Evaluating the performance of the reanalyzed ERA-Interim database in temporal-spatial distribution and wind speed trend in eastern Iran

Document Type : Full length article


1 PhD Student, Faculty of Geography, University of Tehran

2 Professor of Climatology, Faculty of Geography, University of Tehran

3 Assistant Professor, Faculty of Geography, University of Tehran

4 Associate Professor, Faculty of Geography, University of Tehran


Wind is the horizontal displacement of air, under one meter per second of speed. It is a dynamic phenomenon with three main characteristics: intensity, direction, and frequency. Therefore, good knowledge of its characteristics in every area of importance is quite remarkable. For instance, while the impact of global warming on temperature and precipitation at global level over the past decades, have been considered in many studies, little attention has been dedicated to wind speed and its influence on climate change. Wind speed alterations can affect the energy of storms, shipping industries, soil moisture, evaporation, and water resources. It may even influence the evolution of dry and semi-arid environments. Furthermore, a lot of research on wind and meteorology has shown that the performance of wind turbines is sensitive to climate change. Possible changes to future wind regimes have been widely considered under changing weather conditions and due to global warming, the intensity and frequency of wind events are expected to alter at the end of this century.
Materials and Methods
The study area in this research on the eastern strip of Iran included four provinces of Khorasan Razavi, South Khorasan, Kerman, and Sistan and Baluchestan. The study used wind speed data in an altitude of 10 meters at 10 synoptic stations. It was provided with daily statistical information between 1985 and 2015, i.e. 30 years of data. When choosing this station, in addition to proper distribution within the region, an attempt was made to select more stations than the one, affected by the 120-day winds of Sistan. The study also employed 10-meter-high wind speed data of the ERA-Interim version with a resolution of 0.125 × 0.125 degrees on a daily basis between 1980 and 2015. For the study area, as many as 3772 pixels with an inter-pixel distance of about 12.5 km were obtained and to evaluate the performance of simulated data against observational data, several indicators were used from the Root-Mean Square Error (RMSE), Mean Bias Error (MBE), Mean Absolute Error (MAE), and the coefficient of determination (R2). It made use of non-parametric Man-Kendall method to order to investigate the trend of wind speed changes.
Results and Discussion
The ECMWF ERA-Interim version delivers a high and good performance for wind speed. Results showed that the output of the mentioned base in all studied stations was on average between 0.722 and 0.984. RMSE, MBE, and MAE characteristics in Zahedan, Khash, and Saravan stations were below 1 m/s. In other words, the wind speed of ECMWF base in these three stations had the highest performance of all 11 stations studied. The monthly statistical assessment of wind speed in the selected stations in eastern Iran during the statistical period (1985-2015) demonstrated that the average wind speed was 3.56 m/s. The correlation between wind speed with negative altitude and positive longitude was significant at the level of 0.05. Also, the relation between latitude and wind speed showed it to be negative during the cold months of the year and positive during the warm ones. The average wind speed fluctuated significantly during the 30-year statistical period, varying between 2.82 and 4.57 m/s. The minimum and maximum wind speeds occurred in December and July, respectively. The average 30-year wind speed at selected stations in eastern Iran turned out to be 2 m/s. The maximum wind speed in eastern Iran displayed many fluctuations, with autumn showing the lowest statistical value of maximum wind speed. In December, this value was 3.98 m/s. The maximum wind speed increased during all studied months. All studied months proved to be statistically significant, except for January, which though increasing was not remarkable at 0.05 and 0.01 levels. Other wind speed studies showed a significant incremental trend at α = 0.01. The average wind speed in the study area was negative in 7 months (i.e., January, April, May, July, August, October, and December) of the year and positive in 5 months (i.e., February, March, June, September, and November) of the other. The maximum wind speed belonged to January (with 4.42 m/s), February (4.86 m/s), and March (with 5.02 m/s.) The next area in the form of a fertile one in winter, Zabol, was also the center of Iran's borders with Afghanistan, near the borderlines of South Khorasan Province. Here, the wind speed trend was positive at the time of 120-day wind onset (June with 0.79), and negative at the time of its termination (October with -0.15).
The average wind speed in the study area (Khorasan Razavi, South Khorasan, Kerman, and Sistan and Baluchestan Provinces) during the long-term statistical period of 30 years (from 1985 to 2015) was 3.56 m/s. The minimum and maximum wind speeds occurred in July and December, respectively. The reason for this increase in wind speed in July was due to the 120-day wind activity in Sistan, which started in June. The average wind speed in the study area was negative in 7 months (January, April, May, July, August, October, and December) of the year and positive in 5 months (February, March, June, September, and November). Investigating wind speed process via non-parametric Man-Kendall (M-K) test showed that the wind speed trend in eastern Iran in the first month of June (June) 120-day winds showed an increasing trend (Z score of the Man-Kendall test 0.795), while in the last month (October) it decreased (-0.1152). Also, in July, when the wind speed was maximum, the average trend in the study area, having a Z score of 0.242, began declining. Pearson correlation test showed that the relation between wind speed and topography in the study area was statistically significant at 0.05. In contrast, the relation between longitude and wind speed was remarkable in all studied moles at an alpha level of 0.05, while neither the longitude nor the altitude in the study area did not show a uniform relation between latitude and wind speed. While this relation was exactly so during the warm months of the year, it was vice versa during the cold ones. In October alone, the relation between wind speed and latitude was not significant.


