جستجوی مقالات مرتبط با کلیدواژه "کم فشار دینامیک" در نشریات گروه "جغرافیا"

One of the most important conditions to have dusty weather beside of unstable weather is existence or non-existence of humidity. Unstable weather having enough humidity will produce rain and thunder storm, else if the result will be dust storm. Number of particles of dusty storm is depended to wind speed, sec of soil and its dimension. Furthermore, vegetation type has importance on dust storms. Vision reduction is one of the main causes of dust storm beside of inspiration problem, environmental pollution and airline traffic. In the recent years, a lot of flights especially in west and south-western part of Iran have been cancelled because of dusty storm. One of the criteria to measure dusty storm is vision ability. Recently, Kermanshah has a growth in industrial development, urbanization and transportation that cause increasing of pollutant elements in atmosphere. Pollutant density causes major problems for citizens of Kermanshah especially elderly, infant and sick people. Thus, studies and analyses of air pollution and its causes are necessary in Kermanshah. In this paper, the cause of air pollution from synoptic sight is carefully considered.

Kermanshah is the capital of Kermanshah province and is located in west of Iran. This city is one of the seventh biggest major cities in Iran and has population around one million. Longitude of this city is 47/3 and its latitude is 34/13 and the altitude from see is about 1300 meter. Irregular development of the city, increasing of transportation vehicles and industrial development beside of entrance of dusty in recent years becaus e intensifying of air pollution in this city.

In this paper we are focused on pollution and present of synoptic algorithms using by synoptic ground level maps and upper level of atmosphere data.
1. Air pollution data is depending on environmental protection organization of Kermanshah obtained from control center in Zibapark between 1385-1386 years.
2. Data of metrology is obtained from metrology organization of Iran.
3. Average of daily air pressure maps in 700 hpa level is obtained from NOAA organization site.
4. SkewTcharts for different hours are obtained from Wyoming University in USA.
The method in this paper is synoptic approach consist of the following steps:1. Suitable Station selection for this study is synoptic station in Kermanshah and air pollution station of environmental protection organization located in Ziba park of Kermanshah
2. Detection and study of weak and strong of pressure systems that affects the air pollution of Kermanshah
3. Determination of polluted days in period of hourly and daily basis for pollutants as NO, NO2, etc….Based on air pollution standard index (PSI).
Based on daily and hourly data of air pollution, air pollution period events in each month in statistic periods have been determined and the charts have been prepared. Following, based on sequence of days with pollution, air polluted periods has been determined. Then, based on synoptic map, ground level and upper atmosphere, the condition of pressure systems are considered. With detection of trajectory of pressure system and their impacts on weakness and strong of air pollution in Kermanshah, the dependent patterns have been presented.

In this study, retrieve of pressure centers beside of its origins and trajectory of pressure system that affect air pollution in periods of pollution based on pollutant have been studied. In this regards, affected pressure system from average pressure maps for 3 and 4 days waves from NOAA organization have been details studied. With study of pressure maps in ground level and adaptability with average pressure maps in altitude of geopotential levels of 850,700 and 500 hpa affective systems on air pollution have been detected. Regarding to similarity behavior of trajectory of air pollution in each pressure system, one the periods as sample and index have been selected. Then, more details of behavior of each system have been detected and finally the main affective system on air pollution has been identified. Regarding to, array of systems in ground level and upper levels of atmosphere and also synoptic and dynamics condition are placed in three main groups. They are called as A, B and C patterns.
In A pattern, a high pressure center, European dynamic high pressure with central pressure of 1035 hpa will be establishes in the region. Eastern movement of this system from north-western and south- western of Europe and north of black sea cause in western region govern of Iran and Kermanshah too.
This system, in following days moves towards eastern part. In critical days of air pollution with rotation of this high pressure cell, pole cold weather will be combined with cold weather of Caucasus. Thus, a cold weather will govern the region. This condition, cause stable weather and inversion of temperature and will increase the air pollution of Kermanshah.
The second pattern B shows in the critical days of air pollution, the different condition will govern in the ground level and upper levels of atmosphere in region. Maps and charts shows that in commence and pick of air pollution of Siberian high pressure will come to the region and intensify and stability and air pollution in Kermanshah. Ground cooling, losses of long wave radiation, shortage of cloud in sky, no mixture of in atmosphere and stability of air; establish an unpleasant condition in point of air pollution.
The C pattern of air pollution is completely different compare to two last patterns.In the last two patterns, air stability and high pressure system cause intensifying of air pollution in the city. While in the this pattern that can be called as low pressure, instability intensifying cause intensifying of air pollution in the city. Pollutant kind that can be called dust pollutant, are different in this pattern. Thus, we can conclude that their origin is based outside of Iran frontier.

Investigation of intensifying of air pollution in periods of study and temperature inversion shows that the second pattern has the maximum pollutant compare to others. The reason is in specification of air mass responsible for these systems. In the second pattern, weather dynamic subsidence cause strong temperature inversion in level of 850 hpa. Thus, an inversion layer will be established and intensify the air pollution. In the first pattern that will happen mostly in the winter, temperature is lower compared to the second pattern. The humidity of temperature is higher in A pattern compared to others.
In the most days of a pattern, humidity is high and in the most of times is combined with fog. While in the B pattern, for the reason of entrance of air mess from pole toward region, and also the cold weather from Siberian high pressure cause weather become dry.
In the C pattern, because of the strong instability in the different level of atmosphere cause reduction of continuity of air pollution and doesn’t last more than half day. The other point has to be considered is the direction of wind in the air pollution. The study of wind direction shows that wind direction is similar in all the patterns. In the most times, wind comes from west, North West and south western of Kermanshah. It is clear that topographical situation in Kermanshah has causes this situation .This point has to be considered in urbanization and industrial development considered by responsible organization and managers.