شناسایی رژیم بارش ناحیه خزری

نوع مقاله : مقالات پژوهشی

نویسندگان

• حسین عساکره ¹
• نسرین ورناصری قندعلی ²

¹ استاد اقلیم شناسی، دانشگاه زنجان، زنجان، ایران

² دانشجوی دکتری تغییرات آب و هوایی، دانشگاه زنجان، زنجان، ایران

https://doi.org/10.22067/jsw.2021.67063.0

چکیده

در پژوهش حاضر با استفاده از داده­های روزانه 385 ایستگاه ‌همدید، اقلیم‌شناسی و باران­سنجی سازمان هواشناسی کشور و ایستگاه‌های باران­سنجی وزارت­نیرو طی بازة زمانی 2016-1966 جنبه­های پنهان بارش و رژیم بارشی ناحیه خزری مورد بررسی قرار گرفت. در ابتدا نقشه‌های بارش روزانه با تفکیک مکانی 3 × 3 کیلومتر ایجاد شد و برای هر پیکسل ایجاد شده در نقشه، افت­و­خیز سینوسی بارش 12 ماه سال براساس روش همسازها بررسی گردید. به­منظور شناسایی الگوهای مکانی بارش براساس سهم تناوب­های مختلف و نیز پهنه­بندی آن از شگرد تحلیل خوشه­ای استفاده­شد. سپس نمایه یکنواختی و فصلی بارش برآورد شد. نتایج نشان می­دهد، بیش­ترین ضریب­تغییرپذیری ماه­به­ماه بارش در خط ساحلی دریای خزر می­باشد. این وضعیت گویای تغییرات فراوان ماه­به­ماه و عدم ثبات فصل بارشی در این مناطق است، با دور شدن از خط ساحلی ضریب تغییرات نیز به­تدریج کاسته می­شود به‌طوری­که، کمینه آن در بخش­هایی از ارتفاعات البرز می­باشد. این امر گویای فعالیت سامانه‌های متنوع باران­زایی و یا حداقل تداوم سامانه­های باران­زا در این نقاط و ثبات فصل بارشی است. نمایه یکنواختی نشانگر این است، در بخش­های ساحلی دریای خزر توزیع بارش متمرکزتر است و با پیشروی به‌سمت مناطق جنوبی ناحیه توزیع زمانی بارش یکنواخت­تر می­گردد. نمایه­فصلی بارش بیانگر وجود سه نوع رژیم بارش است. کم­ترین وسعت مکانی مربوط به رژیم بارش یکنواخت می­باشد، که در بخش­های کوچکی از ارتفاعات البرز دیده­می­شود. گسترده­ترین رژیم بارشی مربوط به رژیم یکنواخت با یک فصل مرطوب­تر است. این رژیم بارشی در شرق و غرب ناحیه و جنوب دریای خزر مشاهده می­شود. رژیم سوم که به رژیم عمدتاً فصلی با یک فصل خشک کوتاه مربوط می­باشد، خط ساحلی دریای خزر، بخش­هایی از ارتفاعات تالش و بخش کوچکی از شرق ناحیه را پوشش می­دهد.

کلیدواژه‌ها

• رژیم بارش
• ناحیه خزری
• نمایه ضریب تغییرات
• نمایه فصلی
• نمایه یکنواختی

20.1001.1.20084757.1400.35.3.10.9

موضوعات

• هواشناسی کشاورزی

عنوان مقاله [English]

Identifying the Precipitation Regime of the Iranian Coast of Caspian Sea

نویسندگان [English]

• H. Asakereh ¹
• N. Varnaseri ²

¹ Professor of Climatology, University of Zanjan, Zanjan, Iran

² Ph.D. Candidate in Climate Changes, University of Zanjan, Zanjan, Iran

چکیده [English]

