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The Tanana River in the interior of Alaska freezes over during October and November. The ice continues to grow throughout the winter accumulating an average maximum thickness of 110 cm, depending upon winter weather conditions.
The Nenana River Ice Classic competition began in 1917 when railroad engineers bet a total of 800 dollars, winner take all, guessing the exact time (month, day, hour, minute) the Tanana River ice would break. Each year since then, Alaska residents have guessed at the timing of ice breakup. A tripod (connected to an on-shore clock that stops when the ice breaks) is planted in approximately a half meter of river ice during freeze-up in October or November. The following spring, the clock automatically stops when the tripod moves determining the official time of ice breakup.
Many factors influence ice breakup, such as air temperature, ice thickness, snow cover, wind, water temperature, and depth of water below the ice. Generally, ice on the Tanana River breaks up in late April or early May (historically, April 20 to May 20). The time series of the Nenana ice breakup dates can be used to indicate climate change in the region.
Data are provided in ASCII format. The first data column indicates the year data were collected, the second column indicates the day and time in Julian date format that the ice breakup occurred. The third column lists the date and time of the ice breakup. These will be updated over successive years.
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| Time series of the Tanana River Ice break-up dates for the period from 1917 through 2000. (The Tanana River is located in the Alaskan interior.) The blue line represents the annual river ice break-up dates in Julian days. The red line is a smoothed curve using a low-pass filter with a cut-off frequency of 0.091. The thin black line represents the mean river ice break-up date (May 5). |
To broaden awareness of our services, NSIDC requests that you acknowledge the use of data sets distributed by NSIDC. Please refer to the citation below for the suggested form, or contact NSIDC User Services for further information. We also request that you send us one reprint of any publication that cites the use of data received from our Center. This helps us to determine the level of use of the data we distribute. Thank you.
National Snow and Ice Data Center. 1998. Nenana Ice Classic: Tanana River ice annual breakup dates. Boulder, CO: National Snow and Ice Data Center. Digital media.
Official Nenana Ice Classic Web site
Document Revision Date: 30 July 1998
Document Review Date: 4 August 1998
Document Curator: NSIDC Writers
Document URL: http://nsidc.org/data/docs/daac/nsidc0064_nenana.gd.html
