Abstracted/indexed

We perform 50-year-long time-slice experiments using the Met Office HadGEM3 global climate model in order to decompose the Brewer–Dobson circulation (BDC) response to an abrupt quadrupling of CO₂ in three distinct components, (a) the rapid adjustment, associated with CO₂ radiative effects; (b) a global uniform sea surface temperature warming; and (c) sea surface temperature patterns. This demonstrates a potential for fast and slow timescales of the response of the BDC to greenhouse gas forcing.

This work investigates the influence of orography on atmospheric blocking dynamics, spatial frequency, and duration. Using an idealized model, a landless integration and integrations with mountains are analyzed. The dynamical evolution of blocking in the idealized model is found to be similar to reanalysis. Orography is found to significantly increase blocking and anchors where blocks most likely occur (i.e., just upstream from mountains and near storm track exits).

We study the interactions between the tropical convective activity and the mid-latitude circulation in the Northern Hemisphere during boreal summer. We identify two circumglobal wave patterns with phase shifts corresponding to the South Asian and the western North Pacific monsoon systems at an intra-seasonal timescale. These patterns show two-way interactions in a causal framework at a weekly timescale and assess how El Niño affects these interactions.

Troughs and ridges are ubiquitous flow features in the upper troposphere and are centerpiece elements of weather and climate research. A novel method is introduced to identify and track the life cycle of troughs and ridges and their orientation. The aim is to close the existing gap between methods that detect the initiation phase and methods that detect the decaying phase of Rossby wave development. Global climatologies, the influence of ENSO and Lagrangian characteristics are discussed.

The 2013–2014 winter sea surface temperature (SST) was anomalously cool in the mid-North Atlantic region. We investigate the processes by which cyclones can lead to SST cooling and their contribution towards the 2013–2014 SST anomaly. We find that cyclones induce a cold wake, which extends along the cyclones' cold front. Cyclones account for over 40 % of the observed cooling in the mid-North Atlantic. Thus, cyclones play a major role in determining the extreme 2013–2014 winter SST cooling.

We studied how mid-latitude cyclones are likely to change in the future. We used a state-of-the-art numerical model and performed a control and a warm experiment. The total number of cyclones did not change with warming and neither did the average strength, but there were more stronger and more weaker storms in the warm experiment. Precipitation associated with the most extreme mid-latitude cyclones increased by up to 50 % and occurred in a more poleward location in the warmer experiment.