scholarly journals Multi-annual analysis and trends of the temperatures and precipitations in West Anatolia

2017 ◽  
Vol 8 (3) ◽  
pp. 456-473 ◽  
Author(s):  
Turgay Partal
Keyword(s):  
Kendall Test ◽  
Temperature Data ◽  
Significance Level ◽  
Time Frequency ◽  
Pettitt Test ◽  
Frequency Representation ◽  
Mann Kendall Test ◽  
Scale Levels ◽  
Increasing Trends ◽  
Periodic Components

This study has been carried out to analyze the historical precipitation and temperature data for West Anatolia (Turkey) to understand the annual and multi-annual changes. The wavelet transform technique was used for time–frequency representation of the data. The trends in the data were estimated with the non-parametric Mann–Kendall test. A change point in the time series was determined by the Pettitt test. According to the wavelet analysis, some strong short-term periodical events at the scale levels of 1–4 were determined. The application of the Mann–Kendall test resulted with the identification of some decreasing trends in the observed annual precipitations and also in some periodic components, such as in 32 yearly periodic components. As well, 16 yearly periodic components of the temperature data showed very strong increasing trends at the 5% significance level.

scholarly journals Innovative Trend Analysis of Precipitation in the Lake Issyk-Kul Basin, Kyrgyzstan

Atmosphere ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 332 ◽  
Author(s):  
Yilinuer Alifujiang ◽  
Jilili Abuduwaili ◽  
Balati Maihemuti ◽  
Bilal Emin ◽  
Michael Groll
Keyword(s):  
Trend Analysis ◽  
Resource Planning ◽  
Kendall Test ◽  
Trend Test ◽  
Lake Basin ◽  
Positive Trend ◽  
Monthly Precipitation ◽  
Innovative Trend Analysis ◽  
Mann Kendall Test ◽  
Increasing Trends

The analysis of various characteristics and trends of precipitation is an essential task to improve the utilization of water resources. Lake Issyk-Kul basin is an upper alpine catchment, which is more susceptible to the effects of climate variability, and identifying rainfall variations has vital importance for water resource planning and management in the lake basin. The well-known approaches linear regression, Şen’s slope, Spearman’s rho, and Mann-Kendall trend tests are applied frequently to try to identify trend variations, especially in rainfall, in most literature around the world. Recently, a newly developed method of Şen-innovative trend analysis (ITA) provides some advantages of visual-graphical illustrations and the identification of trends, which is one of the main focuses in this article. This study obtained the monthly precipitation data (between 1951 and 2012) from three meteorological stations (Balykchy, Cholpon-Ata, and Kyzyl-Suu) surrounding the Lake Issyk-Kul, and investigated the trends of precipitation variability by applying the ITA method. For comparison purposes, the traditional Mann–Kendall trend test also used the same time series. The main results of this study include the following. (1) According to the Mann-Kendall trend test, the precipitation of all months at the Balykchy station showed a positive trend (except in January (Zc = −0.784) and July (Zc = 0.079)). At the Cholpon-Ata and Kyzyl-Suu stations, monthly precipitation (with the same month of multiple years averaged) indicated a decreasing trend in January, June, August, and November. At the monthly scale, significant increasing trends (Zc > Z0.10 = 1.645) were detected in February and October for three stations. (2) The ITA method indicated that the rising trends were seen in 16 out of 36 months at the three stations, while six months showed decreasing patterns for “high” monthly precipitation. According to the “low” monthly precipitations, 14 months had an increasing trend, and four months showed a decreasing trend. Through the application of the ITA method (January, March, and August at Balykchy; December at Cholpon-Ata; and July and December at Kyzyl-Suu), there were some significant increasing trends, but the Mann-Kendall test found no significant trends. The significant trend occupies 19.4% in the Mann-Kendall test and 36.1% in the ITA method, which indicates that the ITA method displays more positive significant trends than Mann–Kendall Zc. (3) Compared with the classical Mann-Kendall trend results, the ITA method has some advantages. This approach allows more detailed interpretations about trend detection, which has benefits for identifying hidden variation trends of precipitation and the graphical illustration of the trend variability of extreme events, such as “high” and “low” values of monthly precipitation. In contrast, these cannot be discovered by applying traditional methods.

scholarly journals Air Temperature Change in the Southern Tarim River Basin, China, 1964–2011