آبخرابات، ش.؛ کریمی، م.؛ فتحنیا، ا. و شام بیاتی، م.ح. (1396). بررسی نقش باد 120روزۀ سیستان در وزش دمایی شرق و جنوب ‏شرق ایران، پژوهش‏های جغرافیای طبیعی، 49 (3): 477-489.
بابائیان، ا.؛ بداق جمالی، ج.؛ جوانمرد، س. و خزانهداری، ل. (1381). بررسی خطای دادههای پیشیابی مرکز اروپایی پیشبینیهای میانمدت جوی (ECMWF) بر روی خاورمیانه، دومین همایش پیشبینی عددی وضع هوا، تهران.
حمیدیان‏پور، م. (1392). بررسی نحوة شکل‏گیری باد سیستان با ریزگردانی دینامیکی جریان‏های تراز زیرین در شرق فلات ایران، رسالة دکتری اقلیم‏شناسی دانشگاه خوارزمی، تهران.
حیدری علمدارلو، ا.؛ زهتابیان، غ.؛ خسروی، ح.؛ رایگانی، ب.؛ خلیقی، ش. و تقیزاده، ر. (1398). بررسی نوسان پارامتر‏های اقلیمی با استفاده از داده‍‏های مرکز پیش‏بینی میانمدت جوی اروپایی (مطالعة موردی: منطقة شیرکوه- استان یزد)، مجلة علوم ومهندسی آبخیزداری ایران، ۱۳(۴۶): ۲۲-۳۱.
دارند، م. و زند کریمی، س. (1394). واکاوی سنجش دقت زمانی- مکانی بارش پایگاه دادۀ مرکز پیش‏بینی میان‏مدت جوی اروپایی (ECMWF) بر روی ایران‏زمین، پژوهشهای جغرافیای طبیعی، 47(4): 651-675.
دارند، م. و زند کریمی، س. (1395). ارزیابی دقت داده‏های بارش مرکز اقلیم‏شناسی بارش جهانی بر روی ایران، مجلة ژئوفیزیک ایران، 10(3): 95-113.
دلبری، م.؛ که‏خامقدم، پ.؛ محمدی، ا. و احمدی، ت. (1395)، برآورد الگوی پراکنش مکانی تندی باد برای پتانسیل‏یابی تولید انرژی بادی در ایران، پژوهش‏های جغرافیای طبیعی، 48(۲): 265-285.
ذوالفقاری، ح.؛ صحرایی، ج.؛ معصومپور سماکوش، ج. و برزو، ف. (1395). بررسی شار گرمای محسوس و ارتباط آن با تغییرات دما و باد طی دورۀ گرم سال در ایران، پژوهش‏های جغرافیای طبیعی، 48(۳): 431-450.
رضیئی، ط. و ستوده، ف. (1396). بررسی دقت مرکز اروپایی پیش‏بینی‏های میان‏مدت جوی (ECMWF) در پیش‏بینی بارش مناطق گوناگون اقلیمی ایران، فیزیک زمین و فضا، 43(۱): 133-147.
سبزیپرور، ع. ا. و شادمانی، م. (1390). تحلیل روند تبخیر و تعرق مرجع با استفاده از آزمون من-کندال و اسپیرمن در مناطق خشک ایران، آب و خاک (علوم و صنایع کشاورزی)، 25(4): 823-834.
سلیقه، م. (1396). آب و هواشناسی سینوپتیک ایران، تهران: سمت.
عزیزی، ق.؛ فرید مجتهدی، ن.؛ شعبانزاده، ف.؛ نگاه، س. و عابد، ح. (1396). رفتارشناسی باد در ایستگاه‏های کوهستانی البرز غربی تحت تأثیر واداشت‏های محیطی، نشریة جغرافیا و برنامه‏ریزی، 21(۶۲): 203-222.
علیجانی، ب. (1389)، آب‏وهوای ایران، چ ۱۰، تهران: انتشارات دانشگاه پیام نور.
قهرمان، ن. و قرهخانی، ا. (1389). بررسی روند تغییرات زمانی سرعت باد در گسترة اقلیمی ایران، مجلة آبیاری و زهکشی ایران، 4(۱): 31-43.
مسعودیان، س.ا. (1390). آب‏وهوای ایران، مشهد: شریعة توس.
میراکبری، م.؛ مصباحزاده، ط.؛ محسنی ساروی، م.؛ خسروی، ح. و مرتضایی فریزهندی، ق. (1397). ارزیابی کارایی مدل سری CMIP5 در شبیه‏سازی و پیش‏بینی پارامترهای اقلیمی بارندگی، دما، و تندی باد (مطالعۀ موردی: استان یزد)، پژوهش‏های جغرافیای طبیعی، 50(۳): 593-609.
میرعباسی، ر. و دینپژوه، ی. (1394). بررسی روند تغییرات سرعت باد در ایستگاههای منتخب ایران، جغرافیا و برنامهریزی،52: 277-301.
Abkharabat; sh., Karimi, M., Fathnia, A., Shambaiati, M.(2017), The Role of Sistan 120 Days Wind in Thermal Advection of East and Southeast Iran, Physical geography research quarterly: 49 (3), 477-489.
Alijani, b. (2010), Iran Climate, 10th Edition, Tehran: Payame Noor University Press.
Azizi, G., Farid Mojtahedi, N., shabanzadeh, F., Negah, S., Abed, H. (2018). 'Analysis of wind behavior by environmental forcing in the western Alborz mountainous stations', Geography and Planning, 21(62), pp. 203-222. doi: 3-6.
