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Study on Dust Storms Climatological Trends,
Transportation Paths and Source Identification
Dr. Silvia 
Alonso-Pérez , Consultant ,Climate Modeling Specialist
Spanish Meteorological Agency (AEMET)
[email protected]
Prof. Dr. Moutaz A.M. Al-Dabbas , Sedimentology and Dust Mineralogy
,College of Science, University of Baghdad, IRAQ
[email protected]
Dr Abdulkareem Abd Ali Mohammed, Remote Sensing and Satellite Imagery
Remote Sensing and Space Centre-Ministry of Science and Technology
[email protected]
Dr Tahir Hassan Hantosh, Ground Observation and Meteorological Aspects
Department of Meteorology and Seismology –Ministry of Transport
[email protected]
Study on Dust Storms Climatological Trends,
Transportation Paths and Source Identification
Introduction
Mineral dust is the most important source of natural aerosols in the
atmosphere and can be of natural or anthropogenic origin. Natural mineral
dust particles from arid and semiarid regions of the Earth can be lifted to
the atmosphere if the wind velocity is higher than the wind friction
velocity, which depends on both the soil type and the presence of
roughness elements over the erodible surface .
Anthropogenic dust generated by human activities as farming, changes in surface
water, transportation and other industrial activities and desertification due to
anthropogenic climate change represents up to 20% of the total dust content in
the atmosphere, 71% of the total aerosol mass load of the Earth is generated from
natural mineral dust sources in arid and semiarid areas .
Study on Dust Storms Climatological Trends, Transportation Paths and
Source Identification
Mineral dust
impacts
Mineral dust also significantly impacts in human health , transportation
due to damages in aircrafts and train railroads, and biochemical cycles of
both oceanic and terrestrial ecosystems mainly by the deposition of dust.
The effects of the atmospheric particulate matter on health have been
assessed through epidemiologic studies since the 1980 decade, showing
that there is a clear relationship between particulate matter concentrations
and the number of daily deaths and hospitalizations due mainly to
respiratory and cardiovascular diseases. The effects of mineral dust
include causation and aggravation of respiratory and cardio-respiratory
diseases (asthma, allergic rhinitis, severe chronic obstructive lung diseases
heart failure and heart disease, fibrosis, lung cancer and cancer of the
pleura), allergies and eyes infection. Toxic chemicals, bacteria and fungi
may also contaminate dust, so these chemicals and microorganisms can
also adversely affect the health of people when deposited on the skin,
swallowed or inhaled.
Climate of Iraq
Due to its hot and dry climate, desert areas cover about 60% of
Iraq. Soils in these arid and semi-arid regions are susceptible of
being lifted to the atmosphere if winds are higher than the wind
friction velocity, causing dust storms. During summer, two
kinds of winds phenomena occur, namely sharqi and shamal.
Sharqi are south or southeast dry winds, which often lead to
dust storms. It occurs during summer, mainly from April to
June and also from late September to November. Shamal winds
occur from mid-June to mid-September, coming from north and
northwest. This kind of wind can last three to five days in
winter or almost daily in summer, being strongest during the
day and less intense at night. As Sharqi, Shamal winds also
cause dust storms. Mean annual dust storm days during the
period 1951-1990 across Iraq are shown in Table A1.
Climate of Iraq
Clear Definition of
Sand and Dust Storms
"The difference among sand storms and dust storms relies in
the type of particulate matter lifted by winds, which depends
on the type of soil. The term sand storm is usually used in the
context of desert or places where sand (particles with average
diameters between 2.0 and 0.06 mm) prevails over other type
of soils . In sand storms, in addition to fine particles, large
sand particles are blown closer to the surface, typically to
height of no more than 15 m.
The term dust storm is used for the dust episodes where finer
particles (particles of silt and clay with average diameters
less than 0.06 mm), which can travel long distances, are lifted
to the atmosphere."
Types of Sand Dust Storms
in IRAQ
Shamal Dust Storms
In Iraq, two types of dust storms stand out, the shamals and
the haboobs, although frontal dust storms also occur.
The shamal dust storms are caused by the northerly winds;
occur in the summer, from mid-June to mid-September, and
during winter, from late September to November. Depending
on the season, its characteristics are quite different due to
specific dynamical processes. Shamal dust storms are the
most severe both in horizontal and vertical extent in Iraq, and
extreme visibility reductions up to 0 m occur during some
winter events .
A small number of shamal dust storms are not caused by frontal
systems, but by the funneling of very cold air masses coming from
Turkey or Syria towards the southern area of the Tigris/Euphrates
River valley in Iraq and also over the Gulf .