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Benfu Zhao ◽  
Jianhua Xu ◽  
Zhongsheng Chen ◽  
Ling Bai ◽  
Peng Li
Keyword(s):  
Correlation Analysis ◽  
River Basin ◽  
Air Temperature ◽  
Negative Correlation ◽  
Kendall Test ◽  
Temperature Data ◽  
Tarim River ◽  
Tarim River Basin ◽  
Change Rate ◽  
Mann Kendall Test

The temperature data from 3 meteorological stations (Kashi, Ruoqiang, and Hotan) in the South of Tarim River Basin (STRB) during 1964–2011 were analyzed by Mann-Kendall test and correlation analysis. The results from Mann-Kendall test show that the surface temperature (ST), 850 hPa temperature (T850), and 700 hPa temperature (T700) exhibited upward trends, while 300 hPa temperature (T300) revealed a downward trend. On the whole, the change rate of ST, T850, T700, and T300 was 0.26~0.46°C/10a, 0.15~0.40°C/10a, 0.03~0.10°C/10a, and −0.38~−0.13°C/10a, respectively. For the periods, ST and T850 declined during 1964–1997 and then rose during 1998–2011. T700 declined during 1964–2005 and then rose during 2006–2011, while T300 rose from 1964 to 1970s and then declined. The results from correlation analysis show that T850 and T700 positively correlated with ST (P<0.01) at the all three stations and there was a negative correlation between T300 and ST at Hotan (P<0.1), while the correlation is not significant at Kashi and Ruoqiang. The results indicate that there were gradient differences in the response of upper-air temperature (UT) to ST change.

scholarly journals Ondas de calor nas capitais do Sul do Brasil e Montevidéu - Uruguai (Heat waves in the capitals of southern Brazil and Montevideo - Uruguay)

2019 ◽  
Vol 12 (4) ◽  
pp. 1259
Author(s):  
Rafael Brito Silveira ◽  
Maikon Passos Amilton Alves ◽  
Marcelo Barreiro ◽  
Daniel Pires Bitencourt
Keyword(s):  
Heat Wave ◽  
Air Temperature ◽  
Heat Waves ◽  
Kendall Test ◽  
Temperature Data ◽  
Extreme Weather Events ◽  
Southern Brazil ◽  
Porto Alegre ◽  
Significance Level ◽  
Weather Events

Múltiplas partes do globo, possivelmente, passarão a ter dias e noites mais quentes e, com a elevação das temperaturas globais, há tendências de acréscimo do risco de eventos atmosféricos extremos, tais como as ondas de calor. O objetivo principal desse estudo foi verificar as características gerais das ondas de calor nas três capitais da região Sul do Brasil (Curitiba, Florianópolis e Porto Alegre) e também em Montevidéu, capital do Uruguai. Esta análise baseou-se nos parâmetros: frequência, intensidade, duração e suas respectivas tendências. As ondas de calor foram identificadas em uma série de 30 anos de dados diários de temperatura média do ar. As análises de tendência foram averiguadas por meio do teste de Mann-Kendall a um nível de significância de α = 5%. Os resultados mostraram que todos os parâmetros nas quatro cidades apresentam tendências estatisticamente significativas e, com exceção da duração em Montevidéu, todas as demais são positivas. Para além do âmbito das tendências, analisando os parâmetros, comparativamente, conclui-se que Porto Alegre apresenta maior destaque nas médias. Além disto, afirma-se que o inverno é a estação com maior frequência de ondas de calor para todas as cidades.  A B S T R A C TMultiple parts of the globe are likely to have warmer days and nights, and with rising global temperatures, there is a tendency to increase the risk of extreme weather events, such as heat waves. The main objective of this study was to verify the general characteristics of heat waves in the three capitals of southern Brazil (Curitiba, Florianópolis and Porto Alegre) and also in Montevideo, capital of Uruguay. This analysis was based on the parameters: frequency, intensity, duration and their respective trends. Heat waves were identified in a series of 30 years of daily average air temperature data. Trend analyzes were performed using the Mann-Kendall test at a significance level of α = 5%. The results showed that all the parameters in the four cities present statistically significant trends and, except for the duration in Montevideo, all the others are positive. In addition to the scope of the trends, analyzing the parameters, comparatively, it is concluded that Porto Alegre presents greater prominence in the averages. In addition, it is claimed that winter is the season with the highest frequency of heat waves for all cities.Keywords: heat wave, subtropical, capitals, trends, parameters.

scholarly journals Rainfall Dynamics of Terengganu Malaysia and Its Recent Trends Analysis Using the Mann-Kendall Test.

