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Geology topics

R. M. Krimmel

Publications and source records attributed to R. M. Krimmel.

12 recordsLinked to original sources
USGS2017

The slow advance of a calving glacier: Hubbard Glacier, Alaska, U.S.A

Hubbard Glacier is the largest tidewater glacier in North America. In contrast to most glaciers in Alaska and northwestern Canada, Hubbard Glacier thickened and advanced during the 20th century. This atypical behavior is an important example of how insensitive to climate a glacier can become during parts of the calving glacier cycle. As this glacier continues to advance, it will close the seaward entrance to 50 km long Russell Fjord and create a glacier-dammed, brackish-water lake. This paper describes measured changes in ice thickness, ice speed, terminus advance and fjord bathymetry of Hubbard Glacier, as determined from airborne laser altimetry, aerial photogrammetry, satellite imagery and bathymetric measurements. The data show that the lower regions of the glacier have thickened by as much as 83 m in the last 41 years, while the entire glacier increased in volume by 14.1 km3. Ice speeds are generally decreasing near the calving face from a high of 16.5 m d-1 in 1948 to 11.5 m d-1 in 2001. The calving terminus advanced at an average rate of about 16 m a-1 between 1895 and 1948 and accelerated to 32 m a-1 since 1948. However, since 1986, the advance of the part of the terminus in Disenchantment Bay has slowed to 28 m a-1. Bathymetric data from the lee slope of the submarine terminal moraine show that between 1978 and 1999 the moraine advanced at an average rate of 32 m a-1, which is the same as that of the calving face.

Annals of Glaciology↗
USGS2003

A macroscopic approach to glacier dynamics

A simple approach to glacier dynamics is explored in which there is postulated to be a relationship between area and volume with three parameters: the time for area to respond to changes in volume, a thickness scale, and an area characterizing the condition of the initial state. This approach gives a good fit to the measurements of cumulative balance and area on South Cascade Glacier from 1970-97; the area time-scale is roughly 8 years, the thickness scale about 123 m, and the 1970 area roughly 4% larger than required for adjustment with volume. Combining this relationship with a version of mass continuity expressed in terms of area and volume produces a theory of glacier area and volume response to climate in which another time constant, the volume time-scale, appears. Area and volume both respond like a damped spring and mass system. The damping of the South Cascade response is approximately critical, and the volume time-scale is roughly 48 years, six times the area time-scale. The critically damped spring and mass analogy reproduces the time dependence predicted by the more complicated traditional theory of Nye.

Journal of Glaciology↗
USGS1999

Analysis of difference between direct and geodetic mass balance measurements at South Cascade Glacier, Washington

Net mass balance has been measured since 1958 at South Cascade Glacier using the ‘direct method,’ e.g. area averages of snow gain and firn and ice loss at stakes. Analysis of cartographic vertical photography has allowed measurement of mass balance using the ‘geodetic method’ in 1970, 1975, 1977, 1979–80, and 1985–97. Water equivalent change as measured by these nearly independent methods should give similar results. During 1970–97, the direct method shows a cumulative balance of about −15 m, and the geodetic method shows a cumulative balance of about −22 m. The deviation between the two methods is fairly consistent, suggesting no gross errors in either, but rather a cumulative systematic error. It is suspected that the cumulative error is in the direct method because the geodetic method is based on a non‐changing reference, the bedrock control, whereas the direct method is measured with reference to only the previous year's summer surface. Possible sources of mass loss that are missing from the direct method are basal melt, internal melt, and ablation on crevasse walls. Possible systematic measurement errors include under‐estimation of the density of lost material, sinking stakes, or poorly represented areas.

Washington↗
USGS1998

Climate variations and changes in mass of three glaciers in western North America

Time series of net and seasonal mass balances for three glaciers in western North America, one in the Pacific Northwest and two in Alaska, show various relationships to Pacific hemisphere climate indexes. During the winter season the two coastal, maritime-regime glaciers, over 2000 km apart, are affected almost identically, albeit inversely, by atmospheric and oceanic conditions in both the tropical and North Pacific. The two Alaska glaciers, only 350 km apart, have almost no coherence. Lag correlations show that in winter the maritime glaciers are influenced by concurrent conditions in the North Pacific, but by conditions in the tropical Pacific in August-September of the prior northern summer. The winter balance variations contain interannual El Nino-Southern Oscillation variability superimposed on North Pacific interdecadal variability; the interdecadal 1976-77 climate regime shift is clearly evident. The summer balances and the continental-regime glacier have a general lack of correlations, with no clear, strong, consistent patterns, probably a result of being influenced more by local processes or by circulation patterns outside the Pacific Ocean basin. The results show the Pacific Northwest is strongly influenced by conditions in the tropical Pacific, but that this teleconnection has broken down in recent years, starting in 1989. During the seven years since then (1989-95), all three glaciers have shown, for the first time, coherent signals, which were net mass loss at the highest rate in the entire record. The authors' results agree with those of other recent studies that suggest these recent years are unusual and may be a signature of climate warming.

