Mesoscale structure of a frontal snow system around Barrow, Alaska: an observational and modeling study
Poster PDF
Authors
Mariko Oue — Stony Brook University
Johannes Verlinde — The Pennsylvania State University
Jerry Y. Harrington — Pennsylvania State University
Kara Jo Sulia — University of Albany
Eugene E. Clothiaux — Pennsylvania State University
Hugh Clifton Morrison — University Corporation for Atmospheric Research
Description
To elucidate the characteristics of Arctic frontal snow cloud systems, the mesoscale structure of a frontal system passing through Barrow from 16–18 October 2012 was analyzed, taking advantage of the new radar systems deployed at Barrow. This same frontal system is further analyzed using the Weather Research and Forecasting (WRF) Model version 3.4.1. During the passage of this system, the -10 dBZ echo-top heights measured by the Ka-band ARM zenith radar (KAZR) decreased from a height of 7 km. For the period of lower echo-top heights, the radar reflectivity below a height of 2 km reached peak values up to 20 dBZ. Vertical profiles of horizontal winds were estimated by a velocity azimuth display method using plan position indicator scans from the X-band scanning ARM precipitation radar (X-SAPR). These radar-estimated horizontal winds showed a predominance of northerly winds below a height of 3 km and southeasterly winds above a height of 4 km. The top of the layer of northerly winds decreased with height even as the winds above backed, becoming easterly. In order to understand the features observed in the radar measurements, the finest domain of WRF simulations utilized a 0.5-km horizontal resolution and 49 vertical levels with 15 levels in the lowest 1 km. The Morrison double-moment microphysical scheme was used. The 0.5-km simulations revealed that a high equivalent potential temperature (> 278°K) air mass overran a preexisting lower equivalent potential temperature air mass from the east to west. The simulated frontal system formed in an environment of northerly winds below a height of 3 km and southwesterly winds above the height of 3 km. The frontal system moved towards the west. The simulated wind fields are in good agreement with radar-estimated vertical wind profiles. Moreover, the simulated snow mixing ratio dramatically increased below heights of 2 km. This is consistent with the measured radar reflectivity.
