scholarly journals Monotonic trend and change points in southern Brazil precipitation

2013 ◽  
Vol 33 (2) ◽  
pp. 258-268 ◽  
Author(s):  
Rita de C. F. Damé ◽  
Claudia F. A. Teixeira ◽  
Luiz C. S. Bacelar ◽  
Antoniony S. Winkler ◽  
Jacira P. dos Santos
Keyword(s):  
Scientific Evidence ◽  
Kendall Test ◽  
Nonparametric Tests ◽  
Change Points ◽  
Annual Precipitation ◽  
Monotonic Trend ◽  
Two Samples ◽  
Complete Series ◽  
Weather Stations ◽  
Impacts Of Climate Change

Scientific evidence on climate changes at global level has gained increasing interest in the scientific community in general. The impacts of climate change as well as anthropogenic actions may cause errors in hydro-agricultural projects existent in the watershed under study. This study aimed to identify the presence or absence of trend in total annual precipitation series of the watershed of the Mirim Lagoon, state of Rio Grande do Sul-RS / Brazil / Uruguay (Brazilian side) as well as to detect the period in which they occurred. For that, it was analyzed the precipitation data belonging to 14 weather stations. To detect the existence of monotonic trend and change points, it was used the nonparametric tests of Mann-Kendall and Mann-Whitney, the "t" test of Student for two samples of unpaired data (parametric), as well as the technique of progressive mean. The Weather Station 3152014 (Pelotas) presented changes in the trend in the series of annual precipitation in the period from 1953 to 2007. The methodologies that use subdivided series were more efficient in detecting change in trend when compared with the Mann-Kendall test, which uses the complete series (from 1921 to 2007).

Multi-Time Scale Analysis on Characteristics of Precipitation in Hebei Province

2015 ◽  
Vol 1092-1093 ◽  
pp. 1165-1170 ◽  
Author(s):  
Meng Wang ◽  
Bao Hong Lu ◽  
Han Wen Zhang ◽  
Cong Fei Zhu
Keyword(s):  
Abrupt Change ◽  
Linear Trend ◽  
Kendall Test ◽  
Hebei Province ◽  
Change Points ◽  
Annual Precipitation ◽  
Precipitation Trend ◽  
Multi Scale ◽  
Weather Stations ◽  
Autumn And Winter

Based on the precipitation data observed monthly of 19 weather stations in Hebei province from 1960 to 2011, three methods, linear trend estimation, Mann-Kendall test as well as Morlet wavelet transformation, were adopted to analyze the characteristics of precipitation trend, abrupt change points and cyclical variations under the circumstance of multi-time scales in the past 52 years. Annual precipitation had a decreasing trend, and precipitation in spring increased dramatically, meanwhile precipitation of summer decreased significantly; however, precipitations in autumn and winter were fluctuated in an acceptable range. There were various abrupt change points both in annual precipitation series and in spring as well as in summer, yet any abrupt change points were found in autumn and winter. Multi-scale periodicities were found by wavelet analysis in annual and seasonal precipitations.

Are males in a relationship flirted with more? Testing for mate choice copying in humans

2016 ◽  
Author(s):  
Niels van de Ven ◽  
Monique Maria Henriettte Pollmann ◽  
Rob Nelissen ◽  
Nadiya Sayenko
Keyword(s):  
Mate Choice ◽  
Scientific Evidence ◽  
Mate Choice Copying ◽  
Two Samples ◽  
Absolute Measure ◽  
Cast Doubt

Ample anecdotal and some scientific evidence suggests that men who enter a relationship feel that they are flirted with more frequently than before they had a partner. This phenomenon has been interpreted as a form of mate choice copying; the idea that females prefer males that are in a relationship with another female. In two samples (N = 271 and N = 396) we replicate that people indicate that flirting increased after entering a relationship. However, on a more absolute measure (how often people feel they are flirted with), we did not find that those in a relationship felt to be flirted with more than those without one. Our findings cast doubt on the interpretation that ours (and similar) findings are support for mate choice copying, and we argue that alternative explanations should be considered.

scholarly journals Trends in urban storm water quality in Tallinn and influences from stormflow and baseflow

2016 ◽  
Vol 2 (1) ◽  
Author(s):  
Bharat Maharjan ◽  
Karin Pachel ◽  
Enn Loigu
Keyword(s):  
Temporal Trends ◽  
Oxygen Demand ◽  
Road Dust ◽  
Kendall Test ◽  
P Value ◽  
Upward Trend ◽  
Monotonic Trend ◽  
Acidic Rain ◽  
Interpretation Of Change

