Impacts of Jet Biases on Summertime Transport into the Arctic

There is a large spread among numerical climate models in the location and intensity of the Northern Hemisphere midlatitude jet. These jet biases lead to a wide variety of dynamic influences, such as differences in the frequency of midlatitude blocking and the persistence of the northern annular mode, but the impact on tracer transport has been less examined. Here we examine the connection between jet structure and the transport of various idealized and chemical tracers from the northern midlatitude surface into the Arctic using a suite of chemistry climate models. It is shown that shifts in the climatological mean location of the jet can have a substantial influence on this transport. For example, there is a 10%-30% decrease in tracer concentrations within the tropospheric polar cap for models with a poleward bias in the latitude of the summer jet. These differences are related to differences in Rossby wave breaking between models.