Analysis of changes in maximum snow cover duration in Northwest Iran

Document Type : Research/Original/Regular Article

Authors

1 Professor, Department of Physical Geography, Faculty of Social Sciences, University of Mohaghegh Ardabili, Ardabil, Iran

2 Associate Professor, Department of Geography, Payame Noor University, Tehran, Iran.

3 Ph.D Student of Climatology, Department of Physical Geography, Faculty of Social Sciences, University of Mohaghegh Ardabili, Ardabil, Iran

Abstract

Extended Abstract
Introduction
Variations in snow cover, along with its phenological aspects such as the duration, onset, and cessation of snowfall, are critical to understanding mountainous ecosystems. These changes heavily influence water resource accessibility in nearby regions. Snow cover serves as a vital component in energy and temperature regulation and is intricately connected to hydrological, biological, chemical, and geological processes. Furthermore, it plays a significant role in both the hydrological cycle and the overall energy balance of the environment. Recent research indicates that mountain regions are undergoing temperature increases at twice the global average rate, with this trend intensifying at higher altitudes. As a result, mountains have come to be regarded as critical indicators for monitoring climate change over the past few decades. This study focused on examining variations in the maximum snow cover persistence in the northwest of Iran, analyzed across monthly, seasonal, and annual time scales.
 
Materials and Methods
This study utilized MOD10A1 and MOD10A1 version 6 products from the Terra and Aqua satellites to conduct a daily analysis of snow phenology spanning the years 2003 to 2020. These datasets, accessible as digital network data derived from the NDSI index, were retrieved through Earthdata's online portal at earthdata.nasa.gov. A threshold value of 0.1 or higher was applied for snow cover estimation to facilitate the conversion of snow cover data into binary format. All adjustments, data processing, and analytical procedures were carried out using Python. Cloudiness reduction was accomplished using data fusion algorithms, spatial neighborhood filtering, and temporal filtering techniques. By combining the Terra and Aqua databases and applying spatio-temporal filtering with a threshold range of 0.1 to 1, a binary database of daily snow cover was generated. This database served as the basis for evaluating snow cover persistence and maximum snow cover persistence parameters, which were analyzed across monthly, seasonal, and annual intervals.
 
Results and Discussion
During January, the maximum consecutive snow cover pattern is marked by two prominent peaks in the Sahand and Sabalan Mountains, specifically around Ghoch-Goli Daghi and Sultan-Sabalan, with intervals spanning 20 to 30 days. In February, the MaxSCDur indicates a noticeable rise in snow cover duration, influenced by various surface roughness features and an expansion of areas showing high persistence. By March, this pattern shifts as regions of high persistence shrink and areas with low persistence expand. As the cold season concludes, the snow cover significantly decreases. The spatial pattern observed in April reveals a notable reduction in snow cover, with snow retreating from mid- and low-altitude areas while remaining concentrated on high peaks. This pattern underscores the crucial influence of altitude on the persistence of snow cover during the melting season. Between May and September, spatial patterns for MaxSCDur exhibit a gradual decline in duration, decreasing from 20.87 to 24.24 days in May to just 5.91 to 7.5 days by September. During August and September, the maximum consecutive snow cover is confined exclusively to the summit of the Sabalan Glacier. From October to December, MaxSCDur spatial patterns display an upward trend in frequency, with durations increasing from 20.84 to 23.24 days in October to approximately 30 to 31.25 days by December. The MaxSCDur pattern for October highlights a notable increase in snow cover range and duration as autumn sets in, marked by declining temperatures, especially at higher altitudes. Analysis of the spatial distribution for winter’s MaxSCDur reveals the highest snow cover duration at the summits of Sabalan and Sahand, ranging between 25.6 and 29.25 days. The spring pattern shows a reduction in MaxSCDur, decreasing progressively from southern to northern parts of the studied area when compared to winter. During summer, the maximum consecutive snowfall period is limited to 0–2 days across most regions, except for notable peaks such as Sabalan (4–20 days), Sahand, Avarin, Barda-Rash, Kale-Shin, and Qandil (2–4 days). The autumn MaxSCDur pattern records durations of 4–20 days in Sabalan and its slopes, 4–8 days in the Sahand and Bazgush mountains, and 4–6 days in Qara-Dagh, Barda-Rash, Dalampar, and Kale-Shin. On an annual scale, areas with extended MaxSCDur have shown strong regression towards central and high troughs during 2010 and 2018. Conversely, years such as 2008, 2012, and 2017 exhibit visible rock formations predominantly at higher altitudes, encompassing foothills and slopes within these geomorphologic units.
 
