scholarly journals Trends in frost days in Bosnia and Herzegovina

2017 ◽  
Vol 97 (1) ◽  
pp. 35-55
Author(s):  
Tatjana Popov ◽  
Slobodan Gnjato ◽  
Goran Trbic
Keyword(s):  
Time Series ◽  
Bosnia And Herzegovina ◽  
21St Century ◽  
Statistical Significance ◽  
Kendall Test ◽  
Plant Phenology ◽  
Climate System ◽  
Annual Number ◽  
Recent Trends ◽  
Banja Luka

The paper analyzes the recent trends in the occurrence of frost days in Bosnia and Herzegovina. Trends during the 1961-2015 periods were determined based on data from fourteen meteorological stations. MAKESENS procedure, which uses the nonparametric Mann-Kendall test and the nonparametric Sen?s method, was applied on time series of annual number of frost days to assess trends magnitude and its statistical significance. Given the results, negative and largely significant trends are present all over Bosnia and Herzegovina territory. The estimated decreasing trend was in the range of 2.1-6.4 days per decade. The percentile analysis of the annual number of frost days in Bosnia and Herzegovina suggests that a decreasing trend has become more pronounced since 1990s and particularly since the beginning of the 21st century. The observed downward trends were primarily a consequence of high negative trends in the coldest winter months - in January and December. The most prominent decrease in annual number of frost days was observed in Banja Luka, Bugojno, Zenica and Bjelasnica area. Further research on the effects of the determined trends in the frost occurrence on plants is necessary particularly due to the observed changes in plant phenology as a result of climate system warming.

scholarly journals A discrete wavelet spectrum approach for identifying non-monotonic trends in hydroclimate data

2018 ◽  
Vol 22 (1) ◽  
pp. 757-766 ◽  
Author(s):  
Yan-Fang Sang ◽  
Fubao Sun ◽  
Vijay P. Singh ◽  
Ping Xie ◽  
Jian Sun
Keyword(s):  
Time Series ◽  
Statistical Significance ◽  
Kendall Test ◽  
Wavelet Spectrum ◽  
Spatiotemporal Variability ◽  
Discrete Wavelet ◽  
Potential Evaporation ◽  
Monotonic Trend ◽  
Warming Hiatus ◽  
Synthetic Time Series

Abstract. The hydroclimatic process is changing non-monotonically and identifying its trends is a great challenge. Building on the discrete wavelet transform theory, we developed a discrete wavelet spectrum (DWS) approach for identifying non-monotonic trends in hydroclimate time series and evaluating their statistical significance. After validating the DWS approach using two typical synthetic time series, we examined annual temperature and potential evaporation over China from 1961–2013 and found that the DWS approach detected both the “warming” and the “warming hiatus” in temperature, and the reversed changes in potential evaporation. Further, the identified non-monotonic trends showed stable significance when the time series was longer than 30 years or so (i.e. the widely defined “climate” timescale). The significance of trends in potential evaporation measured at 150 stations in China, with an obvious non-monotonic trend, was underestimated and was not detected by the Mann–Kendall test. Comparatively, the DWS approach overcame the problem and detected those significant non-monotonic trends at 380 stations, which helped understand and interpret the spatiotemporal variability in the hydroclimatic process. Our results suggest that non-monotonic trends of hydroclimate time series and their significance should be carefully identified, and the DWS approach proposed has the potential for wide use in the hydrological and climate sciences.

scholarly journals Trends in Childbearing and Nuptiality in Sweden: An Update with Data up to 2007

2011 ◽  
pp. 21-29 ◽  
Author(s):  
Gunnar Andersson ◽  
Martin Kolk
Keyword(s):  
Time Series ◽  
21St Century ◽  
Upward Trend ◽  
Marriage Rates ◽  
Marriage And Divorce ◽  
Relative Risks ◽  
Demographic Behavior ◽  
Recent Trends ◽  
Trend Reversal

We present an update of the main features of recent trends in vital family-demographic behavior in Sweden. For this purpose, time series of relative risks of childbearing, marriage, and divorce by calendar year are updated with another five years of observation added to previously published series. We demonstrate that fertility in Sweden continued its upward trend during much of the first decade of the 21st century. The rise pertains to all birth orders. It is driven by the halt in postponement of first childbearing at the younger ages and the continued fertility recuperation at higher ages. Marriage propensities increased as well, reversing a decades-long trend of decreasing marriage rates. The trend reversal comprises first marriages and remarriages alike. Interestingly, the increased popularity of marriage and childbearing is accompanied with a slight decline in divorce risks during the first decade of the new century.

