Microphysical properties of cold frontal rainbands
Article first published online: 30 SEP 2013
© 2013 Royal Meteorological Society
Quarterly Journal of the Royal Meteorological Society
How to Cite
Crosier, J., Choularton, T. W., Westbrook, C. D., Blyth, A. M., Bower, K. N., Connolly, P. J., Dearden, C., Gallagher, M. W., Cui, Z. and Nicol, J. C. (2013), Microphysical properties of cold frontal rainbands. Q.J.R. Meteorol. Soc.. doi: 10.1002/qj.2206
- Article first published online: 30 SEP 2013
- Accepted manuscript online: 5 JUN 2013 12:11PM EST
- Manuscript Accepted: 27 MAY 2013
- Manuscript Revised: 1 MAY 2013
- Manuscript Received: 9 NOV 2012
- ice multiplication;
- cold front;
- in situ microphysics;
Observations have been obtained within an intense (precipitation rates > 50 mm h−1) narrow cold-frontal rainband (NCFR) embedded within a broader region of stratiform precipitation. In situ data were obtained from an aircraft which flew near a steerable dual-polarisation Doppler radar. The observations were obtained to characterise the microphysical properties of cold frontal clouds, with an emphasis on ice and precipitation formation and development.
Primary ice nucleation near cloud top (−55°C) appeared to be enhanced by convective features. However, ice multiplication led to the largest ice particle number concentrations being observed at relatively high temperatures (> −10°C). The multiplication process (most likely rime splintering) occurs when stratiform precipitation interacts with supercooled water generated in the NCFR. Graupel was notably absent in the data obtained.
Ice multiplication processes are known to have a strong impact in glaciating isolated convective clouds, but have rarely been studied within larger organised convective systems such as NCFRs. Secondary ice particles will impact on precipitation formation and cloud dynamics due to their relatively small size and high number density. Further modelling studies are required to quantify the effects of rime splintering on precipitation and dynamics in frontal rainbands. Available parametrizations used to diagnose the particle size distributions do not account for the influence of ice multiplication. This deficiency in parametrizations is likely to be important in some cases for modelling the evolution of cloud systems and the precipitation formation. Ice multiplication has significant impact on artefact removal from in situ particle imaging probes.