ES 694 Seminar Report
On
IMPACT OF DUST STORMS ON AIR
POLLUTION
Submitted by
Kirtika Singh
(Roll Number: 23M1434)
Under the supervision of
Professor Virendra Sethi
and
Professor Srinidhi Balasubramanian
Environmental Science and Engineering Department
INDIAN INSTITUTE OF TECHNOLOGY, BOMBAY
November 2023
APPROVAL SHEET
This seminar report entitled “Impact of Dust Storms on Air Pollution” prepared by Kirtika
Singh (Roll No. 23M1434) is hereby approved for submission.
Professor Virendra Sethi
(Supervisor)
Professor Srinidhi Balasubramanian
(Co-supervisor)
Date: 10 November, 2023
Place: Mumbai
ii
DECLARATION
I Kirtika Singh Roll No 23M1434 understand that plagiarism is defined as anyone or
combination of the following:
1. Uncredited verbatim copying of individual sentences, paragraphs, or illustrations (such as
graphs, diagrams, etc.).
2. Uncredited improper paraphrasing of pages or paragraphs (by changing a few words or
phrases, or rearranging the original sentence order)
3. Credited verbatim copying of a major portion of a paper (or thesis chapter) without clear
delineation of who did or wrote what.
I have made sure that all the ideas, expressions, graphs, diagrams, etc., that are not a result of
my work, are properly credited. Long phrases or sentences that had to be used verbatim from
published literature have been clearly identified using quotation marks.
I affirm that no portion of my work can be considered as plagiarism and I take full responsibility
if such a complaint occurs. I understand fully well that the adviser/guide/co-guide of the seminar
report may not be in a position to check for the possibility of such incidences of plagiarism in
this body of work.
Full Signature of the Student with the Date
Name of the Student: Kirtika Singh
Roll Number: 23M1434
iii
ACKNOWLEDGMENTS
I want to express my sincere gratitude to my supervisor Professor Virendra Sethi, and cosupervisor Professor Srinidhi Balasubramanian for their constant support, and valuable
guidance, in carrying out the seminar work. Their encouragement, and belief in me have made
a profound impact on this journey and I am extremely grateful for their guidance and directions
that aided me in accomplishing my work. I would also like to thank my sisters, and my parents
for their love and moral support along with the APRL members.
Regards,
Kirtika Singh
Roll no. 23M1434
Program: M. Tech.
ESED, IIT Bombay
iv
ABSTRACT
Sand and dust storms have a direct impact on 11 out of the 17 Sustainable Development Goals,
but their recognition as a hazard and awareness of their long-term effects remain relatively
limited on a global scale. Annually, approximately 2000 million metric tons of dust are released
into the atmosphere, with 75% settling on land and the remaining 25% dispersing into the ocean.
Dust storm is a metrological phenomenon; common in arid and semiarid regions that have a
wide range of effects on both the environment and people. Dust is thrust into the atmosphere
during these dust events and travels hundreds and thousands of kilometres in the stratosphere.
Though these dust events last for a short duration the air pollution caused by them has a severe
and long-term impact on air quality. This study explores the prominent global dust sources and
transmission pathways using satellite data. This study is focused on understanding the global
dust sources and transport pathways traversed by dust using satellite data such as MODIS,
NOAA HIYSPLIT, and the impact of dust storms on air quality.
Keywords: Dust Storm, Air Pollution, Transport, MODIS, NOAA HIYSPLIT
v
Table of Content
Report
Section
1
1.1
1.2
1.3
2
2.1
2.2
2.3
2.4
2.5
2.5.1
2.5.2
2.5.3
2.6
2.7
2.7.1
2.7.2
2.8
2.9
2.9.1
2.9.2
2.9.3
2.9.4
3
3.1
3.2
3.3
4
Section Title
Approval Sheet
Declaration
Acknowledgments
Abstract
Table of Contents
List of Figures
List of Tables
Chapter 1 Introduction
Background
Objective of the Study
Organization of the Report
Chapter 2 Dust Stoms and its impact on air quality
Anatomy of Dust Storm
Mechanism of dust storm generation
Characteristics of dust storm events
Impact of Dust Storms on Air Quality
Other collateral damages of dust storms
Changes in the hydrological cycle
Increased ocean fertility
Effect on Human Health
Environmental and Climatic Factors Shaping Dust Storms
Prominent Global Dust Emission Sources and Dust Transport Routes
Dust sources across the globe
Global transport pattern
Transport Routes for India and Neighbouring Countries
Factors Contributing to Increased Dust Storm Events (Middleton &
Kang, 2017)
Low Rainfall and Prolonged Drought Conditions
Change in agriculture practices
Urbanization and City Development
Anthropogenic activities
Chapter 3 Approaches for the Quantification of Dust
MODIS (Moderate Resolution Imaging Spectroradiometer)
AERONET (AErosol RObotic NETwork)
NOAA HYSPLIT
Chapter 4 Summary
References
vi
Page
Number
ii
iii
iv
v
vi
vii
viii
1
1
2
2
3
3
4
5
5
6
6
6
7
7
9
9
20
14
16
16
16
17
17
18
18
19
21
22
23
LIST OF FIGURES
Figure
Number
2.1
2.2
2.3
2.4
2.5
2.6
Caption
Mechanism of dust storm formation (Idso, 1976)
Page
Number
4
A worldwide representation of the recorded daily TOMS Aerosol Index
values and the positions of prominent dust source regions. These regions
are categorized as follows: 1-Saharan; 2-Arabian; 3-Asian; 3b-East
Asian; 4-North American; 5-South American; 6-South African; 7- 11
Australian Domains.