scholarly journals Effects of the prewhitening method, the time granularity, and the time segmentation on the Mann–Kendall trend detection and the associated Sen's slope

2020 ◽  
Vol 13 (12) ◽  
pp. 6945-6964
Author(s):  
Martine Collaud Coen ◽  
Elisabeth Andrews ◽  
Alessandro Bigi ◽  
Giovanni Martucci ◽  
Gonzague Romanens ◽  
...  
Keyword(s):  
Time Series ◽  
Trend Analysis ◽  
Statistical Significance ◽  
Parametric Method ◽  
Kendall Test ◽  
Trend Detection ◽  
Temporal Segmentation ◽  
Sen’S Slope ◽  
Power Of The Test ◽  
Original Time

Abstract. The Mann–Kendall test associated with the Sen's slope is a very widely used non-parametric method for trend analysis. It requires serially uncorrelated time series, yet most of the atmospheric processes exhibit positive autocorrelation. Several prewhitening methods have therefore been designed to overcome the presence of lag-1 autocorrelation. These include a prewhitening, a detrending and/or a correction of the detrended slope and the original variance of the time series. The choice of which prewhitening method and temporal segmentation to apply has consequences for the statistical significance, the value of the slope and of the confidence limits. Here, the effects of various prewhitening methods are analyzed for seven time series comprising in situ aerosol measurements (scattering coefficient, absorption coefficient, number concentration and aerosol optical depth), Raman lidar water vapor mixing ratio, as well as tropopause and zero-degree temperature levels measured by radio-sounding. These time series are characterized by a broad variety of distributions, ranges and lag-1 autocorrelation values and vary in length between 10 and 60 years. A common way to work around the autocorrelation problem is to decrease it by averaging the data over longer time intervals than in the original time series. Thus, the second focus of this study evaluates the effect of time granularity on long-term trend analysis. Finally, a new algorithm involving three prewhitening methods is proposed in order to maximize the power of the test, to minimize the number of erroneous detected trends in the absence of a real trend and to ensure the best slope estimate for the considered length of the time series.

scholarly journals Effects of the prewhitening method, the time granularity and the time segmentation on the Mann-Kendall trend detection and the associated Sen's slope

2020 ◽  
Author(s):  
Martine Collaud Coen ◽  
Elisabeth Andrews ◽  
Alesssandro Bigi ◽  
Gonzague Romanens ◽  
Giovanni Martucci ◽  
...  
Keyword(s):  
Time Series ◽  
Trend Analysis ◽  
Statistical Significance ◽  
Parametric Method ◽  
Kendall Test ◽  
Trend Detection ◽  
Temporal Segmentation ◽  
Sen’S Slope ◽  
Power Of The Test ◽  
Mann Kendall Test

Abstract. The most widely used non-parametric method for trend analysis is the Mann-Kendall test associated with the Sen's slope. The Mann-Kendall test requires serially uncorrelated time series, whereas most of the atmospheric processes exhibit positive autocorrelation. Several prewhitening methods have been designed to overcome the presence of lag-1 autocorrelation. These include a prewhitening, a detrending and/or a correction for the detrended slope and the original variance of the time series. The choice of which prewhitening method and temporal segmentation to apply has consequences for the statistical significance, the value of the slope and of the confidence limits. Here, the effects of various prewhitening methods are analyzed for seven time series comprising in-situ aerosol measurements (scattering coefficient, absorption coefficient, number concentration and aerosol optical depth), Raman Lidar water vapor mixing ratio and the tropopause and zero degree levels measured by radio-sounding. These time series are characterized by a broad variety of distributions, ranges and lag-1 autocorrelation values and vary in length between 10 and 60 years. A common way to work around the autocorrelation problem is to decrease it by averaging the data over longer time intervals than in the original time series. Thus, the second focus of this study is evaluation of the effect of time granularity on long-term trend analysis. Finally, a new algorithm involving three prewhitening methods is proposed in order to maximize the power of the test, to minimize the amount of erroneous detected trends in the absence of a real trend and to ensure the best slope estimate for the considered length of the time series.

