Current Status of Time Series Analysis in Hydrological Sciences - Hydrologic Time Series Analysis: Theory and Practice - page 109

neighbouring rural stations in Turkey. The results indicated that there is a shift
towards the warmer side in the frequency distributions of both the series,
which is an indication of urban heat island. The seasonal analysis of individual
21.00 h temperature series suggested that the regional warming is the strongest
in spring and the weakest in autumn and winter. Urban warming is detected to
be more or less equally distributed over the year with a slight increase in
autumn. Using the Mann-Kendall trend test for the temperature difference
series, the urban heat island effect was found to be significant at all urban
sites. On the other hand, no significant urban effects on the precipitation were
found.
Kadioglu (1997) analyzed the mean annual temperature records of Turkey
for the period 1939 to 1989. A warming trend was found from 1939 to 1989
but a cooling trend was detected from 1955 to 1989. These trends in the mean
annual temperature series, however, were not found to be statistically
significant. Comparatively greater warming effects were found in spring and
minimum in winter. A regional increase in the mean minimum temperature
around 1955 is attributed to the urban heat island effect. In general, the
predictions of general circulation model (GCM) were consistent with a sign of
trends only in the Turkish climatic records during the entire (1939 to 1989)
period.
Keiser and Griffiths (1998) used a homogeneity test developed by
Alexandersson (1986, 1995) and applied it to the mean monthly maximum,
minimum, and mean temperature data from 22 stations in the northern Great
Plains of USA. One of these stations, Valentine, is a first-order station and is
used as the reference station. When Valentine station was adjusted for a possible
inhomogeneity due to its move, it was found that the Valentine's adjustments
have a distinct seasonal pattern. The testing of other stations against Valentine
revealed that the position of a significant discontinuity in a station's monthly
mean or annual temperature series is not always the same as in the
corresponding monthly maximum and minimum series. In addition, a seasonal
pattern similar to that of Valentine station was found in every station's
adjustment values.
Tayanç et al. (1998) presented a combination of different methods (i.e.,
graphical analysis, nonparametric Kruskal-Wallis homogeneity test and Wald-
Wolfowitz runs test) to test climatological time series for inhomogeneities.
These methods were applied to the annual mean difference temperature series
of 82 Turkish weather stations, and the inhomogeneity detection efficiencies
of these tests were determined by a series of Monte Carlo simulation studies.
It was concluded that the procedure is statistically rigorous, provides estimates
of the time and magnitude of change in the mean, and is a valuable tool for
testing time series.
Vincent and Gullett (1999) developed the Canadian historical temperature
database (CHTD) to produce an improved historical climate change database
based on the datasets of monthly mean maximum and minimum temperatures