Trend analysis and change point detection of annual and seasonal precipitation and temperature series over southwest Iran

This paper presents results of trend analysis and change point detection of annual and seasonal precipitation, and mean temperature (TM), maximum temperature (TMAX) and minimum temperature (TMIN) time series of the period 1950-2007. Investigations were carried out for 50 precipitation stations and 39 temperature stations located in southwest Iran. Three statistical tests including Pettitt's test, Sequential Mann-Kendall test (SQ-MK test) and Mann-Kendall rank test (MK-test) were used for the analysis. The results obtained for precipitation series indicated that most stations showed insignificant trends in annual and seasonal series. Out of the stations which showed significant trends, highest numbers were observed during winter season while no significant trends were detected in summer precipitation. Moreover, no decreasing significant trends were detected by statistical tests in annual and seasonal precipitation series. The analysis of temperature trends revealed a significant increase during summer and spring seasons. TMAX was more stable than TMIN and TM, and winter was stable compared to summer, spring and autumn seasons. The results of change point detection indicated that most of the positive significant mutation points in TM, TMAX and TMIN began in the 1990s

Trends and projections of temperature, precipitation, and snow cover during snow cover-observed period over southwestern Iran

In the present study, tendencies in temperature, precipitation, and snow cover area over the southwestern part of Iran have been assessed. The research mainly focused on snow cover-observed period which included the months of December, January, February, March, and April in the area. This research has been divided into two parts. First part consists of an analysis of the trends in temperature, precipitation, and snow cover area during the above months. Trends in these parameters were tested by linear regression, and significance was determined by t test. Mann-Kendall rank test (MK test) was also employed to confirm the results of linear regression. Sequential Mann-Kendall test (SQ-MK test) was applied for change point detection in the series. For snow cover analysis, remote sensing images from National Oceanic and Atmospheric Administration (NOAA) satellite with advanced very high resolution radiometer (AVHRR) sensor for the period 1987�2007 were used. The second part of the research involved future projections based on four models under B1 and A1B emission scenarios. The models used were centre national de recherches meteorologiques (CNRM), European Center Hamburg model (ECHAM), Model for Interdisciplinary Research on Climate (MIROCH) and United Kingdom Meteorological Office (UKMOC) under the Intergovernmental Panel on Climate Change (IPCC) AR4. The analysis of temperature trends revealed a significant increase during February and April. Temperature projections showed that temperature may increase between 1.12 to 7.87 °C by 2100 in the study area. The results of precipitation series indicated that majority of the stations registered insignificant trends during the twentieth century. However, precipitation may decrease according to most of the models under both scenarios, but the decrease may not be large, except according to MIROCH model. The results of trend analysis of snow cover area indicated that no significant trends were detected by any statistical tests at 95 confidence level during the twentieth century. Snow cover projection showed that snow cover area may decrease as indicated by all the models under both scenarios at the end of twenty-first century consistent with the projected increase in temperature

Trends and projections of temperature, precipitation, and snow cover during snow cover-observed period over southwestern Iran

In the present study, tendencies in temperature, precipitation, and snow cover area over the southwestern part of Iran have been assessed. The research mainly focused on snow cover-observed period which included the months of December, January, February, March, and April in the area. This research has been divided into two parts. First part consists of an analysis of the trends in temperature, precipitation, and snow cover area during the above months. Trends in these parameters were tested by linear regression, and significance was determined by t test. Mann-Kendall rank test (MK test) was also employed to confirm the results of linear regression. Sequential Mann-Kendall test (SQ-MK test) was applied for change point detection in the series. For snow cover analysis, remote sensing images from National Oceanic and Atmospheric Administration (NOAA) satellite with advanced very high resolution radiometer (AVHRR) sensor for the period 1987–2007 were used. The second part of the research involved future projections based on four models under B1 and A1B emission scenarios. The models used were centre national de recherches meteorologiques (CNRM), European Center Hamburg model (ECHAM), Model for Interdisciplinary Research on Climate (MIROCH) and United Kingdom Meteorological Office (UKMOC) under the Intergovernmental Panel on Climate Change (IPCC) AR4

Temperature analysis over southwest Iran: trends and projections

The present study intends to show the effect of climate change on trends and patterns of temperature over the southwestern part of Iran. The research has been divided into two parts. The first part consists of an analysis of the temperature trends of mean temperature (TM), maximum temperature (TMAX), and minimum temperature (TMIN) over 39 stations in the study region for the period 1950-2007. The trends in these parameters were detected by linear regression, and significance was tested by t test. Mann-Kendall rank test (MK test) was also employed to confirm the results. The second part of the research involved future projection of temperature based on four models. The models used were Centre National de Recherches Meteorologiques, European Center Hamburg Model, Model for Interdisciplinary Research on Climate, and UK Meteorological Office. Temperature projections were done under B1 and A1B emissions scenarios. The analysis of temperature trends revealed a significant increase during summer and spring seasons. TMAX was stable than TMIN and TM, and winter was stable as compared with summer, spring, and autumn seasons. Results of modeling showed that temperature may increase between 1.69 and 6.88 °C by 2100 in the study area. Summer temperatures may increase with higher rates than spring, winter, and autumn temperatures

Precipitation analysis over southwest Iran: Trends and projections

Analysis of trends and projection of precipitation are of significance for the future development and management of water resource in southwest Iran. This research has been divided into two parts. The first part consists of an analysis of the precipitation over 50 stations in the study region for the period 1950-2007. The trends in this parameter were detected by linear regression and significance was tested by t test. Mann-Kendall rank test was also employed to confirm the results. The second part of the research involved future projection of precipitation based on four models. The models used were Centre National de Recherches Meteorologiques (CNRM), European Center Hamburg Model (ECHAM), Model for Interdisciplinary Research on Climate (MIROCH) and United Kingdom Meteorological Office (UKMOC). Precipitation projections were done under B1 and A1B emissions scenarios. The results of precipitation series indicated that most stations showed insignificant trend in annual and seasonal series. The highest numbers of stations with significant trends occurred in winter while no significant trends were detected by statistical tests in summer precipitation. No decreasing significant trends were detected by statistical tests in annual and seasonal precipitation series. The result of projections showed that precipitation may decrease according to majority of the models under both scenarios but the decrease may not be large, except according to MIROCH model. Autumn precipitation may increase with higher rates than other seasons at the end of this century