Temporal trends provide a good interpretation of change in stormwater quality over time. This study aimed to analyse trends and influences due to stormflow and baseflow. Grab samples of 18-19 years from 1995 to 2014 recorded at outlets of 7 Tallinn watersheds were analysed for monotonic trend through seasonal Mann Kendall test for long-term, short-term, baseflow and stormflow. Statistically significant downward trends (P-value (p) < 0.05) were found for 6 – hydrocarbon (HC), 1 – suspended solids (SS), 3 – biological oxygen demand (BOD), 4 – total nitrogen (TN) and 2 – total phosphorus (TP) out of 7 sampling outlets over the last 10 years. Less significant decreasing trends (p > 0.05 and < 0.2) for 3 – SS, 1 – BOD, 1 – TN and 1 – TP were identified. Statistically significant long-term upward trends of pH were re-vealed in 5 basins, which reduced to 2 with 5 less significant upward trends over the 10 year period, indicating improve-ments in pH reduction. Härjapea has the highest pH without trend but it includes an upward trend of TN at p = 0.051. The highly possible causes for downward trends are street sweeping, sewer network improvement, decline in sub-urban agri-cultural areas, etc. The upward trend results of pH are related to increased alkalinisation due to acidic rain, weathering of carbonate rocks, sewage discharge and alkaline road dust. In most of the basins, stormflow has more influence on trends than baseflow.

scholarly journals Temporal and spatial distributions of precipitation on the Huang-Huai-Hai Plain during 1960–2019, China

2021 ◽  
Author(s):  
Minhua Ling ◽  
Hongbao Han ◽  
Xingling Wei ◽  
Cuimei Lv
Keyword(s):  
Spatial Distribution ◽  
Large Scale ◽  
Kendall Test ◽  
Winter Precipitation ◽  
Annual Precipitation ◽  
Temporal And Spatial Distribution ◽  
Global Pattern ◽  
The North ◽  
Variance Contribution ◽  
Temporal And Spatial

Abstract The Huang-Huai-Hai Plain is an important commercial grain production base in China. Understanding the temporal and spatial variations in precipitation can help prevent drought and flood disasters and ensure food security. Based on the precipitation data for the Huang-Huai-Hai Plain from 1960 to 2019, this study analysed the spatiotemporal distribution of total precipitation at different time scales using the Mann–Kendall test, the wavelet analysis, the empirical orthogonal function (EOF), and the centre-of-gravity model. The results were as follows: (1) The winter precipitation showed a significant upward trend on the Huang-Huai-Hai Plain, while other seasonal trends were not significant. (2) The precipitation on the Huang-Huai-Hai Plain shows a zonal decreasing distribution from southeast to northwest. (3) The application of the EOF method revealed the temporal and spatial distribution characteristics of the precipitation field. The cumulative variance contribution rate of the first two eigenvectors reached 51.5%, revealing two typical distribution fields, namely a ‘global pattern’ and a ‘north-south pattern’. The ‘global pattern’ is the decisive mode, indicating that precipitation on the Huang-Huai-Hai Plain is affected by large-scale weather systems. (4) The annual precipitation barycentres on the Huang-Huai-Hai Plain were located in Jining city and Taian city, Shandong Province, and the spatial distribution pattern was north-south. The annual precipitation barycentres tended to move southwest, but the trend was not obvious. The annual precipitation barycentre is expected to continue to shift to the north in 2020.

scholarly journals Trends, change points and spatial variability in extreme precipitation events from 1961 to 2017 in China

2020 ◽  
Vol 51 (3) ◽  
pp. 484-504 ◽  
Author(s):  
Linchao Li ◽  
Yufeng Zou ◽  
Yi Li ◽  
Haixia Lin ◽  
De Li Liu ◽  
...  
Keyword(s):  
Extreme Precipitation ◽  
Extreme Event ◽  
Heavy Precipitation ◽  
Kendall Test ◽  
Temporal Variations ◽  
Change Points ◽  
Monthly Precipitation ◽  
Flood Peak ◽  
Extreme Precipitation Events ◽  
Precipitation Events