Introduction: Precipitation is one of the most important climatic variables playing a decisive role for different purposes. Temporal changes in precipitation affect many climatic and environmental phenomena (such as runoff, floods, air temperature, and humidity) as well as many human activities (such as agriculture and housing). The precipitation regime includes all characteristics and statistics of precipitation in relation to its distribution throughout the year, and the temporal distribution of precipitation according to the months or seasons of the year is called the "Precipitation Regime".
Materials and Methods: The daily data of 385 stations were obtained from Iran Meteorological Organization and the Ministry of Energy for the period of 2016-1966 (51 years). The hidden aspects of precipitation and precipitation regime of the Iranian coast of Caspian Sea were studied. At first, these stations were used in order to create maps with a spatial resolution of 3 × 3 km, and the general specifications of the monthly and annual precipitation were presented. Sinusoidal behaviors of monthly precipitation in each pixels were then investigated. Accordingly, first to sixth harmonics were extracted. Finally, the cluster analysis method was used based on the Euclidean distance and the "Ward" method of linkage to identify the spatial patterns of precipitation based on the contribution of different periodic and its zoning. Then, the homogeneity and seasonal index of precipitation was estimated.
Results and Discussion: The results show that the mean annual precipitation is higher on the coastline, especially in the southwest of the Caspian Sea, and decreases as it passes from the coast. In the southwest parts of the Caspian Sea, maximum precipitation occurs in the autumn. At the Alborz highlands, the maximum and minimum precipitation fall during winter and summer, respectively. The monthly precipitation coefficient of variation indicates that with seasonal changes from winter to spring, precipitation changes in the Caspian region are declining, and with changes in seasonal precipitation from summer to autumn, precipitation changes are in the ascendant. The largest variability coefficient of the month to month of the precipitation (60 to 70 percent) was calculated at the coastline of the Caspian Sea. This shows notable month to month precipitation changes and seasonal instability in these areas. The coefficient of variation is gradually reduced by distance from the coastline. The lowest coefficient of variation was obtained in the southern parts of the Caspian Sea (the Alborz altitudes) between 15% and 30%. This suggests a small difference in rainfall over the course of the months. In other words, they indicate the activity of various rainy systems, or at least the continuity of rainy systems in these areas, and the stability of the precipitation season. The homogeneity index indicates that the precipitation distribution is more concentrated in the coastal areas of the Caspian Sea, and it becomes more uniform with the advance towards the southern parts of the area (part of the Alborz heights). The seasonal precipitation index of the Caspian Sea region indicates three types of precipitation regime. The lowest spatial extent (6.28%) is related to the uniform precipitation regime, found in small parts of the Alborz heights. The most abundant regime has a wetter season. This precipitation regime, which includes 76.13% of the Iranian coast of Caspian Sea, is observed in the eastern and western regions of the Caspian Sea. The third regime (13.25% of the study area), which is mainly seasonal with a short dry season, covers the Caspian Sea coastline, parts of the Talesh heights, and a small part of the eastern region.
Conclusion: The results revealed that the precipitation classes obtained based on the seasonal index were closer to the reality due to the similarity of these classes with the average monthly and annual precipitation. Therefore, this index seems to be the most optimal tool for determining precipitation regimes in the Caspian region. According to this precipitation regime classification, there are three classes of precipitation regime in the Caspian region. The existence of these three classes indicates the presence and activity of different synoptic and local systems in the Caspian region.

کلیدواژه‌ها [English]

• Precipitation regime
• Caspian region
• Coefficient of variation Index
• Seasonal Index
• Homogeneity Index

مراجع

1-       Abaje I.B., Ishaya S., and Usman S.U. 2010. An Analysis of Rainfall Trends in Kafanchan, Kaduna State, Nigeria. Research Journal of Environmental and Earth Sciences 2(2): 89-96.

2-       Albaurrea J., Asın J., Centelles A., and Gonz´alez B. 2003. Spatial-temporal analysis of the precipitation in the Ebro basin. Journal of Hydrology 210: 67–99.

3-       Alexandersson H. 1986. A Homogeneity Test Applied to precipitation data.Journal of Climatology, 6:661- 675.

4-       Alijani B. 2008. Climate of Iran. Payam Noor University Press, Tehran. (In Persian)

5-       Alijani B., Mohammadi H., and Bigdeli A. 2008. The Role of Pressure Patterns on the Precipitation of the South Coast of Caspian Sea. Territory 4(16): 37-52. (In Persian with English abstract)

6-       Asakareh H. 2010. An analysis of precipitation regime change in Zanjan province. NIVAR Journal of Meteorological Organization 34(70,71): 63-76. (In Persian with English abstract)

7-       Asakareh H., and Razmi R. 2011. Change of the Precipitation Regime in Northwest of Iran. Journal of Climate Research 2(7,8): 99-114. (In Persian with English abstract)

8-       Asakareh H., and Razmi R. 2014. Temporal Distribution and Regime of Precipitation of Northwest of Iran. Geographical Researches 29(1): 145-160. (In Persian with English abstract)

9-       Asakereh H. 2011. Fundamentals of Statistical Climatology. University of Zanjan Press, Zanjan. (In Persian)

10-   Asakereh H., and Varnaseri ghandali N. 2021. Decade changes in monthly mean of precipitation in recent five decades over the Caspian coast of Iran territory. Journal of Climate Research 11(42):31-46. (In Persian with English abstract)

11-   Clark S., Reeder M.J., and Jakob C. 2018. Rainfall regimes over northwestern Australia. Quarterly Journal of the Royal Meteorological Society 144: 458–467.