Desert Dust Transport Routes and Source Location (Middleton & Kang,
13
2017)
Backward air parcel trajectories depict the extensive movement of soil
dust over long distances, reaching Bangladesh and India during the 15
month of February 2003 (Begum et al., 2011)
Backward air parcel trajectories depict the extensive movement of soil
dust over long distances to regions in Pakistan and Sri Lanka during the 15
month of February 2004. (Begum et al., 2011)
The reverse paths of air parcels illustrating the long-range transport
of soil dust, reaching areas in Pakistan and Sri Lanka in February 16
2004. (Begum et al., 2011)
The left image displays a brownish-yellow haze resulting from a mixture
of aerosols, while the right image depicts the proportion of small aerosols
(green) to large aerosols (red). Small particles indicate pollution, while
large particles indicate dust. This indicates the movement of a dust cloud
from the Taklimakan and Gobi Deserts towards western China
3.1
3.2
3.3
19
The WRF-Chem model domain is depicted, showcasing (a) the
topography and (b) the spatial distribution of dust emissions averaged
from April 13 to 25, 2010. AERONET sites are marked with black
circles, and a black triangle indicates the site where the time series of
WRF-Chem dust emissions is presented in (c) for the same period the
dust emiision., (b) illustrates the location of the Thar Desert (bounded by
solid black lines) and the CALIPSO satellite overpass (grey line) within
the model domain on April 20, 2010.
20
The 5-day retrograde paths originating from (a) May 9, 2001, (b) May
20, 2002, and (c) May 27, 2002, at altitudes of 500, 1500, and 2500
meters above the surface
21
vii
LIST OF TABLES
Table
Number
2.1
2.2
Caption
Classification of Dust Storms in India according to intensity
(Middleton, 1986)
Environmental and Climatic Factors Shaping Dust Storms (Varga,
2012)
viii
Page
Number
3
8
Chapter 1
Introduction
1.1 Background
Dust consists of microscopic particles of various substances that are visible to the naked eye
and lightweight enough to be transported by the wind. Its composition may vary including a
mix of elements such as pollen, bacteria, smoke, ash, salt crystals originating from the sea, and
minute particles of soil or stones, and sand. Additionally, dust may include tiny remnants of
skin cells from both humans and animals, as well as pollution and hair (URL 1).
Dust is a common aerosol in the atmosphere, with significant implications on air quality
(Prospero, 1999). Dust events increase the dust load in the stratosphere which has several
implications that can be beneficial such as dust from the Sahara Desert has been thought to
fertilize the Amazon rainforest as it transports nutrients such as iron and phosphorous to both
marine and land ecosystems, the loess deposition from wind-blown air which is good for
agriculture. A study done by Zhuang et al., 2001 highlights a positive feedback loop where
transported Fe (III) becomes Fe (II) in seawater, during dust storms, promoting phytoplankton
growth and DMS production, potentially impacting global climate and Pacific primary
productivity. Along with that, the dust lifted in the atmosphere has a serious impact on human
health; depending on the size of the particles that get deposited into respiratory tract. Dust has
also been associated with the proliferation of diseases such as Meningococcal meningitis in
sub–Saharan Africa, and valley fever in the southwest US. Dust particles impact precipitation
patterns as they can act as condensation nuclei (Vinoj et al., 2014).