Abstract Extreme precipitation events vary with different sub-regions, sites and years and show complex characteristics. In this study, the temporal variations, trends with significance and change points in the annual time series of 10 extreme precipitation indices (EPIs) at 552 sites and in seven sub-regions were analyzed using the modified Mann–Kendall test and sequential Mann–Kendall analysis. Three representative (extremely wet, normal and extremely dry) years from 1961 to 2017 were selected by the largest, 50%, and smallest empirical frequency values in China. The spatiotemporal changes in the EPIs during the three representative years were analyzed in detail. The results showed that during 1961–2017, both the consecutive wet or dry days decreased significantly, while the number of heavy precipitation days had no significant trend, and the other seven wet EPIs increased insignificantly. The abrupt change years of the 10 EPIs occurred 32 and 40 times from 1963 to 1978 and from 1990 to 2016, respectively, regardless of sub-region. The extremely dry (or wet) events mainly occurred in western (or southwestern) China, implying a higher extreme event risk. The extremely wet, normal and extremely dry events from 1961 to 2017 occurred in 2016, 1997 and 2011 with empirical frequencies of 1.7%, 50% and 98.3%, respectively. In addition, 1998 was the second-most extremely wet year (empirical frequency was 3.7%). The monthly precipitation values were larger from February to August in 1998, forming a much earlier flood peak than that of 2016. The 10 EPIs had close connections with Normalized Difference Vegetation Indexes during the 12 months of 1998 and 2016. This study provides useful references for disaster prevention in China.

scholarly journals Homogeneity tests and non-parametric analyses of tendencies in precipitation time series in Keszthely, Western Hungary

2019 ◽  
Vol 139 (3-4) ◽  
pp. 849-859 ◽  
Author(s):  
Tímea Kocsis ◽  
Ilona Kovács-Székely ◽  
Angéla Anda
Keyword(s):  
Time Series ◽  
Change Points ◽  
Annual Precipitation ◽  
Trend Test ◽  
Climate Data ◽  
Homogeneity Tests ◽  
Break Points ◽  
The Mean ◽  
Parametric Analyses ◽  
Precipitation Records

Abstract This study aims to investigate the precipitation trends in Keszthely (Western Hungary, Central Europe) through an examination of historical climate data covering the past almost one and a half centuries. Pettitt’s test for homogeneity was employed to detect change points in the time series of monthly, seasonal and annual precipitation records. Change points and monotonic trends were analysed separately in annual, seasonal and monthly time series of precipitation. While no break points could be detected in the annual precipitation series, a significant decreasing trend of 0.2–0.7 mm/year was highlighted statistically using the autocorrelated Mann-Kendall trend test. Significant change points were found in those time series in which significant tendencies had been detected in previous studies. These points fell in spring and winter for the seasonal series, and October for the monthly series. The question therefore arises of whether these trends are the result of a shift in the mean. The downward and upward shift in the mean in the case of spring and winter seasonal amounts, respectively, leads to a suspicion that changes in precipitation are also in progress in these seasons. The study concludes that homogeneity tests are of great importance in such analyses, because they may help to avoid false trend detections.

scholarly journals Spatio-Temporal Trends of Monthly and Annual Precipitation in Aguascalientes, Mexico

Atmosphere ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 437
Author(s):  
Osías Ruiz-Alvarez ◽  
Vijay P. Singh ◽  
Juan Enciso-Medina ◽  
Ronald Ernesto Ontiveros-Capurata ◽  
Arturo Corrales-Suastegui
Keyword(s):  
Time Series ◽  
Annual Precipitation ◽  
Irrigated Agriculture ◽  
Monthly Precipitation ◽  
Precipitation Trend ◽  
Precipitation Time Series ◽  
June July August ◽  
Precipitation Decrease ◽  
Weather Stations ◽  
June July