Types of Sand Dust Storms
in IRAQ
Haboobs Dust Storms
Haboobs are strong convective sand dust storms, that reduce
the visibility very drastically, frequently to less than 200 m.
They occur during the late fall and spring, and they are
difficult to monitor and forecast because of its short temporal
and spatial scales. The spatial extensions of haboobs are
usually of no more than 100-150 km. In Iraq, this kind of dust
storms is associated with thunderstorms, which generate
downrush winds resulting in giant walls of dust with average
heights of 1.5 to 2.5 km.
Types of Sand Dust Storms
in IRAQ
Frontal Dust Storms
Three types of frontal dust storms exist:
Prefrontal, postfrontal and shear-lines.
The prefrontal dust storms are those caused by the southerly sharqi
winds. These dust storms occur because of the movement of low
Pressure areas across an area comprising Jordan, Palestine, the
Northern Arabian Peninsula, Iraq and the western Iran.
The velocity of the sharqi winds is lower than those of the shamal.
The postfrontal dust storms take place during winter, when northerly
or northwesterly winds under shamal conditions blows on the
backside of a cold front that crosses dust source areas.
Frontal dust storms caused by shear-lines are frequent in winter
Across the Arabian Peninsula and the Red Sea, but this is not a type
of dust storm common in Iraq.
Dust sources and
transport
Many studies have been carried out, both globally and regionally, to
identify mineral dust sources in arid and semi-arid regions.
All these studies highlight the Middle East as an important dust source.
In fact, this region is the second largest dust source after the Sahara desert,
and Iraq stands as the country with the higher number of dust storms
per year within this geographical area.
Most of the studies were monitor dust events and identify dust sources
over Iraq make extensive use of satellite imagery (MODIS imagery).
An identification of dust sources were found and located in the northwest
and in the alluvial plain between the Tigris and Euphrates rivers.
Dust sources and
transport
A recent study of surface meteorological data and Meteosat-9 color
composite imagery, with also Cloud-Aerosol Lidar with Orthogonal
Polarization (CALIOP) data to characterize in both its horizontal and
vertical extent 18 dust storms occurred from March to December 2011.
Eight dust sources across Iraq were identified, seven of them distributed
between the Aljazeera area, southern Iraq between the Tigris and
Euphrates Rivers and in the southern desert. The remaining dust
source was identified in the northeast of Iraq, a mountainous area
where dust storms rarely originate.
The latter may have been formed because of the scarcity
of rainfall during some years before 2011, which lead to a gradual
formation of a barren area where soils can be disjointed
by winds from 9 m/sec.
Dust sources and
transport
Different composite images from the MODIS sensor have been used to
identify gypsiferous soils as dust sources, using the MODIS images and
an unsupervised classification method. Regarding the rise of new dust
sources in Iraq, the new dust sources are being formed because the
increasingly number of exposed lakes and marsh were dried and due to
recent changes in land use. This increasingly number of dust sources
was found to be followed by an increase of dust episodes occurrence in
recent years.
Analysis of dust transport based on dust storm occurred on 25 March 2011
in southern Iraq using true color composite images from the SEVIRI
instrument aboard the Meteosat-9 satellite; show that the resulting speed
of the dust storm was 37.62 km/h.
Chemical, mineralogical and allergenic composition of dust
The particle size analysis indicates that 72% of the samples were sandy
clayey, and 28% clayey sandy silt. 80% of the quartz grains were
sub-rounded, while the remaining 20% was rounded. X-Ray diffraction
analysis reveals that the dust samples were composed of quartz, feldspars
and calcite, with small amount of gypsum. Chlorite, illite, montmorillonite
palygorskite and kaolinite, all of them within the group of clay minerals,
were also identified in the samples. The analysis of toxic trace heavy
metals concentration on the dust samples results reflects that many
such as Pb ,Ni, Cd, Fe, Cu, Co, and Zn were in good agreement with
other studies of heavy metals concentration in soils, sand dunes and dust
storms. Results regarding pollen content indicate that he most common
pollen in the samples was Chenopodiaceous, followed, in descending
order, by Gramine, Pine, Artemisia, Palmae, Olea and Typha.
Some microorganisms were also identified in the samples, being the most
common the gram-positive Bacillus (40.6%).
Vertical Structure
of the Dust Layer
The CALIOP lidar instrument aboard the Cloud-Aerosol Lidar
and Infrared Pathfinder Satellite Observations (CALIPSO)
satellite was designed to acquire vertical profiles of elastic
backscatter from a near nadir-viewing geometry at two
wavelengths (532 nm and 1064 nm), operating during both day
and night phases of the orbit.