Conclusion
The MaxSCDur map for February reveals that areas with high snow cover persistence have expanded and intensified when compared to January. An evaluation of the MaxSCD models for November and December indicates a marked increase in both the thickness and duration of snow cover across all snow types as the cold season advanced. December serves as the turning point when full winter conditions are established in the study area. In a seasonal context, winter is characterized by peak precipitation levels and prolonged snow cover, especially across rugged terrains throughout the region analyzed. As spring arrives, rising temperatures lead to the gradual retreat and melting of snow cover. By summer, most regions are entirely devoid of snow, with only fleeting patches visible on the highest summits. Autumn brings a shift as falling temperatures initiate the gradual accumulation of snow at elevated altitudes, resulting in a higher maximum snowfall compared to summer. These patterns reflect a transition from warmer to colder conditions and signal the region's preparation for increased winter precipitation. Historical observations show that minimum MaxSCD values occurred in 2010 and 2018, while peak values were recorded in 2008, 2012, and 2017 within the study area.

Keywords

Main Subjects

References

منابع:
آصفی، مصطفی، و فتح‌زاده، علی (1401). شبیه‌سازی توزیع مکانی عمق برف با استفاده از هوش مصنوعی و رگرسیون خطی مبتنی بر کاهش ویژگی‌ها (مطالعه موردی: حوزه آبخیز چلگرد). مدل‌سازی و مدیریت آب و خاک، 3(4)، 29-43. doi: 10.22098/mmws.2022.11560.1141
الحسینی المدرسی، سیدعلی، حاتمی، جواد، و سرکارگر، علی (1395). محاسبه خصوصیات فیزیکی برف با استفاده از تکنیک تداخل سنجی تفاضلی راداری و تصاویر سنجنده ترا سارایکس باند (TerraSAR-X) و مادیس (MODIS). سنجش از دور و سیستم اطلاعات جغرافیایی در منابع طبیعی، 2، 59-76. https://sanad.iau.ir/fa/Journal/girs/Article/901956/FullText.
بهرامی پیچاقچی، حدیقه، رائینی سرجاز، محمود، و نوروز ولاشدی، رضا (1399). بررسی اثرگذاری گرمایش فراگیر بر تغییرات زمانی و مکانی پوشش برف و ماندگاری آن در گستره‌ی دامنه شمالی البرز مرکزی. هواشناسی کشاورزی، 8(15)، 15-25. doi: 10.22125/agmj.2020.200876.1071
شاهزیدی، سمیه سادات (1402). بررسی ارتباط مؤلفه‌های ژئومورفولوژیک (ارتفاع، شیب و جهت شیب) با ماکزیمم ماندگاری برف‌پوش در ارتفاعات تالش. جغرافیا و توسعه، 21(73)، 166-198. doi: 10.22111/gdij.2023.44795.3497
قنبرپور، محمدرضا، محسنی ساروی، محسن، ثقفیان، بهرام، احمدی، حسن، و عباس‌پور، کریم (1384). تعیین مناطق مؤثر در انباشت و ماندگاری سطح پوشش برف و سهم ذوب برف در رواناب. منابع طبیعی ایران، 58(3)، 503-515. https://ijnr.ut.ac.ir/article_25249.html?lang=en.
کاشانی، عباس، صلاحی، برومند، حلبیان، امیرحسین، و زینالی، بتول (1403). وردش‌های فضایی- زمانی روزهای برف‌پوشان در پهنه شمال غرب ایران با استفاده از داده‌های دورسنجی. سنجش از دور و سامانه اطلاعات جغرافیایی در منابع طبیعی، 1، 94-117. doi:10.30495/girs.2022.697117.
کاشانی، عباس، صلاحی، برومند، حلبیان، امیرحسین و زینالی، بتول. (1404). واکاوی روزهای برف‌پوشان در ارتباط با سنجه توپوگرافیکی ارتفاع در شمال غرب ایران. جغرافیا و روابط انسانی، (1)8: 31-45. doi: 10.22034/gahr.2024.435665.2035
مرشدی، علی، و حسینی بروجنی، بهروز (1400). پایش و مقایسه تغییرات NDSI با استفاده از داده‌های سنجنده‌های MODIS و ETM+ به‌منظور برآورد پوشش برفی در حوضۀ آبریز کارون شمالی. مدل‌سازی و مدیریت آب و خاک، 1(4)، 68-82. doi: 10.22098/mmws.2021.9453.1045
یغمایی، لیلا، جعفری، رضا، سلطانی، سعید، و جهانبازی، حسن (1400). اثر تغییرات سطح و ماندگاری پوشش برف بر پوشش گیاهی در استان چهارمحال و بختیاری. مرتع و آبخیزداری، 74(4)، 917-938. doi:10.22059/jrwm.2022.317220.1559
 
