The Day Night Band is a special channel on the Suomi National Polar Partnership (SNPP) weather satellite that can detect very faint sources of light even over Alaska during the darkest time of the year. This image was taken at 3:21 am Alaska Standard Time on Friday, December 23.
Note the prominent waves of aurora streaking across the state. Sometimes the aurora can move faster than the Day Night Band can really keep up with, and in those situations the aurora can have a slightly smeared or striped appearance. Zoom into the aurora shown in this image, and you can see the aurora’s jagged edge. This phenomenon has been observed before and is described nicely in this blog post http://rammb.cira.colostate.edu/projects/npp/blog/index.php/uncategorized/aurora-australis-from-the-day-night-band/
Also note in the lower left corner of this image a faint smudge of light shining through a deck of clouds down at the end of the Alaska Peninsula (area highlighted in the yellow circle). This is Bogoslof Volcano erupting, and is right next door to Palvolf Volcano whose previous eruptions have also been observed in the Day Night Band. Similar activity at Bogoslof continued through the holidays and into this first week of January. The latest information concerning Bogoslof is available at the Alaska Volcano Observatory’s website https://www.avo.alaska.edu/
And lastly, even in the middle of an Alaskan night just a couple of days after the winter solstice, the Day Night Band detects clouds and their associated weather systems. Note the clear skies over Kodiak Island and the western Gulf of Alaska, while much of the Bering Sea and Southeast Alaska have patchy cloud cover. Day Night Band imagery, as well as other kinds of imagery from weather satellites, are available at GINA’s website http://feeder.gina.alaska.edu/
Plume of Copper River glacial silt dust captured in a great series of Suomi NPP images. Nice write up of the science by Curtis Seaman of CIRA. HIs blogging comes highly recommended and often addresses Alaska topics.
Recent imagery from the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument shows condensation trails over Alaska’s eastern Interior and over the eastern Brooks Range.
A condensation trail, or “contrail,” is a thin cloud left behind when the ambient humidity and temperature of the air allows the water vapor in an aircraft’s exhaust to condense and form a cloud. Some contrails dissipate rather quickly, while others may linger and even spread out over time, again all depending on the conditions of the ambient atmosphere.
This particular case is from the afternoon of Friday, October 7, and shows the true colors the human eye would see if we had hitched a ride on the satellite. Note the corkscrew contrails over the eastern Interior, and the more linear contrails over the eastern Brooks Range. At this time of year in northern Alaska the sun hangs low over the southern horizon during the afternoon, and shadows from the contrails can be seen on the ground below, offset slightly to the north.
Eielson Air Force Base’s “Red Flag-Alaska” exercise kicked off on October 6th, so these contrails appearing the following day may be associated with those activities. Contrails from civilian aircraft tend to appear more linear than the wide looping tracks evident in this imagery.
More information about the VIIRS instrument is available at http://ncc.nesdis.noaa.gov/VIIRS/ More information about Red Flag-Alaska is available at http://www.eielson.af.mil/Info/REDFLAG-Alaska.aspx
A massive new DEM data set for Alaska from our colleagues at the University of Minnesota was released On September 1, 2016. A great collaboration among academia, the National Science Foundation, and the National Geospatial-Intelligence Agency.
We recently put together a prototype time enabled Web Mapping Service (WMS) with data from MODIS and VIIRS from 2015 to mid July 2016, and as an experiment, generated a short time lapse from it. The data in this video is a false color presentation using VIIRS “I” bands 3,2, and 1, a band combination we call “Landcover”. The video spans January 2015 to July 2016, and has some interesting natural processes in it - check out the ice movement, and the spring snow melt process. The affect the seasons have on the sensor’s coverage is also visible as the visible bands of VIIRS are only active over areas of the earth illuminated by the sun.
The above animation of VIIRS polar satellite imagery over interior Alaska south of the Brooks Range from the afternoon of 15 Jul 2016, shows how quickly
fires can spread in less then 4 hours. The three images used for this
animation were modified versions of the NaturalColor RGB, where the 2.3
um channel was assigned to the red color component (rather than 1.6 um),
0.86 um to green, and 0.64 um to blue. The 2.3 um has
similar ice and snow absorption characteristics as the 1.6 um, but with
more sensitivity to hot spots and fires. In this imagery the
red pixels are the hottest and most active fires with bluish colored
smoke blown eastward by strong west winds.