Distribution Properties of a Measurement Series of River Water Temperature at Different Time Resolution Levels (Based on the Example of the Lowland River Noteć, Poland)

Abstract

The paper investigates the distribution properties of measurement series of river water temperatures for the lowland River Noteć and its tributaries (Western Poland), as well as air temperatures at different data time resolution levels (1987-2013). The aspect of distribution normality was examined in quantile plots, the series' stationarity was assessed with an augmented Dickey-Fuller test, while autocorrelation was studied using an Autoregressive Integrated Moving Average (ARIMA) model. It was demonstrated that distributions of river water and air temperature series at different levels of analyses are generally close to normal but also display a certain skewness. Both daily temperature measurement series are stationary series. The periodic component accounts for about 93% (water temperature) and 77% (air temperature) of the daily variability of the variable, while the random factor equals 6-7% and 22%, respectively. The Autoregressive Integrated Moving Average (ARIMA) model confirmed a clear annual seasonality in temperature distribution and indicated the long memory of the autoregressive process AR (2-4). The temperature prediction performed on the basis of a 4th-order Fourier series is consistent with the course of historical data. In the multiannual period 1987-2013, particularly high maximum temperatures were recorded for the Upper Noteć in the summer half-years (28.4 • C); these are related to anthropogenic factors and increase the threat to the existence of cyprinids and salmonids. The thermal anomalies identified in the River Noteć clearly point to the necessity of intensifying the monitoring of its waters.

Relationship between Water Temperature of Polish Rivers and Large-Scale Atmospheric Circulation

“…The existence of a relationship between fluctuations in air temperature and river water temperature has been confirmed under differing climatic conditions and at various levels of temporal resolution of measurement data [4,10,11,[14][15][16]. The majority of studies result in high and statistically significant coefficients of correlation between variables and coefficients of determination (R 2 > 0.8), which means that more than 80% of river water temperature variability may be explained by the variability of air temperature [2,17,18].…”

“…The temperature of river water constitutes an important element of the hydrological regime, being subjected to daily, seasonal, annual, and multi-annual change [1]. Seasonal changes are the consequence of the influence of climatic factors predominant in a given geographical zone, whereas multi-annual changes may additionally point to the impact of local factors, also anthropogenic [2][3][4][5].…”

“…The majority of studies result in high and statistically significant coefficients of correlation between variables and coefficients of determination (R 2 > 0.8), which means that more than 80% of river water temperature variability may be explained by the variability of air temperature [2,17,18]. Research has shown that, in the case of rivers in the Northern Hemisphere, we may observe a seasonal distribution of water temperature, while exceptions to this rule may be the result of weather anomalies or of the impact of anthropogenic factors [2,4,12,19]. High correlations between annual and monthly air and river water temperature values have been demonstrated for various regions, among others in the United States and Canada [16,[20][21][22][23][24], in Asia and Eurasia [25][26][27][28], and in Europe [29][30][31][32][33][34][35][36].…”

“…High correlations between annual and monthly air and river water temperature values have been demonstrated for various regions, among others in the United States and Canada [16,[20][21][22][23][24], in Asia and Eurasia [25][26][27][28], and in Europe [29][30][31][32][33][34][35][36]. Studies concerning the thermal regime of Polish rivers have also confirmed the existence of significant relations and the impact of air temperature on the variability of river water temperature [4,5,13,[37][38][39].…”

Analysis of Granger Causality Between Daily and Monthly Temperatures of Water and Air, as Illustrated With the Example of Noteć River

“…With the aid of the Augmented Dickey-Fuller Test ADF (Dickey and Fuller 1981) we have characterizes a series of daily temperature data in terms of station-arity. A detailed description and results of the test are presented in the work by Graf (2018). The studies of the stationarity of the data series were the procedure necessary in order to select the method for analysing the strength of the correlation between the analysed variables.…”