نویسندگان
1 کارشناس ارشد هواشناسی، گروه پژوهشی اقلیم شناسی کاربردی، پژوهشکده اقلیم شناسی
2 استادیار، گروه پژوهشی مخاطرات و تغییرات اقلیم،پژوهشکده اقلیم شناسی
3 استادیار، گروه پژوهشی اقلیم شناسی کاربردی، پژوهشکده اقلیم شناسی
4 کارشناس ارشد کامپیوتر، گروه پژوهشی مخاطرات و تغییرات اقلیم،پژوهشکده اقلیم شناسی
5 دانشیار، گروه پژوهشی اقلیم شناسی کاربردی، پژوهشکده اقلیم شناسی
6 استادیار، گروه پژوهشی مدلسازی و پیش آگاهی اقلیمی ، پژوهشکده اقلیم شناسی
7 استادیار، گروه پژوهشی مدلسازی و پیش آگاهی اقلیمی، پژوهشکده اقلیم شناسی
چکیده
کلیدواژه‌ها
عنوان مقاله [English]
نویسندگان [English]
Introduction
This project is an updated estimate of the climate change trend in Iran. The time series of monthly and annually mean, maximum and minimum temperature (°C), relative humidity (%) at 2 m height, wind speed (m.s
) at 10 m height, sun hours (h), precipitation (mm), radiation (Mj.m-2day-1) and cloudiness data at 27 weather stations over Iran are collected from IRIMO for the period 1958-2017. Quality control, detection and modification of non-climate heterogeneity of data was performed. Due to missing data, the Sun hours trend was calculated for the period 1992-2017.
Methodology and data
Among all stations of Iran, 27 stations have 60-yearly data in the period of 1958-2017. In this research the changes in temperature, precipitation, humidity, radiation, cloudiness and wind during the period of 2017-1958 (for sunshine the period was 1992-2017) were investigated. At first, the data were checked for quality controlling. Then their non-climatic heterogeneities were fixed. The slope of the trend was determined using the least squares method and the slope estimator and their significance was assessed using nonparametric Man-Kendal test and regression.
Results
Temperature: The results showed that all stations in the country face a significant increase in the annual minimum temperature. The minimum temperature increasing rate per decade calculated to be between 0.2 and 0.4 degree of Celsius in Bandar-Abbas and Tehran, alternatively. In general, minimum temperatures rise were detected at all stations and in all seasons, especially in autumn and winter. The annual maximum temperature trend is also increasing, but the rate of increase in maximum temperature is less than the minimum temperature. The increasing rate per decade calculated to be between 0.08 and 0.3 degree of Celsius in Zanjan and Ahwaz, alternatively
Precipitation: The 60, 30, and 10-years averaged annual precipitation of Iran calculated to be 230.8, 222.4 and 199.3 mm, respectively. The results showed that during the 60-year period, the average rainfall of the Iran decreases, with a rate of 0.43 mm per year (4.3 mm per decade), although the precipitation decline is not significant at 95% level.
However, during the last 30 years (2017-1988), the average precipitation of the country has dropped by 2.2 millimeter per year (22 mm per decade), which is significant in 95% confidence level; meaning that precipitation reduction in the most recent 30 years is about four times higher than that of past 60 years.
In Figures 2 and 3, the all-country time series of rainfall and temperature changes are shown in the 60- and 30-yearly basis.
The country's declining precipitation for the most recent 30 years is about four times faster than the decline of most recent 60 years. The rapid decline in country precipitation over the past 30 years, which is significant in 95% level, is consistent with the intensification of global warming in the most recent 30 years period.
Other parameters: The average wind speed in many parts of the country has increasing trend, which is significant in many stations located in the west, center, and northern part of the country. Average relative humidity has decreased in many regions of the country. The most decreasing trend was observed in southwest and west of the country. Of course, in a few cases such as Gorgan and Rasht, there was an increase, which was not statistically significant. Sunny hours trend was calculated in the period of 1992-1992, and interestingly, seasonal and annual trends at most stations indicate an increase in the number of sunny hours. The total number of days with sky overcast in the west of the Caspian Sea, western part of the country, and stations such as Kerman, Sabzevar and Shahrood has decreased significantly..
کلیدواژه‌ها [English]
10. Alijani, B.; Roshani, Ahmad; Parak, Fateme; Heydari, Rouhollah, Trends in extreme daily temperature using climate change indices in Iran , Geography and environmental Hazards, 2012, Vol 1(2),pp.17-28.
11. Asakareh, H., Kriging, 2008, Application in Climatic Element Interpolation A Case Study: Iran Precipitation in 1996.12.16, Geography and Development Iranian Journal, 6(12), pp.25-42.
12. Azizi, G., Rowshani, M., 2009, An analysis of concepts and effects of climate change on temperature and rice cultivated calendar in Gilan, Studies of human settlements planning, No. 8, pp.143-155.
13. Alijani, B., Mahmoudi, P., Ghogan, A. J., 2012, A Study of Annual and seasonal Precipitation Trends using a Nonparametric Method (Sens Estimatro), Journal of Climate Research, Vol.3, Nob. 9, pp.106-101.