However, the focus of this study is on the effect of resulting air pollution from dust storms
which is generally short-lived but the high concentrations achieved during these events have
severe implications for human health, they can also travel long distances affecting densely
populated areas far from their source (Hagen & Woodruff, 1973 and Johnston et al., 2011).
1
While global warming has made the issue more intricate, it has introduced simultaneous
alterations in both meteorological elements and the circumstances surrounding dust sources,
further complicating the matter (Li et al., 2008).
1.2 Objective of the Study
The objective of this literature review is to explore:
i.
The global dust sources and transport pathways traversed by the dust and the impact of
dust storms on air quality.
ii.
The methods and approaches used to quantify the amount of dust emitted during dust
events.
1.3 Organization of the Report
The report entitled; “Impact of Dust Storms on Air Pollution” is organized as follows. The first
chapter gives an overview of Dust storms. The second chapter includes the basics of the
generation mechanism, global dust emission, and transverse pathway. It also includes factors
affecting the frequency of dust storms. The third chapter deals with the approaches of
quantification of dust storms. The fourth chapter talks about the impact of dust storms on air
quality.
2
Chapter 2
Dust Storm and its Impact on Air Quality
2.1 Anatomy of a Dust Storm
A dust storm is a meteorological occurrence characterized by powerful winds carrying a
substantial amount of dust, debris, sand, and other particulate matter. These events pose
significant threats to our environment, including climate, agriculture, and ecology, while also
disrupting everyday life. In extreme cases, dust storms can be life-threatening, causing
suffocation, reducing visibility to the point of road accidents, and more. The intensity of a dust
storm, including wind speed and other features, is contingent upon factors such as relative
humidity and air temperature drop (Idso, 1976).
A universally accepted definition of a dust storm is given by the World Meteorological
Organisation which necessitates a reduction in visibility to less than 1000 meters, discussed by
Middleton in 1986. In severe instances, this reduced visibility can reach a point where it
effectively becomes zero. Additional criteria, such as relative humidity below 80%, a minimum
wind speed of 3 m/s, and no precipitation, are set to exclude other weather conditions like fog,
haze, or rain that can reduce visibility (Li et al., 2022).
Table 2.1: Classification of Dust Storms in India according to intensity (Middleton, 1986)
Intensity of Dust storms
Wind force on the
Beaufort scale
Visibility
Light
4 to 6
Less than 1000 m, up to 500
m
Moderate
6 to 8
Less than 500 m, up to 200
m
Severe
9 or more
Less than 200 m
3
2.2 Mechanism of dust storm generation
There are various events both natural and anthropogenic that inject dust into the atmosphere
such as volcanic eruptions, and forest fires that thrust high amounts of ash and debris into the
stratosphere; biomass burning, and industrial emissions etc are some of the anthropogenic
activities that introduce dust into the lower strata of the atmosphere.
Dust storms, particularly the squall-line type, typically start when there's a thunderstorm with
rain and hail. These storms create a rush of cold air that descends and spreads along the ground,
moving forward. This cold air is heavier and as it moves, it collects loose dust and sand from
the ground. Furthermore, the heavy, cool air pushes the warm light air it meets upward, which
helps in forming more rain clouds and keeps the cycle going.
The smallest unit of a dust storm that's significant in meteorology is often caused by this
downward rush of cool air from a single cumulonimbus cloud. When this cloud reaches a point
where rain starts falling from it, the air cools significantly as the rain passes through it and
evaporates partially or entirely. Because this cooler air is denser than the air around it, it
descends in a downward flow, and the speed of this descent is related to the height of the cloud.
When this dense, cool air reaches the ground, it's pushed forward picking up surface debris,
dust, and loose materials due to the turbulent flow at the front (Idso, 1976).
Figure 2.1: Mechanism of dust storm formation (Idso, 1976)
4
2.3 Characteristics of dust storm events
Dust events can persist for a range of durations, spanning from a few hours to several days. The
intensity of a dust storm is often quantified by measuring the concentration of particles in the
atmosphere. In severe cases, the atmospheric concentration of PM10 (particulate matter with a
diameter of 10 micrometers or less) can surpass 15,000 μg/m³, and the maximum hourly
concentrations of PM2.5 (particulate matter with a diameter of 2.5 micrometers or less) may
exceed 1,000 μg/m³.
From a chemical standpoint, the primary component of dust particles is quartz, also known as
silica (SiO2). Desert dust also contains a variety of other elements, including anthropogenic
pollutants, organic matter, and a range of salts, as well as iron, calcium, magnesium, and
potassium. In addition to these elements, dust particles can carry potentially harmful
microorganisms such as bacteria, viruses, fungi, and other biologically active aerosols
(Middleton & Kang, 2017).
