White, BA, Blyth, AM and Marsham, JH orcid.org/0000-0003-3219-8472 (2016) Simulations of an observed elevated mesoscale convective system over southern England during CSIP IOP 3. Quarterly Journal of the Royal Meteorological Society, 142 (698 Part A). pp. 1929-1947. ISSN 0035-9009
Abstract
Simulations of an elevated mesoscale convective system (MCS) observed over southern England during the Convective Storm Initiation Project (CSIP) provide the first detailed modelling study of a case of elevated convection occurring in the UK. The study shows that many factors can influence the maintenance of elevated deep convection, from large-scale flow through to surface heating processes and diabatic cooling within the convective system. It is also shown that interactions and feedback mechanisms between a stable layer and the storm can act to maintain deep convection. The simulation successfully reproduced an elevated MCS above a low-level stable undercurrent, with a wave in the undercurrent linked to a rear-inflow jet (RIJ). Convection was fed from an elevated (840hPa) source layer with CAPE of about 350Jkg-1. The undercurrent in the simulation was approximately 1km deep, about half that observed. Unlike the observed MCS, a transition from elevated to surface-based convection occurred in the simulation due to the combined effects of a pre-existing large-scale θe gradient, advection and surface heating causing the system to encounter increasingly unstable low-level air and a shallower stable layer that was more susceptible to penetration by downdraughts. The transition to surface-based convection was accompanied by the development of cold-pool outflow and an increase in system velocity from about 6 to 10ms-1. Diabatic cooling from microphysical processes in the simulation enhanced the undercurrent and strengthened the RIJ. This strengthened the wave in the undercurrent and led to more extensive convection. The existence of a positive feedback process between the convection, RIJ and stable layer is discussed. Uncertainty in the synoptic scale generating errors in the undercurrent is shown to be a major source of error for convective-scale forecasts.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2016, Royal Meteorological Society. This is the peer reviewed version of the following article: "White, B. A., Blyth, A. M. and Marsham, J. H. (2016), Simulations of an observed elevated mesoscale convective system over southern England during CSIP IOP 3. Q.J.R. Meteorol. Soc., 142: 1929–1947", which has been published in final form at http://dx.doi.org/10.1002/qj.2787. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. |
Keywords: | MCS; elevated convection; WRF; Convective Storm Initiation Project; rear-inflow jet; cloud microphysics; cold pool |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Inst for Climate & Atmos Science (ICAS) (Leeds) The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > National Centre for Atmos Science (NCAS) (Leeds) |
Funding Information: | Funder Grant number NERC NE/E006124/1 |
Depositing User: | Symplectic Publications |
Date Deposited: | 17 Aug 2016 11:50 |
Last Modified: | 14 Apr 2017 02:19 |
Published Version: | http://dx.doi.org/10.1002/qj.2787 |
Status: | Published |
Publisher: | Wiley |
Identification Number: | 10.1002/qj.2787 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:98050 |