Interannual to decadal variability in climate and the glacier mass balancein Washington, western Canada, and Alaska

The authors examine the net winter, summer, and annual mass balance of six glaciers along the northwest coast of North America, extending from Washing ton State to Alaska. The net winter (NWB) and net annual (NAB) mass balance anomalies for the maritime glaciers in the southern group, located in Wash ington and British Columbia, are shown to be positively correlated with loc al precipitation anomalies and storminess (defined as the rms of high-passe d 500-mb geopotential anomalies) and weakly and negatively correlated with local temperature anomalies. The NWB and NAB of the maritime Wolverine glac ier in Alaska are also positively correlated with local precipitation, but they are positively correlated with local winter temperature and negatively correlated with local storminess. Hence, anomalies in mass balance at Wolv erine result mainly from the change in moisture that is being advected into the region by anomalies in the averaged wintertime circulation rather than from a change in storminess. The patterns of the wintertime 500-mb circula tion and storminess anomalies associated with years of high NWB in the sout hern glacier group are similar to those associated with low NWB years at th e Wolverine glacier, and vice versa. The decadal ENSO-like climate phenomenon discussed by Zhang et al. has a la rge impact on the NWB and NAB of these maritime glaciers, accounting for up to 35% of the variance in NWB. The 500-mb circulation and storminess anoma lies associated with this decadal ENSO-like mode resemble the Pacific-North American pattern, as do 500-mb composites of years of extreme NWB of South Cascade glacier in Washington and of Wolverine glacier in Alaska. Hence, t he decadal ENSO-like mode affects precipitation in a crucial way for the NW B of these glaciers. Specifically, the decadal ENSO-like phenomenon strongl y affects the storminess over British Columbia and Washington and the moist ure transported by the seasonally averaged circulation into maritime Alaska . In contrast, ENSO is only weakly related to NWB of these glaciers because (i) the large-scale circulation anomalies associated with ENSO do not prod uce substantial anomalies in moisture advection into Alaska, and (ii) the s torminess and precipitation anomalies associated with ENSO are far to the s outh of the southern glacier group. Finally, the authors discuss the potential for short-term climate forecasts of the mass balance for the maritime glaciers in the northwest of North Am erica.