A Global Survey of Rotating Convective Updrafts in the GFDL X-SHiELD
2021 Global Storm Resolving Model
Abstract
We present the characteristics of rotating convective updrafts in the
2021 version of GFDL’s Experimental System for High-resolution
prediction on Earth-to-Local Domains (X-SHiELD), a kilometer scale
global storm resolving model (GSRM). Rotation is quantified using 2–5
km Updraft Helicity (UH) in a year-long integration forced by analyzed
SSTs. Updrafts with UH magnitudes above 50 m2/s2; are common over the
mid-latitude continents, especially in the warm seasons where they are
associated with severe weather but are also common over most tropical
ocean basins. In nearly all areas cyclonically rotating convection
dominates, with larger UH values increasingly preferring cyclonic
rotation. The ratio of cyclonic to anticyclonic updrafts is largest in
the subtropical and mid-latitude oceans and is slightly lower over
mid-latitude continents. The ratio of cyclonic to anticyclonic updrafts
can be substantively explained by the mean storm-relative helicity (SRH)
in convective regions, indicating the importance for environmental
controls on the sense of storm rotation, although internal storm
dynamics also plays a role in the generation of anticyclonic updrafts.