Hi, Rick T. here. One of the omnipresent issues in doing climate-scale analysis for Alaska is the comparatively short record of most variables at most places. So when a chance comes along to extend a record, we jump at it. To that end, yesterday I stumbled across several lists of break-up dates on the Chena River at Fairbanks. The version below was published in the Fairbanks Daily News-Miner on March 19, 1951. You will immediately notice this record starts in 1903 and is unbroken through 1950. In the same issue, the News-Miner also published break-up dates and times for the Tanana River at Nenana, which are the same as we use today and are available from many sources.
USGS report on Noyes Slough Restoration Project. So while this list may be primarily of historical interest for Fairbanks, can we use it to learn something about the timing of break-up of the Tanana River at Nenana prior to the start of observations in 1917?
The first thing I did was look at the correlation of the Chena River at Fairbanks dates against the Tanana at Nenana dates for the 34 years of overlapping data, 1917-1950 (plotted below). The correlation is considerably higher than I expected (+0.94), with 1940 (and to a lesser extent 1919) the only significant outlier. In general, break-up on the Chena River occurred a few days before the ice went out at Nenana, but there are several years (e.g. 1919 and 1920) when Chena dates are later than the Tanana at Nenana. So how can we use this to estimate break-up dates 1903-1916, when we have dates for the Chena at Fairbanks but not the Tanana at Nenana?