A shift in winter season timing in the Northern Plains of the USA as indicated by temporal analysis of heating degree days
✍ Scribed by Hartley, Suzanne; Robinson, David A.
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- English
- Weight
- 398 KB
- Volume
- 20
- Category
- Article
- ISSN
- 0899-8418
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✦ Synopsis
The temporal distribution of monthly heating degree days (HDD) approximates a bell-shaped curve, usually with a January maximum. The first moment, or centroid, of this distribution can be taken as the midpoint of the heating season. Analysis of seasonal HDD centroids reveals significant inter-decadal trends in the Northern Plains. From 1950 to 1990, the timing of the HDD centroid is observed to have advanced at a rate of 1.6 days per decade, a trend largely explained by cooling in October and warming in March and April. A trend of comparable magnitude (2.2 days per decade), but opposite direction, is observed for the period 1925 -1950, and is again primarily associated with temperature trends in autumn and spring. The results suggest that changes in seasonal timing could be a feature of natural climate variability, and that it may be premature to infer an unprecedented climate change from a subtle shift in the timing of the winter season.