Changes in mass balance of South Cascade Glacier, North Cascades, 1959 to 1994

EXTRACT (SEE PDF FOR FULL ABSTRACT): Annual, winter, and summer mass balance measurements at South Cascade Glacier in the North Cascade Mountains of Washington State constitute a continuous time series 36 years long, from 1959 to 1994. ... The long-term trends at South Cascade Glacier are decreased winter accumulation and increased summer ablation, neither of which is conducive to glacier growth, so the trend in the Pacific Northwest is clearly away from an ice-age type of climate at the current time. The data also demonstrate that a glaciologically significant long-term change in snow precipitation can occur rapidly, in as short an interval as 1 year, much more rapidly than changes in temperature

Melt water input from the Bering Glacier watershed into the Gulf of Alaska

The annual runoff from the melting of large glaciers and snow fields along the northern perimeter of the Gulf of Alaska is a critical component of marine physical and biological systems; yet, most of this freshwater is not measured. Here we show estimates of melt for the watershed that contains the largest and longest glacier in North America, the Bering Glacier. The procedure combines in situ observations of snow and ice melt acquired by a long-term monitoring program, multispectral satellite observations, and nearby temperature measurements. The estimated melt is 40 km3 per melt season, ± 3.0 km3, observed over the decadal period, 2002–2012. As a result of climate change, these estimates could increase to 60 km3/yr by 2050. This technique and the derived melt coefficients can be applied to estimate melt from Alaska to Washington glaciers

Satellite passive microwave observations of the upper Colorado River snowpack

Seasonal snow cover in the mountains of the Upper Colorado River Basin is a major source of water for a large portion of the southwestern United States. The extent and amount of this snowpack not only reflects changes in weather patterns and climate but also influences the general circulation through modification of the energy exchange between land and atmosphere. ... Satellite observations and remote sensing techniques can enhance the standard snowpack observations to provide the temporal and spatial measurements required for understanding the role of snow in the surface energy balance and improving the management of water resources

Greenland Sea Odden sea ice feature: Intra-annual and interannual variability

The “Odden” is a large sea ice feature that forms in the east Greenland Sea that may protrude eastward to 5 °E from the main sea ice pack (at about 8 °W) between 73° and 77 °N. It generally forms at the beginning of the winter season and can cover 300,000 km2. Throughout the winter the outer edge of the Odden may advance and retreat by several hundred kilometers on timescales of a few days to weeks. Satellite passive microwave observations from 1978 through 1995 provide a continuous record of the spatial and temporal variations of this extremely dynamic phenomenon. Aircraft synthetic aperture radar, satellite passive microwave, and ship observations in the Odden show that the Odden consists of new ice types, rather than older ice types advected eastward from the main pack. The 17-year record shows both strong interannual and intra-annual variations in Odden extent and temporal behavior. For example, in 1983 the Odden was weak, in 1984 the Odden did not occur, and in 1985 the Odden returned late in the season. An analysis of the ice area and extent time series derived from the satellite passive microwave observations along with meteorological data from the International Arctic Buoy Program (IABP) determined the meteorological forcing associated with Odden growth, maintenance, and decay. The key meteorological parameters that are related to the rapid ice formation and decay associated with the Odden are, in order of importance, air temperature, wind speed, and wind direction. Oceanographic parameters must play an important role in controlling Odden formation, but it is not yet possible to quantify this role because of a lack of long-term oceanographic observations

