Gravity Waves and Vertical Mixing in the Tropical Tropopause Layer during ATTREX

Vertical mixing in the Tropical Tropopause Layer is thought to be weak outside regions of convective injection. Nevertheless, some studies indicate a role for nonconvective vertical mixing processes in maintaining tracer distributions. The TTL also has a broad spectrum of high amplitude gravity waves, which have been shown to play an important role in the water vapor distribution. These gravity waves, a result of tropical convection, also have substantial shears associated with them (which may produce turbulent mixing). Recent aircraft experiments, specifically the Airborne Tropical TRopopause EXperiment (ATTREX), have yielded an unprecendented meteorological dataset in the TTL, including not only the temperatures and horizontal winds (which can be obtained from radiosondes), but high frequency vertical winds. These high frequency measurements yield an opportunity to study turbulence in the nonconvective environment. The numerous vertical profiles, essentially producing curtains of high resolution measurements across broad regions of the tropics, also yield an opportunity to obtain both horizontal and vertical information about medium scale gravity waves.

This presentation examines three phases of ATTREX (fall 2011, winter 2013, and winter 2014) in the eastern and western Pacific. The focus will be on high amplitude wave motions, their structure, and turbulence.