 
References
Alhossaini Almodaresi, S. A., Hatami, J., & Sarkargar, A. (2016). Calculating the physical properties of snow, using differential radar interferometry and TerraSAR-X and MODIS images. Journal of RS and GIS for Natural Resources, 2, 59-76. [In Persian]
Asefi, M., & Fathzadeh, A. (2022). Simulating spatial distribution of snow depth using artificial intelligence and linear regression based on feature reduction (Case study: Chalgerd watershed). Water and Soil Management and Modelling, 3(4), 29-43. doi: 10.22098/mmws.2022.11560.1141. [In Persian]
Bahrami Pichaghchi, H., Raeini-Sarjaz, M., & Norooz Valashedi, R. (2020). Investigation of the effect of global warming on temporal and spatial changes of snow cover and its durability in the northern slope of Central Alborz. Journal of Agricultural Meteorology, 8(1), 15-25. doi: 10.22125/agmj.2020.200876.1071. [In Persian]
Balk, B., & Elder, K. (2000). Combining binary decision tree and geostatistical methods to estimate snow distribution in a mountain watershed. Water Resources Research, 36(1), 13–26. doi:10.1029/1999WR900251.
Barnett, T. P., Adam, J. C., & Lettenmaier, D. P. (2005). Potential impact of a warming climate on water availability in snow-dominated regions. Nature, 438, 303–309. doi:10.1038/nature04141.
Beniston, M., Farinotti, D., Stoffel, M., Andreassen, L.M., Coppola, E., Eckert, N., Fantini, A., Giacona, F., Hauck, C., Huss, M., Huwald, H., Lehning, M., López-Moreno, J.-I., Magnusson, J., Marty, C., Morán-Tejéda, E., Morin, S., Naaim, M., Provenzale, A., Rabatel, A., Six, D., Stötter, J., Strasser, U., Terzago, S., & Vincent, C. (2018). The European Mountain cryosphere: a review of its current state, trends, and future challenges. Cryosphere 12, 759–794. doi: 10.5194/tc-12-759-2018.
Bormann, K. J., Brown, R. D., Derksen, C., & Painter, T. H.(2018). Estimating snow-cover trends from space. Nature Clim Change, 8, 924–928. doi: 10.1038/s41558-018-0318-3
Brown R., & Armstrong R. L. (2010). Snow-cover data measurement, products and sources in snow and climate. In Physical Processes, Surface Energy Exchange and Modeling, Armstrong RL, Brun E (eds). Cambridge University Press: Cambridge, UK.
Brown, R., Derksen, C., & Wang, L. (2007). Assessment of spring snow cover duration variability over northern Canada from satellite datasets, Remote Sensing of Environment, 111(3), 367-381. doi: 10.1016/j.rse.2006.09.035.
Chen, W., Wu, Y., Wu, N., & Luo, P. (2008). Effect of snow-cover duration on plant species diversity of alpine meadows on the eastern Qinghai-Tibetan Plateau. Journal of Mountain Science, 5, 327-339. doi: 10.1007/s11629-008-0182-0.
Chen, X., Liang, S., Cao, Y., He, T., & Wang, D. (2015). Observed contrast changes in snow cover phenology in northern middle and high latitudes from 2001-2014. Scientific reports, 5(1), 1-9. doi.org/10.1038/srep16820.
Cui, C., Yang, Q., & Wang, S. (2005). Comparison analysis of long-term variations of snow cover between mountain and plain areas in Xinjiang region from 1960 to 2003. Journal of Glaciology and Geocryology, 27(4), 486–490. doi: 10.7522/j.issn.1000-0240.2005.0072
Dietz, A. J., Conrad, C., Kuenzer, C., Gesell, G., & Dech, S. (2014). Identifying changing snow cover characteristics in Central Asia between 1986 and 2014 from remote sensing data. Remote Sensing, 6(12), 12752-12775.
Foster, J. L., Hall, D. K., & Chang, A. T. C. (1999). Effects of snow crystal shape on the scattering of passive microwave radiation. Geoscience & Remote Sensing IEEE Transactions on Selected Topics, 37(2): 1165–1168. doi:10.1109/36.752235.
Ghanbarpour, M. R., Mohseni Saravi, M., Saghafian, B., Ahmadi, H., & Abbaspour, K. (2005). An Evaluation of Regions Effective in Accumulation and Persistence of Snow Cover and Snowmelt Contribution in Runoff. Iranian Journal of Natural Resources (Not Publish), 58(3), 503-515. [In Persian]