During the dust storms occurred in June 2011, the top of the
dust layer was estimated to be at a height of about 3 km. During
the second dust storm, which occurred in August 2011, the top
of the dust layer reached heights about 2-3 km.
Many authors have studied the seasonal variability and long-term trends
of dust at both global or regional scale, using in-situ particle
concentration measurements, in-situ horizontal visibility measurements
and/or remote sensing data. Evaluated global and regional Aerosol
Optical Depth (AOD) trends in view of aerosol emission changes
during the period 2000-2009 and AOD data from different remote
sensing sensor, namely MODerate resolution Imaging Spectro
radiometer (MODIS), Multi-angle Imaging Spectro Radiometer (MISR)
and also from sunphotometers of the AErosol RObotic NETwork
(AERONET) network was used. For the estimation of emissions they
used data from the Co-operative Programme for Monitoring
and Evaluation of the Long-range Transmission of Air Pollutants in
Europe (EMEP), Region Emission Inventory for Asia (REAS)
and Intergovernmental Panel on Climate Change (IPCC) inventories.
Climatology and
trends of dust in Iraq
Studies of the long-term spatio-temporal variability of both dust
storms occurrence and dust source areas have been made
specifically for the Middle-East by analyzing visibility reduction
records in that region. Show that the major dust activity area in
the Middle East is the Lower Mesopotamian plains in Iraq,
where the highest frequency of dust episodes occurrence were
found from spring to summer. Also , four main regions within
the Middle East were identified, one of them being Iraq.
Regarding Iraq, they conclude that dust storms in the northeast
of the country are more frequent in summer, while in western
Iraq they mainly occur in spring.
Impact of dust
on health in
Iraq
Although epidemiological studies of dust-related diseases have been
made for countries in the Middle East. During an intense dust storm
occurred in 11 April 2008 in Iraq, which covered 75% of the country,
many people had to be attended in hospitals due to sustaining
breathing problems. Epidemiological studies of military personnel show
that from the most common respiratory illness to other diseases as the
Al Eskan, also known as the Gulf syndrome, could be related to inhalation
of high concentrations of dust in Iraq.
Impact of dust
on health in
Iraq
Of 15,459 surveyed military personnel, 69.1% of them reported at least
one form of respiratory illness. In 17.0% of the cases, those affected by
respiratory problems needed medical care.
Regarding the Al Eskan disease, which is a type of pneumonia acquired
from exposure to inorganic and organic material in dust storms, many
efforts have been made to study this illness of uncertain etiology and
its potential relation to desert dust.
They concluded that the continued exposure to dust particles less than
1 µm, that has been experienced by the Gulf War veterans, leads to the
immunodepression that explains the symptoms of the phase II of Al Eskan
disease. This immunodepression also explains the symptoms of the
phase I of the hyperegic lung condition.
Assessment of long-term spatial and temporal variability of dust
over Iraq using available satellite based observations.
Temporal variability of dust episodes and their long-term trends, as well
as spatial variability of dust hot spots and sources, are important topics of
study, which are often linked. A better knowledge on these topics leads to
improvements of both mid-range and long-range dust forecasting
models. Also, identification of dust source areas is important,
among other reasons, for the improvement of climate change models.
Most of studies use satellite remote sensing data or in-situ horizontal
visibility measurements as primary tools. Other techniques as in-situ
measurements of airborne dust concentration sand in-situ measurements
of aerosol optical depth are scarce, or not available at all, in most areas
of interest, especially in remote desert areas. This is the case or Iraq,
where in-situ airborne dust concentration or aerosol properties
measurements are not available. Satellite remote sensing data can be
used to monitor dust aerosols and to identify areas of high dust
loadings.
Analysis of longterm trends in
visibility reductions
in Iraq.
Horizontal visibility is a measurement of the maximum distance at
which an object or light can be clearly discerned. The degradation
of visibility is mainly attributed to the scattering and absorption of
visible light by particulate matter with diameters below 2.5 µm.
Horizontal visibility can be used as a proxy for defining dust
episodes occurrence, more reliably in dust dominated areas and
under dust storm conditions .
Visibility Classification
The WMO protocol establishes four categories under which a dust event
can be classified according to visibility:
Dust haze or dust in suspension: widespread dust homogeneously
suspended in the atmosphere. These particles have not been uplifted near
the station or at the time of the observation, but from a considerable
distance or from the ground by a dust event that occurred prior to the
time of observation. Visibility is usually not greater than 10 km.
Blowing dust: horizontal visibilities in the range from 1 to 100 km,
which indicates the presence of aeolian dust. The dust or sand has been
uplifted at the time of the observation.
Dust storm: horizontal visibilities below 1000 m and greater than 200 m.
