Seminar: Heikki Järvinen: An evaluation of current capabilities of modelling atmospheric low-frequency variability

Thursday, 12th May 2016, 13:15
Room F6, 1st floor, FMF, Jadranska 19, Ljubljana

Meteorology Group will host Heikki Järvinen from University of Helsinki, Department of Physics, who will also present a seminar. The seminar will be in English. Everyone is kindly invited.

Abstract:

Earth system models are expected to simulate well the climate mean state and climate variability. Here we concentrate on representation of inter-annual to multi-decadal variability in 12 CMIP5 climate model simulations.
Reference climate is provided by two 20th century reanalysis data sets of monthly mean near-surface air temperature. The spectral decomposition is based on Randomised Multi-Channel Singular Spectrum Analysis (RMSSA). The main results are as follows. (1) the 5 total spectra for the two reanalysis data sets are remarkably similar in all time scales, except that spectral power of decadal variability (10–30 yr) differ in these data by about 30 %, (2) none of the 12 coupled climate models closely reproduce all aspects of the reference spectra, although some models represent many aspects well. For instance, the IPSL-CM5B-LR model is close to reanalyses but has too little multi-decadal variability, and the HadGEM2-ES model is close to reanalyses except the notable over-activity at periods at and around 10 yr.