The Influence of Large-Scale Spatial Warming on Jet Stream Extreme
Waviness on an Aquaplanet
Abstract
The effect of modified equator-to-pole temperature gradients on the jet
stream by low-level polar warming and upper-level tropical warming on
jet streams is not fully understood.
We perform four aquaplanet simulations to quantify the impact of
different sea surface temperature distributions on jet stream strength,
wave amplitudes and jet stream waviness, quantified by a modified
Sinuosity Index.
A large-scale uniform warming scenario increases the jet strength
whereas decreases in jet strength occur in two scenarios where the
meridional temperature gradient is reduced. However, all scenarios
indicate substantial decreases in the magnitude of large wave
amplitudes, jet stream extreme waviness and reduced variability of these
diagnostics, suggesting a relationship with weakened baroclinicity.
Our findings contradict the earlier proposed mechanism that low-level
polar warming weakens the jet stream and increases wave amplitudes and
jet stream waviness. We conclude that a weaker jet stream does not
necessarily become wavier.