تحلیل فضایی سطح پوشش برف در غرب ایران با بهره‌گیری از تصاویر ماهواره‌ای

نوع مقاله : مقالات پژوهشی

نویسندگان

• عبدالله فرجی ¹
• محمد کمانگر ¹
• سعیده اشرفی ²

¹ گروه آب و هواشناسی، دانشکده علوم انسانی، دانشگاه زنجان، زنجان، ایران

² دانشکده برنامه‌ریزی و علوم محیطی، دانشگاه تبریز، تبریز، ایران

10.22067/jsw.2024.83893.1323

چکیده

تغییرات پوشش برف می‌تواند اثرات مهمی بر اکوسیستم‌ها داشته باشد، به‌ویژه در جاهایی که پراکندگی در پوشش زیاد است و بر شرایط بیوژئوشیمیایی خاک زیرین و همچنین پوشش گیاهی تأثیر می‌گذارد. در این پژوهش پایش و روند سطوح پوشش برف در بازه زمانی (2020-2001) در غرب ایران برای فصل زمستان با کاربرد تصاویر سنجنده MODIS و شاخص پوشش برف (NDSI) به‌صورت میانه تصاویر به‌وسیله الگوریتم نوشته‌شده در سامانه گوگل ارث اینجین استخراج و نقشه­های آن ترسیم شد، سپس سری زمانی تصاویر روزانه استخراج و روند داده­ها و الگوسازی آن با کاربرد آزمون تاو کندال و رگرسیون خطی انجام گرفت. نتایج این پژوهش نشان از روند کاهشی در مساحت پوشش برف در فصل زمستان دارد. همچنین با توجه به رفتار سالیانه سینوسی برف می‌توان بیان کرد که مؤلفه فصلی بودن بر تمام محدوده حاکم است، که به علت دور بودن نسبی محدوده غرب کشور از استوا، تغییرات دمایی با توجه فصلی بودن در این محدوده نمود دارد. نتایج تحلیل فضایی نشان داد که جهت بیضی مکانی پراکندگی برف در راستای شمال غربی به جنوب شرقی قرار گرفته و به تبعیت از آرایش مکانی ارتفاعات در این راستا گسترش یافته است. نقشه لکه‌های داغ نشان داد برف سطحی خاک به‌صورت خوشه‌ای در راستای غرب و به جنوب شرق و در ارتفاعات بالاتر از 2200 متر قرار دارد. تحلیل لکه‌های داغ  نشان داد پوشش برف به سمت عرض­های بالا و بیشتر به طرف مرزهای غربی الگوی خوشه‌بندی قراردارد. نتایج این تحقیق می‌تواند در برنامه‌ریزی‌های مربوط به مدیریت منابع آبی، پیش‌بینی خشکسالی و برنامه‌ریزی برای مقابله با آن مورد استفاده قرار بگیرد.

کلیدواژه‌ها

• پوشش برفی
• روند من کندال
• سنجنده MODIS
• موران

موضوعات

• هواشناسی کشاورزی

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عنوان مقاله [English]

Spatial Analysis of Snow Cover in Western Iran Using Satellite Imagery

نویسندگان [English]

• A. Faraji ¹
• M. Kamangar ¹
• S. Ashrafi ²

¹ Department of Hydrology and Meteorology, Faculty of Humanities, Zanjan University, Zanjan, Iran

² Faculty of Planning and Environmental Sciences, University of Tabriz, Tabriz, Iran

چکیده [English]

