of Ireland and its approximate location to a few European countries such as the United Kingdom, France, Spain, and Portugal. The emitted city lights from these countries can be seen as well. Additionally, this image was taken during the ‘new moon’ phase of the lunar cycle, and where the moon is physically below the horizon, not providing adequate moonlight to see atmospheric features via satellite. Due to the lack of moonlight, the satellite imagery can still see the atmospheric features primarily by a phenomena called ‘airglow’. ‘Airglow’ are produced via photochemical reactions during the daytime, that produce a faint ‘glow’ during the nighttime, wherein the satellite can sense the ‘airglow’ and the ambient atmospheric features. Lastly, notice the orange ellipse in Spain and Portugal, this is the general location of where the wildfires were occurring. We’ll refer to this area in the next image.
Imagery Band (I-4), (3.74um), Inverse Gray Scale
The I-4 band is at a spatial resolution of 375-meters, and is used in complement of the DNB to identify wildfire ‘hotspots’, areas that are significantly hotter than their surroundings. If you look within the orange ellipse, you will see ‘hotspots’, one hotspot in Western Spain, and a few in Northern Portugal, highlighted by the darker, black colors. Within the ellipse, the brighter white colors are combination of clouds and smoke, although one cannot clearly differentiate between the two. It is inferred that the smoke and clouds are advecting to the north/northeast as Hurricane Ophelia approaches Ireland.
Imagery Band (I-4), (3.74um), New Color Scale
Utilizing the same I-4 band image from above, and implementing a new color scale to it, to identify the locations of the wildfire ‘hotpsots’ (hotter brightness temperatures sensed by satellite) in Spain and Portugal, are shown in red.