The objective of this research was to analyze the temporal patterns of monthly and annual precipitation at 36 weather stations of Aguascalientes, Mexico. The precipitation trend was determined by the Mann–Kendall method and the rate of change with the Theil–Sen estimator. In total, 468 time series were analyzed, 432 out of them were monthly, and 36 were annual. Out of the total monthly precipitation time series, 42 series showed a statistically significant trend (p ≤ 0.05), from which 8/34 showed a statistically significant negative/positive trend. The statistically significant negative trends of monthly precipitation occurred in January, April, October, and December. These trends denoted more significant irrigation water use, higher water extractions from the aquifers in autumn–winter, more significant drought occurrence, low forest productivity, higher wildfire risk, and greater frost risk. The statistically significant positive trends occurred in May, June, July, August, and September; to a certain extent, these would contribute to the hydrology, agriculture, and ecosystem but also could provoke problems due to water excess. In some months, the annual precipitation variability and El Niño-Southern Oscillation (ENSO) were statistically correlated, so it could be established that in Aguascalientes, this phenomenon is one of the causes of the yearly precipitation variation. Out of the total annual precipitation time series, only nine series were statistically significant positive; eight out of them originated by the augments of monthly precipitation. Thirteen weather stations showed statistically significant trends in the total precipitation of the growing season (May, June, July, August, and September); these stations are located in regions of irrigated agriculture. The precipitation decrease in dry months can be mitigated using shorter cycle varieties with lower water consumption, irrigation methods with high efficiency, and repairing irrigation infrastructure. The precipitation increase in humid months can be used to store water and use it during the dry season, and its adverse effects can be palliated with the use of varieties resistant to root diseases and lodging. The results of this work will be beneficial in the management of agriculture, hydrology, and water resources of Aguascalientes and in neighboring arid regions affected by climate change.

Monotonic Trend Analysis of Temperature Series over Mandya City, Karnataka

2021 ◽  
Vol 9 (VII) ◽  
pp. 1530-1535
Author(s):  
Madhusudhan M S
Keyword(s):  
Climate Change ◽  
Trend Analysis ◽  
Agricultural Sector ◽  
Kendall Test ◽  
Temperature Series ◽  
Maximum Temperature ◽  
Positive Trend ◽  
Significance Level ◽  
Monotonic Trend ◽  
Indirect Impacts

Climate change is mostly driven by global warming. Climate change is one of the most critical long-term development issues, particularly for developing countries like India. India is one of the world's most climatically diverse countries, making it sensitive to climatic change and impacting the livelihoods of millions of people who rely on agriculture. Temperature and its fluctuation have direct and indirect impacts on crop development in the agricultural sector. Understanding the temperature and its variability in a changing environment would aid in improved decision-making and suggest feasible adaption strategies. The present study focuses on temperature trend analysis in Mandya city, Karnataka, India. The analysis was carried out through the non-parametric Mann-Kendall test and Sen's slope estimator. The findings demonstrate that, there has been a rising trend in temperature in the study area over the last 30 years as a result of climate change. From the analysis, there is a significant positive trend for all the seasons considered for the significance level of 90%, 95% and 99%. The magnitude of the increasing trend will be in the range of 0.46 °C/year for the average time series. Also, there will be an average increase of 0.07 °C/year for the various scenarios considered in Mandya city for the Maximum temperature series.

scholarly journals Trends in daily precipitation in highlands region of Santa Catarina, southern Brazil

2018 ◽  
Vol 13 (1) ◽  
pp. 1
Author(s):  
Eder Alexandre Schatz Sá ◽  
Carolina Natel de Moura ◽  
Victor Luís Padilha ◽  
Claudia Guimarães Camargo Campos
Keyword(s):  
Daily Precipitation ◽  
Kendall Test ◽  
Rainfall Anomaly ◽  
La Niña ◽  
Southern Brazil ◽  
Santa Catarina ◽  
La Nina ◽  
Daily Precipitation Data ◽  
Precipitation Anomalies ◽  
Weather Stations

This study evaluates the occurrence of trends in time series of precipitation in the highlands region of Santa Catarina, Southern Brazil. Daily precipitation data of three weather stations at Lages, São Joaquim and Campos Novos were used to evaluate rainfall trends. The trends were analyzed through the Seasonal Mann Kendall test, to include occurrence of maximum annual 1-day precipitation (RX1), maximum annual consecutive 2-day precipitation (RX2) and maximum annual consecutive 3-day precipitation (RX3) and evaluation of Rainfall Anomaly Index (RAI). Trends were identified in two of three weather stations investigated. Positive precipitation trends were found in the spring and winter for Lages, and in the spring and summer for São Joaquim. Also, there is a trend of increase in the RX1, RX2 and RX3 frequencies and an increase in positive anomalies in the last decade for these stations. There are no statistically significant trends in the precipitation of Campos Novos, which may be associated with the short series of available data for the analysis. The occurrence of El Niño phenomenon with moderate to strong intensity was usually associated with the occurrence of positive precipitation anomalies and the La Niña phenomenon was related to the occurrence of negative anomalies. However, the influence of La Niña in the periods of negative anomaly has been reduced since the beginning of the 21st century.

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