DEVELOPMENT OF STREAMFLOW DROUGHT INDICES IN THE MORAVA RIVER BASIN

2020 ◽  
Author(s):  
Ondrej Ledvinka ◽  
◽  
Pavel Coufal ◽  
Keyword(s):  
Time Series ◽  
Kendall Test ◽  
Drought Indices ◽  
Drought Period ◽  
Left Hand ◽  
Low Flows ◽  
Current Period ◽  
Catchment Size ◽  
Morava River ◽  
The Stability

The territory of Czechia currently suffers from a long-lasting drought period which has been a subject of many studies, including the hydrological ones. Previous works indicated that the basin of the Morava River, a left-hand tributary of the Danube, is very prone to the occurrence of dry spells. It also applies to the development of various hydrological time series that often show decreases in the amount of available water. The purpose of this contribution is to extend the results of studies performed earlier and, using the most updated daily time series of discharge, to look at the situation of the so-called streamflow drought within the basin. 46 water-gauging stations representing the rivers of diverse catchment size were selected where no or a very weak anthropogenic influences are expected and the stability and sensitivity of profiles allow for the proper measurement of low flows. The selected series had to cover the most current period 1981-2018 but they could be much longer, which was considered beneficial for the next determination of the development direction. Various series of drought indices were derived from the original discharge series. Specifically, 7-, 15- and 30-day low flows together with deficit volumes and their durations were tested for trends using the modifications of the Mann– Kendall test that account for short-term and long-term persistence. In order to better reflect the drivers of streamflow drought, the indices were considered for summer and winter seasons separately as well. The places with the situation critical to the future water resources management were highlighted where substantial changes in river regime occur probably due to climate factors. Finally, the current drought episode that started in 2014 was put into a wider context, making use of the information obtained by the analyses.

Trend analysis of fire season length and extreme fire weather in North America between 1979 and 2015

2017 ◽  
Vol 26 (12) ◽  
pp. 1009 ◽  
Author(s):  
Piyush Jain ◽  
Xianli Wang ◽  
Mike D. Flannigan
Keyword(s):  
North America ◽  
Statistical Significance ◽  
Kendall Test ◽  
Fire Season ◽  
Fire Weather ◽  
Season Length ◽  
Eastern Canada ◽  
Reanalysis Dataset ◽  
Fire Weather Index ◽  
Extreme Fire

We have constructed a fire weather climatology over North America from 1979 to 2015 using the North American Regional Reanalysis dataset and the Canadian Fire Weather Index (FWI) System. We tested for the presence of trends in potential fire season length, based on a meteorological definition, and extreme fire weather using the non-parametric Theil–Sen slope estimator and Mann–Kendall test. Applying field significance testing (i.e. joint significance of multiple tests) allowed the identification of the locations of significant trends, taking into account spatial correlations. Fire season length was found to be increasing over large areas of North America, especially in eastern Canada and the south-western US, which is consistent with a later fire season end and an earlier fire season start. Both positive and negative trends in potential fire spread days and the 99th percentile of FWI occurred in Canada and the contiguous United States, although the trends of largest magnitude and statistical significance were mostly positive. In contrast, the proportion of trends with significant decreases in these variables were much lower, indicating an overall increase in extreme fire weather. The smaller proportion of significant positive trends found over Canada reflects the truncation of the time series, necessary because assimilation of precipitation observations over Canada ceased in the reanalysis post-2002.

scholarly journals McTaggart’s paradox and its consequences

2015 ◽  
Vol 26 (1) ◽  
pp. 226-242
Author(s):  
Strahinja Djordjevic
Keyword(s):  
Time Series ◽  
21St Century ◽  
History Of Philosophy ◽  
Temporal Relations ◽  
Philosophy Of Time ◽  
Human Understanding ◽  
Contrary View ◽  
History Of ◽  
Mctaggart's Paradox

McTaggart?s explanation of the human understanding of time, which uses the time series, is a significant moment in the history of philosophy, and his attempt to prove time?s unreality had strong but diverse reactions. The majority of thinkers who wrote after him agree that time is indeed real, but the intellectual division that was created around the question of which part of the paradox in dispute will dominate philosophy of time in the 20th and 21st century. It can be concluded that both major theories within this field have an undeniable influence on the division of time series which McTaggart made. After analyzing the paradox, the focus will be on clarifying the debate between tensed and tenseless theorists. The former dispute the claim that the A-series is contradictory and argue that the tensed time is the proper determination of events in time, while the latter claim that the B-series is independent and that time can be determined only by temporal relations. By recognizing the differences between these two lines of thought, it will become easier to understand the nature of their relationship to the time series, namely by considering the ways in which they defend their own and attack the contrary view.

scholarly journals Urbanizacija bosanskohercegovačkih prostora u vrijeme rimske uprave / The urbanisation of Bosnian and Herzegovinian areas under the Roman rule

