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Mann-Whitney-Pettitt test, precipitation trend analysis

Fu, Xiaoqing

Supervisor and department: Dr. Thian Yew Gan Civil and Environmental Engineering

Examining committee member and department: Dr. Peter Steffler Civil and Environmental Engineering Dr. David Chanasyk Renewable Resources Dr. Thian Yew Gan Civil and Environmental Engineering

Department: Department of Civil and Environmental Engineering

Specialization:

Date accepted: 2012-07-12T13:04:22Z

Graduation date: 2012-11

Degree: Master of Science

Degree level: Master's

Abstract: Continuous and long weather records are essential to assess possible long-term, hydrologic-climatic changes at local and regional scales by applying appropriate statistical analysis on daily climate data that may require data quality control, adjustments or gap filling of missing data. In this study, a statistical technique called Markov chain was employed to gap fill missing values of daily precipitation observed at 30 stations in western Canada. The gap filling approach was based on 20 years of selected historical meteorological data. The statistical properties of the daily precipitation data with gap filled values are compared with those of the original data before gap filling to ensure that this approach preserves the statistical characteristics of the historical data.Next, after gap filling precipitation data of those selected stations in western Canada with missing values, ten precipitation indices that represent different precipitation properties were computed from daily data of a total of 30 climate stations, each with at least 50 years of record length up to 2006. Statistical tests such as the Mann-Whitney-Pettitt statistics and linear regression were used to detect possible change points present and trend magnitudes of these precipitation indices. Results reveal that an increasing trend in the maximum number of consecutive wet days and the annual maximum monthly 5-day precipitation and a decreasing trend in the maximum number of consecutive dry days over majority of the stations of Western Canada. Except for a small area located in southern British Columbia, the annual total precipitation index of many stations had increased but only about 1-3 of these stations show a statistically significant increase in the annual total precipitation index. However, no consistent change was detected in the number of days when precipitation is equal and greater than 10 mm or 20 mm. Finally, indices of many stations in the Prairie Provinces for the annual monthly maximum 1-day precipitation, precipitation that exceeds the 95 and 99 percentile thresholds, and simple precipitation intensity index SDII have decreased but only some of changes are statistically significant. In contrast, no consistent changes in these extreme precipitation indices were detected in British Columbia.

Language: English

DOI: doi:10.7939-R35114

Rights: Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.





Autor: Fu, Xiaoqing

Fuente: https://era.library.ualberta.ca/


Introducción



University of Alberta Evaluating Long-term Trends and Variations in Daily and Extreme Precipitation Indices over Western Canada by Xiaoqing Fu A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science in Water Resources Engineering Department of Civil and Environmental Engineering ©Xiaoqing Fu Fall 2012 Edmonton, Alberta Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only.
Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the authors prior written permission. Abstract Continuous and long weather records are essential to assess possible long-term, hydrologic-climatic changes at local and regional scales by applying appropriate statistical analysis on daily climate data that may require data quality control, adjustments or gap filling of missing data.
In this study, a statistical technique called Markov chain was employed to gap fill missing values of daily precipitation observed at 30 stations in western Canada.
The gap filling approach was based on 20 years of selected historical meteorological data. The statistical properties of the daily precipitation data with gap filled values are compared with those of the original data (before gap filling) to ensure that this approach preserves the statistical characteristics of the historical data. Next, after gap filling precipitation data of those selected stations in western Canada with missi...





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