Nivar

Nivar

Synoptic -Dynamic study of Snow Shower in North Khorasan During 2011-2013, (Case study: Snow Shower Over Bojnurd)

Authors
Mehri Hashemi Devin 1
Ali Elahi Gol 2
Mostafa Hadizadeh 3
1 PhD student of Meteorology, Head of North Khorasan Forecasting Division,cyclone
2 PhD student of Meteorology, senior forecaster, North Khorasan Meteorological Administration
3 Senior Forecaster, North Khorasan Meteorological Administration
10.30467/nivar.2020.125306.1084
Abstract
Snow shower is the phenomena that caused problems in mountainous roads of North Khorasan province. The goal of this paper is the analysis of three case studies of snow shower in Bojnurd during 2011-2013. We used Bojnurd synoptic data to determine three snow shower case studies during 2011-2013 and then analyzed using synoptic maps of surface, 850, 500, and 300 hpa. Dynamical analysis is done by using sodar output data, helicity, the cross section of relative humidity and vertical wind speed. The maximum value of helicity was 348 (m2/s2) on 17.3.2012 which show sever instability during this phenomena. The vertical wind speed from sodar data in the third case study is very similar to meso scale shear instability. The cross section of vertical wind speed and humidity shows an increasing in relative humidity that accompanying with improvement in upward and downward motions which increase instabilities in the clouds and increase snow shower. Finally we concluded that atmospheric instabilities such as temperature reduction, increase in pressure, humidity and wind speed, increasing in helicity, suddenly changes in wind speed and direction which improve instabilities are the main factors of the formation and intensification of snow showers in the region.
Keywords
Snow Shower
Bojnurd
Sodar
Helicity
Mesoscale Shear Instability
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  • Receive Date 17 March 2018
  • Revise Date 12 January 2020
  • Accept Date 12 May 2020
  • Publish Date 20 March 2020