Glacier-mediated streamflow teleconnections to the Arctic Oscillation

Abstract

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.

Seasonal flows of international British Columbia-Alaska rivers: The nonlinear influence of ocean-atmosphere circulation patterns

“…Also interesting are the results for the Arctic Oscillation, as the prior body of work on AO forcing of streamflow is far smaller than for ENSO and PDO, particularly in the BC-AK border region. To the extent the two studies can be compared given significant differences in methods and goals, our finding of higher temperature, precipitation, and streamflow during positive-phase AO years shows both similarities and differences with results for southwest Yukon Territory [21], a nearby but hydroclimatically distinct region to the northwest of our study area. A point of particular interest is the degree of nonlinearity in the observed responses.…”

Complex network theory, streamflow, and hydrometric monitoring system design

“…A 10-year record is insufficient to analyze climatic effects. For example, El Niño-Southern Oscillation, the Pacific Decadal Oscillation, and the Arctic Oscillation impact the hydrology of the Coast Range in British Columbia (BC) and Yukon, and some of those effects differ between regime types (Fleming et al, 2006Whitfield et al, 2010). Likewise, longer-term climatic trends may affect different hydrologic regime types within the region in different ways or, eventually, lead to regime transitions from one type to another (Whitfield et al, 2002;Fleming and Clarke, 2003;Stahl and Moore, 2006;Schnorbus et al, 2014).…”

Pacific Decadal Oscillation and the Hydroclimatology of Western Canada—Review and Prospects

“…Any given climate mode only captures some limited proportion of the total climatic variability experienced by a watershed. Nevertheless, the compactness of such summary metrics, along with the explanatory value of climate modes, is such that they can serve as a convenient, effective, and holistic means for assessing the impacts of climate variability on water resource systems (Stenseth et al, 2003;Fleming et al, 2006).…”