Simulation of Late Summer Arctic Clouds during ASCOS with Polar WRF
2017 (English)In: Monthly Weather Review, ISSN 0027-0644, E-ISSN 1520-0493, Vol. 145, no 2, 521-541 p.Article in journal (Refereed) Published
Low-level clouds are extensive in the Arctic and contribute to inadequately understood feedbacks within the changing regional climate. The simulation of low-level clouds, including mixed-phase clouds, over the Arctic Ocean during summer and autumn remains a challenge for both real-time weather forecasts and climate models. Here, improved cloud representations are sought with high-resolution mesoscale simulations of the August-September 2008 Arctic Summer Cloud Ocean Study (ASCOS) with the latest polar-optimized version (3.7.1) of the Weather Research and Forecasting (Polar WRF) Model with the advanced two-moment Morrison microphysics scheme. Simulations across several synoptic regimes for 10 August-3 September 2008 are performed with three domains including an outer domain at 27-km grid spacing and nested domains at 9- and 3-km spacing. These are realistic horizontal grid spacings for common mesoscale applications. The control simulation produces excessive cloud liquid water in low clouds resulting in a large deficit in modeled incident shortwave radiation at the surface. Incident longwave radiation is less sensitive. A change in the sea ice albedo toward the larger observed values during ASCOS resulted in somewhat more realistic simulations. More importantly, sensitivity tests show that a reduction in specified liquid cloud droplet number to very pristine conditions increases liquid precipitation, greatly reduces the excess in simulated low-level cloud liquid water, and improves the simulated incident shortwave and longwave radiation at the surface.
Place, publisher, year, edition, pages
2017. Vol. 145, no 2, 521-541 p.
Earth and Related Environmental Sciences
Research subject SWEDARCTIC 2008, ASCOS
IdentifiersURN: urn:nbn:se:polar:diva-3384DOI: 10.1175/MWR-D-16-0079.1OAI: oai:DiVA.org:polar-3384DiVA: diva2:1075193