2.4 Impact of Dust Storms on Air Quality
In a study done by Johnston et al 2011, in Sydney, Australia 1994–2007 during extreme air
pollution events associated with dust storms and bushfires. Dust events were associated with a
15% increase in non-accidental mortality at a lag of 3 days.
Hagen and Woodruff, 1973 in their study of air pollution from dust storms in the Great Planes
after analyzing national service records, and hourly weather observation for 10 years of
consecutive data (1979 to 1950) reported that the average dust concentrations ranged from 5 to
10 mg/m3 (5000 to 10,000 ug/m3) in the least erosive areas and 10 to 15 mg/m3 in the driest
regions of southern great plane. The average dust storm duration was found to be 6.6 hours.
In 1982, Iwasaka et al conducted a study on the dust event that occurred in Japan in April 1979.
Using laser lidar technology and the geosynchronous satellite HIMAWARI to track the
movement of the dust storm cloud and estimated the total dust particle mass to be approximately
1.63 million tons over an area of 1.36 million square kilometers i.e.; ~1.2 tons of dust per unit
area.
5
Their lidar measurements revealed that the dust cloud had two distinct layers. Through air mass
trajectory analysis, they determined that the upper layer, located at an altitude of 6 kilometers,
originated from the Taklimakan desert and had a dust concentration of 136 micrograms per
cubic meter. The lower layer, situated at 2 kilometers, was traced back to the Gobi Desert and
Huang-Ho basin, and it had a higher dust concentration of 608 micrograms per cubic meter.
Zhuang et al in 2001, collected TSP and performed a size distribution analysis for the samples
collected during dust storm events and non-dust events. the concentration of TSP on the days
of dust storms was found to be 6000 ug/m3 which was nearly 30 times more than the non-dusty
days. The concentrations of other minerals such as Al and Fe, were also found to be high.
2.5 Other collateral damages of dust storms
2.5.1 Changes in the hydrological cycle:
Dust storms influence various aspects of human life and the environment, from fertilization of
faraway lands, land degradation, disruption of the hydrological cycle and change in the intensity
of rainfall (Vinoj et al., 2014), formation of loess, affecting satellite communication and
transport, etc.
2.5.2 Increased ocean fertility:
Zhuang's research revealed that as mineral Fe (II) is transported over long distances, it
transforms Fe (III), which readily dissolves in seawater, providing nutrients for phytoplankton.
During dust storm events, phytoplankton tend to flourish and produce more dimethyl sulfide
(DMS) when they receive increased soluble Fe. Strong and frequent dust storms can introduce
higher concentrations of Fe (II), leading to a higher concentration of Fe (III). This, in turn,
results in more DMS production. The increased DMS can further reduce Fe (II) to Fe (III),
creating a positive feedback loop. These interactions between iron (Fe) and sulfur (S) in the
atmosphere and ocean represent crucial mechanisms that impact primary productivity in the
6
Pacific and potentially have broader implications for global climate change. Further
investigation into these processes is warranted.
2.5.3 Effect on Human Health
There have been multiple studies to understand the effect of dust on human health. A study done
by Preze et al, 2008 in Barcelona from March 2003 to December 2004 on the effect of exposure
to PM10 and PM2.5 on daily morbidity concluded that an average increase of 10 ug/m3 of
PM10 and PM2.5 resulted in an 8.4 % increase in daily mortality during Saharan dust days.
Further chemical analysis was done which provided indirect evidence of health effects as these
dusts carry a high load of metals such as Al, Fe, Cu, Zn, etc which cause oxidative stress.
Mineral dust is suspected to be one of the most important health risk factors for allergies in
elderly and young people and contributes to meningitis in Sistan and West Africa. Studying dust
storms and regional climate, weather, air quality, and human health in the Middle East and
southwest Asia is crucial (Rashki et al., 2015).
2.6 Environmental and Climatic Factors Shaping Dust Storms
Various factors influence the formation and emission of dust. Monitoring dust storms and the
quantity of dust emitted into the atmosphere can serve as indicators of these alterations (Varga,
2012).
