High-latitude cold season frontal cloud systems and their precipitation efficiency

Abstract

A weak high-latitude warm-frontal precipitation system was simulated by using a 2D cloudresolving model. It was found that many of the structural characteristics of the system were consequences of the subfreezing temperatures and enhanced planetary rotation in the region. The coupling of cloud microphysical processes to frontal scale dynamics caused the precipitation efficiency (defined as the ratio of integrated surface precipitation rate to the net water vapor influx into the storm) of the model storm to exhibit strong sensitivity to low-level humidity conditions. A relatively high (zero) precipitation efficiency is associated with a storm if it develops over regions having near surface relative humidity with respect to ice ≤ (>) 80%. In addition, the model results show that the precipitation efficiency of a system is 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 for the parameterization of Arctic clouds and precipitation in GCMs.