Download The Persian Gulf 12th April 2007 dust storm

The Persian Gulf 12th April 2007 dust storm :
Observation and model Analysis
F.Taghavia*, A.Asadia
a
space physics Department, Institute of Geophysics, University of Tehran, Tehran ,IRAN
(* author for correspondence, e-mail: [email protected])
Abstract
The frequency and intensity of dust storms may likely to change in southwest of Iran near
to Persian Gulf. In recent years, several complex dust and sand storms occurred which
caused huge damage and imposed a heavy toll on society. In this study, the behavior of the
Persian Gulf 12th April dust storm is investigated using satellite images and meteorological
observations .The numerical models are also going to use to study the dynamics of this
phenomenon in order to investigate evolution and mechanism of the meteorological system
and its physical effects, such as visibility reduction, heavy winds, red sky, hailstone and
severe lightning.
Keywords: Dust storm, Persian Gulf, Satellite Image, Weather models.
1. Introduction
In recent years, several complex dust storm occurred in southwest of Iran near the Persian
Gulf (e.g. March 25 2003, April 17 2003, April 12 2007, May 17 2007) which caused huge
damage and imposed a negative impacts on traffic, air quality, and people’s daily life in local
and downstream areas . Since the 1970s, scientists have succeeded in identifying the
outbreaks of dust storms from satellite images by use of two different techniques, the VIR
(visible and near infrared) technique and the TIR (thermal infrared) window technique.
Shenk and Curran (1974) studied the detection of dust storm over land and water with
satellite visible and infrared measurement and showed that there was insufficient contrast in
the infrared measurements between clear and dust covered ocean to delineate the dust
boundaries. Idso (1976) recognized Arabia as one of five world regions where dust storm
generation is especially intense.
The Carlson (1978) results from analyses satellite brightness Data on Atmospheric Turbidity
in Saharan Dust Outbreaks revealed several interesting features of the dust outbreaks, in
particular the shape and approximate boundaries of the plume, which include a much larger
area than the visible plume as seen on the satellite photographs. The identified source regions
of dust in the atmosphere had been studied by various researchers using remote
sensing(Brooks, N., Legrand, M., 2000),surface dust observations( Herrmann,etal., 1999),
and total ozone mapping spectrometer (TOMS) (Hsu etal.,1999,Washington etal.,2003).
Barnum et al.(2003) uses the dust forecast model CARMA and found that this model is an
effective forecast tool with Probability of Detection of dust storm occurrence A sourcereceptor model has been used to identify potential source areas of mineral dust reaching
eastern Mediterranean region by Gullu et al. (2005). The TOMS data indicate that the
Middle East especially Ad Dahna erg region of eastern and central Saudi Arabia is an
important area of dust-storm activity (Washington et al., 2003).
The frequency of dust events is, in large part, the opposite of the frequency for precipitation
events. Obviously, drier, hotter conditions favor more dust storms (Leslie and Speer, 2005).
Dust storms, a kind of severe natural disaster in dust source regions, have a negative impact
human health, and industrial products and activities. They reduce visibility, layer on skin and
cloths, infiltrate buildings and find their way into food and drinking water — leaving a
permanent sandy feeling in your mouth. These events sometimes unrecognized by weather
observers and satellite images provide a useful means for detect and monitor of dust.
The aims of this study are to analyze the trends in dust storm frequency over the period
1960 to 2007 by investigating their relation first to synoptic scale circulation features over
south west Iran and, second, to compare intensity of dust storms using satellite images
features and meteorological observations.
2- Synoptic Analysis of Dust Storms in the Middle East
Major dust and/or sand storms can be produced over the Middle East. These storms occur
when the sub-tropical jet stream pushing up from south of the Arabian peninsula and a polar
front jet stream pushing down from the European continent (Fig1). These storms are most
prevalent in the spring and summer when a prevailing northwesterly wind. The unique
topography and human intervention within the region also contribute to the frequency and
intensity of dust and sand storms in this area. The natural funneling of large air masses by the
high mountains in Turkey and Iran combined with the high plateaus in Saudi Arabia, help to
funnel air across the Mediterranean into the Persian Gulf. Specifically, dust and sand storms
occur when the strong (mostly dry) storms-that often accompany well-defined cold fronts-stir
up these particles (see e.g. Forecasting Dust Storms http// www.meted.ucar.edu)
In most areas, dust storms can be classified by prefrontal and postfrontal winds that primarily
occur in the winter, and summer dust storms caused by persistent northerlies. In the winter
months, frontal passage leads to strong northwesterly winds on the backside of the front. The
resulting dust storm is referred to as a Shamal, from the Arabic for north. The Shamal
produces the most widespread hazardous weather known to the region. On 26 March 2003, a
rare heavy dust storm (with respect to the last decade) occurred in southwest of Iran. Figure
2 depicts this intense dust storm on over the Middle East by NOAA. The yellow arrows
indicated dust. This particular storm was a mid-latitude cyclonic system. Fig 3 shows a
Meteosat5 water vapor image of this storm over the Middle East and the Persian Gulf .Figure
4 shows Part of this low pressure system that is bringing showers and storms to parts of the
southwest of Iran.