12-   Dalezios N.R., and Bartzokas A. 1995. Daily precipitation variability in semiarid agricultural regions in Macedonia, Greece. Hydrological Sciences Journal 40(5): 569-585.

13-   Domroes M., Kaviani M., and Schaefer D. 1998. An analysis of regional and intra-annual precipitation variability over Iran using multivariate statistical methods. Theoretical and Applied Climatology 61: 151-159.

14-   Farshadfar E. 2010. Principles and Methods of Multivariate Statistics. Sadaf Publications, Kermanshah. (In Persian)

15-   Fetene Z.A., Weldegerima T.M., Zeleke T.T., and Nigussie M. 2018. Harmonic Analysis of Precipitation Time Series in Lake Tana Basin, Ethiopia. Advances in Meteorology 3: 1-9.

16-   Ghashghaei Gh. 1996. Investigation of the effect of Siberian high pressure on the autumn Precipitation of the southern coast of the Caspian Sea. Master's thesis of natural geography. Tarbiat Moallem University. (In Persian with English abstract)

17-   Ghayoor H.A., and Masoudian S.A. 1998. Spatial study of the uniformity index of temporal distribution of precipitation in Iran. Geographical Researches 13(2,3): 19-28. (In Persian)

18-   Ghayoor H.A., Masoodiyan S.A., Azadi M., and Noori H. 2011. Temporal and Spatial Analysis of Precipitation Events in the Southern Coasts of Caspian Sea. Geographical Researches 26(100): 1-30. (In Persian with English abstract)

19-   Halabian A.H., Dehghanpour A.R., and Ashori Ghaleroodkhany Z. 2016. Synoptic Analysis of Extreme and Widespread Precipitations in Caspian Eastern Coasts. Geography and Environmental Hazards 5(19): 37-57. (In Persian with English abstract)

20-   Hosseini M., Masoodian S.A., and Movahedi S. 2015. Analysis of the Concurrence of Black Sea High Pressure System and Daily Precipitation in IRAN. Geographical Researches 30(1): 1-16. (In Persian with English abstract)

21-   Jackson I.J., and Weinand H. 1995. Classification of tropical rainfall stations: a comparison of clustering techniques. International Journal Climatology 15(9): 985–994.

22-   Jahanbakhsh S., Abtahi V., Ghorbani M.A., Tadaiyoni M., and Valaei A. 2015. Temporal and Spatial Distribution of Rainfall in Tabriz County Using Hierarchical Cluster Analysis. Geographic Space 15(50): 59-81. (In Persian with English abstract)

23-   Jahanbakhsh S., and Karami F. 1999. Synoptic analysis of the effect of Siberian high-pressure on precipitation on the southern coasts of the Caspian Sea. Geographical Researches 54,55: 107-131. (In Persian)

24-   Janbaz Ghobadi Gh.R., Mofidi A., and Zarrin A. 2011. Recognizing the Synoptic Patterns of Wintertime Heavy Precipitation in the Southern Coast of the Caspian Sea. Geography and Environmental Planning 22(2): 23-40. (In Persian with English abstract)

25-   Justino F., Setzer A., Bracegirdle T.J., Mendes D., Grimm A., Dechiche G., and Schaefer C.E.G.R. 2010. Harmonic analysis of climatological temperature over Antarctica: present day and greenhouse warming perspectives. International Journal Climatology 31(4): 1-17.

26-   Kadioglu M., Ozturk N., Erdun H., and Sen Z. 1999. on the precipitation climatology of Turkey by harmonic analysis. International Journal Climatology 19: 1717-1728.

27-   Kansakar S.R., and Hannah D.M., Gerrard J., and Rees G. 2004. spatial pattern in the precipitation regime of Nepal. International Journal Climatology 24(13): 1645–1659.

28-   Karagianndis A., Bloutsos A., Mahers P., and Sachsamanoglou Ch. 2008. Some statistical characteristics of precipitation in Europe. Theoretical and Applied Climatology 91: 193-204.

29-   Khalili A. 1973. Precipitation patterns of Central Elburz. Theoretical and Applied Climatology 21(2): 215–232.

30-   Khorshiddoust A.M., and  Shirzad A.A. 2014. The Study of Precipitation in North of Iran Using Cluster and Discriminative Function Analyses. Journal of Geography and Planning 18(49): 101-118. (In Persian with English abstract)

31-   Khoshhaldastjerdi J. 1997. Analysis and presentation of synoptic climatological models for precipitation of more than one hundred millimeters on the southern coasts of the Caspian Sea. Ph.D Thesis in Natural Geography. Trabiat Modares University. (In Persian with English abstract)

32-   Kirkyla K.I., and Hameed S. 1989. Harmonic analysis of the seasonal cycle in precipitation over the united state: Acomparison between observations and a general circulation model. Journal of Climate 2(12): 1463-1475.

