TY - JOUR JF - geospace JO - جغرافیایی VL - 20 IS - 71 PY - 2020 Y1 - 2020/11/01 TI - Synoptic conditions of heavy and widespread snowfall in arid environment (case study: Kerman province) TT - تحلیل همدیدی-ماهواره ای مخاطره برف سنگین در استان کرمان N2 - Introduction Heavy snowfall impacts the ski resort industry, outdoor activities such as snowmobiling and mountain climbing, homes, transportation networks, and vegetation. In the desert environment, such events as considered an unexpected climate hazard, due to incompatibility of human societies of these areas. The purpose of this study is a comparison of two widespread snowfalls during January 2008 and 2014 in the Kerman province, Using remote sensing and reanalysis data. Our results are presented in two main sections. First the temporal variation of the snow area over the Kerman province was investigated. In the next step, synoptically condition during heavy snowfall presented using NCEP/ NCAR data set. The results of the present study can increase our knowledge about the synoptic condition of heavy and widespread snowfall over arid environments. Data and method The area of snow cover was calculated in order to determine the duration of snow cover on land surface. For this, we used from MODIS data. For analysis of synoptic reasons during heavy snowfall used from 2.5°×2.5° NCEP/ NCAR data. These data include the sea level pressure (SLP), air at the surface level, Geopotential height, Temperature of the upper levels, specific and relative humidity and uwnd and vwnd: zonal and meridional components. Results Snow cover area during January 2008 and 2014 During January of 2008 Iran has experienced a severe cold wave and more widespread snowfall, compared to the January of 2014. However, despite the severe cold wave of Iran, snow depth and area as well as the minimum temperatures of Kerman province were higher during January of 2014. The snow cover area was maximum at 16 and 17 January 2008 and 8 and 9 January 2014. Variation of daily changes in snow cover area represent important points. First, the snow precipitation was occurred during of the period, and second, temperature condition was suitable for persistence of snow cover on land. Therefore, our synoptic analysis is basis on the beginning and the end of the snow cover on the land. The maximum snow depth at Kerman station during January 2008 and 2014 were reached in 13 and 23 centimeters, respectively. In addition, the minimum temperature at this station during January 2008 and 2014 dropped to -13.8 and -20.8, respectively. Undoubtedly, differences in the minimum temperature, snow depth and area (during 2008 and 2014), can be justified in patterns of pressure on a synoptic scale. Synoptically condition during heavy snowfall Mean of Sea level pressure during the presence of maximum snow cover (16- 20 January 2008) indicates the high pressure center over eastern parts of Russia. Following this high pressure, Kerman province is covered 1025 hPa isobaric. On the other hand, there is a similar pattern during 7-10 January 2014. The correlation coefficient between two SLP maps (R= 0.86) confirms this similarity. In addition to, such similarities can be seen at zero temperature isotherm which surrounds the Kerman province. There is a trough axis over the Kerman province, both on January 2008 and 2014. However, the vorticity and relative humidity values are various during two heavy snowfall events. In the January 2014 the vorticity and relative humidity values were higher in comparison of January 2014. Conclusion The main objective of this study is an estimation of area under snow cover and synoptic condition during heavy snowfall in Kerman province. During January of 2008 the land surface temperature in throughout the Iran is significantly lower compared to the January of 2014. However, the area and depth of snow, severity of cold-temperature is higher during January of 2014. Results show that, there is a similar pattern in the sea level pressure, the thickness of the atmosphere and surface temperature during maximum snow cover in Kerman province (16 - 20 January 2008 and 7- 10 January 2014). The southerly incursions of Siberian high-pressure systems (1015 hPa over study area), 0℃ Isothermal curve and thickness of 5500 geopotentioal height was seen during either two event over the study area. The correlation coefficients between Geopotential heights at different levels is stronger in January of 2014 in comparison to January of 2008. In addition, Positive values of vorticity and relative humidity conditions was better during January 2008. All these factors caused that the snow depth and spatial distribution of snow cover were higher in the January of 2014 compared to January of 2008. This study confirms that the remotely sensed products are valuable in the synoptic climatology study. SP - 121 EP - 133 AU - rezaei, mohammad AU - Sadeghi, Ali AU - pourghayyom, Ali AD - Tarbbiat modares KW - Snowfall KW - remote sensing KW - synoptic factors KW - Kerman province UR - http://geographical-space.iau-ahar.ac.ir/article-1-3302-en.html ER -