Quality Control of Precipitation Measurement for Selected Stations in Iraq

Abstract

In this research, quality control and homogeneity tests were performed for 20 surface meteorological stations records in Iraq. For this purpose, the annual precipitation data series at the stations of Iraqi meteorological organizations and seismology for the period (1981-2010) were considered. Quality control procedure involving outlier detection using Mandel’s k method. Homogenization were analyzed by using four absolute methods tests namely SNH test, Pettitt test, BR test and VNR test, these tests were chosen to detect the inhomogeneity in data, the results of each test were evaluated at significance level 0.05. Results of Mandel’s K methodwere classified into four categories (Normal, Abnormal 1, Abnormal 2 and Extreme) and represented in GIS software.The results showed that 5% of station classified as Normal, 20% of stations classified as Abnormal 1, 25% of stations classified as Extreme and 50% of stations were classified as Abnormal 2. The homogeneity tests results displayed that 5% of station assigned as “doubtful” class with break years found in (1998) for (Pettitt and BR) tests, 50% of stations assigned as “useful” class , and the other stations which represent 45% assigned as “suspect” class with break years detected for (Pettitt, SNH and BR) tests most found in (1998 ad 1999) were represents 28% of break years, 21% of break years found in (1997) and other break years found between (1991-2004).

Keywords

• quality control (qc), homogeneity tests, snh test, pettitt test, br test, vnr test