Exploring the atmospheric moisture transport as a bridge between ocean evaporation and Arctic ice melting

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Tuesday, 6 January 2015
Phoenix Convention Center - West and North Buildings
Luis Gimeno, University of Vigo, Ourense, Spain; and R. Nieto and M. Vazquez

If we could choose a region where the effects of global warming are likely to be pronounced and considerable, and at the same time one where the changes could affect the global climate in similarly asymmetric way with respect to other regions, this would unequivocally be the Arctic. The atmospheric branch of the hydrological cycle lies behind the linkages between the Arctic system and the global climate. Changes in the atmospheric moisture transport have been proposed as a vehicle for interpreting the most significant changes in the Arctic region. This is because the transport of moisture from the extratropical regions to the Arctic has increased in recent decades, and is expected to increase with warming. This increase could be due either to changes in circulation patterns which have altered the moisture sources, or to changes in the intensity of the moisture sources because of enhanced evaporation, or a combination of these two mechanisms. Most studies of changes in the Arctic Climate linked to changes in moisture transport make use of one of three possible techniques, namely (1) Eulerian approaches, which can be used to estimate the ratio of advected-to-recycled moisture and to calculate the moisture transport between predetermined source and sink regions, although these techniques are unable to identify the moisture source regions directly; (2) isotope analysis, but neither this nor the Eulerian techniques does not permit a proper geographical identification of the sources; or (3) more complex Lagrangian computational techniques, which can overcome the limitations of (1) and (2). Several such methods have recently been developed in order to diagnose the net changes in water vapour along a large number of back trajectories, and thereby infer the sources of the precipitation that falls in a target region. In this study, we will critically analyze previous results suggesting links between moisture transport and the extent of sea-ice in the Arctic, this being one of the most distinct indicators of continuous climate change both in the Arctic and on a global scale. In addition, we will use a sophisticated Lagrangian approach to contrast these existing results using new information and insights.