MOPITT (Measurements Of Pollution In The Troposphere) is a carbon monoxide and methane remote sounder launched in 1999 with the Terra spacecraft. An aircraft replica (MOPITT-A) was developed at the University of Toronto to perform validation of MOPITT radiances as well as small-scale pollution studies. MOPITT-A is based on the engineering model of MOPITT, modified for flight in NASA's ER-2 research aircraft. The instrument was first tested over California from the NASA Dryden Flight Research Center in July 2000.