Skip to main content

Research Repository

Advanced Search

Quality control and homogeneity analysis of precipitation time series in the climatic region of Iraq

Mohammed, R; Scholz, M

Quality control and homogeneity analysis of precipitation time series in the climatic region of Iraq Thumbnail


Authors

R Mohammed

M Scholz



Contributors

MM Miglietta
Editor

Abstract

Non-climatic reasons, such as station replacement and changing the measurement device and calculation method, may make climate data unrepresentative of the actual variation of the regional climate. Data quality control and homogenization tests for climate data are critical. Thus, this study aims to evaluate the quality and homogeneity level of precipitation time series in arid and semi-arid climatic zones and specify the breakpoint in the datasets. The proposed methodology has been used to conduct arid and semi-arid representative case studies comprising 40 annual precipitation series for Iraq between 1979 and 2014. A Box-Cox transformation has been used to adjust the non-normally distributed datasets. Outliers have been censored by truncating extreme values. The results of the outliers indicate that they may be caused more by climate variability than by human-induced reasons. Homogeneity adjustments have been developed by applying these four homogeneity tests: Pettitt’s test, the Standard Normal Homogeneity method, Buishand’s test, and von Neumann’s check. Approximately 40% of the series (i.e., 16 stations out of 40) were homogeneous. Each homogeneity test was evaluated separately, and non-homogeneous stations were identified. Then, the series was classified into three groups that were assigned the labels “useful”, “doubtful”, and “suspect”. The results indicated that twenty-one stations were associated with the class ‘suspect’, three of the stations belonged to the class ‘doubtful’, and sixteen locations were within the class ‘useful’. Furthermore, the data analysis indicated no influence of the outliers on the results of the homogeneity tests. Accordingly, the study recommends further research on homogeneity tests that can be applied without considering outlier tests for similar case studies.

Citation

Mohammed, R., & Scholz, M. (2023). Quality control and homogeneity analysis of precipitation time series in the climatic region of Iraq. Atmosphere, 14(2), 197. https://doi.org/10.3390/atmos14020197

Journal Article Type Article
Acceptance Date Jan 16, 2023
Online Publication Date Jan 17, 2023
Publication Date Jan 17, 2023
Deposit Date Feb 21, 2023
Publicly Available Date Feb 21, 2023
Journal Atmosphere
Publisher MDPI
Volume 14
Issue 2
Pages 197
DOI https://doi.org/10.3390/atmos14020197
Keywords Article, change point detection, climate change and variability, interpolation, local rainfall, normality test, outlier detection
Publisher URL https://doi.org/10.3390/atmos14020197

Files





Downloadable Citations