Spatiotemporal trend and abrupt change analysis of temperature in Iran

Abstract

The long-term trends in temperature over Iran were examined over 34 synoptic stations during a 50 year period on seasonal and annual time scales. Two methods, a modified version of the Mann-Kendall test by eliminating the effect of all significant autocorrelation co-efficients and the regional Kendall test, were used in trend identification. The results revealed that the temperature had experienced significant positive trends in autumn, spring and especially summer over the study area. On an annual time scale and in the winter, the highest increasing trends were observed at stations located in the southern and southeastern parts of Iran. For regional analysis of trends, the stations were divided into five clusters based on the K-means clustering method and the silhouette index. Subsequently, the regional trend of temperature was analysed on seasonal and annual time scales using the regional Kendall test. The results of the regional Kendall test also indicated the rising trends in temperature during the last 50 years throughout the country on both seasonal and annual time scales. After verifying the presence of an increasing trend in the temperature time series, the non-parametric Pettitt test was used to detect the change points in the annual and seasonal time scales. The results showed that the change point of average temperature began from the summer of 1972 (Sabzevar station) and continued until the summer of 1998 (Zahedan station). The most frequent change point occurrence was between the years 1986 and 1994.

New indices for assessing changes in seasons and in timing characteristics of air temperature

“…5; Fig. A2), as also reported in recent literature (Ahmadi et al 2018;Tabari et al 2012). The abrupt change in mean daily temperature at Ahvaz occurred in 1994 for winter, 1990 for spring, 1986 for summer, and 2002 for autumn (Table 3).…”

“…In addition, climate change has strong influences on health (McMichael et al 2006;Patz et al 2005;Watts et al 2015), agriculture (Peña-Lévano et al 2019), and water availability (Christensen et al 2004;Haddeland et al 2014;Piao et al 2010). A number of metrological parameters are affected, among which temperature plays a major role in the impact of climate change (Ahmadi et al 2018). Therefore, extensive research has been performed to determine the impact of climate change on temperature in different parts of the world (Alexander et al 2006;Fallah-Ghalhari et al 2019;Yin et al 2019).…”

Spatio‐temporal precipitation and temperature trend analysis of the Seyhan–Ceyhan River Basins, Turkey

“…Various trend analyses have been conducted previously, considering meteorological data covering the variation of temperature and precipitation in different parts of the world and non-parametric trend tests are generally applied to quantify the trend (Gocic and Trajkovic, 2013;Ahmad et al, 2015;Ahmadi et al, 2018;Hadi and Tombul, 2018).…”

SPATIO‐TEMPORAL VARIATIONS OF SEVEN WEATHER VARIABLES IN IRAN: APPLICATION OF CRU TS AND GPCC DATA SETS†

“…Increasing trends in temperature and decreasing or insignificant trends in precipitation have been reported in different regions of Iran over the last few decades with marked regional variations (e.g. Ghahraman, ; Modarres and Sarhadi, ; Sohrabi et al, ; Tabari and Hosseinzadeh Talaee, ; Saboohi et al, ; Raziei et al, ; Khalili et al, ; Soltani et al, ; Ahmadi et al, ). Raziei et al .…”

“…Increasing trends in temperature and decreasing or insignificant trends in precipitation have been reported in different regions of Iran over the last few decades with marked regional variations (e.g. Ghahraman, 2006;Modarres and Sarhadi, 2009;Sohrabi et al, 2009;Tabari and Hosseinzadeh Talaee, 2011;Saboohi et al, 2012;Raziei et al, 2014;Khalili et al, 2016;Soltani et al, 2016;Ahmadi et al, 2018). Raziei et al (2012Raziei et al ( , 2014 and Araghi et al (2018) are among the few studies that used high-resolution gridded data sets to explore spatio-temporal patterns of precipitation and temperature in Iran.…”