Hydrologic processes at Bering Glacier, Alaska

Runoff from the mountains and large glaciers on the rim of the Gulf of Alaska is a critical driver for ocean circulation in the gulf and a major contributor to global sea level rise. Bering Glacier is the foremost glacier of this system, with one of the largest proglacial lake-river systems in the world, Vitus Lake, which is linked to the Gulf of Alaska by the Seal River. Vitus Lake, at sea level and \u3e250 m deep in some locations, receives all of the runoff, rainfall, and glacial melt from the Bering Lobe, which then flows into the Gulf of Alaska in the 8-km-long Seal River. Six years of conductivity-temperature-depth (CTD) surveys in Vitus Lake show a highly stratified system with 50% diluted seawater at the bottom. The annual surveys show changes in the deep water temperature and salinity that are the result of seawater intrusions. To understand the complex interaction between lake level and area, glacier discharge, river morphology and flow, sea level fluctuations, and their associated impacts on the lacustrine ecology of Vitus Lake, we developed a hydrodynamic flow model that was calibrated using field measurements of lake level and the flow in Seal River. The model is used to analyze present conditions in Vitus Lake and shows that even with no runoff entering the lake, the distance from the Gulf of Alaska through Seal River to Vitus Lake is too great for typical tidal inflow to reach the lake. Furthermore, the model is used to understand the response of the glacier-lake system to possible future scenarios of glacier retreat or advance and changes in runoff. Finally, properly calibrated, such a model would be able to gauge the discharge from the Bering Glacier System by measuring only the lake level

Measurements of velocity and ablation from Bering Glacier during the recent surge

Bering Glacier, in south central Alaska, the largest and longest glacier in continental North America, is once again surging. The last surge occurred in the 1993-1995 time period; the current surge was first documented by satellite observations in January 2011. In mid-May 2011 we deployed Glacier Ablation Sensing System (GASS) units at six sites from the terminus (sea level) to the Bagley Ice field (1200m). At each GASS site the date, time, GPS WAAS enabled location, air temperature, melt, wind speed, upward and downward looking light intensity are measured and recorded on an hourly basis. The melt is determined by measuring acoustically the distance between the sensor\u27s housing which is mounted on an aluminum pole stream drilled approximately 10 m in to the ice or snow surface. Two of the GASS sites nearest the terminus transmit data back via the iridium network and are reported on the web (www.beringglacier.org - click on 2011 ablation monitoring). As of late July 2011, the glacier had moved approximately 785m at the terminus (B1) and 858m at B2 approximately 15 km up glacier at an altitude of approximately 340m. B1 total melt from mid-May was 494 cm, while B2 melted 383 cm. From previous observations, the average daily melt at Bering in the summer is approximately 5cm/day, and the velocity at B2 was 4.5 m/day, with a total displacement in 2010 of approximately 280m. B2 is presently moving 12m/day down from its peak observed displacement of 18m/day in late May. In late July, B1 at the terminus is moving approximately 7m/day, slower than its maximum daily displacement of over 15m/day observed in late May. In contrast, the 2010 GASS unit measurement at the glacier terminus observed a daily movement of only .14m/day with a total displacement of only approximately 10 meters. The hourly observations for all six GASS units will be presented along with interpretation as to why the melts and displacements vary over the observation period

Remote sensing of the Bering Glacier region

Satellite remote sensing is an invaluable tool for monitoring and characterizing the Bering Glacier System. Applications of glacier remote sensing include, but are not limited to, mapping extent and features, ice velocities through sequential observations, glacier terminus locations, snow line location, glacier albedo, changes in glacier volume, iceberg surveys and calving rates, hydrographic and water quality parameters in ice marginal lakes, and land-cover classification maps. Historical remote sensing images provide a much needed geospatial time record of the dynamic changes that Bering Glacier has undergone, including changes from its surge behavior and response to climate change. Remote sensing images dating back to the early 1990s have been used to map the glacier terminus retreat of ~5 to 7 km, which has resulted in Vitus Lake increasing in volume 9.4 km3 (~260%) from 1995 to 2006. Using elevation data obtained from remote sensing and GPS surface points, we have determined that the glacier elevation has decreased by ~150 m at the terminus and 30 m at the equilibrium line (~1300 m) since 1972. Satellite observations have recorded the upward migration in altitude of the equilibrium line to its present (2006) position (slightly \u3e1200 m). The decrease in glacier volume, obtained using remote sensing–derived elevation data, from 1957 to 2004 is estimated at ~104 km3. Remote sensing data also have mapped the sediment-rich (rock flour) water flowing into Vitus Lake, providing insight into the hydrologic circulation of the Bering Glacier System, showing major glacier discharge from the Abandoned River, Arrowhead Point, and Lamire Bay in the area of Vitus Lake west of Taggland