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Coherent evolution of potential vorticity anomalies associated with deep moist convection
Author(s) -
Weijenborg C.,
Chag J. M.,
Friederichs P.,
Gray S. L.,
Hense A.
Publication year - 2017
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.3000
Subject(s) - convection , vorticity , potential vorticity , dipole , geology , convection cell , hydrostatic equilibrium , geophysics , atmospheric sciences , mechanics , climatology , meteorology , physics , vortex , natural convection , quantum mechanics , combined forced and natural convection
Potential vorticity (PV) elegantly describes synoptic‐ and planetary‐scale dynamics, but it has received less attention on smaller scales. On the convective scale, PV is characterised by dipoles associated with convective cells. We show that the PV dipoles are statistically significant and associated with statistically significant flow anomalies. Our hypothesis is that there is a coherent evolution of the PV dipoles. This hypothesis is tested by tracking convective cells in the non‐hydrostatic COSMO‐DE numerical weather prediction model during nine severe weather events. The 3135 convective cells used in this study are representative of deep moist convection over Western Europe in the COSMO‐DE model. Composites of the evolution of convective cells are made, and differences between ‘normal’ and intense cells are discussed. Even when averaging over 3135 cells during nine cases, a clear horizontal PV dipole pattern can be seen with associated flow anomalies. Compared to normal cells, intense cells (identified using PV, precipitation rate or vertical velocity) have a more monopole morphology, which resembles that of supercells. The statistically significant flow anomalies associated with the PV anomalies imply that the PV dipoles might be invertible in a statistical way.