Journal of Climate↗
USGS1996

Water, ice, and meteorological measurements at South Cascade Glacier, Washington, 1995 balance year

Winter snow accumulation and summer snow, firn, and ice melt were measured at South Cascade Glacier, Washington to determine the winter and net balances for the 1995 balance year. The 1995 winter balance, averaged over the glacier, was 2.86 meters, and the net balance was -0.69 meter. The winter balance was approximately 0.5 meter greater than the 1977-94 average winter balance. The net balance was approximately 0.3 meter less negative than the 1977-94 average net balance. Runoff was measured from the glacier and an adjacent non-glacierized basin. Air temperature, precipitation, barometric pressure, solar radiation, and wind speed were measured adjacent to the glacier. This report makes these data available to the glaciological and climatological community.

Washington↗
USGS1995

Water, ice, and meteorological measurements at South Cascade Glacier, Washington, 1994 balance year

Winter snow accumulation and summer snow, firn, and ice melt were measured at South Cascade Glacier, Washington to determine the winter and net balances for the 1994 balance year. The 1994 winter balance, averaged over the glacier, was 2.39 meters, and the net balance was -1.60 meters. The winter balance was approximately that of the 1977-94 average winter balance. The net balance was more negative than the 1977-94 average net balance of -1.02 meters. Runoff was measured from the glacier and an adjacent non- glacierized basin. Air temperature, precipitation, barometric pressure, solar radiation, and wind speed were measured nearby. This report makes these data available to the glaciological and climatological community.

Washington↗
USGS1987

Columbia Glacier in 1986; 800 meters retreat

Columbia Glacier, in Prince William Sound, Alaska, continued its rapid retreat in 1986, with a retreat of 800 m. Average velocity of the lower portion of the glacier, 10 September 1986 to 26 January 1987, was three km/yr, or about one-half of the velocity during similar periods for the previous three years. This reduced velocity is a new development in the progression of the retreat, and if the calving rate follows the pattern of previous years, will result in continued retreat. (Author 's abstract)

Open-File Report↗
USGS1987

Columbia Glacier, Alaska, photogrammetry data set, 1981-82 and 1984-85

Photogrammetric processing of 12 sets of vertical aerial photography of the Columbia Glacier, Alaska, has measured the altitude and velocity fields of the lowest 14,000 m of the glacier during the periods of September 1981 to October 1982 and October 1984 to September 1985. The data set consists of the location of 3,604 points on the glacier, 1,161 points along the glacier terminus, and 1,116 points along the top of the terminus ice cliff. During the 1981 to 1985 period the terminus of the glacier receded 1,350 m, the ice near the terminus thinned at a rate of 18 m/year, and ice velocity near the terminus tripled, reaching as much as 6,000 m/year. (Author 's abstract)

Open-File Report↗
USGS1986

Velocity and surface altitude of the lower part of Hubbard Glacier, Alaska, August 1978

The terminus position and locations of numerous points on the lower part of Hubbard Glacier were determined from 1:58,000 scale vertical aerial photographs taken July 30, 1978 and August 23, 1978. The same surface features were located on each set of photography, allowing displacement during the time interval to be measured. Velocity of the lower glacier for the 24-day interval was about 7 m/day. The terminus receded 45 m between the two dates. (Author 's abstract)

Open-File Report↗
USGS1985

Short-term velocity measurements at Columbia Glacier, Alaska: August-September 1984

Ice velocity data are presented for the lower reach of Columbia Glacier, Alaska. The data span a 29 day period and contain 1,072 angle sightings from two survey stations to 22 markers placed on the ice surface, and 1,621 laser measurements of the distance to one of those markers (number 11) from another station. These short-interval observations were made to investigate the dynamics of the glacier and to provide input to models for estimation of future retreat and iceberg discharge. The mean ice velocity (at marker number 11) was approximately 9 m/day and ranged from 8 to < 15 m/day. The data set includes a well defined 2-day, 50% velocity increase and a clear pattern of velocity fluctuations of about 5% with approximately diurnal and semiurnal periods. (Author 's abstract)

Alaska↗