Evaluating decadal predictions of northern hemispheric cyclone frequencies

Tim Kruschke,Henning W Rust,Christopher Kadow,Gregor C Leckebusch,Uwe Ulbrich

doi:10.3402/tellusa.v66.22830

Abstract

Mid-latitudinal cyclones are a key factor for understanding regional anomalies in primary meteorological parameters such as temperature or precipitation. Extreme cyclones can produce notable impacts on human society and economy, for example, by causing enormous economic losses through wind damage. Based on 41 annually initialised (1961–2001) hindcast ensembles, this study evaluates the ability of a single-model decadal forecast system (MPI-ESM-LR) to provide skilful probabilistic three-category forecasts (enhanced, normal or decreased) of winter (ONDJFM) extra-tropical cyclone frequency over the Northern Hemisphere with lead times from 1 yr up to a decade. It is shown that these predictions exhibit some significant skill, mainly for lead times of 2–5 yr, especially over the North Atlantic and Pacific. Skill for intense cyclones is generally higher than for all detected systems. A comparison of decadal hindcasts from two different initialisation techniques indicates that initialising from reanalysis fields yields slightly better results for the first forecast winter (month 10–15), while initialisation based on an assimilation experiment provides better skill for lead times between 2 and 5 yr. The reasons and mechanisms behind this predictive skill are subject to future work. Preliminary analyses suggest a strong relationship of the model's skill over the North Atlantic with the ability to predict upper ocean temperatures modulating lower troposphere baroclinicity for the respective area and time scales.

Highlights

In recent years, research on decadal climate prediction has evolved, responding to the growing demand for near-term climate predictions by different societal, economic and political stakeholders
We estimated the skill of probabilistic decadal forecasts of cyclone frequency made by MPI-ESM-LR within MiKlip Á the German initiative for decadal predictions
The effect of different initialisation techniques was investigated by comparing the hindcasts of the baseline1-system to baseline0; the former was initialised from reanalysis fields and the latter from an assimilation experiment

Summary

Introduction

Research on decadal climate prediction has evolved, responding to the growing demand for near-term climate predictions by different societal, economic and political stakeholders This is due to the combination of increased awareness of potential implications of any climate change signal (natural or anthropogenic) on the one hand and typical time spans of economic or societal planning on the other hand. As anthropogenically forced climate change signals and natural decadal variations may be of similar magnitude for the decades, initialised decadal predictions could be of great socio-economic value (Solomon et al, 2011) For this reason, the Coupled Model Intercomparison Project in its fifth phase (CMIP5) introduced a framework for initialised decadal predictions, in order to. Two recent studies analyse the decadal prediction skill regarding the frequency of temperature and precipitation extremes creativecommons.org/licenses/by/4.0/), allowing third parties to copy and redistribute the material in any medium or format and to remix, transform, and build upon the material for any purpose, even commercially, provided the original work is properly cited and states its license

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