Large quantities of dust particles have been lifted by strong winds.
Severe dust storm: horizontal visibilities below 200 m. Large quantities
of dust particles have been lifted by very strong winds.
.
Visibility Studies
17 stations with horizontal visibility records used in this study.
These 17 stations are located in the dust corridor that cross Iraq
northwest to southeast. Data availability is not the same for all this 17
stations, but in general long-term measurements are available (Fig.1).
In order to analyze the temporal variation of visibility reduction data
across Iraq, percentages of both annual and monthly frequency of records
of suspended dust and dust storms events were studied in each station.
Frequencies for each of these two types of dust episodes have been
calculated counting the number of days reported as dust episode, divided
by the total number of days, and then converting the result into a
percentage. Although most of the stations have long-term visibility
records, most of the data series are not continuous.
Fig. 1:Location of the 17 stations with horizontal visibility records used in this study
Visibility Studies
The analysis of the inter-annual and seasonal variation of dust episodes
frequencies has been done at selected sites. For selecting the sites, they
were grouped into three different groups according to its geographical
location, namely North, center and South groups.
Also, in order to study how the seasonal variability of both dust storms
and suspended dust occurrence varies according to geographical location,
mean frequencies of occurrence for each month were obtained averaging
the monthly frequencies for the period 1981-2007. Annual means of air
temperature, relative humidity, rainfall and wind velocity data measured
at the synoptic stations (where available) were also used in order to
explore the relation between in-situ meteorological conditions and the
occurrence of dust episodes.
Comparison of visibility reduction records within close stations
A comparison of site-to-site dust storm and suspended dust
episodes frequencies was done by calculating Spearman
correlation coefficients between annual visibility reduction series
for common periods.
Taking into account the correlation matrices, the temporal
availability of records and the location of the sites, three groups
have been formed among all the stations used in this study, which
are:
North group: Sinjar, Telafar and Mosul stations.
Center group: Baghdad, Kerbala, Najaf and Diwaniya stations.
South group: Nasiriya and Basra-Huss stations.
.
Monthly Climatology
of Visibility Reductions
(North group).
In Figures 2, 3 and 4 the seasonal variation of dust storm and suspend
dust frequency of occurrence is shown for stations representative of each
of the three groups in the period 1982-2007.
a
b
Figure 2. Percentages of monthly frequencies of (a) dust storms and
(b) suspended dust episodes for the period 1982-2007 at Sinjar, Tel-Afar
and Mosul (North group).
Monthly Climatology
of Visibility Reductions
(Center group).
a
b
Figure 3. Percentages of monthly frequencies of (a) dust storms and
(b) suspended dust episodes for the period 1980-2011 at Baghdad,
Kerballa, Najaf and Dinawaniya (Center group).
Monthly Climatology
of Visibility Reductions
(Center group).
a
b
Figure 4. Percentages of monthly frequencies of (a) dust storms and
(b) suspended dust episodes for the period 1970-2012 at Nasiriya and
Basra-Huss (South group).
Frequency of Occurrence
(in % of days/month)
Suspended dust frequency dominates over that of dust storms(Fig.5& 6).
From April up to September frequencies > 45% can be found on sites
located indistinctly in the North, Center and South of Iraq. Contrary to
dust storms, a temporal trend of occurrence of suspended dust episodes
during the year depending on latitude cannot be found (Fig 6). Southern
stations do not show more suspended dust frequencies than other stations
across the country, contrary with what was observed for dust storms. At
Baghdad, suspended dust episodes are recorded more than 20%
days/month throughout the year (more than 50% from April to
September). This occurs even during the seasons of minor dust activity
with suspended dust frequencies less than 10% days/month in most of the
sites across the country. This supports the hypothesis of Baghdad being
affected by high levels of anthropogenic air pollution stated above.
Figure 5. Spatial distribution of dust storms frequency of occurrence (in % of days/month) across
Iraq for the period 1981-2007. The radius of the circles is proportional to percentage
Figure 6. Spatial distribution of suspended dust frequency of occurrence (in % of
days/month) across Iraq for the period 1981-2007.
Inter-annual climatology
of visibility reductions.
Long-term trends.
The inter-annual variation of dust storm and suspended dust frequencies
of occurrence, in % of days/year, for the selected stations of the North,
Center and South groups, shown in Figures 7, 8 and 9 respectively.
Although all stations have data with different temporal domains,
all temporal series have a length of at least 40 years.