2014 ◽  
Vol 4 (2) ◽  
pp. 372-381 ◽  
Author(s):  
Musa Garba Abdullahi ◽  
Mohd Ekhwan Toriman ◽  
Mohd Barzani Gasim ◽  
Hafizan Juahir
Keyword(s):  
Rainfall Intensity ◽  
Daily Rainfall ◽  
Kendall Test ◽  
Southwest Monsoon ◽  
The State ◽  
Northeast Monsoon ◽  
Monsoon Period ◽  
Mann Kendall Test ◽  
Recent Trends ◽  
Increasing Trends

This study investigated the pattern and trends of the daily rainfall data in Terengganu Malaysia based on seasonal rainfall indices. The statistics of rainfall indices were calculated in terms of their means for seven stations in Terengganu Malaysia for the period 2000 to 2012. The findings indicate that the trend in the study area has no significant changes in stations (1, 4 and 6) while station (2, 3, 5 and 7) shows significant changes and southwest monsoon had the greatest impact on the whole stations, particularly in characterizing the rainfall pattern of the area. During this season, the study area could be considered as the wettest region since all rainfall indices tested are higher than in other neighboring state of the Peninsula. Otherwise, the northwest of the area is denoted as the driest part of the state during the northeast monsoon period. The northwest of the state is less influenced by the northeast monsoon because of the existence of the Titiwangsa Range, which blocks some part of the region from receiving heavy rainfall. On the other hand, it is found that the areas with lowlands are strongly characterized by the northeast monsoonal flow.The results of the Mann-Kendall test, shows that, trends of the total amount of rainfall during the southwest monsoon decrease at some of the stations. The rainfall intensity increases in contrast, increasing trends in the total amount of rainfall were observed at three stations during the northeast monsoon, which give rise to the increasing trend of rainfall intensity. The results for the combined stations in both seasons indicate that there are no significant changes in trends during the extreme events for the Terengganu Malaysia. However, a smaller number of significant trends were found for extreme intensity. 

scholarly journals The modified Mann-Kendall test: on the performance of three variance correction approaches

Bragantia ◽  
2013 ◽  
Vol 72 (4) ◽  
pp. 416-425 ◽  
Author(s):  
Gabriel Constantino Blain
Keyword(s):  
Serial Correlation ◽  
Kendall Test ◽  
Trend Test ◽  
Climate Trends ◽  
Nominal Significance Level ◽  
Trade Off ◽  
Significance Level ◽  
Mk Test ◽  
Nominal Significance ◽  
Mann Kendall Test

The Mann-Kendall test has been used to detect climate trends in several parts of the Globe. Three variance correction approaches (MKD, MKDD and MKRD) have been proposed to remove the influence of serial correlation on this trend test. Thus, the main goal of this study was to evaluate the probability of occurrence of types I and II errors associated with these three approaches. The results obtained by means of Monte Carlo simulations and from a case of study allowed us to drawn the following conclusions: All approaches are capable of meeting the adopted significant level when they are applied to trend-free uncorrelated series. The approaches are as powerful as the original MK test when they are applied to uncorrelated series. Regarding serially correlated series it was verified that: (i) the performance of the MKDD and MKRD are comparable; (ii) both approaches may not be able to preserve the adopted significance level and (iii) although the MKD is capable of preserving the adopted significance level, it is less powerful than the MKDD and MKRD. Thus, there is a trade-off between the power of the three approaches and their capability of meeting the nominal significance level. Accordingly, we recommend the use of at least two approaches -MKD and MKDD(MKRD)- to evaluate the presence of trends in a given dataset.

scholarly journals Minimum trends in air temperature in the municipality of Porto Velho - RO from 1971 to 2016

2019 ◽  
Vol 23 ◽  
pp. 39
Author(s):  
Camila Bermond Ruezzene ◽  
Renata Gonçalves Aguiar ◽  
Graciela Redies Fischer ◽  
Nara Luísa Reis de Andrade ◽  
Renato Billia de Miranda ◽  
...  
Keyword(s):  
Air Temperature ◽  
Sudden Change ◽  
Kendall Test ◽  
Data Series ◽  
Positive Trend ◽  
Pettitt Test ◽  
Temperature Trends ◽  
Mann Kendall Test ◽  
Porto Velho ◽  
Minimum Air Temperature

