HIRDLS

Aura's High Resolution Dynamics Limb Sounder (HIRDLS) instrument can obtain profiles over most of the globe, both day and night. Complete Earth coverage can be obtained in twelve hours. Observations of the lower stratosphere and upper troposphere were possible using special narrow and more-transparent spectral channels. The science goals of HIRDLS were to observe the global distributions of temperature and several trace species in the stratosphere and upper troposphere at high vertical and horizontal resolution.

HIRDLS measured nitrogen dioxide, nitric acid, and CFCs—gases that play a role in stratospheric ozone depletion. Although international agreements have banned their production, CFCs are long-lived and will remain in the stratosphere for several more decades. By measuring profiles of the long-lived gases at 1.2 km vertical resolution, from the upper troposphere into the stratosphere, HIRDLS will make it possible to quantify the transport of air from the troposphere into the stratosphere.

After launch, activation of the HIRDLS instrument revealed that the optical path was blocked so that 20% of the aperture could view the earth's atmosphere. Engineering studies suggest that a piece of thermal blanketing material ruptured from the back of the instrument during the explosive decompression of launch. Attempts to remove this material mirror failed. However, even with the 80% blockage, measurements at high vertical resolution can be made at one scan angle.

Although HIRDLS lost is azimuth scanning capability, much of the science can be retained using chemical transport and data assimilation models.

HIRDLS stopped taking data on March 17, 2008, due to failure of the chopper unit.