These horizontal visibility reduction records are longer than those
derived from satellite retrievals, which dates back at most to the 1990s .
a)
b)
Figure 7. Percentages of annual frequencies of dust storms (a) and suspended dust
episodes (b) at Sinjar, Tel –Afar and Mosul stations (North group).
a)
Figure 8. Percentages of annual frequencies of dust storms (a)
and suspended dust episodes (b) at Baghdad, Kerbala,
Najaf and Diwaniya stations (Center group)
.
.
b)
a)
Figure 9. Percentages of annual frequencies of dust storms (a)
and suspended dust episodes (b) at Nasiriya and Basra-Huss stations
(South group
).
The spatial distribution of dust episodes frequencies
found in our study, decreasing from southeast to
northwest, and with maximum values in Nasiriya, is in
very good agreement with previous studies (AlDabbas, 2011; Kutiel and Furman, 2003). In Fig.10,
extracted from an Iraqi Meteorological Organization
recent report (2013), the same spatial distribution is
observed for the period 1981-2011.
Figure 10. Average annual number of days of
dust storms across Iraq, using monthly
means, for the period 1981-2011.
After Iraqi Meteorological Organization, 2013.
The effects of climate variability
and anthropogenic land use
changes on dust episodes
Among the environmental conditions, high speed low level winds, low
precipitation rates, low relative humidity and high temperatures at both
surface and low levels, are necessary to trigger a dust episode in a
geographical location with potentially dust-producing soil. The analysis of
the relationship between temporal variability of environmental conditions
and dust episodes frequency of occurrence can help us to identify the causes
of past dust events. If this analysis is performed in different sites across the
country, it can also help us to detect dust sources by studying correlations of
low visibility frequencies with precipitation, relative humidity, winds and
land properties .Dust is known to be sensitive to climate change, and also to
anthropogenic changes in land use.
In this study, we perform an analysis of the relationship between
long-term climate variability and dust episodes occurrence over
selected sites across Iraq.
.
Figure 11. Inter-annual variation of air temperature (a), relative humidity (b),
total rainfall (c) and wind velocity (d) for selected stations across Iraq.
Figure 12. Mean annual relative humidity
(%) across Iraq, for the period 1981-2011.
After Iraqi Meteorological Organization, 2013.
Figure 13. Mean annual rainfall (in mm)
across Iraq, for the period 1981-2011.
After Iraqi Meteorological Organization, 2013.
Overall, some important changes in both visibility reduction and dust
loading interannual variability across Iraq are found to be related with
changes in relative humidity and precipitation rate, but the timing effect
mentioned about makes the interpretation of the results a not straight
forward matter. No consistent patterns in correlations are found. The
comparison of long-term trends of visibility reduction (i.e., of dust
episodes frequency of occurrence) and those of temperature, and
precipitation rate in several sites across Iraq suggest that in a climate
scale dust variability is being modulated by meteorology, but the effect
of human activities on the environment should not be dismissed.
The construction of new dams that alter the flow of the Tigris and Euphrates rivers and
its tributaries, drain of marshes during the 1990s decade in the lower part of the
Mesopotamian basin for political, economical and military reasons ,inappropriate
farming practices, cropland intensification, increase of dirty roads especially since the
late 1970s , military actions and other changes in land use might affect to the variability
of dust emissions by contributing to reducing vegetation cover, increasing
desertification and facilitating dust resuspension.
Visibility reduction records suggest that, overall, the 1990s decade is not one of the
most important as for dust episodes frequency of occurrence in the selected sites
studied. However positive trend on these frequencies during the 2000s decade in almost
all cases (except in the case of dust storms in the South group) is evident. This positive
trend might be related with the increasing availability of resuspendible material due to
the decrease of the rivers flow. The effects of the marshes restoration program started
after 2003, which has been negatively affected by the drought in 2009 and also by
reduced flow from Iran, are not noticeable in neither the satellite remote sensing northe
visibility reduction data analyzed in this study.
Conclusions
1- satellite remote sensing data for the period 1998-2012 has been used to detect high
dust loadings regions.
2- monthly records of number of both dust storms and suspended dust episodes have
been analyzed in selected sites of the Northwest, center and Southeast regions of the
country to identify areas of high dust episodes frequency of occurrence.
3- Once the areas with both high dust loadings and high frequency of dust episodes
were identified, we compared them with soil types maps of Iraq to determine if those
areas present the required characteristics to act as dust sources.
4- Three principal dust source areas in Iraq have been identified (Fig. B33): 1) The
Aljazera region south of the Sinjar Mountains and northwest ofthe Tharthar lake, in the
upland plain of northwestern Iraq. This region is formed by bare land and sand dune
areas, composed of mainly dry gypsum soils;2) the alluvial plain between the Tigris and
Euphrates rivers and areas East of the Tigris river, where exposed marsh beds consisting
of clay deposits from rivers exists; and 3) the Zubair desert in Low Mesopotamia,
which is formed by bare land composed of calcareous deposits.
