The Challenge of Clouds and Surface Energy Fluxes in the Coupled Arctic System

Abstract:

Recent changes to the Arctic cryosphere have heightened societal requirements for understanding the Arctic system in a more sophisticated, coupled manner. Key drivers include the need for improved sea ice forecasting, understanding the fate of permafrost, and constraining hemispheric linkages with Arctic change. To make advances in all of these areas requires models that reliably represent Arctic surface fluxes and the coupled processes responsible for their variability on multiple scales. In the highly coupled Arctic system, clouds and related atmospheric boundary layer processes exert significant control on the flow of energy and how it ultimately affects surface energy budgets.

Targeted observational and modeling studies over the past decade have provided foundational knowledge on Arctic cloud processes. Yet, these have also revealed significant challenges that inhibit accurate model representations of clouds and surface energy fluxes. This presentation highlights key advances in understanding Arctic clouds and their influential role in the coupled Arctic system by examining cloud phase partitioning, the surface response to cloud forcing, the role of vertical mixing processes, and others. Regional model simulations are used to demonstrate the sensitivity of modeled surface energy fluxes to cloud properties and to illustrate the influence of unconstrained cloud processes. Critical knowledge gaps and observational deficiencies are identified as a means for providing guidance on coupled-system observational and model development activities that are needed to improve future model predictive capabilities.