The Airborne Tropical TRopopause EXperiment (ATTREX): overview of the 2013 flights in the central and eastern Pacific

During February 2013, six 24+ hour ATTREX Global Hawk flights were conducted out of Dryden Flight Research Center. The flights provided extensive sampling of the tropical tropopause layer in the central and eastern Pacific. Over 100 vertical profiles through the TTL were obtained. The payload included measurements of numerous chemical tracers, water vapor, clouds, meteorological conditions, and radiation. We will give an overview of the flights and the data collected. In addition, we will discuss a case study of cloud formation and dehydration driven by transport in the anticyclonic circulation north from the western Pacific convective region, eastward in the subtropical jet, and then south into the cold region southwest of Hawaii. The implications of the cloud formation and dehydration associated with this transport mechanisms for regulation of stratospheric humidity will be discussed.