In recent years, studies focused on the climate of the Amazon have been the focus of major research mainly to identify possible temperature trends. The objective of this study was to analyze the trends and the years of abrupt changes in temperature that occurred in the Southwest Amazon from 1971 to 2016 in the municipality of Porto Velho-RO. The study area is located in the municipality of Porto Velho at the Meteorological Station of Surface, we used average daily temperature data and subdivided into climatological series from 1971 to 2006 and 1981 to 2016. The Mann-Kendall and Pettitt tests were used to verify trends. A positive trend was observed for the Mann-Kendall test for the months of January, February, March, April, June, September, October and December of 1971 to 2006 and for the years 1981 to 2016 only the months of March and June presented a trend temperature increase. The Pettitt test indicated a sudden change in the data series coinciding with most of the months that showed a tendency to increase the minimum air temperature by the Mann-Kendall test in the years 1971 to 2006. From 1981 to 2016 the Pettitt test indicated the months of March and June with changes in the minimum air temperature, this result also coincided with the months with positive trends.

scholarly journals Trend analysis of temperature and precipitation in Trarza region of Mauritania

2018 ◽  
Vol 10 (3) ◽  
pp. 484-493 ◽  
Author(s):  
Ely Yacoub ◽  
Gokmen Tayfur
Keyword(s):  
Trend Analysis ◽  
Time Series Data ◽  
Series Data ◽  
Trend Test ◽  
Significance Level ◽  
Temperature And Precipitation ◽  
Pettitt Test ◽  
Almost All ◽  
Trend Identification ◽  
Increasing Trends

Abstract Trend analysis of annual temperature and precipitation time series data collected from three stations (Boutilimit (station 1), Nouakchott (station 2) and Rosso (station 3)) has been used to detect the impacts of climate change on water resources in Trarza region, Mauritania. The Mann–Kendall, the Spearman's rho, and the Şen trend test were used for the trend identification. Pettitt's test was used to detect the change point of the series while the Theil–Sen approach was used to estimate the magnitude of the slope in the series. For precipitation, two stations (1 and 3) indicated statistically significant increase in trends. In the case of temperature, almost all the stations show statistically significant increasing trends in the maximum, minimum, and average temperatures. The magnitude of precipitation detected by the Theil–Sen test for stations 1 and 3, respectively, was found to be at the rate of 2.93 and 3.35 mm/year at 5% significance level. The magnitude trend of temperature detected by the Theil–Sen approach was found to be at the rate of 0.2–0.4 °C per decade for almost all the stations. The change points of temperature trends detected by Pettitt test are found to be in the same year (1995) for all the stations.

scholarly journals Spatial and temporal characteristics of the daily precipitation concentration index over China from 1979 to 2015

2020 ◽  
Vol 51 (3) ◽  
pp. 562-582
Author(s):  
Huihua Du ◽  
Yimin Wang ◽  
Zongzhi Wang ◽  
Kelin Liu ◽  
Liang Cheng
Keyword(s):  
Concentration Index ◽  
Temporal Distribution ◽  
Kendall Test ◽  
Northwest China ◽  
Meteorological Forcing ◽  
Significance Level ◽  
Precipitation Concentration Index ◽  
Precipitation Concentration ◽  
Pettitt Test ◽  
Abrupt Changes

Abstract Irregular precipitation has a nontrivial influence on hydrological processes and regional agriculture. The precipitation concentration index provides convenient quantitative characterizations of precipitation variability. To explore the spatial and temporal distribution of the precipitation concentration index, the long-term concentration index (LCI) and the annual concentration index (ACI) during 1979–2015 were calculated based on the China Meteorological Forcing Dataset. The results are as follows: (1) The LCI in China ranged from 0.4571 to 0.9197, and the values between 0.6 and 0.7 accounted for 61.61% of the dataset. The highest and lowest LCI values were both recorded in Northwest China, which features low precipitation levels. Additionally, there are high LCI values (greater than 0.6) in Southeast China, which features high precipitation levels. (2) Application of the Mann-Kendall test (M-K test) and Sen's slope revealed that more than 88% of the grids exhibited nonsignificant positive or negative ACI trends and that more than 10% of the grid ACI values exhibited positive trends, with approximately 2.8% showing significant changes at the 0.1 significance level. (3) Application of the Pettitt test revealed that approximately 11.9% of the grid ACI values exhibited an abrupt change at the 0.5 significance level, with abrupt changes occurring in 1991, 1992 and 1993, together accounting for 45.89% of all grids with abrupt changes.

