Current Status of Time Series Analysis in Hydrological Sciences - Hydrologic Time Series Analysis: Theory and Practice - page 102

Kremsmünster and Prague. Results of the statistical analysis of homogenized
series are presented.
Fortuniak (1995) used the daily precipitation totals and mean daily
temperature for the period 1956-1990 from 10 Polish meteorological stations
(Gdansk, Szczecin, Suwalki, Poznan, Lódz, Warszawa, Wroclaw, Kraków,
Przemysl and Zakopane) to test their periodicity. The annual course of
temperature was removed by subtracting the 35 th Fourier harmonic. The
classical Blackman and Tukey test was used to detect the cyclic behaviour of
the analysed series. The power spectrum of temperature for each station
exhibited two significant peaks: around 7.4 years and 193 days. For the
precipitation, the power spectra were found different for each station and it
was impossible to find a characteristic cycle for the entire region.
Nieplová (1995) applied five statistical homogeneity tests (Student's,
Bartlett's, Kruskal-Wallis's, Abbe criterion, and Spearman rank correlation
method) and the Craddock's relative homogeneity test to the annual and monthly
air temperature means, precipitation totals and relative air humidity means of
40 years and longer series. It was found that most of inhomogeneities were
caused by changed observation terms and by the relocation of measuring
stations. These results were used for selecting stations for long-term monitoring
of climate change in Slovakia.
Kristev and Koleva (1995) studied the variation of some important
characteristics of the snow cover pattern in Bulgaria during the period of
1935/6-1992/3. The basic data used were number of days with snow cover,
dates of the first and last days with snow cover and maximum snow depths.
The presence of some forms of trend in the data was examined by the Spearman
test and the Mann-Kendall rank test statistics.
Walanus-Gliwice (1995) analyzed the periodicity by using the Fast Fourier
Transform (FFT). The water stages of Vistula River at Szczucin, discharges of
Warta (Poland) and Tisa (Hungary) rivers, Dnieper River (Ukraina),
precipitation from Warsaw, Cracow, Wroclaw and other towns, air temperature,
dendroclimatological curves and the thickness of yearly strata (Warws) from
Gosciaz Lake (Central Poland) were analyzed. The 3.5-year (3.5±0.15 yr)
periodicity of unknown origin in the river discharge and the precipitation was
confirmed. For rivers, the 3.5-yr signal was found much less in Szczucin, but
it was visible. For the precipitation, the signal was still less, especially in
comparison to the more dominant seasonal periodicity. The periodicity in
rivers' discharges was of higher amplitude than that in the precipitation. Finally,
a detailed analysis revealed that the 3.5-yr peak in frequency domain should
be treated as a random event.
Aulenbach et al. (1996) evaluated the trends in precipitation and surface
water quality at a network of 15 small watersheds (<10 km 2 ) in USA using the
seasonal Kendall test for monotonic trends and a graphical smoothing technique
for the visual identification of trends. A relation between precipitation and
surface water trends was not evident either for individual inorganic solutes or