Scientists at the National Center for Atmospheric Research (NCAR), University of Colorado, and University of Oxford developed HIRDLS (pronounced "hurdles") with funding from NASA and United Kingdom sources. The U.S. space agency plans to launch the 21-channel radiometer along with three other instruments July 10 aboard its Aura satellite from Vandenberg Air Force Base in California.
HIRDLS will capture the chemistry and dynamics of four layers of the atmosphere that together span a region 8 to 80 kilometers (5 to 50 miles) above Earth's surface: the upper troposphere, the tropopause, the stratosphere, and the mesosphere.
Using infrared radiation as its yardstick, the radiometer will look through Earth's atmosphere toward the planet's limb, or edge. It will find and measure ten different chemical species, characterize airborne particles known as aerosols, and track thin cirrus clouds, all at a vertical resolution of half a kilometer (a third of a mile) and a horizontal resolution of 50 kilometers (30 miles). The signal-to noise ratio is one tenth that of previous detectors.
"The angular resolution of the instrument's mirror position is equivalent to seeing a dime eight miles away," says principal investigator John Gille, of NCAR and the University of Colorado.
A few questions HIRDLS data will answer
The answer should reveal where Earth will warm or cool as the global climate changes.
Convection was once thought to be the vehicle, but scientists now know warm, rising air normally stops at the frigid, dry tropopause.
The answer could shed light on how a changing climate is modifying the atmosphere and how those modifications could in turn feed back into our climate and weather near the ground.
The answer will help scientists separate natural ozone pollution from human-made sources and give new information on how the gas is affecting chemistry closer to the ground.
Scientists also expect to see clearly for the first time the dynamic processes that cause water vapor filaments and tendrils to break off and mix with other gases in the troposphere.
Good and bad ozone at different altitudes
At 50 kilometers (30 miles) above the ground, ozone is good: it blocks dangerous ultraviolet radiation and prevents it from harming life and materials at ground level. At 10 kilometers (6 miles), ozone is a greenhouse gas, which is good because the natural greenhouse effect is necessary to warm the planet, but bad if the warming continues to increase at too rapid a rate. At 5 kilometers (3 miles), ozone is a source of the hydroxyl radical, which cleanses the atmosphere of pollutants. But at ground level, ozone is a primary pollutant in smog, causing respiratory problems and damaging trees and crops.
NCAR's primary sponsor, the National Science Foundation, provided additional support for the research that made HIRDLS possible.
Opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.