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Distribution of dust particles with wind direction in Baghdad
Solar & WindTechmdogvVol. 7, No. 4, pp. 495M.96.1990 Printed in Great Britain.
0741 983X/90 $3.00+.00 PergamonPresspie
TECHNICAL NOTE Distribution of dust particles with wind direction in Baghdad A . A . A L - B A A L I , S. A L - J U B O O R Y , N . A L - H A M D A N I a n d
M. AL-RIAHI
Solar Energy Research Center, Scientific Research Council, Jadiriyah, P.O. Box 13026, Baghdad, lraq (Received 4 July 1989; accepted 5 September 1989)
A b s t r a c ~ I r a q and neighbouring countries lack protective cover of vegetation, they are also subject to fresh or strong winds. Moreover, unstable conditions are more frequent in spring and summer therefore vertical motion of air takes place in these two seasons. A large a m o u n t of dust and sand, which is very frequent in Iraq is raised and carried by the south-east and north-west winds. In this paper distribution of dust is studied and correlated with the wind direction during April and May of 1989 where the dust and duststorms are concentrated in these two seasons. The data were obtained from several dust samples measured at four different periods during the day using a high volume dust sampler which is located in the south section of down-town Baghdad at an altitude of 20 m above ground level and at least 100 m away from any potential air pollution source.
INTRODUCTION Dust and duststorms are a c o m m o n phenomenon in all arid and semiarid regions, and Iraq suffers from this environmental problem especially in spring and s u m m e r [1]. This is mainly due to the strong surface winds and the occurence of vertical movement of the air during these two seasons. Dust, which is considered as a major natural pollutant source [2, 3], has diverse effects on the solar system [4-6], health, visibility [7], composition of soil and plants, in addition to system design and related topics [8]. The problems of dust were investigated by many workers around the world, their work tackled such factors as size distribution of ground- and airborne-particles [9], mass concentration, frequency distribution of all types of dust [101, chemical and mineral composition of settling particles collected during dust storms [11, 12], etc. Different dust problems in Iraq were investigated in the Solar Energy Research Center, Solar Physics Laboratory, which was established in 1986. The output of these studies helped to shed light on some of the characters of the phenomenon and pin-point their relation to other variables and define the needs for further research. In the present work frequency distribution of all types of dust was studied as a function of wind direction, and the distribution of dust concentration with wind direction was investigated for the period between 1 April and the middle of June, since wind is one of the most important meteorological factors related to d u s t ~ u e to the role of wind raising and transporting dust.
E X P E R I M E N T A L DETAILS The samples were taken at an interval of 6 h and at the height of 20 m above ground level using a programable digital high volume dust sampler type DH-80 with controlled flow rate and automatic exchange of filters of up to 15 cassettes. The dust was deposited on cellulose and membrane filters. The samples of dust were collected during several days, 495
under normal and storm conditions and at the site of the Iraqi Solar Energy Research Center which is located in the south section of down-town Baghdad. The desired volume of air, in litres per minute, was preselected on the flow rate meter, and the selected sample volume was 1000 l/min. The variation of the concentration of dust with respect to the wind direction was studied in this work. Data of wind direction were obtained from an Automatic Weather Station (FA 510 Wilh. Lambrecht GmbH), which is located in our center. D I S C U S S I O N AND C O N C L U S I O N The frequency of wind direction over Baghdad for the m o n t h of April, and for the period of 1960 1980 is shown as follows. N 13.2
NE 6.8
E 6.4
SE 16.7
S 5.0
SW 4.4
W 9.6
NE 24.6
Calm 14.2
This indicates that SE and N W directions are the two main wind directions dominant in Baghdad during the m o n t h of the study. The variation of dust concentration obtained from different dust samples measured at four different periods during the day (00:00~06:00), (06:00-12:00), (12:00 18:00) and (18:00~24:00) respectively, were studied in this work with respect to the wind direction. Figure 1 shows that the dust is mainly distributed in a SE and N W direction. This is completely compatable to the long term frequency of wind direction over Baghdad, which is mentioned above. These distributions are 17%, 48.5%, 13.5% and 21% for the directions NE, SE, SW and NW, respectively. Dust distribution depends also on the vegetation cover and the rocky structure of the surface. For instance, in the case of the N W direction, the structure type of the land which the wind passes over is either rocky or covered with vegetation. Hence in spite of the high frequency of a N W
496
Technical Note
360
(NW)
*
~"
270 (SW) ~e o H E-, L)
180 tt
,7
(SE)
9O w
(NE)
i
I
i
I
I
I
5
10
15
20
25
30
315
i
,
i
i
40
45
50
55
X 10-2
CONCENTRATION
Fig. 1. Distribution of dust concentration within different ranges of wind direction.