Hammond, J. C., Saavedra, F.A., & Kampf, S. K. (2018). Global snow zone maps and trends in snow persistence 2001–2016. Int. J. Climatol. 38, 4369–4383. https://rmets.onlinelibrary.wiley.com/doi/abs/10.1002/joc.5674
Huss, M., Bookhagen, B., Huggel, C., Jacobsen, D., Bradley, R. S., Clague, J. J., Vuille, M., Buytaert, W., Cayan, D. R., Greenwood, G., Mark, B. G., Milner, A. M., Weingartner, R., & Winder, M. (2017). Toward mountains without permanent snow and ice. Earth’s Future, 5, 418–435.ISSN 0034-4257, doi: 10.1016/j.rse.2006.09.035.
Kashani, A., Salahi, B., Halabian, A., & Zeinali, B. (2024). Spatio-temporal variations of snow-covered days in the Northwest of Iran using remote sensing data. Journal of RS and GIS for Natural Resources, 1: 94-117. doi:10.30495/girs.2022.697117. [In Persian]
Kashani, A., Salahi, B., Halabian, A., & Zeinali, B. (2024). Analysis of the relationship between snow-covered days and topographic elevation in Northwestern Iran. Geography and Human Relationships, 29: 31-45. doi: 10.22034/gahr.2024.435665.2035 [In Persian]
Ke, C., & Liu, X. (2014). MODIS-observed spatial and temporal variation in snow cover in Xinjiang, China. Climate Research, 59, 15-26. doi: 10.3354/cr01206
Keikhosravi Kiani, M. S., Masoodian, S. A. (2021). Climatology of snow cover accumulation and melting in Iran using MODIS data, Physical Geography Research, 53(1), 109-121. doi: 10.22059/jphgr.2021.290500.1007446
Klein, G., Vitasse, Y., Rixen, C., Marty, C., & Rebetez, M. (2016). Shorter snow cover duration since 1970 in the Swiss Alps due to earlier snowmelt more than to later snow onset. Climatic Change, 139, 637-649. doi: 10.1007/s10584-016-1806-y.
Kohler, T., Wehrli, A., & Jurek, M. (2014). Mountains and climate change: A global concern. In: Centre for Development and Environment (CDE) (Ed.), Sustainable Mountain Development Series. Swiss Agency for Development and Cooperation (SDC) and Geographica Bernensia, Bern, Switzerland (136 pp).
Li, D., Wrzesien, M.L., Durand, M., Adam, J., & Lettenmaier, D.P. (2017). How much runoff originates as snow in the western United States, and how will that change in the future? Geophys. Res. Lett. 44, 6163–6172. doi: pdfdirect/10.1002/2017GL073551
Li, H., Zhong, X., Zheng, L., Hao, X., Wang, J., & Zhang, J. (2022). Classification of snow cover persistence across China. Water, 14, 6: 933. doi: 10.3390/w14060933.
Morshedi, A., & Hoseini Boroujeni, B. (2021). Monitoring and comparing NDSI changes using MODIS and ETM+ sensor data to estimate snow cover in North Karun Basin. Water and Soil Management and Modelling, 1(4), 68-82. doi: 10.22098/mmws.2021.9453.1045. [In Persian]
Mote, P. W., Li, S., Lettenmaier, D. P., Xiao, M., & Engel, R. (2018). Dramatic declines in snowpack in the western US. Npj Climate and Atmospheric Science, 1(1), 2.doi: 10.1038/s41612-018-0012-1
Notarnicola, C. (2020). Hotspots of snow cover changes in global mountain regions over 2000–2018, Remote Sensing of Environment, 243, 111781, doi: 10.1016/j.rse.2020.111781.
Olefs, M., Koch, R., Schöner, W., & Marke, T. (2020). Changes in Snow Depth, Snow Cover Duration, and Potential Snowmaking Conditions in Austria, 1961–2020—A Model Based Approach. Atmosphere, 11(12), 1330. doi: 10.3390/atmos11121330
Liang, T., Zhang, X., Xie, H., Wu, C., Feng, Q., Huang, X., & Chen, Q. (2008). Toward improved daily snow cover mapping with advanced combination of MODIS and AMSR-E measurements. Remote Sensing of Environment, 112(10): 3750-3761. doi: 10.1016/j.rse.2008.05.010
