A254-05
Summertime Transport Pathways from Different Northern Hemisphere Regions into the Arctic
Thursday, 17 December 2020: 07:16
Virtual
Cheng Zheng, Lamont-Doherty Earth Observatory, Palisades, NY, United States, Yutian Wu, Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY, United States, Mingfang Ting, Lamont Doherty Earth Observ, Palisades, NY, United States, Clara Orbe, NASA Goddard Institute for Space Studies, New York, NY, United States, Xinyue Wang, Purdue University, EAPS, West Lafayette, IN, United States and Simone Tilmes, National Center for Atmospheric Research, Atmospheric Chemistry, Observations, and Modeling Laboratory, Boulder, CO, United States
Abstract:
Trace gases and aerosols play an important role in Arctic chemistry and climate. As most Arctic tracers and aerosols are transported from midlatitude source regions, long-range transport into the Arctic is one of the key factors to understand the current and future state of Arctic climate. While previous studies have investigated the airmass fraction and transient time distribution in the Arctic, the actual transport pathways and their underlying dynamics and efficiencies are yet to be understood. In this study, we implement a large ensemble of idealized tagged pulse passive tracers in the Whole Atmosphere Community Climate Model version 5 to identify and analyze the transport pathways from different Northern Hemisphere surface regions into the Arctic during summer.
Three different transport pathways are identified as those associated with fast, intermediate and slow time scales. Midlatitude tracers can be transported into the Arctic in the troposphere via the fast transport pathway (~ 8 days), which moves tracers northward from the source region mainly through transient eddies. For the intermediate transport pathway, which happens on one to two weeks’ time scales, midlatitude tracers are zonally transported by the jet stream, and then advected northward into the Arctic over Alaska and northern North Atlantic. Tropical and subtropical tracers are transported into the Arctic lower stratosphere via the slow transport pathway (one to three months), as the tracers are first lifted upward into the tropical and subtropical lower stratosphere, and then transported into the Arctic following the isentropic surfaces. While the contribution from different source regions differ in their importance, the total amount of tracers reaching the Arctic is dominated by tracers released in the midlatitudes.
