Climate Change and Climate Disaster

Detection of structural breaks and nonlinear trends in temperature and precipitation in Kermanshah Province

Document Type : Original Article

Authors

Manuchehr Farajzadeh
ّFaryan Mohammadi Nejad

Physical Geography department, Tarbiat Modares University

10.30740/cccd.2026.2084781.1101
Abstract
Analysis of climatic changes in semi-arid regions requires the detection of nonlinear behaviors and structural breaks. This study was conducted with the aim of simultaneously detecting uniform trends and regime shifts in temperature and precipitation in Kermanshah Province. Annual mean temperature and precipitation data from 12 synoptic stations were extracted for the period 1989–2018. First, uniform trends were estimated using the Mann–Kendall test and Sen's slope estimator. Then, the Innovative Trend Analysis (ITA) was employed to examine the asymmetry of trends and sub-trends. In a complementary step, the Pettitt and SNHT tests were applied to identify structural breaks. The results showed that annual temperature increased at all stations, with significant structural breaks occurring in the late 1990s and mid-2000s; particularly, Qasr-e Shirin and Sonqor stations showed higher synchrony and significance in temperature breaks. In contrast, precipitation exhibited more scattered and location-dependent behavior, and only in Gilan-e Gharb was a significant break observed in both tests, which was accompanied by a jump in mean precipitation after the break. The before/after analysis showed that temperature increase was evident at most stations after the break points, whereas precipitation changes were heterogeneous in terms of sign and magnitude.

Keywords

Climate change
Structural break
Innovative Trend Analysis
SNHT
Pettitt
Subjects

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