NOAA Image of the Day
Dust Entrained in North Africa Low Pressure
The Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard the NOAA/NASA Suomi NPP satellite captured this true-color image of Saharan dust being swept up into a low pressure system over north Africa on February 21, 2017. Improving our ability to detect dust in the atmosphere is beneficial because just how much dust enters the atmosphere each year is unclear - projections range from 200 to 5,000 teragrams a year (a teragram, Tg, equals one trillion grams). Scientists estimate that, on average, about 20 Tg of dust are suspended in the atmosphere at any given time, but seasonal variability is common. Inter-annual variability is also a factor, as ocean-related weather phenomena such as the North Atlantic Oscillation and El Nińo have been associated with greater Saharan dust transport across the Atlantic. Three of the VIIRS instrument's 22 channels -- the RGB color channels 5, 4, and 3, which are sensitive to the red, green, and blue wavelengths of light respectively -- were combined to create this "true color" image. Several other channels are also included to cancel out atmospheric interference, such as clouds and aerosols, which can cause a blurry picture.
Courtesy of NOAA Environmental Visualization Laboratory