Figure 14. Major dust source areas in Iraq identified in our study
.
Conclusions
5- Maps of dust sources identification over Iraq performed (Fig. 15 a) shows the
probability of finding accumulated alluvium sediments which are composed of fine,
easily eroded by winds, particles . This map indicate that the most probable sources of
dust in Iraq are located in the lower Mesopotamia, followed by areas in the alluvial
plains between the Tigris and Euphrates rivers, and in the Northwest uplands south of
the Sinjar mountains. This figure shows also some areas of moderate to high
probability of being dust sources East of the Euphrates river.
6- In (Fig. 15 b) the most recent dust source identification for the Middle East is
depicted. This identification is based on the relative frequency of days per season
(March, April and May) with MODIS Dust Optical Depth > 0.2, and uses a land use
classification. Iraq is marked as the Mesopotamian source (number 11). Inside this
region the highest frequencies are located in areas of the Northwest upland (south of
the Sinjar Mountains and Northwest of the Tharthar Lake), Lower Mesopotamia and
areas in the alluvial plain between Tigris and Euphrates rivers and East of the
Euphrates river,
Figure 15. Dust source locations according to a) Guinoux et al. (2001)
b)Ginoux et al., 2012;
.
Conclusions
7-n (Fig. 15 b) shows the identification of dust sources over Iraq and
Syria. The identification of dust sources was made using Terra/MODIS
imagery. The major number of dust sources in Iraq is located in the
Northwest of the country, South of the Sinjar Mountains and in
surroundings of the Tharthar Lake.
8-in (Fig. 15 b) , the frequency of visibility reductions due to high dust
loadings across Iraq. These two maps coincide in the Low
Mesopotamia, and more precisely the surroundings of Nasiriya, being
the area with the highest frequency of dust events, and then a potentially
important dust source. The spatial distribution of low visibility
frequencies in both maps highlights a corridor from Southeast to
Northwest of Iraq, in good agreement with the dust source
identifications cited above.
Figure 15. Dust source locations according to c) Abdulkareem, 2013;
d) Kutiel and Furman, 2003;
Conclusions
9-The areas highlighted in Fig.14 indeed coincide with those areas
where dust sources have been identified by other authors. Our results
for the Zubair desert (Southern Iraq, Al-Mutanna and Basra regions) are
particularly important, as it is revealed as one of the most important
high dust loading areas but, in general, other authors identifies few dust
sources there. This should mean that those dust sources are particularly
active.
10-Dust in Iraq follows a clear seasonal pattern with higher dust content
in the atmosphere in spring and summer, from April to August.
Maximums of dust storms frequency are observed later in the year as
latitude decreases.
Conclusions
11- In the northern sites studied, and also in those in the center area of
the country, these maximums (up to 3.8% days/month and 6.45%
days/month respectively) occur in April or May and a secondary
maximum is observed in October.
12- In the southernmost sites, the dust storm maximum frequency of
occurrence occurs in June and reaches values up to 17.4% days/month.
Within these southernmost sites, Nasiriya shows a higher frequency of
dust storms occurrence than Basra-Huss during almost all year for the
period 1970-2012.
Conclusions
13-The Suspended dust frequency dominates over that of dust storms.
From April up to September frequencies > 45% can be found on sites
located indistinctly in the North, center and South of Iraq (in
days/month for the period 1982-2007).
14- Mosul and Baghdad being the sites with higher number of days with
horizontal visibility < 11 km suggest that these visibility reductions are
not only due to natural causes, but also due to anthropogenic pollution.
15- Inter-annual variation of satellite remote sensing observations
within the period 2001-2013 show an increase of dust load over the
identified dust source areas in Iraq, starting in 2007, with a maximum in
2008.
Conclusions
15- In this study, analysis of the inter-annual variation of visibility
reduction records, with data series longer than those available of
satellite measurements (at least 40 years), allowed us to asses if this
positive trend have been occurring only during the last decade or if it is
a long-term trend.In general, inter-annual variations of dust load
observed with remote sensing data are well reproduced by horizontal
visibility reduction records.
16- Maximums of both annual dust storm and suspended dust frequency
of occurrence long-term series are found from 2007 onwards in almost
all sites studied, even if no long-term trends are observed.
Conclusions
17- Positive long-term trends of dust storms frequency of occurrence
are observed in two of the three northernmost sites studied (area 1 in
Fig. 14).
18- No evidence of any long-term dust storm trend is observed in any of
four stations located in the center of Iraq.
19- Negative long-term trends are observed in the meteorological
stations located in the South (Nasiriya and Basra-Huss), with
maximums in the 1970s decade.