Pepin, N., Bradley, R. S., Diaz, H. F., Baraer, M., Caceres, E. B., Forsythe, N., Fowler, H., Greenwood, G., Hashmi, M. Z., Liu, X. D., Miller, J. R., Ning, L., Ohmura, A., Palazzi, E., Rangwala, I., Schöner, W., Severskiy, I., Shahgedanova, M., Wang, M. B., Williamson, S. N., & Yang, D. Q. (2015). Elevation-dependent warming in mountain regions of the world. Nat. Clim. Chang, 5, 424:430.
Pu, Z., Xu, L., & Salomonson, V. V. (2007). MODIS/Terra observed seasonal variations of snow cover over the Tibetan Plateau. Geophysical Research Letters, 34(6). doi: 10.1029/2007GL029262
Ramage, J. M., & Isacks, B. L. (2003). Interannual variations of snowmelt and refreeze timing in southeast Alaskan icefields, USA. Journal of Glaciology, 49(164), 102–116. doi:10.3189/172756503781830908
Shahzeidi, S. (2023). Investigating the Relationship between Geomorphological Components (Elevation, Slope and Aspect) and the Maximum Snow-Cover Duration in Talesh Mountains. Geography and Development, 21(73), 166-198. doi: 10.22111/gdij.2023.44795.3497. [In Persian]
She, J., Zhang, Y., Li, X., & Chen, Y. (2014). Changes in snow and glacier cover in an arid watershed of the western Kunlun Mountains using multisource remote-sensing data‚ International journal of remote sensing, 35(1), 234- 252. doi:10.1080/01431161.2013.866296
Simpson, J.J., Stitt, J.R., & Sienko, M. (2001). Improved Estimates of the Areal Extent of Snow Cover from AVHRR Data, Journal of Hydrology, 204(1-4), 1-23. doi: 10.1016/S0022-1694(97)00087-5.
Stocker T., Qin D. H., & Plattner, G. K. (2014). Climate change, 2013: The Physical Science Basis. Cambridge and New York: Cambridge University Press.
Udnaes, H., Alfnes, C. E., & Andreassen, L. M. (2007). Improving runoff modeling using satellite-derived snow cover area. Nord. Hydrol. 38, 21–32. doi:10.2166/nh.2007.032
Yaghamei, L., Jafari, R., Soltani, S., & Jahanbazi, H. (2022). The effect of snow cover area and duration changes on vegetation cover in Chaharmal and Bakhtiari Province. Journal of Range and Watershed Managment, 74(4), 917-938. doi:10.22059/jrwm.2022.317220.1559. [In Persian]
Yang, K., Guyennon, N., Ouyang, L., Tian, L., Tartari, G., & Salerno, F. (2018). Impact of summer monsoon on the elevation-dependence of meteorological variables in the south of central Himalaya. Int. J. Climatol. 38, 1748–1759. doi: 10.1002/joc.5293
Yang, Q., Song, K., Hao, X., Chen, S., & Zhu, B. (2018). An assessment of snow cover duration variability among three basins of Songhua River in Northeast China using binary decision tree. Chinese Geographical Science, 28, 946-956. doi: 10.1007/s11769-018-1004-0
Ye, B., Yang, D.K., Jiao, T., Han, Z., Jin, H., Yang, H., & Li, Z. (2005). The Urumqi River source glacier No. 1, Tianshan, China: changes over the past 45 years. Geophysical Research Letters, 32: 1-4. doi: 10.1029/2005GL024178
Zhang, H., Immerzeel, W. W., Zhang, F., De Kok, R. J., Chen, D., & Yan, W. (2022). Snow cover persistence reverses the altitudinal patterns of warming above and below 5000 m on the Tibetan Plateau. Science of the Total Environment, 803, 149889. doi: 10.1016/j.scitotenv.2021.149889.
Zhang, H., Zhang, F., Zhang, G., Che, T., Yan, W., Ye, M., & Ma, N. (2019). Ground-based evaluation of MODIS snow cover product V6 across China: Implications for the selection of NDSI threshold, Science of the Total Environment, 651: 2712–2726. doi: 10.1016/j.scitotenv.2018.10.128.
Zhong, X., Zhang, T., Kang, S., & Wang, J. (2021). Spatiotemporal variability of snow cover timing and duration over the Eurasian continent during 1966-2012. Science of the Total Environment, 750, 141670. doi: 10.1016/j.scitotenv.2020.141670
 
Water and Soil Management and Modelling
Volume 6, Issue 1
March 2026
Pages 208-225

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  • Receive Date: 22 August 2025
  • Revise Date: 01 October 2025
  • Accept Date: 01 October 2025

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