Carvalho, D.; Rocha, A.; Gómez-Gesteira, M. and Santos, C. S. (2017). Potential impacts of climate change on European wind energy resource under the CMIP5 future climate projections. Renewable Energy, 101: 29-40.
Cheng, C. S.; Lopes, E.; Fu, C. and  Huang, Z. (2014). Possible impacts of climate change on wind gusts under downscaled future climate conditions: Updated for Canada. Journal of climate, 27(3): 1255-1270.
Darand, M., Zand Karimi2, S. (2016). 'Evaluation of the accuracy of the Global Precipitation Climatology Center (GPCC) data over Iran', Iranian Journal of Geophysics, 10(3), pp. 95-113.
Darand, M., Zande Karimi, S. (2015). 'Evaluation of Spatio-Temporal Accuracy of Precipitation of European Center for Medium-Range Weather Forecasts (ECMWF) over Iran', Physical Geography Research Quarterly, 47(4), pp. 651-675. doi: 10.22059/jphgr.2015.56054.
Debernard, J. B. and Røed, L. P. (2008). Future wind, wave and storm surge climate in the Northern Seas: a revisit. Tellus A: Dynamic Meteorology and Oceanography, 60(3): 427-438.
Delbari, M., Kahkha Moghaddam, P., Mohammadi, E., Ahmadi, T. (2016). 'Estimation of the spatial distribution pattern of wind speed for assessment of wind energy potential in Iran', Physical Geography Research Quarterly, 48(2), pp. 265-285. doi: 10.22059/jphgr.2016.59368.
Hamidianpour, M. (2014). Investigating the formation of Sistan wind with dynamic downscaling of low-level currents in the east of the Iranian plateau, Ph.D. thesis in Kharazmi University, Tehran.
Heydari Alamdarloo, H., Zehtabian, G., Khosravi, H., Raygani, B., Khalighi, S., Taghizadeh, S. (2019) Investigation on the Climatic Parameters Fluctuation Using Data from the European Centre for Medium-Range Weather Forecasts, Iran-Watershed Management Science & Engineering, Vol. 13, No. 46, Fall 2019.
Hobbins, M. (2004). Regional evapotranspiration and pan evaporation: complementary interactions and long-term trends across the conterminous United States. Colorado State University.
Iman Babaian, I., Bodagh Jamali, J., Javanmard, S.,Khazanedari, L. (2002), Investigation of Error in Prediction Data of the European Center for Medium-Term Weather Forecasting (ECMWF) on the Middle East, 2nd Conference on Numerical Weather Forecasting, Tehran.
Kendall, M. G. (1955). Rank correlation methods (2nd ed.). Charles Griffin & Co. Ltd., London, 1955.
Klink, K. (2002). Trends and interannual variability of wind speed distributions in Minnesota. Journal of Climate, 15(22): 3311-3317.
Mann, H. B. (1945). Nonparametric tests against trend. Econometrica: Journal of the Econometric Society, 245-259.
McVicar, T. R.; Van Niel, T. G.; Li, L. T.; Roderick, M. L.; Rayner, D. P.; Ricciardulli, L. and Donohue, R. J. (2008). Wind speed climatology and trends for Australia, 1975–2006: Capturing the stilling phenomenon and comparison with near‐surface reanalysis output. Geophysical Research Letters, 35(20).
Mirabbasi Najafabadi, R., Dinpashoh, Y. (2015). 'Analysis of the Wind Speed Trend over Iran', Geography and Planning, 19(52), pp. 277-301.
Mirakbari, M., Mesbahzadeh, T., Mohseni Saravi, M., Khosravi, H., Mortezaie Farizhendi, G. (2018). 'Performance of Series Model CMIP5 in Simulation and Projection of Climatic Variables of Rainfall, Temperature and Wind Speed (Case Study: Yazd)', Physical Geography Research Quarterly, 50(3), pp. 593-609. doi: 10.22059/jphgr.2018.248177.1007156.