Fig1: Weather map for Middle East showing
conditions for a prefrontal occurrence of
dust storms.
Fig2: NOAA 17 image depict the
intense dust storm on 26 march 2003
over the Middle East
Fig3: Meteosat5 water vapor image on 26 March
2003
Fig4: Part of a low pressure system that is bringing
showers and storms to parts of the Middle East.
3. Data and Method
In spring, the southwest of Iran is dry and often windy, providing the favorable condition
for the development of dust storms. In April 2007, a faint plume of sand storm swept
through the southwest of Iran bringing with it sand and dust from the deserts of Saudi
Arabia Home to large deposits of fine sand and silt, the Middle East produces numerous
dust storms throughout the year. This faint plume of dust is a relatively mild event with a
circular system of low pressure centered Saudi Arabia (Fig5).The most intense period of the
sandstorm occurred on April 12. Note the closely-spaced isobar lines directly over the
southwest of Iran. Figures 6 shows the IR Meteosat images of this sand storm.
Fig 5. Sea level pressure map on April 12
Fig 6. IR image of meteosat7 2007 04 12
During this sand storm event the concentration of dust particles in the atmosphere increases
significantly. The increased dust concentration produces air quality hazards along the
transportations routes and cause to cancel out the flights in all of airports in this region. To
understand the dynamics of this storm, we can consider a number of meteorological variables
collected at Ahwaz station during the 5-day period of April 10-14, 2007. Ahwaz is at 31º 20"
north latitude, 48º 40" east longitude. These variables can be retrieved from the
NCEP/NCAR Reanalysis web site .Variations in the temperature, pressure, wind , direction
and visibility for Ahwaz are shown during the study period at 1-hour intervals. In addition,
changes in dust storm occurrence are investigated using trend analysis in dust storm
frequency over the period 1960 to 2007.
4- Data processing and results:
The temperature history of Ahwaz during the dust of April 12 2007 reveals a diurnal cycle of
solar heating superimposed over the passage of fronts associated with the low-pressure
system. There are five peaks in temperature on the graph, corresponding to the 12Z hours of
the five study days. (Fig7). The hottest temperature occurred at 11Z on April 10 (34ºc),
when the fierce winds of the dust brought hot air advection from the south into the city and
surrounding areas. Hours 10 and 11 also represents the peak wind velocity (9-10m/s), with
winds blowing in from angle 160-180 degrees (south south-east). Recall from Figure 6 that
these strong winds correspond to the closely-spaced isobars on the east side of the Low. The
wind abruptly changed direction on April 12, now coming from the west south-west. This
change marks the passage of the cyclone's cold front through the area, as displayed by a drop
in temperature at the same time (27ºс -14ºс).Sea level pressure began to rise again on April
12.The results from the analysis of trends in dust storm frequency in Ahwaz station reveals
that frequency over the period (1960-2007) have increasing trend (Fig8) .In addition, the
distribution of monthly dust occurrence show that the maximum frequency of dust days is in
June and July in the period 1970-2000, but in recent years it is distributed over April to July
(Fig9).
