High latitude cold season frontal cloud systems and their precipitation efficiency

K.K. Szeto, R.E. Stewart and J.M Hanesiak

Tellus
49, 439-454.

ABSTRACT

A weak high-latitude warm-frontal precipitation system was simulated by using a 2D cloud-resolving model. Several unique characteristics of the observed system were reproduced in the model. Sensitivity experiments were performed to investigate the effects of environmental conditions on the development of the system. It was found that many of the structural characteristics of the system were consequences of the enhanced planetary rotation in the region.

The coupling of cloud microphysical processes to frontal scale dynamics caused the precipitation efficiency of the model storms to exhibit strong sensitivity to low-level humidity. A high (zero) precipitation efficiency is associated with storms developed over regions having surface RH > (<=) 80% . In addition, the model results show that the precipitation efficiency of the systems will be decreased (increased) when the background static stability is increased (decreased) or when the Coriolis parameter is increased (decreased).

These model results may have great implications for the Arctic water cycle as well as the parameterization of Arctic clouds and precipitation in GCMs.