On any given day, the Alaska Region presents a wide assortment of challenges to forecasters, with an ever-changing mix of sea ice, snow cover, and multi-layered cloud patterns. When one of the Aleutian Chain volcanos erupts, spewing ash into all levels of the atmosphere, the stakes are raised for forecasters in the region.
Volcanic ash is a notorious hazard to the jet aircraft which frequent these skies on domestic and international routes. The fine, glass-like particles of some ash plumes can sand-blast cockpit windows, melt-upon and damage engine turbine blades, and even lead to engine flame-outs.
Such a catastrophe could not have been far from the minds of forecasters on the afternoon of March 27, 2016, when the Pavlof Volcano, one of the Aleutian Range’s most active, erupted with a 20,000 foot high ash plume tracking rapidly to the northeast and into the heart of the Alaskan mainland.
To gain a better perspective on the Alaska Region, forecasters appeal to their ‘eyes in the sky.’Some weather satellites carry instruments that provide critical information on a volcanic ash plume’s height and content.
The image to the right, for example, was collected by the Suomi NPP satellite at about 1:30 a.m. local time, roughly nine hours after the initial eruption. Information from Suomi NPP’s Day/Night Band sensor (measuring reflected moonlight off snow, clouds, and ash) has been blended with other measurements that are sensitive to the temperature and composition of water/ice clouds and volcanic ash.
With each unique observation playing its part, the low water clouds and snow cover are shown in yellow, higher/thicker ice clouds in shades of blue, and the heart of Pavlof’s ash plume streaming to the northeast is depicted in red/orange. For reference, the coastal boundaries are drawn in purple.
Pavlof's eruption was ongoing as Suomi NPP passed overhead, with a sharp blue point defining the exact location of the volcano. The brightening of the yellow near the point of eruption is light being emitted from Pavlof’s lava.
Using a variety of satellite data, forecasters issued timely and accurate guidance for this rapidly changing hazard. Airlines used information provided by the Anchorage Volcanic Ash Advisory Center (VAAC) to re-route, and in some cases, cancel flights. NOAA operates the Washington D.C. and Anchorage, Alaska VAAC, two of nine worldwide.
Data from polar-orbiting satellites like Suomi NPP (and the upcoming JPSS-1 satellite, which will launch in 2017) remain the most crucial sources of data for the Alaskan Region, providing a broad and accurate view of weather, climate, environmental and oceanographic conditions unavailable from other sources.
Providing data to support severe weather forecasting requires many types of observations from a variety of orbits, though. Measurements from polar-orbiting satellites, like the NOAA/NASA Suomi NPP satellite, are used in tandem with observations from NOAA’s geostationary satellites. Learn more about all of NOAA’s satellite missions here!