wind, the sample concentration frequency is lower than the SE wind. This is due to the lack of vegetation cover, and of rocky structures and a relatively small a m o u n t of rainfall comes from the SE direction. In order to expose the seasonal variation under different weather parameters, statistical analysis of dust distribution with respect to wind speed, wind direction and composition of dust particles, can be made when further measurements are obtained for a longer period of more than two years. REFERENCES
1. N. I. A1-Hamdani, M. A. A1-Abbasi and A. A. A1-Baali, Analysis of the dust parameters in Baghdad during the period 1962~ 1984. Proc. 4th Scientific Con£, Scientific Research Council, Baghdad, Vol. 3, pp. 421 436 (1986). 2. S. B. ldso, J. Air Pollution Control Assoc. 22, No. 5 (1971). 3. S. B. ldso, Atmos. Environ. 5, 599 604 (1971). 4. N. I. A1-Hamdani, A. A. A1-Baali and F. S. Hasson, J. Heliograph 4, 33 37 (1988).
5. R. M. Bethea, M. T. Barriger, P. F. Williams and S. Chin, Solar Energy 27, 479 51 l (1981). 6. Fu-Tien Jeng and J u n - C h a n g Iee, J. Chinese Inst. Engng (Taiwan) 7, 81-99 (1984). 7. Riyad Irani and Clyton Callis, Particle Size Measurement, Interpretation and Application. John Wiley (1963). 8. IBM Technical Disclosure Bulletin (U.S.A.), Vol. 28, No. 11, 50312 (1986). 9. S. B. Golentskly, T. N. Zhigalovskaya and S. I. Golentskaya, Institute of Experimental Meteorology, Obninsk, Pochvoedeniy, No. 2, pp. 4 1 4 8 (1981). 10. M. 1. Safar, Dust and duststorms. Meteorological Department, Directorate General of Civil Aviation, Kuwait (1985). 11. E. G a n o r and Y. Mamane, Atmos. Environ. 16, 581 587 (1982). 12. A. A. AI-Baali, N. 1. Al-Hamdani, Z. Abdul Ridha and M. A1-Riahi, Scanning electron microscope examination of dust particles in Baghdad. Proc. 5th Scienti~ Con~i, Scientific Research Council, Baghdad (1989).
0741 983X/90 $3.00+.00 PergamonPresspie
TECHNICAL NOTE Distribution of dust particles with wind direction in Baghdad A . A . A L - B A A L I , S. A L - J U B O O R Y , N . A L - H A M D A N I a n d
M. AL-RIAHI
Solar Energy Research Center, Scientific Research Council, Jadiriyah, P.O. Box 13026, Baghdad, lraq (Received 4 July 1989; accepted 5 September 1989)
A b s t r a c ~ I r a q and neighbouring countries lack protective cover of vegetation, they are also subject to fresh or strong winds. Moreover, unstable conditions are more frequent in spring and summer therefore vertical motion of air takes place in these two seasons. A large a m o u n t of dust and sand, which is very frequent in Iraq is raised and carried by the south-east and north-west winds. In this paper distribution of dust is studied and correlated with the wind direction during April and May of 1989 where the dust and duststorms are concentrated in these two seasons. The data were obtained from several dust samples measured at four different periods during the day using a high volume dust sampler which is located in the south section of down-town Baghdad at an altitude of 20 m above ground level and at least 100 m away from any potential air pollution source.
INTRODUCTION Dust and duststorms are a c o m m o n phenomenon in all arid and semiarid regions, and Iraq suffers from this environmental problem especially in spring and s u m m e r [1]. This is mainly due to the strong surface winds and the occurence of vertical movement of the air during these two seasons. Dust, which is considered as a major natural pollutant source [2, 3], has diverse effects on the solar system [4-6], health, visibility [7], composition of soil and plants, in addition to system design and related topics [8]. The problems of dust were investigated by many workers around the world, their work tackled such factors as size distribution of ground- and airborne-particles [9], mass concentration, frequency distribution of all types of dust [101, chemical and mineral composition of settling particles collected during dust storms [11, 12], etc. Different dust problems in Iraq were investigated in the Solar Energy Research Center, Solar Physics Laboratory, which was established in 1986. The output of these studies helped to shed light on some of the characters of the phenomenon and pin-point their relation to other variables and define the needs for further research. In the present work frequency distribution of all types of dust was studied as a function of wind direction, and the distribution of dust concentration with wind direction was investigated for the period between 1 April and the middle of June, since wind is one of the most important meteorological factors related to d u s t ~ u e to the role of wind raising and transporting dust.
