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Responses of midlatitude blocks and wave amplitude to changes in the meridional temperature gradient in an idealized dry GCM
Author(s) -
Hassanzadeh Pedram,
Kuang Zhiming,
Farrell Brian F.
Publication year - 2014
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2014gl060764
Subject(s) - middle latitudes , amplitude , zonal and meridional , geopotential height , geopotential , forcing (mathematics) , atmospheric sciences , climatology , geology , physics , precipitation , meteorology , optics
The response of atmospheric blocks and the wave amplitude of midlatitude jets to changes in the midlatitude to pole, near‐surface temperature difference ( Δ T ), is studied using an idealized dry general circulation model (GCM) with Held‐Suarez forcing. Decreasing Δ T results in slower zonal winds, a mean state with reduced meridional gradient of the 500 hPa geopotential height ( Z 500), a smaller variance of Z 500 anomalies, and a robust decrease in blocks and meridional amplitude of waves. Neglecting the decrease of variance associated with reduced Δ T would lead to the incorrect expectation that mean states with smaller Z 500 gradients produce more blocks and higher wave amplitudes. Our results suggest further investigation of the hypothesis that reduced Δ T due to Arctic Amplification would increase blocking events and wave amplitude, hence leading to more midlatitude extreme weather events.