TITLE:
Trend and Periodicity of Temperature Time Series in Ontario
AUTHORS:
Syed Imran Ahmed, Ramesh Rudra, Trevor Dickinson, Motahir Ahmed
KEYWORDS:
Time Series, Trend, Periodicity, Mann-Kendall Test, t-Test, Frost Free Days
JOURNAL NAME:
American Journal of Climate Change,
Vol.3 No.3,
September
22,
2014
ABSTRACT: The
trends and periodicities in the annual and seasonal temperature time series at
fifteen weather stations within Ontario Great Lakes Basins have been analyzed,
for the period 1941-2005, using the statistical analyses (Fourier series
analysis, t-test, and Mann-Kendall
test). The stations were spatially divided into three regions: northwest (NW),
southwest (SW), and southeast (SE) to evaluate spatial variability in
temperature. The results of the study reveal that the annual maximum mean
temperature showed increasing trend for NW, and mixed trends for SW and SE
regions. The variability was found to be more for northern stations as compared
to southern stations for annual extreme minimum temperature. In addition, the
trend slope per 100 years for the average annual extreme minimum temperature
increased within the range of -0.8°C (Stratford) to 15°C (Porcupine). The seasonal
analysis demonstrated that extreme maximum temperature has an increasing trend
and maximum mean temperature has a decreasing trend during summer and winter.
The extreme minimum temperature for winter illustrated an increasing trend
(90%) with 22% statistically significant for NW region. For the SW region, the
trend is also increasing (80%) for most of the temperature variables and 25% of
temperature data were significantly increased in the SW region. The SE region
stations showed overall very clear increasing trends (95%) for all the
temperature variables. The data also showed that 47% of data were statistically
significant in the SE region. The analysis of variance accounted for by trend,
significant periodicities, and random component show that the pattern is
similar for the percent of variance accounted for periodicities, and random
component contribute dominantly for the four temperature variables and frost
free days (FFD) for all three regions. Overall, the study reveals that the
extreme minimum temperature is increasing annually and seasonally, with
statistically significant at many stations.