[THREAD] Our article (with @NedjeljkaZ from @CENunihh and Khalil Karami) on Atmospheric Subseasonal Variability and Circulation Regimes: Spectra, Trends and Uncertainties is out in @AMSJCLi
journals.ametsoc.org/jcli/article/d…
We decompose 35-year long datasets of the atmospheric circulation in the global reanalyses systems (ERA5 and ERA-Interim of @ECMWF, MERRA of @NASAEarth and JRA-55) into balanced (Rossby) and unbalanced (inertio-gravity) circulation using #MODES:
modes.cen.uni-hamburg.de/modes-software
Most striking: all reanalyses show a reduction of subseasonal variability in Rossby waves with zonal wavenumber k=6-8 and an increase in wavenumbers k=3-5 in Northern Hemisphere summer (June-July-August) over 1980-2014. Similar but smaller signal is found also in other seasons.
Decreased subseasonal variability in waves 6-8 implies those waves have become more persistent, stationary, which leads to extreme weather events such as heat waves, as explained by the theory of quasiresonant amplification of planetary waves of Petoukhov
pnas.org/content/110/14…
Our findings are in line with that of @MichaelEMann @rahmstorf @KKornhuber @SonyaKMiller @DimCoumou and colleagues, who have shown that QRA events are likely to become more frequent this century...
advances.sciencemag.org/content/4/10/e…
There are significant changes in the tropical dynamics as well...
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