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1

the primary dust sources 

the Tigris and Euphrates River alluvial plain 

2

 mean threshold velocity 

10 m s−1 

3

About 86% of the high pressure systems are located in three main regions and the rest of %14 in other areas. These 14% consist of places of  

anticyclones which are far from the mentioned region and their coordinates do not exist in the selected range. The high pressure systems extended from northern Africa to central Europe. 

4

These main areas consist of: 

  • 86% high pressure systems, 43% is located in the north of Africa and south of Mediterra- nean Sea. 

    • the main place of anticyclones, which are centered in north of Libya.

    • This area extends from north of Egypt to south of Tunisia and center of Libya to center of Mediterranean Sea. 

  •  Of the 86% high pressure systems, 25% of the high pressure system is positioned from south of Bulgaria and east of Greece to east of Spain and south of France (east to west) and from south to north of Italy (south to north). 

  • The third region of high pressure system in Shamal dusty days 

    • In 18% Shamal dusty days, the high pressure system is placed on west of Ukraine 

    • This area extended from east of Ukraine to east of Germany (east to west) and from Hungary to north of Poland (south to north).  

5

................................. also play an important role in dust transport 

Along with the high pressure systems, low pressure systems

6

About .............of low pressure systems associated with the dust events are located in four areas. The remaining................ are located 

90%

10%

outside of the study domain. 

7

The low pressure areas extend from 

north-west of the Persian Gulf to the Indian subcontinent. 

8

the areas of low pressure systems associated with the Shamal dust storms, which are: 

  • The region with the highest frequency of low pressure system is located in central to southern Iran 
    • This area extends from Sistan- Bluchestan to Khuzestan of Iran (east to west) and from north of Persian Gulf and Hormuz strait to center of Iran (south to north).

    • In 44% of Shamal dusty days, the cyclone is positioned in SLP1. 

  • In 19% of Shamal dusty days, the cyclone is consist of some parts of south-east of Iran, south-west of Pakistan and south of Afghanistan.
  • In 17% of Shamal dusty days, the low pressure system is placed on SLP3 area, which extends from west of Iran and north-east of Iraq to the center of Iraq

  • In 10%  This region extends on north-east of India subcontinent with less frequency of occurrence.

9

The synoptic patterns are classified into three types. The

synoptic patterns classification is based on  

positioning of high and low pressure systems. 

10

total number of shamal dust storms

12 

11

The three types of synoptic pattern are as follows: 

  • Type 1: 29%  the extension of a high pressure system over northern Africa and Libya 
  • Type 2: 17% of the Shamal dust storms belongs to this category. The main feature of Type 2 is the extension of a high pressure system from south to south-east of Europe 
  • Type 3: 14% of the Shamal dust storms belongs to this category. The main feature of Type 3 is the extension of a high pressure system from center to east of Europe 

 

12

Type 1: 29% of the Shamal dust storms belongs to this category. The main feature of Type 1 is the extension of a high pressure system over northern Africa and Libya 

wind direction

The wind direction over the Tigris and Euphrates alluvial plain is northwesterly and westerly over Syria and Iraq and the emitted dust is transported to west and center of Iran by the westerly winds associated with the low and high- pressure systems.  

13

Type 1: 29% of the Shamal dust storms belongs to this category. The main feature of Type 1 is the extension of a high pressure system over northern Africa and Libya (described in SHP1). The wind direction over the Tigris and Euphrates alluvial plain is northwesterly and westerly over Syria and Iraq and the emitted dust is transported to west and center of Iran by the westerly winds associated with the low and high- pressure systems. Because of the position of the cyclone 

dust can be transported to east and north-east of Iran. The most destructive dust storms observed in Iran are associated with this synoptic pattern 

14

Type 2: 17% of the Shamal dust storms belongs to this category. The main feature of Type 2 is the extension of a high pressure system from south to south-east of Europe (described in SHP2). The wind direction  

over the Tigris and Euphrates alluvial plain is northwesterly and northerly over Syria and north of Iraq. The wind direction changes from north-westerly to westerly in west of Iran and dust may be transport to west and center of Iran by the westerly winds. 

