Flight 24: Dryden-Wallops Transit (10 April, 2001)

This flight was planned to fly directly to from Dryden to Wallops with a stop to perform a spiral over the DOE CART site in Oklahoma where ground measurements for MOPITT validation are conducted.  The only threat to this plan was a forecast for intense thunderstorm activity in the afternoon over Oklahoma.

Results: The plan was scuttled early as the pilots were informed that convective cells over 50 Kft had already developed over Oklahoma by midmorning, earlier than expected.  The aircraft was diverted to a more southerly route across Texas before heading notheast to Wallops.  At a flight altitude of 21 Kft several airmass types were encountered that included both convected surface pollution and stratospheric air over the southwestern US.  Over Texas, the cleanest airmass sampled during the entire TRACE-P mission was observed.  This airmass contained 30 ppbv O₃, 40 ppbv CO, and 140 ppbv NOy.  While aerosol mass was very low, it was dominated by chloride signalling a marine origin.  This air was most likely convected over the equatorial Pacific and transported in the southwesterly flow across Mexico and over Texas.