كليدواژه :
البرز مركزي , برف-پوش , تغييرات زماني-مكاني , دماي سطح زمين
چكيده فارسي :
ﭼﮑﯿﺪه
ﭘﻬﻨﻪﻫﺎي ﭘﻮﺷﯿﺪه از ﺑﺮف و ﻧﻮﺳﺎﻧﺎت آنﯾﮑﯽ از ﻣﺆﻟﻔﻪﻫﺎي ﻣﻬﻢ در ﺑﺮرﺳﯽﻫﺎي اﻗﻠﯿﻤﯽ و ﻫﯿﺪروﻟﻮژﯾﮏ اﺳﺖ ﮐﻪ اﻟﺒﺘﻪ در ﺗﺮﮐﯿﺐ ﺑﺎ ﺗﻮﭘﻮﮔﺮاﻓﯽ زﻣﯿﻦ و ﻣﺸﺨﺼﺎت ﻧﺎﻫﻤﻮاريﻫﺎ ﻣﯽﺗﻮاﻧﺪ در ﻣﻨﺎﺑﻊ آب و ﺷﻨﺎﺧﺖ ﻧﺴﺒﺖﻫﺎ و رواﺑﻂ ﺑﯿﻦ ﻣﺆﻟﻔﻪﻫﺎي ﻣﺤﯿﻄﯽ ﻣﻮرد ا ﺳﺘﻔﺎده ﻗﺮار ﮔﯿﺮد. در اﯾﻦ را ﺳﺘﺎ و ﺿﻌﯿﺖ دﻣﺎي ﺳﻄﺢ زﻣﯿﻦ و ارﺗﺒﺎط آن ﺑﺎ ﻣﻮﻟﻔﮥ ﻣﺤﯿﻄﯽ ﺑﺮف-ﭘﻮش
ﻣﻮرد ﺗﻮﺟﻪ ﻗﺮار ﮔﺮﻓﺖ. ارﺗﺒﺎط اﯾﻦ ﻣﺆﻟﻔﻪﻫﺎي ﻣﺤﯿﻄﯽ ﺑﺎ ﺟﻬﺖ ﺷــﯿﺐ زﻣﯿﻦ ﮐﻪ ﻧﻘﺶ ﺑﺴــﺰاﯾﯽ در ﻣﺎﻧﺪﮔﺎري و ﺣﻔﻆ
ﺑﺮف-ﭘﻮش دارد، در ارﺗﻔﺎﻋﺎت اﻟﺒﺮز ﻣﺮﮐﺰي واﻗﻊ در ﺷــﻤﺎل اﯾﺮان ﻣﺪﻧﻈﺮ ﻗﺮار ﮔﺮﻓﺖ. ﺑﺪﯾﻦ ﻣﻨﻈﻮر از دادهﻫﺎي ﭘﻮش-
ﺑﺮف و دﻣﺎي ﺳﻄﺢ زﻣﯿﻦ ﻣﺎﻫﻮاره ﺗﺮا و آﮐﻮا ﺳﻨﺠﻨﺪة ﻣﺎدﯾﺲ در ﺑﺎزة زﻣﺎﻧﯽ 2003 ﺗﺎ 2018 ا ﺳﺘﻔﺎده ﺷﺪ. دادهﻫﺎي ﭘﻮﺷﺶ ﺑﺮف ﺑﺎ ﻗﺪرت ﺗﻔﮑﯿﮏ ﻣﮑﺎﻧﯽ 500 ﻣﺘﺮ ﺑﺎ اﺳﺘﻔﺎده از ﺑﺮﻧﺎﻣﻪ ﻧﻮﯾﺴﯽ ﭘﺎﯾﺘﻮن در ارﺗﺒﺎط ﺑﺎ ﻣﻮﻟﻔﮥ ﺗﻮﭘﻮﮔﺮاﻓﯿﮏ ﺟﻬﺖ
ﺷﯿﺐ در ﻓﻀﺎي ﻣﺪلﺳﺎزي رﻗﻮﻣﯽ زﻣﯿﻦ ﺑﺎ ﺗﮑﻨﯿﮏ ﭘﺮدازش رﺳﺘﺮي ﭘﻨﺠﺮه ﻣﺘﺤﺮك و ﺗﮑﻨﯿﮏ آﻧﺎﻟﯿﺰ ﺳﻠﻮل ﺑﻪ ﺳﻠﻮل، ﺗﺤﻠﯿﻞ ﮔﺮدﯾﺪ. ارﺗﺒﺎط واﺿﺤﯽ ﺑﯿﻦ ﺟﻬﺖ ﺷﯿﺐ زﻣﯿﻦ و درﺻﺪ ﺑﺮف-ﭘﻮش ﻣﺸﺎﻫﺪه ﺷﺪ. دﻣﺎي ﺳﻄﺢ زﻣﯿﻦ و ﺑﺮف-
ﭘﻮش داراي روﻧﺪ ﻣﻌﮑﻮس، ﺧ ﺼﻮ ﺻﺎً در ﻓ ﺼﻮل زﻣ ﺴﺘﺎن و ﭘﺎﺋﯿﺰ ﻫ ﺴﺘﻨﺪ. اﺧﺘﻼف ﺑﺎرزي ﺑﯿﻦ دﻣﺎي ﺳﻄﺢ زﻣﯿﻦ در داﻣﻨﻪﻫﺎي ﺟﻨﻮﺑﯽ و ﺷﻤﺎﻟﯽ اﻟﺒﺮز ﻣﺮﮐﺰي ﻣﺸﺎﻫﺪه ﻣﯽﺷﻮد ﮐﻪ ﻋﻼوه ﺑﺮﺟﻬﺖ ﺷﯿﺐ، رﻃﻮﺑﺖ درﯾﺎي ﺧﺰر و ﻧﯿﺰ ﭘﻮﺷﺶ ﮔﯿﺎﻫﯽ و ﺟﻨﮕﻠﯽ در داﻣﻨﻪﻫﺎي رو ﺑﻪ ﺷﻤﺎل در اﯾﻦ وﺿﻌﯿﺖ ﺗﺄﺛﯿﺮﮔﺬار اﺳﺖ. در ﺗﻤﺎﻣﯽ ﻣﺎهﻫﺎ ﻧﺮخ دﻣﺎي ﺳﻄﺢ زﻣﯿﻦ در داﻣﻨﻪﻫﺎي ﺟﻨﻮﺑﯽ ﺑﺎﻻﺗﺮ از داﻣﻨﻪﻫﺎي ﺷﻤﺎﻟﯽ ا ﺳﺖ. ﺗﺤﻠﯿﻞ ﺟﻬﺘﯽ دﻣﺎي ﺳﻄﺢ زﻣﯿﻦ ﻧ ﺸﺎندﻫﻨﺪه ﻣﻘﺎدﯾﺮ ﺣﺪاﮐﺜﺮ در ﺟﻬﺎت ﺟﻨﻮﺑﯽ و ﺧﺼﻮﺻﺎً ﺟﻨﻮب ﺷﺮﻗﯽ و ﻣﻘﺎدﯾﺮ ﺣﺪاﻗﻞ در ﺟﻬﺎت ﺷﻤﺎل ﺷﺮﻗﯽ و ﺧﺼﻮﺻﺎً ﺷﻤﺎﻟﯽ در ﺗﻤﺎﻣﯽ ﻣﺎهﻫﺎي
ﺳﺎل اﺳﺖ. داﻣﻨﻪﻫﺎي ﺟﻨﻮﺑﯽ ﺑﺎ ﻋﺮض ﺟﻐﺮاﻓﯿﺎﯾﯽ 36 درﺟﻪ، زاوﯾﻪ ﺑﺮﺧﻮرد ﺑﺎﻻﯾﯽ ﺑﺎ ﺗﺸﻌﺸﻊ ﺧﻮرﺷﯿﺪي داﺷﺘﻪ ﮐﻪ اﯾﻦ
ﻋﺎﻣﻞ ﻧﻘﺶ ﻣﺆﺛﺮي در ﺑﺎﻻ ﺑﺮدن ﻣﻘﺪار دﻣﺎي ﺳﻄﺢ زﻣﯿﻦ در ﺟﻬﺎت ﺟﻨﻮﺑﯽ و ﺟﻨﻮب ﺷﺮﻗﯽ ا ﺳﺖ. در ﺗﻤﺎﻣﯽ ﺑﺎزهﻫﺎي
زﻣﺎﻧﯽ ﻣﺎﻫﺎﻧﻪ، ﻓﺼﻠﯽ و ﺳﺎﻻﻧﻪ ﺟﻬﺎت ﻃﯿﻒ ﺟﻨﻮﺑﯽ )S, SE, SE( داراي ﻧﺮخ دﻣﺎي ﺳﻄﺢ زﻣﯿﻦ ﺑﯿﺸﺘﺮي از ﺟﻬﺎت ﻃﯿﻒ
ﺷﻤﺎﻟﯽ )N, NE, NW( ﺑﻮدﻧﺪ.
چكيده لاتين :