E X P E R I M E N T A L DETAILS The samples were taken at an interval of 6 h and at the height of 20 m above ground level using a programable digital high volume dust sampler type DH-80 with controlled flow rate and automatic exchange of filters of up to 15 cassettes. The dust was deposited on cellulose and membrane filters. The samples of dust were collected during several days, 495
under normal and storm conditions and at the site of the Iraqi Solar Energy Research Center which is located in the south section of down-town Baghdad. The desired volume of air, in litres per minute, was preselected on the flow rate meter, and the selected sample volume was 1000 l/min. The variation of the concentration of dust with respect to the wind direction was studied in this work. Data of wind direction were obtained from an Automatic Weather Station (FA 510 Wilh. Lambrecht GmbH), which is located in our center. D I S C U S S I O N AND C O N C L U S I O N The frequency of wind direction over Baghdad for the m o n t h of April, and for the period of 1960 1980 is shown as follows. N 13.2
NE 6.8
E 6.4
SE 16.7
S 5.0
SW 4.4
W 9.6
NE 24.6
Calm 14.2
This indicates that SE and N W directions are the two main wind directions dominant in Baghdad during the m o n t h of the study. The variation of dust concentration obtained from different dust samples measured at four different periods during the day (00:00~06:00), (06:00-12:00), (12:00 18:00) and (18:00~24:00) respectively, were studied in this work with respect to the wind direction. Figure 1 shows that the dust is mainly distributed in a SE and N W direction. This is completely compatable to the long term frequency of wind direction over Baghdad, which is mentioned above. These distributions are 17%, 48.5%, 13.5% and 21% for the directions NE, SE, SW and NW, respectively. Dust distribution depends also on the vegetation cover and the rocky structure of the surface. For instance, in the case of the N W direction, the structure type of the land which the wind passes over is either rocky or covered with vegetation. Hence in spite of the high frequency of a N W
496
Technical Note
360
(NW)
*
~"
270 (SW) ~e o H E-, L)
180 tt
,7
(SE)
9O w
(NE)
i
I
i
I
I
I
5
10
15
20
25
30
315
i
,
i
i
40
45
50
55
X 10-2
CONCENTRATION
Fig. 1. Distribution of dust concentration within different ranges of wind direction.
wind, the sample concentration frequency is lower than the SE wind. This is due to the lack of vegetation cover, and of rocky structures and a relatively small a m o u n t of rainfall comes from the SE direction. In order to expose the seasonal variation under different weather parameters, statistical analysis of dust distribution with respect to wind speed, wind direction and composition of dust particles, can be made when further measurements are obtained for a longer period of more than two years. REFERENCES
1. N. I. A1-Hamdani, M. A. A1-Abbasi and A. A. A1-Baali, Analysis of the dust parameters in Baghdad during the period 1962~ 1984. Proc. 4th Scientific Con£, Scientific Research Council, Baghdad, Vol. 3, pp. 421 436 (1986). 2. S. B. ldso, J. Air Pollution Control Assoc. 22, No. 5 (1971). 3. S. B. ldso, Atmos. Environ. 5, 599 604 (1971). 4. N. I. A1-Hamdani, A. A. A1-Baali and F. S. Hasson, J. Heliograph 4, 33 37 (1988).
5. R. M. Bethea, M. T. Barriger, P. F. Williams and S. Chin, Solar Energy 27, 479 51 l (1981). 6. Fu-Tien Jeng and J u n - C h a n g Iee, J. Chinese Inst. Engng (Taiwan) 7, 81-99 (1984). 7. Riyad Irani and Clyton Callis, Particle Size Measurement, Interpretation and Application. John Wiley (1963). 8. IBM Technical Disclosure Bulletin (U.S.A.), Vol. 28, No. 11, 50312 (1986). 9. S. B. Golentskly, T. N. Zhigalovskaya and S. I. Golentskaya, Institute of Experimental Meteorology, Obninsk, Pochvoedeniy, No. 2, pp. 4 1 4 8 (1981). 10. M. 1. Safar, Dust and duststorms. Meteorological Department, Directorate General of Civil Aviation, Kuwait (1985). 11. E. G a n o r and Y. Mamane, Atmos. Environ. 16, 581 587 (1982). 12. A. A. AI-Baali, N. 1. Al-Hamdani, Z. Abdul Ridha and M. A1-Riahi, Scanning electron microscope examination of dust particles in Baghdad. Proc. 5th Scienti~ Con~i, Scientific Research Council, Baghdad (1989).