14. Farokhnia, A., Morid, S., 2014, Asessment of the Effects of Temperature and Precipitation Variations on the Trend of River Flows in Urmia Lake Watershed, No. 25(3), pp.86-97.
15. Ghiami Shomami, F., Marofi, S., Sabziparvar, A. A., Zare Abyane, H., Heydari , M., 2011, Detection of climate change using air temperature series in the west of Iran, Journal of Irrigation and water engineering, No.2 (2).pp.10-25.
16. Mohammadi, B., Trend Analysis of annual rainfall over Iran, 2011,Geography and Environmental planning Journal, No.22, 95-106.
17. Masoodian, A., 2004,Temperature Trends in Iran during the Last Half Century, Geography and Development Iranian Journal, Vol. (2), No. 4, 89-106.
18. Noorian, A., Rahimzadeh, F., Sedagatkerdar, A., 2008, warming in the country and its consequences on other parameters of climate in the period of 1951-1951, 3th Water Resource Management Conference, Tabriz, Iran.
19. Barnett, V. and Lewis, T., 1994, outliers in statistical data. John Wiley & Sons, 3rd edition. Mestre O, Domonkos P, Picard F, Auer I, Robin S, Lebarbier E, Bohm R, Aguilar E, Guijarro J, Vertachnik G, Klancar M, Dubuisson B, Stepanek P. 2013. HOMER: a homogenization software – methods and applications. Idojaras, Quart. J. Hungarian Meteorol. Ser. 117 (1), pp. 47 –67
20. Brunet, M.; Saladie, O; Jones, P.D.; Sigro, J.; Aguilar, E.; Moberg, A.; Lister, D.H.; Walther, A.; Lopez, D.; Almarza, 2006, The development of a new dataset of Spanish daily adjusted temperature series (SDATS) (1850-2003), International Journal of Climatology, Vol. 26, pp. 1777-1802.
21. Collins, J. M., Chaves, R. R., Marques, V. D. S., 2009, Temperature variability over South America. Journal of Climate, 22, pp. 5854–5869.
22. Caloiero, T., Coscarelli, R., Mancini, M., 2011,Trend detection of annual and seasonal rainfall in Calabria(Southern Italy) International Journal Of Climatology, International Journal of Climatology. 31, pp. 44–56.
23. Domroes, M., Kaviani, M., Schaefer, D., 1998, An analysis of regional and intra-annual precipitation variability over Iran using multivariate statistical methods. Theoretical and Applied Climatology, 61(3-4), pp.151-159.
24. Folland, C., Coauthors, 1999, Workshop on indices and indicators for climate extremes, Asheville, NC, USA, 3-6 June 1997, Breakout group C: Temperature indices for climate extremes. Climate Change, 42, pp.31-43.
25. IPCC, 2013, Summary for Policymakers, Climate Change 2013: The Physical Science Basis, Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change In: Stocker TF, Qin D, Plattner G. K., Tignor M., Allen SK et al. (eds.), Cambridge University Press, Cambridge, United Kingdom and new York, NY, USA.
26. Onyutha, C.; Tabari, H.; Taye, M.T.; Nyandwaro, G.N., Willems, P., 2015, Analyses of rainfall trends in the Nile River Basin, Journal of Hydro-environment Research, doi: 10.1016/j.jher.2015.09.002.
27. Paulhus J. L.H., Kohler M. A., 1952, Interpolation of missing precipitation records. Month. Weath. Rev., 80, pp.129-133.
28. Patra, J.P.; Mishra, A.; Singh, R., Raghuwanshi, N.S., 2012, Detecting rainfall trends in twentieth century (1871-2006) over Orissa State, India, Climatic Change, 111(3) , pp. 801-817.
29. Rahimzadeha, F., Nassaji Zavareh, M., 2013, Effects of adjustment for non-climatic discontinuities on determination of temperature trends and variability over Iran, International Journal of Climatology.
30. Rhyns Burger, D., 1973, Analytic delineation of Thiessen, polygons. Geographical Analysis, 5(2), pp.133-144.
31. Thiessen, A. H., 1911, Precipitation averages for large areas. Monthly weather review, 39(7), pp.1082-1089.
32. Rahimi, M. Hejabi, S., 2018, Spatial and temporal analysis of trends in extreme temperature indices in Iran over the period 1960–2014, International Journal Of Climatology, pp. 272-282.
33. Tabari, H.; Taye, M.T., Willems, P., 2015, Statistical assessment of precipitation trends in the upper Blue Nile River basin, Stochastic Environmental Research and Risk Assessment, 29(7), pp.1751-1761.
34. Tabari, H. Hosseinzadeh Talaee, P., 2011, temporal variability of precipitation over Iran: 1966–2005, Journal of Hydrology, 396, pp. 313-320.
35. Vincent, L.A., X. Zhang, B.R. Bonsal, Hogg, W.D., 2002, Homogenization of daily temperatures over Canada, J. Climate, 15, pp.1322-1334.
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