20- It is worth noting that the highest frequencies of dust storms among
all the sites studies are observed in Nasiriya.
Conclusions
21- Regarding long-term trends of frequencies of suspended dust,
positive trends are observed in the three northernmost sites studied,
which are located in the area 1 in Fig. 14, and in two of the four stations
located on the center area of the country. No long-term trends are
observed in the two southernmost sites.
22- Inter-annual long-term trends of air temperature, relative humidity
and total rainfall suggest that Iraq is undergoing a regional climate
change.
23- Important changes in both visibility reduction and dust loading
interannual variability across Iraq were found to be related with changes
in relative humidity and precipitation rate, but the interpretation of the
results are not straightforward because of the existence of timing effects
Conclusions
24 - Regardless, the effect of human activities on the environment
should no be dismissed. Decrease of the flow of rivers because of
hydrological programs, inappropriate farming practices, increase of
dirty roads, military actions and other human activities may have
contributed to the increment on dust episodes frequency of occurrence
in Iraq, especially during the last three decades. Datasets on the time
evolution of rivers flow rate, cultivation and grazing activities,
economic growth, and land change uses are needed in order to evaluate
the potential effect of these activities on dust emissions.
Recommendations on
SDS activities in Iraq
1 - D.2.1.1 In-situ observation systems
D.2.1.1.1 Horizontal visibility
It would be interesting to install some SYNOP stations for horizontal visibility records
in the southern half of the Al-Anbar province, in the southern half of the Al-Muthanna
province, south of Niniveh and north of Al-Anbar, and in the Thi-Qar province. This
database should be updated in near real time to achieve the following goals:
Dust nowcasting and early warning.
To apply an empirical relationship between horizontal visibility and particulate matter
concentration (PM10 or TSP) .
Estimations of particulate matter concentration from near real time visibility data can
also be used for model validation.
Climatological analysis of long-term series of horizontal visibility records, both at
SYNOP station level or in areas of interest, must be performed in order to identify
dust trends.
Steps to adopt a standard data format should be taken due to lack of data format
standardization between databases of SYNOP stations in Iraq.
Recommendations on
SDS activities in Iraq
2- D.2.1.1.2 In-situ PM10/PM2.5 measurements
-PM10 and PM2.5 measurements must be used to establish ambient air quality
standards and regulations to mitigate any adverse impact of dust.
- It would be interesting to install dust concentration samplers in Iraq in order to
monitor dust storms, characterize its spatial and temporal variability, estimate the
concentrations of dust to which the population is exposed to through inhalation, and
establish air quality regulations.
Two types of dust concentration samplers could be used, namely dust deposition
gauges and high volume samplers. Particle size being sampled by high volume dust
samplers can be restricted using selective inlets that can be fitted to the instrument. It
would be especially interesting to measure PM10 concentrations.
- It is important to install rural background PM10 stations, far away from
anthropogenic pollution sources located in major cities and industrial centers. Also,
long-term rural background PM10 measurements could be used for dust models
validation.
Recommendations on
SDS activities in Iraq
3- D.2.1.1.3 Aerosol optical depth with sunphotometers
- No sunphotometers are available in Iraq. The installation of three new AERONET
sunphotometers stations in Iraq is desirable in order to monitor atmospheric dust,
characterize its optical properties, and also to contribute to dust models evaluation and
verification. The proposed locations, based on the locations of dust-hotspots areas and
dust storms pathways, but also taken into account the ease of access to the site and the
availability of logistics support, are the following:
Mosul (North Iraq)
Baghdad (central Iraq)
As Smawah (South Iraq)
-The need for calibration of the AERONET sunphotometers in a yearly-basis should
be noted. The experience of regional experts could help the implementation of new
AERONET sites in Iraq.
-Cuevas (2013) recommends Global Atmospheric Watch Precision Filter Radiometer
for long-term high accuracy AOD measurements.
Recommendations on
SDS activities in Iraq
4- D.2.1.1.4 Lidars and ceilometers
- no lidars are available in Iraq. Lidars allow studying the vertical distribution of dust.
In combination with other techniques, as sunphotometry, lidars allow investigating the
transport and deposition of dust, some aspects of atmospheric composition, and also
the dust-clouds interaction. Lidars are expensive and complex instruments (> 100,000
$), and its maintenance costs are high. Moreover, lidars requires specialized personnel
to operate and to perform data treatment. lidars are not recommended for Iraq.