Introduction
Snow is a prevalent form of precipitation, particularly in mountainous and high latitude regions, characterized by ice crystals in various microscopic structures. It naturally accumulates in cold and elevated areas through the freezing of air and the unsuccessful melting of water into crystalline form (WMO, 2022). Snow cover plays a crucial role in determining water reserves, especially during warmer seasons. Monitoring snow cover is a specialized field within weather and climatology. Snow cover plays a key role in the balance of energy due to its high albedo. Climatologists and meteorologists, who analyze global climate changes, emphasize the significance of snow monitoring due to its impact on both daily weather patterns and long-term climate shifts (Bashir et al., 2010). Spatial studies of snow cover by using satellite data have become one of the high priority topics in geomatics research due to their applicability and high accuracy. Considering that the snow cover area in many regions of the world, including mountainous regions, affects water resources and meteorology, accurate spatial analysis and investigation of changes in the area of snow cover is very important. In this regard, use of satellite data and new tools in the spatial analysis of the snow cover area, as an efficient method in geomatics research, has received much attention (Cheng et al., 2019).
Data and Method
This research examines the changes in snow cover in the western part of Iran from 2001 to 2021. The study area includes the provinces of Kurdistan, Kermanshah, Ilam, Hamadan, and Lorestan, covering a total area of 466,121 square kilometers. The region is located between latitudes 31°51'36" to 36°49'45" N and longitudes 45°27'18" to 50°04'26" E. It encompasses the northern part of the Zagros Mountain range, which serves as the entry point for western weather systems into the country. Snow cover was assessed using Modis satellite images, with the NDSI index used to identify snow. The analysis revealed a trend in snow cover, which was further examined using the Mann-Kendall method. The spatial distribution and changes in spatial components (length, width, and height) were assessed using the G* Index.
 
 
 
Results and Discussion
 
To analyze snow cover in the western region, the snow cover index was calculated by averaging the images for each period. The area of snow cover was then determined for each period. Analysis of the winter snow cover area revealed a decreasing trend. The application of the Mann-Kendall method confirmed this decreasing trend, which is statistically significant at the 95% confidence level. Additionally, considering the annual sinusoidal behavior of snow, it can be concluded that the seasonal component is the dominant factor in the region, with temperature changes primarily driven by seasonal variation due to its relative distance from the equator. Spatial analysis indicated that the distribution of snow cover follows a northwest-southeast direction, as evidenced by the standard deviation ellipse. More than 99% of snowfall is concentrated in high-altitude areas with a specific spatial arrangement. The hotspot map shows that surface snow cover is clustered in the west and southeast directions, predominantly at altitudes above 2200 meters. The clustering pattern of snow cover is more pronounced at higher latitudes and towards the western borders. These findings have important implications for water resource management, drought prediction, and the development of strategies to mitigate droughts.
 Conclusion
 This research demonstrates a decreasing trend in the area of snow cover during the winter season in the western part of Iran. Spatial analysis reveals that the major axis of snow distribution follows a northwest-southeast orientation, aligned with the mountainous terrain in that direction. The hotspot map highlights that surface snow cover is concentrated in the west and southeast directions, particularly at altitudes above 2200 meters. Hotspot analysis indicates that snow cover is clustered towards higher latitudes and more pronounced towards the western borders.

کلیدواژه‌ها [English]

• Kendall trend
• Moran
• MODIS sensor
• Snow cover

©2024 The author(s). This is an open access article distributed under Creative Commons Attribution 4.0 International License (CC BY 4.0), which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source.