7
Table 2.2 Environmental and Climatic Factors Shaping Dust Storms (Varga, 2012)
8
2.7 Prominent Global Dust Emission Sources and Dust Transport
Routes
2.7.1 Dust sources across the globe
The major dust sources over the globe are detected at topographical lows in arid regions with
low annual precipitations (Prospero, 1999; Ginoux et al., 2012)
Desert dust sources have been assessed globally using data from satellite-borne sensors and
terrestrial meteorological stations. The most active sources are located in the Northern
Hemisphere, mainly in a broad dryland Dust Belt that extends from the west coast of North
Africa, across the Middle East, to South, Central, and Northeast Asia. Drylands in the Southern
Hemispheres are less active dust sources, with significant local impacts but remain relatively
minor on a global scale (Middleton & Kang, 2017).
Studies have also indicated that 65% of southwest Asian arid terrain has the potential to be a
dust source, with the most effective areas being found in the eastern and southern parts of the
Arabian Peninsula, Oman desert, Syria-Iraqi desert, Aral and Turkmenistan basins to the north,
and closed inland areas of the Iranian plateau. These areas are composed of alluvial silt and clay
material or correspond to dry-bed lakes and abandoned agricultural areas. The Arabian, Iraqi,
and Thar deserts have been identified as major dust sources in South Asia, and Sistan, a lowlying basin with dried lakes at the Iran-Afghanistan borders, may also play a significant role
(Rashki et al., 2015).
Excessive dust loading over South Asia affects the regional environment and climate, modifies
biogeochemical cycles, and modifies the radiative forcing of the atmosphere. Dust aerosols
have been found to have a significant effect on mid-tropospheric warming over the IndoGangetic Plains and Himalayan-Hindu Kush range, and can accelerate the acceleration of
western-Himalayas glacier melting. Dust deposition over the Arabian Sea may affect
chlorophyll blooming, and phytoplankton, and cool the ocean surface. Dust plumes can also
affect the weather by influencing atmospheric thermal structure, suppressing cyclone activity,
and affecting cloud microphysics and the hydrological cycle (Rashki et al., 2015).
9
A global mean map is given by using daily TOMS Aerosol Index values from 1979 to 2011,
showing the spatial distribution of significant dust source regions. These areas are primarily
located in arid and semi-arid regions characterized by loess, fine-grained sediments that are
susceptible to wind-induced lifting into the atmosphere. It's important to note that the
representation of high aerosol emissions in Arctic regions is limited in the mean maps due to
the spatial scope of TOMS AI measurements (covering 70°N–70°S). In certain equatorial zones
and East Asia, elevated aerosol levels can be attributed to factors such as biomass burning and
industrial pollution.
A noticeable pattern is the presence of major dust sources forming a more or less continuous
zone extending from the western coast of North Africa, through the Middle East, and into
Central Asia. This region is commonly referred to as the "Global Dust Belt" as described by
Prospero, J.M. et al. in 2002. Beyond this belt, the average intensity of dust emission and the
annual frequency of dust storms are relatively low and are typically concentrated in isolated
smaller areas
10
Figure 2.2 A worldwide representation of the recorded daily TOMS Aerosol Index values and the positions of prominent dust source regions.
These regions are categorized as follows: 1-Saharan; 2-Arabian; 3-Asian; 3b-East Asian; 4-North American; 5-South American; 6-South
African; 7-Australian Domains
11
The principal pathways for the transportation of desert dust (illustrated by light blue arrows) in
fig 2.3 and the significant dust origins, such as (1) the Sahara, (2) Arabia, (3) Asia, (3b) East
Asia, (4) North America, (5) South America, (6) Southern Africa, and (7) Australia, were
produced using the average daily TOMS Aerosol Index data from 1979 to 2011. Red arrows
indicate dust emissions from different regions, whereas dark blue arrows illustrate the
deposition of dust into the oceans. The worldwide dust transport pattern from the Sahara follows
four primary routes: (i) Dust travels southward over the Sahel and the Gulf of Guinea,
accounting for 60% of Saharan dust emissions, but less than 5% of it reaches as far as 5°N. (ii)
Approximately 25% of the emissions head westward towards the Atlantic. (iii) About 10% of
the dust moves northward, making its way to Europe. (iv) Lastly, 5% of the dust takes an
eastward route, reaching the Middle East (Shao et al., 2011).
12
Figure 2.3 Desert Dust Transport Routes and Source Location (Middleton & Kang, 2017
13
2.8 Transport Routes for India and Neighbouring Countries
(Begum et al., 2011) studied the Asian Brown Cloud, prevalent in November, these brown
clouds are a mixture of various particulate matter. The particles present in haze can originate
from two potential sources: they are either naturally produced (such as sea salt and soil dust) or
human-made (including sulfate and soot).