An alternative for research-oriented lidars is ceilometers, which are based on the same
principle as lidars and can be used to dust monitoring and forecast. The advantages of
ceilometers are its lower cost (about 20,000 $) and its robustness, which enables
continuous operation without much maintenance. Ceilometers are typically found at
airports for cloud base monitoring, although they can not only perform measurements
of cloud base heights, but also measurements of height of the planetary boundary layer
and atmospheric aerosols backscattering profiles. It is recommended to install a
ceilometer in the Baghdad airport. This location is ideal taking into account the
installation of a sunphotometer in Baghdad was recommended. Ceilometers near
suphotometers would have a value-added to ensure data quality.
Recommendations on
SDS activities in Iraq
5- D.2.1.1.5 New or complementary developments
-A useful and inexpensive instrument to monitor the pathways of airborne dust and
also to study dust storms sources in near real time is a simple webcam. Webcams
might be installed in remote sites for dust nowcasting, taking images in few minutes
intervals.
-For the characterization of dust layers, meteorological radiosoundes can be used in
combination with lidars and ceilometers.
Dust monitoring can also be performed using radar techniques, such as a mobile
doppler radar.
Recommendations on
SDS activities in Iraq
6- D.2.1.2 Satellite observations
-It is recommended to use the satellite remote sensing sensors, SEVIRI is the most
appropriate to monitor dust because of its high temporal and spatial resolution, in
addition to the already used ones.
-In order to perform dust climatologies in Iraq, it is recommended to use AOD data
from MISR, MODIS and SeaWiFS,
-It is recommended to continue using backscatter and extinction coefficient vertical
profiles from CALIOP, and also to incorporate data from the Polarization and
Anisotropy of Reflectances for Atmospheric science coupled with Observations from
a Lidar (PARASOL) also on board the CALIPSO satellite. CALIOP data has been
used by Iraqi researchers for case studies, but it is recommended to use both CALIOP
and PARASOL also to perform dust climatologies over the country.
-In order to monitor land use changes, it is recommended to continue using Landsat
images and also the NDVI index from MODIS to detect changes in the vegetation
cover. It is very important to monitor soil conditions in the Mesopotamian area, since
this area is experiencing dramatic changes in land uses and soils characteristics that
might influence the frequency and intensity of dust storms.
Recommendations on
SDS activities in Iraq
7- D.2.1.3 Mesoscale/local (high resolution) models
- It is recommend the implementation of a high resolution dust model for Iraq.A
modeling structure consisting on a three-level scheme (global, regional and local) is
proposed, with the final aim of providing high resolution (1-3 km) simulation.
-The dust model simulations with NMMB/BSC-DUST for Iraq should be performed
in three phases:
Dust model setup: 1-year simulation. The objective of this phase is to configure the
model for the Iraq domain at high resolution. Input data and emission parameterization
will be further improved.
Model evaluation: 5-year evaluation. The model evaluation will be performed using
ground-based (nearby AERONET stations, surface meteorological data, PM data from
air quality stations) and satellite (MODIS, OMI and MISR) observations.
30-year dust reanalysis. After the implementation and evaluation of the model in Iraq,
a 30-year reanalysis will be performed, which could be used for further climate related
studies.
Recommendations on
SDS activities in Iraq
8- D.2.1.4 Regional collaboration mechanisms
-SDS monitoring and forecasting activities in Iraq should be integrated within the
framework of the new Sand and Dust Warning Advisory and Assessment System
(SDS-WAS) Regional Node for West Asia. This new SDS-WAS regional node is an
initiative of World Meteorological Organization to satisfy needs for providing SDS
observations and improving SDS forecasting capabilities in West Asia.
9- D.2.1.5 Data exchange
-Near real time observations and model outputs should be stored in databases in
massive storage systems. These databases should be freely accessed by other partners
of the SDS-WAS Regional Node for West Asia. A standardized file format should be
used.
Recommendations on
SDS activities in Iraq
10- D.2.1.6 SDS products and services
-The most important product of a national SDS programme in Iraq should be an
accurate sand and dust storms early warnings system. These early warnings notify
predicted or observed sand and dust storms to the general public and to specific users.
Sand and dust early warnings also allow authorities from activities such as public
health, civil defense, air quality, environment and transportation to make decisions to
minimize its impacts.
-SDS products in Iraq can be also oriented to more challenging and profitable
purposes, as the support to activities where sand and dust storms can adversely affect,
such as solar power installations, air transportation, highway and railroad
maintenance, and farms and livestock management.
-It is recommended to publish the results of these studies (such as studies on changes
in land use and its relation with frequency and intensity of dust storms, identification
of dust sources, and epidemiological studies on the impact of dust storms in human
health) in peer-reviewed international scientific journals and technical reports because,
generally, policymakers need well-documented and proven results to mobilize
resources.