مراجع

1. Abrifam, M.)2010(. Synoptic analysis of air masses entering western Iran in 1983-84.Sc., Razi University of Kermanshah. (In Persian)
2. Alijani, B. (2008). Effect of the Zagros Mountains on the spatial distribution of precipitation. Journal of Mountain Science, 5, 218–231. https://doi.org/10.1007/s11629-008-0126-8
3. Alijani, B. (2012). Synoptic climatology. Tehran: Samt Publications. (In persian)
4. Alijani, B. (2015). Spatial analysis. Journal of Spatial Analysis of Environmental Hazards, 2(3), 1-14. (In Persian)
5. Arndt, A., Azzoni, R.S., & Stötter, J. (2017). Physical and chemical properties of snow and their impact on the environment: A state-of-the-art review. Snow Engineering and Avalanche Science, 1(1), 1-24. https://doi.org/ 10.1553/scc1s1s1
6. Asakereh, H. (2012). Analysis of Heavy Precipitation Trends in Zanjan City. Geography and Planning, 16(39), 73-88.
7. Asgari, A. (2011). Spatial statistics analysis, Tehran Municipality ICT Organization, First Edition.
8. Azizi, Q.,Rahimi, M.,Mohammadi, H., & Khoshakhlach, F. (2017). Temporal-spatial changes of snow cover on the southern slopes of Central Alborz, Natural Geography Research, 49(3), 393-381. (In Persian)
9. Bashir, F., & Ghulam, R. (2010). Estimation of average snow cover over Northern Pakistan. Pakistan Journal of Meteorology, 7(13), 63-69.
10. Cheng, J., Ma, M., Li, X., Zhang, H., & Wang, Q. (2019). Spatial analysis of snow cover using satellite data and new geospatial tools in geomatics research. Remote Sensing of Environment, 221, 466-482. https://doi.org/10.1016/ j.rse.2018.11.029
11. Eslamian, S.S., Soltani, S.V., & Zarei, A. (2005). Application of statistical methods in water resources. Arkan Press. Esfahan. (In persian)
12. Fatahi, A., & Moghimi, Sh. (2019). The effect of climate change on snow trend in northwestern Iran, Applied Research in Geographical Sciences, 54, 63-47. (In Persian)
13. Ganji, M. (2003). Climatic divisions of Iran.Bulletin of the National Center for Climatology, 3(1), 41. (In Persian)
14. Ghaemi, E., & Nouhi, A. (1976). Statistical Analysis of Snowfall, First Edition. Tehran Meteorological Organization Research Office Publications. (In Persian)
15. Ghulam, A., Zaman, Q.U., Ahmad, S., & Babel, M.S. (2021). Assessment of snow cover variability and trends in the Hindu Kush Himalaya using multi-source satellite data. Science of the Total Environment, 753, 142041. https:// doi.org/10.1016/j.scitotenv.2020.142041
16. Goodinson, B.E., Rango, A., & Walker, A.E. (2000). Snow and ice, remote sensing in hydrology and water management, Springer Pub, Berlin, 539-540.
17. Harvey, D. (1996). Explanation in Geography. London: Arnold
18. Ildermi, A.,Habibnejad Roshan, M.,Safari Shad, M., & Dalal Oglu, A. (2015). Using Modis images to prepare snow cover map (NDSI index and using MODIS case images of Bahar watershed), Ahar Geographical Space, 15(50), 125-140. (In Persian)
19. Khosravi, M.,Tavosi, T.,Raispur, K., & Omidi Qaleh Mohammadi, M. (2017). Investigation of changes in snow cover levels in Bakhtiari Zardkooh heights using remote sensing, Hydrogeomorphology, 12, 44-25. (In Persian)
20. Liu, Y., Lei, Y., Zhang, J., Li, X., Huang, X., & Wang, X. (2021). Spatiotemporal variations of snow cover in the Karakoram Mountains based on MODIS data from 2000 to 2019. International Journal of Digital Earth, 14(3), 313-328. https://doi.org/10.1080/17538947.2020.1869246
21. Masoudian, S.A., & Kaykhosravi Kiani, M.S. (2017). Evaluation of changes in days with snow cover in the altitude groups of Zayandehrud basin, Natural Environment Hazards, 11, 46-33. (In Persian)
22. Mir Mousavi, S.H.,Sabor, L. (2014). Monitoring snow cover changes using MODIS sensor images in northwestern Iran, Geography and Development, 35, 200-181. (In Persian)
23. Mojarad, F.,Masoompour, J. (2013). Estimation of maximum probable precipitation by synoptic method in Kermanshah province.Geographical Studies of Arid regions, 3(1), 1-14. (In Persian)
24. Rasouli, A.A. (2011). An introduction to Satelite meteorology and climatology. Tabriz University Press, first edition. (In Persian)
25. Salahi, B., & Nakhostin Rohi, M. (2018). Spatial and temporal monitoring of snow cover with NOAA-AVHRR images in the period 2006-2007 (Case study of Balighlouchai watershed). Iran Water Research, 3, 97-89. (In Persian)
26. Wang, X., Zhang, Y., Li, W., Zhang, J., Huang, G., & Li, L. (2021). Spatiotemporal analysis of snow cover in the Pamir Mountains using MODIS data from 2000 to 2019. Ecological Indicators, 121, 107103. https://doi.org/ 10.1016/j.ecolind.2020.107103
27. Zare Abyaneh, H. (2013). Estimation of Spatial distribution of snow water equivalent and snow density of the West Azarbaijan Province’s Basins. Water Resources Engineering, 5(15), 1-11. (In Persian)
28. Zhang, Y., Li, W., Wang, X., Yang, X., & Huang, G. (2021). Spatiotemporal variability of snow cover in the Central Tianshan Mountains based on MODIS snow products from 2000 to 2018. Journal of Arid Land, 13(2), 156-168. https://doi.org/10.1007/s40333-021-0062-8