CMIP5 Models in the Arctic: Evaluating near-term processes and distribution shifts in a changing climate

While the long-predicted polar amplification of temperature is now detectable, Arctic air temperature increases have been overshadowed by the rapid decline in sea ice extent and thickness. Data from the ASCOS and the SHEBA field campaigns suggest that the presence and absence of downwelling longwave radiation from opaque clouds preconditions the Arctic ice pack for melt and for freezing. Even a modest increase in Arctic moisture in the absence of a corresponding temperature increase could result in a higher frequency of occurrence of opaque clouds. Hence, the observed sea ice decline and sluggish temperature trends may both be consistent with previous coupled model intercomparison (AR4) results that indicate increased poleward moisture transport and decreased poleward sensible heat transport in a warming climate. To evaluate how well the CMIP5 models represent the relationships between atmosphere, surface, and subsurface observed at ASCOS and at SHEBA, we compare several modeled relationships that are unique to the Arctic. For those models that exhibit similar near-term behavior to the observations, we analyze how that behavior changes in the future, whether increasing differential advection of moisture and temperature contributes to those changes, and specifically, whether fundamental Arctic properties, such as coupled temperature and humidity inversions, become less frequent.