Wintertime precipitation behavior in the western Canadian Arctic region

Abstract

Abstract. To investigate the precipitation formation process in the two major types of weather systems ("Pacific origin" and "storm track" types) in the western Canadian Arctic region, an X-band vertical pointing Doppler radar, microwave radiometer were installed at Inuvik, Northwest Territories, Canada, during the midwinter of 1995/1996. Precise precipitation observations specially for ice crystals with replicator, microscope, and closeup photos were also conducted at the same place. Precipitation formation mechanisms were quite different between these two major weather systems. For the Pacific-origin-type disturbance, warm and moist air was advected from the Pacific Ocean between 1.5 and 3.5 km msl. Convective echo patterns appeared by radar, and a large amount of precipitable water vapor and liquid water path were estimated by a microwave radiometer. As the air temperature was below the freezing point, the liquid water was identified as being in the supercooled state. Densely rimed dendrites and graupel particles were observed predominantly on the ground. Collision and coalescence processes of supercooled cloud droplets were dominant. On the contrary, for the storm track disturbance the moisture came from the Arctic Ocean, and strong winds were observed on the ground. The air mass was colder than -20øC throughout the layer. Stratiform echo patterns were observed by radar, a smaller amount of precipitable water vapor, and only a small liquid water path were observed by a microwave radiometer. It was suggested that the condensation growth was predominant. Snow crystal shapes of plates, columns, and bullet rosettes were observed predominantly on the ground. IntroductionArctic WANTS (water, aerosol, nuclei transportation, and snow) experiments were carried out at Inuvik, Northwest Territories, Canada, from 14 December 14, 1995 to January 15, 1996. The purpose of this field experiment was to better understand the weather systems, water cycle, behavior of precipitation, aerosols, and ice crystal processes in the western Canadian Arctic region during midwinter, focusing primarily on the interaction between larger-scale (synoptic scale and mesoscale) properties and cloud physical (microscale) properties.

Observation of a freezing drizzle episode: A case study

“…(with . These values are characteristic of orographic clouds (Asuma et al, 2000). The profile at 8:00 UTC reveals saturation in only the first few meters above the surface.…”

A Study of the Meteorological Conditions Associated with Anomalously Early and Late Openings of a Northwest Territories Winter Road

“…Pacificorigin disturbances and subsequently lee cyclogenesis could occur over the Mackenzie Mountains and affect weather in Norman Wells, just as they do in the southern MRb (e.g., Lackmann and Gyakum, 1996) or in the northern MRB (Asuma et al, 1998(Asuma et al, , 2000. However, the amount of precipitation would be affected by the presence or absence of lowlevel moisture (e.g., Asuma et al, 1998Asuma et al, , 2000Stewart et al, 2004). Figure 1, which shows the November synoptic climatology, also illustrates two opposing processes that affect winter roads.…”

Surface Snow, Firn and Ice Core Composition in Polar Areas in Relation to Atmospheric Aerosol and Gas Concentrations: Critical Aspects

“…In the Arctic (northern coast of Alaska), Mossop et al [38] and Jayaweera and Ohtake [39] investigated the microphysical characteristics of arctic stratus clouds, observing no riming process in these clouds. Instead, Asuma et al [40] observed both densely rimed dendrites and graupels in the western Canadian Arctic together with crystals grown by diffusion (plates, columns, bullet rosettes). These two different growth [41] collected snow and ice crystals in the air, on the ground and on sea-ice in Alaska to study the deposition of mercury, predominantly present in the atmosphere as a gaseous element.…”