33-   Lana A., Campins J., Genov´es A., and Jans A. 2007. Atmospheric Patterns for Heavy Rain Events in The Balearic Islands. Advances in Geosciences 12: 27-32.

34-   Livada I., and Asimakopoulos D.N. 2005 . Individual seasonality index of rainfall regimes in Greece. Climate Research 28(2): 155–161.

35-   Livada I., Chralambous G., and Assimakopoulos M.N. 2008. Spatial and temporal study of precipitation characteristics over Greece. Theoretical and Applied Climatology 93: 45-55.

36-   Lyra G.B., Oliveira-J ´ unior J.F., and Zeri M. 2014. Cluster analysis applied to the spatial and temporal variability of monthly rainfall in Alagoas state, Northeast of Brazil. International Journal Climatology 34: 3546–3558.

37-   Martinez M.D., Lana X., Burgueno A., and Serra C. 2007. Spatial and temporal daily rainfall regime in Catalonia (NE Spain) derived from four precipitation indices, years1950–2000. International Journal Climatology 27(1): 123–138.

38-   Masoodiyan S.A. 2003. Investigation of Precipitation Geographical Dispersion In Iran through Rotated Factor Analysis. Geography And Development Iranian Journal 1(1): 79-87. (In Persian with English abstract)

39-   Masoodiyan S.A. 2005. Identification of precipitation regimes in Iran by cluster analysis. Geographical Research Quarterly 37(1): 47-59. (In Persian)

40-   Masoodiyan S.A. 2011. Climate of Iran. Sharia Toos Press, Mashhad. (In Persian)

41-   Masoodiyan S.A., and Ataei H. 2005. A Cluster Analysis of Prcipitation Seasons of Iran. Research Bulletin of Isfahan University (Humanities) 18(1): 1-12. (In Persian with English abstract)

42-   Mohammadi H., Azizi Gh., Taghavi F., and Yousefi Y. 2011. Temporal and Spatial Variability of Maximum Monthly Precipitation over Southern Parts of The Caspian Sea. Physical Geography Research Quarterly 43(75): 1-18. (In Persian with English abstract)

43-   Nastos P.T., and Zerefos C.S. 2010. Cyclic Modes of the Intra-annual Variability of Precipitation in Greece. Advances In Geosciences 25: 45–50.

44-   Oliveira-Júnior J.F., Góis G., and Coll Delgado R. 2017. Cluster analysis identified rainfall homogeneous regions in Tocantins state, Brazil. Bioscience Journal 33(2): 333-340.

45-   Pohl E., Gloaguen R., and Seiler R. 2015. Remote Sensing-Based Assessment of the Variability of Winter and Summer Precipitation in the Pamirs and Their Effects on Hydrology and Hazards Using Harmonic Time Series Analysis. Remote Sensing 7: 9727-9752.

46-   Pourasghar F., Jahanbakhsh S., Sari saraf B., Ghaemi H., and Tadayoni M. 2013. Precipitation Regime in South Part of Iran Studying of Iran. Journal of Geography and Planning 17(44): 27-46. (In Persian with English abstract)

47-   Razmi R. 2010. Precipitation regime change in Azerbaijan of Iran. M.A physical Geography (climatology) thesis. Zanjan University. Faculty of Human Science. (In Persian with English abstract)

48-   Reiser H., and Kutiel H. 2007. The rainfall regime and its uncertainty in Valencia and Larnaca. Advances in Geosciences 12: 101–106.

49-   Saligheh M., Nasserzadeh M.H., and Chehreara Ziabari T. 2016. Study of the relation between NCPI and CACO indices with autumn precipitation of Southern Coast of Caspian Sea. Journal of Applied Researches in Geographical Sciences 16(43): 217-238. (In Persian with English abstract)

50-   Scott C.M., and Shulman M.D. 1979. An Areal and Temporal Analysis of Precipitation in the Northeastern United States. Journal of Applied Meteorology 18: 627-633.

51-   Tarawneh Q. 2016. Harmonic analysis of precipitation climatology in Saudi Arabia. Theoretical and Applied Climatology 124: 205-217.

52-   Tarawneh Q., and Kadoglu M. 2003. An analysis of precipitation climatology in Jordan. Theoretical and Applied Climatology 74: 123-126.

53-   Walsh R.P.D., and Lawler D.M. 1981. Rainfall seasonality spatial patterns and change through time. Weather 36(7): 201–208.