30
Degrees C
10
20
0
20
40
Time
60
80
100
120
995
1,005
Pressure
1,015
0
21
41
Time
61
81
101
61
81
101
Time
61
81
101
Time
61
81
101
0
Wind(m/ s)
5
10
15
1
21
41
Time
0
120 Angle 240
360
1
21
41
0
VIS(km)
5
10
1
1
21
41
Fig7 .Variations in the temperature, pressure, wind , direction
and visibility for Ahwaz Station(10-14 April 2007)
a
b
No. of Dust Days in Ahwaz(1960-2000)
No. of Dust Days in Ahwaz(2000-2007)
Num ber of D ust Days
y = 0.7544x + 53.785
150
150
100
50
0
50
2007
2006
2005
2004
2003
Year
2002
2000
0
2001
92
19
84
19
76
19
19
68
100
60
19
Num ber of Dust Days
y = 0.4643x + 74.536
Year
Fig8-Trends in dust storm frequency in Ahwaz station in the period (a) 1960- 2000,(b) 20002007
b
Monthly average Dust Days in Ahwaz(1970-2000)
14.00
14.00
12.00
12.00
A v e ra g e D u s t D a y s
A v e ra g e D u s t D a y s
a
10.00
8.00
6.00
4.00
2.00
0.00
Monthly average Dust Days in Ahwaz(2000-2007)
10.00
8.00
6.00
4.00
2.00
0.00
JAN FEB MAR APR MAY JUNE JULY AUG SEP OCT NOV DEC
JAN FEB MAR APR MAY JUNE JULY AUG SEP OCT NOV DEC
Month
Month
Fig9.Monthly average dust days in Ahwaz in the period (a)1970-2000 , (b) 2000-2007
5-Conclusion:
In this study the behavior of the Persian Gulf dust storms is investigated using satellite
images and meteorological observations. .Analyses from the view point of synoptic
meteorology show that synoptic scale dust storms are related to cold front and cyclone
activities, Strong pressure gradient and well-developed baroclinicity can be found in these
weather conditions, which cause strong near-surface wind, lifting sand and dust particles to
high levels and carrying them to long distances. Results on the based time trend analysis of
dust days on southwest of Iran show increasing trend in the period 1960--2007.
Acknowledgement
We are thankful to EUMETSAT and NOAA for providing satellite data. We would like to
express our gratitude to all of the editors and reviewers.
References
Barnum, B.H. , N.S. Winstead, J. Wesely, A. Hakola, P.R. Colarco, O.B. Toon,
P. Ginoux, G. Brooks, L. Hasselbarth, B. Toth,2003:. Forecasting dust storms using the
CARMA-dust model and MM5 weather data. Environmental Modelling & Software. 19
(2004) ,129–140
Brooks, N., Legrand, M., 2000. Dust variability over Northern Africa and Rainfall in the
Sahel. In: McLaren, S.J., Kniverton, D. (Eds.), Linking Land Surface Change to Climate
Change. Kluwer Academic Publishing, Dordrecht, 1-25.
Carlson, Toby N .1979:.Atmospheric Turbidity in Saharan Dust Outbreaks as Determined by
Analyses of Satellite Brightness Data. .Monthly Weather.Rev.107,322-335.
Gullu,G.,,G.Dogan.,G,Tuncel, 2005: Source Regions of Dust Transported to the
EasternMediteranean
Proceedings of the Third International Symposium on Air Quality Management at
Urban,Regional and Global Scales. 26-30 September 2005, Istanbul – Turkey
Herrmann, L.A., Stahr, K., Jahn, R., 1999. The importance of source region
identification and their propoerties for soil-derived dust: the case of Harmattan Dust Sources
for eastern west Africa. Contributions to Atmospheric Physics, 72, 141-150.
Hsu, N.C., Herman, J.R., Torres, O., Holben, b.N., Tanre, D., Eck, T.F., Smirnou,
A.,Chatenet, B., Lavenu, F., 1999. Comparison of the TOMS Aerosol Index with SunPhotometer Aerosol Optical Thickness: Results and Applications. Journal of
Geophysical Research, 104/D6, 6269-6279.
Idso, S.B., 1976. Dust storms. Scientific American, 235 (4):108-11, 113-14
Lance M. Leslie1 and Milton S. Speer 2005:,Changes in dust storm occurrence over Eastern
Australia 1950 TO 2004, Proceedings of the Third International Symposium on Air Quality
Management at Urban,Regional and Global Scales. 26-30 September 2005, Istanbul – Turkey
Shenk,W.E.,Curran,R.J,1974.:The Detection of Dust Storms Over Land and Water With
Satellite Visible and Infrared Measurements.Monthly Weather.Rev.102,830-837.
Washington, R., Todd, M., Middleton, N.J., Goudie, A.S., 2003. Dust-storm sourceareas
determined by the Total Ozone Monitoring Spectrometer and Surface Observations, Annals
of the Association of American Geographers, 93(2), 297-313.