15

Type 2: 17% of the Shamal dust storms belongs to this category. The main feature of Type 2 is the extension of a high pressure system from south to south-east of Europe (described in SHP2). The wind direction over the Tigris and Euphrates alluvial plain is northwesterly and northerly over Syria and north of Iraq. The wind direction changes from north-westerly to westerly in west of Iran and dust may be transport to west and center of Iran by the westerly winds. A portion of the emitted dust may be 

transported to the southeast of the Arabian Peninsula and southern Iran by the north-westerly winds.

16

Type 3: 14% of the Shamal dust storms belongs to this category. The main feature of Type 3 is the extension of a high pressure system from center to east of Europe (described in SHP3). The wind direction 

over Tigris and Euphrates alluvial plain is northwesterly and northerly over northern Iraq and dust is transported to the west, south-west and south of Iran by the north-westerly winds. 

17

Frontal dust storm 

About 86% of the high and low pressure systems are grouped into a distinct region. The rest 14% are located outside of the study domain.  

18

The low pressure system is placed between 28oE to 48oE and 32oN to 43oN (FLP). This region extends 

east to west from north-west of Iran to west of Turkey and south to north from north of Jordan and east of Mediterranean Sea to center of Black Sea. 

19

The low pressure system is placed between 28oE to 48oE and 32oN to 43oN (FLP). This region extends east to west from north-west of Iran to west of Turkey and south to north from north of Jordan and east of Mediterranean Sea to center of Black Sea. The corresponding high pressure system is  

placed between 51oE to 67oE and 18oN to 33oN (FHP). This region extends east to west from south and south-west of Pakistan to west of Qatar and south to north from east of Oman to west of Afghanistan and east of Iran.  

20

About 82% of the frontal dust storms are associated with  

this distinct synoptic pattern. 

21

About 82% of the frontal dust storms are associated with this distinct synoptic pattern. 

This pattern generates  

prefrontal dust storms in southern Iraq, Kuwait and the Khuzestan Plain of Iran.  

22

This pattern generates prefrontal dust storms in southern Iraq, Kuwait and the Khuzestan Plain of Iran. The most famous postfrontal dust storm is a 

Winter Shamal dust storm that occurs in central and northern Iraq. 

23

This pattern generates prefrontal dust storms in southern Iraq, Kuwait and the Khuzestan Plain of Iran. The most famous postfrontal dust storm is a Winter Shamal dust storm that occurs in central and northern Iraq. Due to  

 the direction of frontal winds, the emitted dust can be transported north-eastwards to western and central Iran and in some severe cases; the dust plume reaches the south coast of the Caspian Sea.  

24

According to the synoptic analysis, the frontal edge extends from  

south-east of Red Sea to north- west of Persian Gulf in 68% of the analyzed frontal dust storms. 

25

Synoptic scale dust storms in the Middle East were classified in two main categories:  

Shamal (Summer Shamal) and

frontal dust storms. 

26

Shamal is 

the main type of synoptic dust storms in this region. The highest frequency of Shamal is in June and July. 

27

The high pressure systems associated with 

68% of the dust storms are located between 0oE to 30oE and 27oN to 45oN extending east to west from north of Egypt to east of Spain and south of France and south to north from center of Libya to north of Italy. 

28

The high pressure systems associated with 68% of the dust storms are located between 0oE to 30oE and 27oN to 45oN extending east to west from north of Egypt to east of Spain and south of France and south to north from center of Libya to north of Italy. Also, low pressure systems in  

67% of dust storms located between 50oE to 70oE and 23oN to 43oN (SLPM) extending from center of Pakistan to north-west of Persian Gulf (east to west) and from north-east of Oman to north-east of Iran and south-east of Turkmenistan (south to north) 

29

Three main patterns for Shamal dust storm were identified. 

About 60% of Shamal dust storms can be classified in these three main types 

30

This analysis confirms that the Shamal dust storm incorporates with  

Anticyclones over north of Africa to east of Europe and Monsoon trough over Iraq, south of Iran and Pakistan and India subcontinent.