An improved version of innovative trend analyses

Alashan, Sadık

doi:10.1007/s12517-018-3393-x

Cited by 67 publications

(28 citation statements)

References 15 publications

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“…Besides, ITA demonstrates many advantages, including allowing the observation of sub-trends and exhibiting graphical results. Alashan [33] proposed the ITA change-boxes (CB) approach to making more detailed interpretations about trend possibilities within a given time series (such as in discharge records, monthly rainfall, and daily temperature) in the USA, UK, and Turkey.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2020

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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.

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Section: Introductionmentioning

confidence: 99%

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

et al. 2020

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“…This new method is not sensitive to the presence of serial autocorrelation and it is launched by Şen with later mathematical and graphical improvements . The method is based on a comparison of two halves from the parent time series, where each half is sorted in ascending order.…”

Section: şEn Innovative Trend Analysismentioning

confidence: 99%

“…This new method is not sensitive to the presence of serial autocorrelation and it is launched byŞen 7 with later mathematical and graphical improvements. 32,35,36 The method is based on a comparison of two halves from the parent time series, where each half is sorted in ascending order. The first half of the series is plotted on the horizontal axis and the second half on the vertical axis leading to a graph with a 1:1 (45 • ) straight-line on it.…”

Section: şEn Innovative Trend Analysismentioning

confidence: 99%

“…Basha et al 31 investigated the vertical trend and obtained warming (cooling) in the lower (upper) troposphere after 1999. Mohorji et al 15 appliedŞen_ITA to global monthly average temperatures between 1881 and 2013 and stated that global warming is about 0.75 • C. Alashan, 32 using theŞen_ITA method, investigated trends in July daily temperatures for Diyarbakır (Turkey). In this study, temperature data are divided into minimum, average and maximum groups, and increasing trends are obtained in percentages and magnitudes for each group.…”

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confidence: 99%

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Combination of modified Mann‐Kendall method and Şen innovative trend analysis

Alashan

2020

Engineering Reports

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Mann‐Kendall (MK) trend test is frequently employed as the most familiar trend detection method. Its application requires serial independence of available hydrometeorological time series records. As suggested in the literature, the serial correlation effect can be removed from the given time series by using prewhitening, variance correction or overwhitening processes such as in the modified Mann‐Kendall (MMK) procedure. The PW process may cause some of the current trends to be removed along with the serial correlation. In this study, the MMK method is supported by Şen innovative trend analysis instead of Sen slope estimator (SSE). The MMK method is applied to monthly maximum temperatures of Oxford station in England, for which the data length is large and the moving trend slope values are calculated starting from 1854 for all durations between 1873 and 2017. The MMK_SSE and MMK_ITA methods yield significant increasing trends between 0.0037 and 0.0125°C/year annual slopes for January, March, May, July, August, September, October, November, December, but for February, there is not any significant trend. While MMK_SSE does not give any significant trend for April that has maximum positive kurtosis and skew, but MMK_ITA reflects an increasing trend of 0.0059°C per year.

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“…The ITA method was further improved by the developer [28,29]. Some modified versions of the method were also proposed by other scholars such as double/triple ITA [30] and ITA-change boxes [31] for making it compatible with their research purposes and for a graphical comparison of the method's results with the other trend methods [32]. Tabari et al [33] suggested an improved version of the ITA for a decadal analysis where the time series in each decade is compared with that in the subsequent decade.…”

Section: Introductionmentioning

confidence: 99%

Combined Use of Graphical and Statistical Approaches for Analyzing Historical Precipitation Changes in the Black Sea Region of Turkey

Cengiz

Tabari

Onyutha

et al. 2020

Water

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Many statistical methods have been developed and used over time to analyze historical changes in hydrological time series, given the socioeconomic consequences of the changes in the water cycle components. The classical statistical methods, however, rely on many assumptions on the time series to be examined such as the normality, temporal and spatial independency and the constancy of the data distribution over time. When the assumptions are not fulfilled by the data, test results are not reliable. One way to relax these cumbersome assumptions and credibilize the results of statistical approaches is to make a combined use of graphical and statistical methods. To this end, two graphical methods of the refined cumulative sum of the difference between exceedance and non-exceedance counts of data points (CSD) and innovative trend analyses (ITA)-change boxes alongside the classical statistical Mann–Kendall (MK) method are used to analyze historical precipitation changes at 16 stations during 1960–2015 in the Black Sea region of Turkey. The results show a good match between the results of the graphical and statistical methods. The graphical CSD and ITA methods, however, are able to identify the hidden trends in the precipitation time series that cannot be detected using the statistical MK method.

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An improved version of innovative trend analyses

Cited by 67 publications

References 15 publications

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

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

Combination of modified Mann‐Kendall method and Şen innovative trend analysis

Combined Use of Graphical and Statistical Approaches for Analyzing Historical Precipitation Changes in the Black Sea Region of Turkey

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