The area, covered by snow or snow-cover variations, is one of the important factor in climatologic and hydrologic studies, that could be also useful and applicable in water management and environmental studies, specifically when it is combined with topographic characteristics. In this research Land Surface Temperature (LST) and snow-cover interactions were considered. These environmental indicators interactions, combined with focal topographic characteristics such as slope, play a major role in snow-cover persistency. As a result, the influences of these factors had taken into account in central Alborz mountainous belt in Iran northern boundary. To achieve this goal, snow-cover (SC) and land surface temperature (LST) obtained from Aqua and Terra satellite images that are carrying Modis sensor, used in a the temporal range of 2003 up to 2018. Snow cover data with spatial resolusion of 500m analyzied using python programming language. The analysis performed related to the aspect as a major topographic characteristic in the scope of terrain modeling with using moving window and cell by cell raster analysis thechniques. The result, shows a strong relationship between terrain aspect and snow coverage in the central sector of Alborz Mountains. Land surface temperature and snow-cover had an inverse trend, specifically during winter and fall seasons. June LST (Khordad) was high according to the higher zenith angle of the sun in this period of year. There is a clear gap between the LST values of northern and southern aspects of central Alborz that could be result of mountain orientations to the sun rays, higher humidity levels and denser vegetation cover in the northern part. Southward areas, show higher temperature in almost all months. Directional analysis of LST, demonstrated, that maximum levels of LST are observed in the south-faced and specifically southeastward area and the minimum levels observed in northeastward and specifically northward area during all months. Southward area of the alborz mountainous wall, located at the latitude band of 36N, experienced a higher sun ray incident angle and thus having higher LSTs in southern and southeastern parts. Finally in almost all temporal periods (including month, season and year) higher LSTs in southern aspects (South, Southeast and southwest) in compared to northern one (North, Northeast and northwest) has been observed.
