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Wyszukujesz frazę "rainfall trend" wg kryterium: Temat


Wyświetlanie 1-3 z 3
Tytuł:
Statistical assessment of rainfall variability and trends in northeastern Algeria
Statystyczna ocena zmienności i trendów opadu w północnowschodniej Algierii
Autorzy:
Merniz, Noureddine
Tahar, Ali
Benmehaia, Amine M.
Powiązania:
https://bibliotekanauki.pl/articles/293385.pdf
Data publikacji:
2019
Wydawca:
Instytut Technologiczno-Przyrodniczy
Tematy:
climate change
Mann-Kendall test
northeastern Algeria
precipitation
rainfall trend
opad
północnowschodnia Algieria
test Manna–Kendalla
trend
zmiana klimatu
Opis:
In the present study, time series for annual, monthly rainfall and number of rainy days per year were analysed to quantify spatial variability and temporal trends for 22 rainfall stations distributed in northeastern Algeria for the period 1978– 2010. The Mann–Kendall test and the Sen’s slope estimator were applied to assess the significance and magnitude of the trend. The results showed that precipitation decreases spatially from North to South and from East to West. The application of the Mann–Kendall test (for 0.05% threshold) to the time series data showed that for annual precipitation, no station showed statistically significant trends, unlike the number of rainy days, where there was a significant negative trend in four stations (Jijel, Constantine, Oum El Bouaghi and Tébessa). For the monthly time series, significant positive trends were observed during the months of September in the coastal stations and July for the plateaus and southern Saharan Atlas stations, while significant negative trends were recorded during the months of February and March for the stations of the extreme East in the study area. These results revealed that for the period analysed, there was no significant climate change in northeastern Algeria but there is a seasonal delay having important agroecological implications.
W przedstawionych badaniach analizowano serie rocznych i miesięcznych opadów oraz liczbę dni z deszczem w ciągu roku celem ustalenia przestrzennej zmienności i czasowych trendów w latach 1978–2010 dla 22 stacji pomiarowych rozmieszczonych w północnowschodniej Algierii. Wykorzystano test Manna–Kendalla i estymator Sena do oceny istotności i rozmiaru trendu. Wyniki dowodzą, że opady malały z północy na południe i ze wschodu na zachód. Zastosowanie testu Manna–Kendalla (p < 0,05) do serii danych pomiarowych nie wykazały w żadnej stacji statystycznie istotnych trendów dla rocznych opadów w przeciwieństwie do liczby dni z opadem, które cechował istotny negatywny trend w czterech stacjach pomiarowych (Jijel, Constantine, Oum El Bouaghi i Tébessa). Analiza serii miesięcznych opadów dowiodła występowania dodatniego trendu w odniesieniu do sierpnia w stacjach na wybrzeżu i w odniesieniu do lipca w stacjach na płaskowyżach i w południowym Atlasie Saharyjskim. Istotny trend ujemny uzyskano w przypadku lutego i marca w stacjach na wschodzie badanego obszaru. Wyniki dowodzą, że w analizowanym okresie nie stwierdzono istotnych zmian klimatu w północnowschodniej Algierii, z wyjątkiem sezonowych opóźnień, które wywołują ważne skutki agro-ekologiczne.
Źródło:
Journal of Water and Land Development; 2019, 40; 87-96
1429-7426
2083-4535
Pojawia się w:
Journal of Water and Land Development
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Trend analysis of rainfall in Satluj River Basin, Himachal Pradesh, India
Autorzy:
Kumar, Sandeep
Gill, G. S.
Santosh, Santosh
Powiązania:
https://bibliotekanauki.pl/articles/1193980.pdf
Data publikacji:
2015
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Himachal Pradesh
Mann-Kendall test
Rainfall
Regression
Satluj River Basin
Trend analysis
Opis:
attention recently, especially in connection with climate change. The changing pattern of rainfall deserves urgent and systematic attention for planning, development, utilisation and management of water resources. The daily data on variable were converted to monthly and then computed to seasonal and annual series. Annual rainfall (mm/yr) was calculated as the sum of monthly values. The missing values in the data were computed by using average method. The records of rainfall were subjected to trend analysis by using both non-parametric (Mann-Kendall test) and parametric (linear regression analysis) procedures. For better understanding of the observed trends, data were computed into standardised precipitation indices (SPI). These standardised data series were plotted against time and the linear trends observed were represented graphically. Trend analysis results of rainfall show that out of 15 annual trends 6 (40%) are increasing and 9 (60%) are decreasing in nature where 1 (6.6%) is statistically significant (increasing) and 2 (13.3%) are statistically significant (decreasing) at 95% confidence level. Similarly, the changes were investigated for the four seasons: winter (December-March), pre-monsoon (April-June), monsoon (July-September) and post-monsoon (October-November). The analysis of rainfall, annual as well as seasonal, of different gauge stations in Satluj River Basin showed a large variability in the trends and magnitudes from 1984 to 2010. The rainfall shows great temporal and spatial variations, unequal seasonal distribution with frequent departures from normal. Majority of gauge stations have experienced decreasing trends, both on seasonal and annual scales. Some were statistically significant at 95% confidence level. The sensitivity of rainfall variations provides important insight regarding the responses and vulnerability of different areas to climate change. It will further strengthen the formulation of future strategy for management of water resources.
Źródło:
World Scientific News; 2015, 14; 1-55
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Maximum daily rainfall analysis at selected meteorological stations in the upper Lusatian Neisse River basin
Autorzy:
Wdowikowski, M.
Kaźmierczak, B.
Ledvinka, O.
Powiązania:
https://bibliotekanauki.pl/articles/108530.pdf
Data publikacji:
2016
Wydawca:
Instytut Meteorologii i Gospodarki Wodnej - Państwowy Instytut Badawczy
Tematy:
trend analysis
Mann-Kendall test
meteorological data
maximum rainfall
GED
Lusatian Neisse
IMWM-NRI
probabilistic distribution
Opis:
The scope of this study was to assess the usefulness of top probability distributions to describe maximum rainfall data in the Lusatian Neisse River basin, based on eight IMWM-NRI meteorological stations. The research material was composed of 50-year precipitation series of daily totals from 1961 to 2010. Misssing measurement data were estimated using a weighted average method. Homogeneity for refilled data were investigated by precipitation double aggregation curve. Correlation between the measurement data varied from 96 to 99% and did not indicate a violation of the homogeneity of rainfall data series. Variability of recorded daily precipitation maxima were studied by linear regression and non-parametric Mann-Kendall tests. Long-term period changes at maximum rainfalls for four stations remained statistically insignificant, and for the other four were significant, although the structure of maximums was relatively similar. To describe the measured data, there were used the Fréchet, Gamma, Generalized Exponential Distribution (GED), Gumbel, Log-normal and Weibull distributions. Particular distribution parameters were estimated using the maximum likelihood method. The conformity of the analyzed theoretical distributions with measured data was inspected using the Schwarz Bayesian information criterion (BIC) and also by the relative residual mean square error (RRMSE). Among others, the Gamma, GED, and Weibull distributions fulfilled the compliance criterion for each meteorological station respectively. The BIC criterion indicated GED as the best; however differences were minor between GED on the one hand and the Gamma and Weibull distributions on the other. After conducting the RRMSE analysis it was found that, in comparison to the other distributions, GED best describes the measured maximum rainfall data.
Źródło:
Meteorology Hydrology and Water Management. Research and Operational Applications; 2016, 4, 1; 53-63
2299-3835
2353-5652
Pojawia się w:
Meteorology Hydrology and Water Management. Research and Operational Applications
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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