Vertical reflectivity profiles of precipitation over Iqaluit, Nunavut during Autumn 2007

Abstract

In this study, information from surface observations, soundings and ground-based X-band Doppler radar is used to examine and better understand three significant precipitation events in Iqaluit, Nunavut. These observations were collected between 15 October 2007 and 5 December 2007 during the Storm Studies in the Arctic (STAR) field campaign and collectively these three events produced 65% of the precipitation during that period although the total of these was only 24 mm. All three events also had periods in which there was reflectivity aloft above the radar but not at the surface. This indicates the presence of dry layers where sublimation of falling particles would have been a factor or the impact of advection of particles away from the vertical radar beam. Furthermore, clouds were inferred to have occurred in as many as five layers. Photographs of the hydrometeors showed aggregation and riming which were consistent with vertical velocities inferred from Doppler information. Overall, the results indicate that there are many similarities and differences between events that occur in the Western and Eastern Canadian Arctic regions. One such similarity is that the precipitation from these storms will be difficult to measure from spaceborne measurement systems.