Apr 20, 2018

Anthropogenic changes in the Walker circulation and their impact on the extra-tropical planetary wave structure in the Northern Hemisphere

by
Reindert J. Haarsma, Frank Selten
,
Climate Dynamics
  • States that a robust change in the tropical circulation induced by anthropogenic warming in CMIP3 models is a weakening of the Walker circulation
  • Demonstrates for the CMIP3 models that the weakening of the Walker circulation has a significant impact on the extra-tropical planetary wave structure and to a large extent explains the projected changes in the mid tropospheric meridional wind in the CMIP3 models
  • Finds that the dominant response is a wave number five pattern similar to the circumglobal waveguide pattern
  • This analysis implies that a correct simulation of the Walker circulation and its response to anthropogenic changes are crucial for a correct simulation of the anthropogenic change in the extra-tropical planetary wave structure
  • Concludes that the simulation of the Walker circulation is a prerequisite to narrow the uncertainty in the projected anthropogenic change in the extra-tropical planetary wave structure