Glacier-mediated streamflow teleconnections to the Arctic Oscillation

We investigated the potential for glacier- and snowmelt-fed rivers to respond differently to the Arctic Oscillation (AO) by applying nonparametric statistical techniques to standardized and deseasonalized monthly hydrometric data from eight watersheds in southwest Yukon and northwest British Columbia, Canada. We first extracted regionally coherent glacial and nival hydroclimatic signals from the station data using empirical orthogonal function analysis. The annually averaged glacial and nival principal component time series were mutually uncorrelated, Suggesting a decoupling of interannual streamflow variability between the two fluvial regimes. Moreover, glacial and nival rivers showed selective teleconnectivity to the AO; the annual glacial signal was significantly positively correlated to the AO index, whereas the nival signal was not. Composite analyses of annual hydrographs, performed using data from individual hydrometric stations, were consistent with the EOF-correlation results and provided details of related changes in hydrologic seasonality. In particular, positive-phase AO events are associated with positive glacial streamflow anomalies in late spring and early Summer and an earlier freshet in nival rivers with little or no net change in annual flow. Parallel composite analyses of locally available homogeneous temperature and precipitation station data suggested that the hydrologic behaviour largely arises from the combination of AO-related late spring to early summer temperature anomalies and the presence or absence of a glacial reservoir potentially available for melting. Synoptic-scale correlation mapping of sea-level pressure fields reinforced these inferences. The results provide significant additional evidence that watershed glacierization can control the fundamental nature and patterns of regional-scale spatiotemporal water resource variability resulting from low-frequency climatic forcing. Copyright (C) 2005 Royal Meteorological Society.