Origins of UTLS Turbulence: Insights from the RRJ-ClimCORE Mesoscale
Reanalysis - The ACCLIP Flight Over the Super Typhoon Hinnamnor (2022)
Abstract
During the Asian Summer Monsoon Chemical and Climate Impact Project
(ACCLIP), National Aeronautics and Space Administration (NASA) WB-57
high altitude research aircraft observed strong turbulence at an
altitude of 15 to 18 km near the outflow of the Super Typhoon Hinnamnor
in the Northwest Pacific. Our analyses based on the trial version of the
“RRJ-ClimCORE” mesoscale reanalysis have revealed that a thin layer of
strong vertical wind shear (VWS) extending just below the tropopause
along the upper surface of the outflow from the typhoon eyewall provides
favorable conditions for shear instability. Further analyses of the
mesoscale background conditions based on RRJ-ClimCORE as well as the
geostationary satellite Himawari-8 cloud imagery suggest that the
convolution of such small-scale processes as convectively generated
concentric gravity waves and shallow convection appearing as
radially-banded cirrus clouds may have further increased the potential
for turbulence generation. Absolute vorticity analysis suggests the
occurrence of inertial instability to the north of the typhoon, which
explains the development of radially-banded cirrus clouds as well as the
layer of strong VWS around the flight altitudes. The present study thus
demonstrates the advantages of the hourly output of RRJ-ClimCORE over
3-hourly output operational mesoscale analysis for investigating source
mechanisms of turbulence in the upper-troposphere and
lower-stratosphere.