scholarly journals Temporal and spatial variability of extreme snowfall indices over northern Xinjiang from 1959/1960 to 2008/2009

2013 ◽  
Vol 1 (6) ◽  
pp. 7059-7092 ◽  
Author(s):  
S. P. Wang ◽  
F. Q. Jiang ◽  
R. J. Hu ◽  
Y. W. Zhang
Keyword(s):  
Temporal Trends ◽  
Kendall Test ◽  
Winter Precipitation ◽  
Kriging Interpolation ◽  
Significance Level ◽  
Northern Xinjiang ◽  
The North ◽  
Mk Test ◽  
Increasing Trends

Abstract. Plentiful snowfall is an important resource in northern Xinjiang. However, extreme snowfall events can lead to destructive avalanches, traffic interruptions or even the collapse of buildings. The daily winter precipitation data from 18 stations in northern Xinjiang during 1959/1960–2008/2009 were selected for purpose of analyzing long-term variability of extreme snowfall events. Five extreme snowfall indices, Maximum 1 day snowfall amount (SX1day), Maximum 1-weather process snowfall amount (SX1process), Blizzard days (DSb), Consecutive snow days (DSc) and Blizzard weather processes (PSb), were defined and utilized to quantitatively describe the intensity and frequency of extreme snowfall events. Temporal trends of the five indices were analyzed by Mann–Kendall test and simple linear regression, and their trends were interpolated using universal kriging interpolation. Temporally, we found that most stations have upward trends in the five indices of extreme snowfall events, and over entire northern Xinjiang, they were all increasing at the 0.01 significance level (MK test), with the linear tendency rates of 0.49 mm (10 a)−1 (SX1day), 0.89 mm (10 a)−1 (SX1process), 0.024 days (10 a)−1 (DSb), 0.14 days (10 a)−1 (DSc), and 0.069 times (10 a)−1 (PSb) respectively. Meanwhile, obvious decadal fluctuations besides long-term increasing trends are identified. Trends in the intensity and frequency of extreme snowfall events show a~distinct difference spatially. In general, trends of five indices were found shifting from decreasing to increasing from the northeast to the southwest and from the north to the south of northern Xinjiang. Furthermore, the regions covered by increasing or decreasing extreme snowfall events were identified, implying the hot or cold spots for extreme snowfall events changes. These results may be helpful for northern Xinjiang on the regional and local resource and emergency planning.

Analysis of Temporal and Spatial Characteristic of Temperature Change over the Last 45 Years in Northeastern China

2012 ◽  
Vol 518-523 ◽  
pp. 1367-1370 ◽  
Author(s):  
Wei He ◽  
Ren Cang Bu ◽  
Yuan Man Hu ◽  
Zai Ping Xiong ◽  
Miao Liu
Keyword(s):  
Kendall Test ◽  
Northern Region ◽  
Northeastern China ◽  
Spatial Characteristic ◽  
Weighted Interpolation ◽  
Spatiotemporal Trends ◽  
Mean Temperature ◽  
Mann Kendall Test ◽  
Inverse Distance Weighted Interpolation ◽  
Increasing Trends

Based on the temperature datasets from 1961 to 2005 at 96 meteorological stations, the spatiotemporal trends of climate change were analyzed in annual and seasonal timescales, by a linear and regression model, cumulative anomaly method, Mann-Kendall test and inverse distance weighted interpolation methods, in Northeastern China. The results showed that: (1) Both annual and seasonal mean temperature showed increasing trends, the annual mean temperature have rised by 0.07°Cwith a rate of 0.38°C/decade, and the highest increasing rates of temperature occured in the winter (0.53°C/decade) and lowest one was the in the summer (0.23°C/decade). (2) The results of Mann-Kendall test on temperature showed that the annual and seasonal mean temperature significantly increased at 95% of confidence. The climate jump of annual mean temperature took place in 1987, and the climate jumps of spring, summer, autumn and winter mean temperature occurred in 1988, 1993, 1989 and 1981, respectively, and these results were confirmed by the cumulative anomaly curve. (3) The higher the latitude, the more obvious the increasing trend, especially in winter, and therefore the temperature increased in most parts of the Northeastern China.However, the increasing trends in the northern region of the Da Hinggan Moutains and Xiao Hinggan Moutains were the most obvious.

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