| Summary: | Average depth of snow in the mountains of southeastern Australia is decreasing at a rate of 0.48 cm a-1, while the duration of the snowpack has been shortened by 18.5 days since 1954 ( - 3 days per decade). The major factors responsible for these declines are an increasing temperature trend of 0.36 C per decade, and a reduction in winter precipitation at the rate of 10.1 mm a-1. While the depth of the snowpack is dependent upon precipitation trends and minimum temperatures (multiple r2 = 0.43), the shortening in the length of the snow period is best predicted by increasing temperatures and reduced humidity. The major forcing of the warming trend involves greenhouse gasses, in particular atmospheric carbon dioxide and water vapor. However, the decline in winter precipitation seems to be unrelated to the forcing of greenhouse gasses, and is instead statistically associated with the Southern Oscillation Index (r = 0.38). Inverse correlations were found between depth of snow and solar irradiance, which in turn is inversely correlated with the number of sunspots per cycle. The latter findings suggest that the declining precipitation and snow trends could additionally be associated with a reduction in solar activity during the past five decades.
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