Geologic Publications for Mount Rainier
Relationship between temperature and dry-weather jökulhlaups from South Tahoma Glacier, Mount Rainier, Washington
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Author(s):
Thomas D. Haskins
Category: PUBLICATION
Document Type: MESSAGe Technical Report Number 047
Publisher: University of Washington
Published Year: 2016
Volume:
Number:
Pages: 27
DOI Identifier:
ISBN Identifier:
Keywords:
Abstract:
Jökulhlaups, or glacial outburst floods, from South Tahoma Glacier on Mount Rainier pose a threat to park visitors, staff, and infrastructure. Jökulhlaups release without surficial precursors, and transition into debris flows as they surge downslope. Walder and Driedger (1995) calculated the relative frequency, called the conditional probability (P
C), for seven dry-weather jökulhlaups between May-November from 1986 and 1992. Dry-weather jökulhlaups are defined as outburst floods that occur during hot, dry conditions. The PC is the number of jökulhlaups that occur at a maximum temperature (T
MAX) divided by the number of days in the entire distribution that have a T
MAX equal to or greater than the given T
MAX.
Walder and Driedger (1995) used 1-day average T
MAX (T
MAX-1) to calculated P
C, which ranged from 0.04 to 0.11 between 17°C and 28°C. I repeated their analyses with a larger data set, using T
MAX-1 between June-September from 1966-2015, which contained 14 outburst floods. The P
C calculated from the larger data set ranged from 0.008 to 0.023 for the same T
MAX-1. This difference in the PC show there are not enough data to produce robust analyses, and so the P
C should not be used to predict jökulhlaups because it will change as data is added.
Dry-weather outburst floods occur later in the summer compared to peak T
MAX-1, so longer intervals of T
MAX are required to melt enough water to produce an outburst flood. I calculated 6-week average T
MAX-1 (T
MAX-42) on the days that jökulhlaups occurred. The peak in T
MAX-42 aligns with the T
MAX-42 of the entire distribution. The P
C for T
MAX-42, calculated in the same way as T
MAX-1, are less than 0.01 for T
MAX-42 <18.0°C. When T
MAX-42 is ≥18.0°C, the P
C increases rapidly from 0.01 to 0.10 at 21.1°C.
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In Text Citation:
Haskins (2016) or (Haskins, 2016)
References Citation:
Haskins, T.D., 2016, Relationship between temperature and dry-weather jökulhlaups from South Tahoma Glacier, Mount Rainier, Washington: MESSAGe Technical Report Number 047, University of Washington, 27 p..