Ghahreman, N. and Gharekhani, A. (2010), Trend analysis of mean wind speed in different climatic regions of Iran, Iranian Journal of lrrigation and drainage: 4(1), 31-43.
Masoudian, S.A. (2012). Iran Climate, Mashhad: sharieye tus, Mashhad.
Naizghi, M. S. and Ouarda, T. B. (2017). Teleconnections and analysis of long‐term wind speed variability in the UAE. International Journal of Climatology, 37(1): 230-248.
Okin, G. S.; Gillette, D. A. and Herrick, J. E. (2006). Multi-scale controls on and consequences of aeolian processes in landscape change in arid and semi-arid environments. Journal of arid environments, 65(2): 253-275.
Pirazzoli, P. A. and Tomasin, A. (2003). Recent near‐surface wind changes in the central Mediterranean and Adriatic areas. International Journal of Climatology: A Journal of the Royal Meteorological Society, 23(8): 963-973.
Pryor, S. C.; Barthelmie, R. J. and Riley, E. S. (2007). Historical evolution of wind climates in the USA. In Journal of Physics: Conference Series, 75(1): 012065. IOP Publishing.
Pryor, S. C.; Schoof, J. T. and Barthelmie, R. J. (2006). Winds of change?: Projections of near‐surface winds under climate change scenarios. Geophysical research letters, 33(11).
Rayner, D. P. (2007). Wind run changes: the dominant factor affecting pan evaporation trends in Australia. Journal of Climate, 20(14): 3379-3394.
Raziei, T., Sotoudeh, F. (2017). 'Investigation of the accuracy of the European Center for Medium Range Weather Forecast (ECMWF) in forecasting observed precipitation in different climates of Iran', Journal of the Earth and Space Physics, 43(1), pp. 133-147. doi: 10.22059/jesphys.2017.57958.
Roderick, M. L.; Rotstayn, L. D.; Farquhar, G. D. and Hobbins, M. T. (2007). On the attribution of changing pan evaporation. Geophysical research letters, 34(17).
Sabziparvar, A., Shadmani, M. (2011). Trends Analysis of Reference Evapotranspiration Rates by Using the Mann-Kendall and Spearman Tests in Arid Regions of Iran, Journal of Water and Soil: 25 (4), p. 823-834.
Smits, A. A. K. T.; Klein Tank, A. M. G. and Können, G. P. (2005). Trends in storminess over the Netherlands, 1962-2002. International Journal of Climatology: A Journal of the Royal Meteorological Society, 25(10): 1331-1344.
Tobin, I.; Jerez, S.; Vautard, R.; Thais, F.; Van Meijgaard, E.; Prein, A.; ... and Noël, T. (2016). Climate change impacts on the power generation potential of a European mid-century wind farms scenario. Environmental Research Letters, 11(3): 034013.
Watson, S. J.; Kritharas, P. and Hodgson, G. J. (2015). Wind speed variability across the UK between 1957 and 2011. Wind Energy, 18(1): 21-42.
Xu, C. Y.; Gong, L.; Jiang, T.; Chen, D. and Singh, V. P. (2006). Analysis of spatial distribution and temporal trend of reference evapotranspiration and pan evaporation in Changjiang (Yangtze River) catchment. Journal of hydrology, 327(1-2): 81-93.
Zhang, Y.; Liu, C.; Tang, Y. and Yang, Y. (2007). Trends in pan evaporation and reference and actual evapotranspiration across the Tibetan Plateau. Journal of Geophysical Research: Atmospheres, 112(D12).
Zolfaghari, H., Sahraei, J., Masoompoor Samakoosh, J., Borzoi, F. (2016). 'Study of Sensible Heat Flux and its Relationship with Temperature Changes and Wind during Warm Periods of Year in Iran', Physical Geography Research Quarterly, 48(3), pp. 431-450. doi: 10.22059/jphgr.2016.60100.