Abstract: Idealised simulations of cyclones with robustsymmetrically-unstable sting jets Ambrogio Volonté, Peter A. Clark, and Suzanne L. Gray Weather Clim. Dynam. Discuss., https://doi.org/10.5194/wcd-2019-8,2019 Manuscript under review for WCD (discussion: open, 0 comments) Sting jets (SJs) descend into the frontal-fracture region of intense extratropical cyclones leading to strong surface winds.In this study we look at idealised simulations of SJ-containing cyclones produced using an improved initial state and a wide set of sensitivity experiments. The results shed light on SJ evolution and the role of dry instabilities in SJ dynamics, supporting a recent conceptual model. The simulations also highlight the robustness of SJ occurrence in these intense cyclones. PubDate: 2019-10-01T02:51:42+02:00
Abstract: The Role of Eddy-Eddy Interactions in Sudden StratosphericWarming Formation Erik Anders Lindgren and Aditi Sheshadri Weather Clim. Dynam. Discuss., https://doi.org/10.5194/wcd-2019-7,2019 Manuscript under review for WCD (discussion: open, 0 comments) Sudden stratospheric warmings (SSWs) are extreme events that influence surface weather up to two months after onset. We remove EEIs in vertical sections of a general circulation model to investigate the role of eddy-eddy interactions (EEIs) in SSW formation. We show that the effects of EEIs depend strongly on the pressure levels where they occur and the zonal structure of the wave forcing in the troposphere. Our results highlight the importance of upper level processes in stratospheric dynamics. PubDate: 2019-09-24T02:51:42+02:00
Abstract: Large impact of tiny model domain shifts for the Pentecost 2014MCS over Germany Christian Barthlott and Andrew I. Barrett Weather Clim. Dynam. Discuss., https://doi.org/10.5194/wcd-2019-5,2019 Manuscript under review for WCD (discussion: open, 1 comment) The mesoscale convective system (MCS) that affected Germany at Pentecost 2014 was one of the most severe for decades. However, the predictability of this system was very low. By moving the model domain by just one grid point changed whether the MCS is successfully simulated or not at all. The main reason for the different model results seems to be the proximity of the track of the initial convective system to the coast and colder sea surface. PubDate: 2019-09-17T02:51:42+02:00
Abstract: Extratropical cyclone induced sea surface temperature anomalies inthe 2013/14 winter Helen F. Dacre, Simon A. Josey, and Alan L. M. Grant Weather Clim. Dynam. Discuss., https://doi.org/10.5194/wcd-2019-6,2019 Manuscript under review for WCD (discussion: open, 2 comments) The 2013/14 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 2013/14 SST anomaly. We find that cyclones induce a cold wake, which extends along the cyclones cold front. Cyclones account for over half of the observed cooling in the mid-North Atlantic. Thus, cyclones play a major role in determining the extreme 2013/2014 winter SST cooling. PubDate: 2019-09-13T02:51:42+02:00
Abstract: Potential vorticity structure of embedded convection in a warm conveyor belt and its relevance for the large-scale dynamics Annika Oertel, Maxi Boettcher, Hanna Joos, Michael Sprenger, and Heini Wernli Weather Clim. Dynam. Discuss., https://doi.org/10.5194/wcd-2019-3,2019 Manuscript under review for WCD (discussion: open, 0 comments) Warm conveyor belts (WCBs) are important, mainly stratiform cloud forming airstreams in extratropical cyclones that can include embedded convection. This WCB case study systematically compares the characteristics of convective versus slantwise ascent of the WCB. We find that embedded convection leads to regions of significantly stronger precipitation. Moreover, it strongly modifies the potential vorticity distribution in the lower and upper troposphere, where its also influences the waveguide. PubDate: 2019-09-03T02:51:42+02:00
Abstract: Medicane Zorbas: Origin and impact of an uncertain potentialvorticity streamer Raphael Portmann, Juan Jesús González-Alemán, Michael Sprenger, and Heini Wernli Weather Clim. Dynam. Discuss., https://doi.org/10.5194/wcd-2019-1,2019 Manuscript under review for WCD (discussion: final response, 3 comments) In September 2018 a Mediterranean cyclone with structural similarities to a hurricane, a so called Medicane, caused severe damages in Greece. The development of the Medicane was uncertain, even a few days ahead. We find that the reason for this was an uncertain state of the jet stream over North America two days earlier. This uncertainty grew and propagated into the Mediterranean where it lead to uncertainty in the location of the cyclone formation and, as a result, its structure and intensity. PubDate: 2019-08-28T02:51:42+02:00
Abstract: The characteristics and structure of extra-tropical cyclones in awarmer climate Victoria A. Sinclair, Mika Rantanen, Päivi Haapanala, Jouni Räisänen, and Heikki Järvinen Weather Clim. Dynam. Discuss., https://doi.org/10.5194/wcd-2019-2,2019 Manuscript under review for WCD (discussion: final response, 3 comments) 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. PubDate: 2019-08-27T02:51:42+02:00
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