2017 ◽  
pp. 56-77
Author(s):  
Mersiha Imamović ◽  
Bego Omerčević
Keyword(s):  
Bosnia And Herzegovina ◽  
Social Relations ◽  
Road Network ◽  
Road Construction ◽  
River Valley ◽  
Eastern Coast ◽  
Special Role ◽  
Economic Activities ◽  
Positive Effects ◽  
Banja Luka

After the conquest of the Bosnian and Herzegovinian territory, the Romans  launched numerous campaigns so this region and its population could be incorporated into the Roman life and Roman civilization of that period as quickly as possible. They believed that this is the only and the best way to make themselves the masters of this region. As part of their extensive activities, those that focused on systematic and full implementation of urbanization in the present-day Bosnia and Herzegovina were especially important. This long process encompassed the infrastructure construction, modelled on the Italic cities, villages, economic and other facilities. The first steps of the Roman authorities were to construct modern and high-quality roads, i.e. a powerful road network that would facilitate a faster and stronger connection between settlements and economic resources around present-day Bosnia and Herzegovina. Publius Cornelius Dolabella, who served as an imperial governor of the province of Upper Illyria from 14 th  to 20  AD, had a special role in the implementation of this plan. The construction of the first roads began upon his initiative and under his strict supervision. He intended to establish a better connection between the regions of present-day Bosnia and Herzegovina with the eastern coast of the Adriatic Sea. These first roads created good foundation for a complete urbanization of this area. th Along with the road construction, the Romans launched the activities that included new settlements, firstly along the Roman roads, then at the crossroads, and then in the regions had were rich in resources. Each settlement, in its appearance, dimensions and layout of facilities and its infrastructure, had to correspond to the Roman building standards. The first settlements were built along the roads. The most famous sites of urban settlements include: Grkovci and Pelva (Livno plateau), Halapići and Salvium (Glamoč plateau), Pecka (the Sana river valley), Baloie (Šipovo), Bjelajac (Mrkonjić Grad), Castra, Laktaši, Gornji Šeher (Banja Luka), Servitium (Bosanska Gradiška), Delminium (Duvno plateau), Varvara (Rama river valley), Ad Matricem (Gornji Vakuf), Bistue Nova (Bugojno), Višnjica (Kiseljak), Ilidža (Sarajevo plateau), Domavia and Skelani (central Podrinje), Blagaj, Maslovare and Bosanski Novi (the Sana and Japra rivers valley), Golubić (Bihać), Bigeste (Čapljina), Leusinium (Bileća), Diluntum (Stolac), Ad Drinum (Drinjača) as well as many others, but less known.  Urbanization had many positive effects in all aspects of work and life of local inhabitants from that period in the region of present-day Bosnia and Herzegovina. A road network was established, as well as numerous economic activities, lifestyle standard and social relations were raised to a significantly higher level, many settlements (cities and villages) and many cultural monuments were built.  

scholarly journals Morphologic variability of the Acer campestre L. populations in Bosnia and Herzegovina

2021 ◽  
Vol 7 ◽  
pp. 327-343
Author(s):  
Stjepan Kvesić ◽  
Mirzeta Memišević Hodžić ◽  
Matijaž Čater ◽  
Dalibor Ballian
Keyword(s):  
Bosnia And Herzegovina ◽  
Interactive Effect ◽  
Morphological Variability ◽  
Geographical Distance ◽  
Multivariate Statistical ◽  
Acer Campestre ◽  
Tight Connection ◽  
Banja Luka ◽  
Leaf Parameters ◽  
Ecological Distance

Morphologic variability from 25 populations of Acer campestre L. in Bosnia and Herzegovina was analyzed. Morphometric structure of variability and between-population variability was performed based on 10 fruit-parameter characteristics and 19 leaf-parameter characteristics using multivariate statistical analysis. Results confirmed the separation of three submediterranean populations as a group in relation to other tested populations, from which the Banja Luka population is different. Measured leaf parameters were confirmed as a predominant carrier of the morphologic separation between populations. In other Acer species populations within A. monspessulanum and A. intermedium species are separated mainly by fruit and much less by leaf parameters. The southernmost submediterranean populations from Trebinje, Ljubuški, and Mostar regions have smaller leaf areas, which consequently places them within the same morphologic group; their variability is in tight connection with eco-geo-graphical factors, where the ecological distance is a much better predictor of morphological variability compared to geographical distance. The air temperature had the biggest influence on morphological variability regarding the highest in-between correlation. Achieved results may serve for the continuation of the research in other areas of Acer campestre to determine the interactive effect of ecological, geographical, climatic, and migrational factors on their morphologic population plasticity.

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