© Author(s) 2009. This work is distributed under the Creative Commons Attribution 3.0 License. Atmospheric Chemistry and Physics Large surface radiative forcing from topographic blowing snow residuals measured in the High Arctic at Eureka

• Main Authors: G. Lesins, L. Bourdages, T. J. Duck, J. R. Drummond, E. W. Eloranta, V. P. Walden
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2009
• Subjects: Correspondence to; G. Lesins; Arctic; Canada; Eureka; Nunavut
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.646.9908; http://www.atmos-chem-phys.net/9/1847/2009/acp-9-1847-2009.pdf

Abstract. Ice crystals, also known as diamond dust, are sus-pended in the boundary layer air under clear sky conditions during most of the Arctic winter in Northern Canada. Oc-casionally ice crystal events can produce significantly thick layers with optical depths in excess of 2.0 even in the ab-sence of liquid water clouds. Four case studies of high opti-cal depth ice crystal events at Eureka in the Nunavut Terri-tory of Canada during the winter of 2006/07 are presented. They show that the measured ice crystal surface infrared downward radiative forcing ranged from 8 to 36 W m−2 in the wavelength band from 5.6 to 20µm for 532 nm opti-cal depths ranging from 0.2 to 1.7. MODIS infrared and visible images and the operational radiosonde wind profile were used to show that these high optical depth events were caused by surface snow being blown off 600 to 800 m high mountain ridges about 20 to 30 km North-West of Eureka and advected by the winds towards Eureka as they settled towards the ground within the highly stable boundary layer. This work presents the first study that demonstrates the im-portant role that surrounding topography plays in determin-ing the occurrence of high optical depth ice crystal events from residual blowing snow that becomes a source of bound-ary layer ice crystals distinct from the classical diamond dust phenomenon.