The main objective of the study was to locate the source of fine soil dust and smoke causing
haze in the South Asian region and to understand long-range particle transport. A vertically
mixed model was employed to calculate backward trajectories, starting at varying altitudes (300
m, 500 m, and 1,000 m above ground level). These trajectories were computed for four different
dates in 2003, namely November 10th for Dhaka, November 3rd for Mumbai, November 15th
for Islamabad, and December 12th for Colombo; for 10 day period.
In all these regions the winter season exists from early December to March and the wind
directions are Northwesterly. They reveal that the air parcel passed over Iran and Pakistan
before arriving at the sample location in Dhaka, and potentially over North Africa before
arriving at the sampling site in Mumbai. In the instance of Dhaka, Bangladesh, it was discovered
that at 1500 m beginning height, air parcels arrived from the northwest direction. A heavy dust
cloud (light brown) swept westward and was driven northward by a strong southerly breeze.
The computed trajectories at lower elevations (300 m and 500 m) indicate regions within Iran
and Oman. Which showed high dust activity.
Consequently, it can be inferred that the substantial contribution of fine soil is likely a result of
the long-distance transportation of desert dust from these specific regions. In the case of India,
an analysis of trajectory plots at initial heights of 1,000 m and 500 m reveals overlapping
patterns, indicating a common origin for desert dust. Information obtained from the NASA
website confirms the occurrence of multiple dust storms in early February 2003, blowing in a
northeasterly direction. Calculated trajectories indicate that the dust particles travel
approximately 7,000 km to reach both receptor sites (Dhaka and Mumbai).
14
Figure 2.4 Backward air parcel trajectories depict the extensive movement of soil dust over
long distances, reaching Bangladesh and India during the month of February 2003 (Begum et
al., 2011)
Figure 2.5 Backward air parcel trajectories depict the extensive movement of soil dust over
long distances to regions in Pakistan and Sri Lanka during the month of February 2004
(Begum et al., 2011)
15
Figure 2.6 The reverse paths of air parcels illustrating the long-range transport of soil dust,
reaching areas in Pakistan and Sri Lanka in February 2004 (Begum et al., 2011)
2.9 Factors Contributing to Increased Dust Storm Events
(Middleton & Kang, 2017)
2.9.1 Low Rainfall and Prolonged Drought Conditions:
A general trend of decrease in annual precipitation and prolonged drought conditions with
increased dust storm activities has been observed in most events. However, this correlation is
not a simple or universally applicable rule, as it may not be valid for instances of dust haze and
reduced visibility resulting from material entrainment.
2.9.2 Change in agriculture practices:
In some cases, changes in agriculture practices led to increased dust events such case was
observed in Portales Valley when wheat farms were moved to dry lands and Wheat was grown
16
on marginal soils, some of which were very vulnerable relict Holocene or late Pleistocene dune
fields and loess. Centre-pivot irrigation was used to water these crops, which necessitated the
removal of linear wind barriers made up of trees erected since the Dust Bowl era to assist in
avoiding wind erosion. Some farmers plowed their fields parallel to the erosive wind direction
rather than transversely, while others neglected to leave a protective coating of stubble mulch
on their fields.
2.9.3 Urbanization and City Development:
Rapid construction activities increase the dust concentration in the growing cities but in later
phases, these activities may help to stabilize the dust source such as the construction of roads,
and the establishment of green belts and parks that will protect the susceptible soil from wind
erosion. However, sustained construction activities over a longer period may have a lasting
impact on dust concentration and may take a long to settle.
2.9.4 Anthropogenic activities:
Activities such as off-road vehicle use (Goudie & Middleton, 1992), and the parching of lakes
and water bodies due to overutilization expose a lot of fine soil area for wind to take up dust.
Other activities such as changes in stream channel may also expose soil to wind erosion.
17
Chapter 3
Approaches for the Quantification of Dust
(Hagen & Woodruff, 1973) attempted to quantify the dust during dust storms by correlating
particulate concentration with the atmospheric visibility reduction given that the particle size
distribution is constant relative humidity is less than 70 percent and deliquescent particles are
negligible.
Studies have found that the average particle size involved in visibility reduction is 50 micrometers and there are little deliquescent particles that are present during dust storms and if
present they will be widely dispersed owing to the meteorological conditions that prevail during
dust storms.
The dust concentration at six feet above the ground is given by
𝐶6 =
56.0
𝑚𝑔/𝑚3
𝑉1.25
where,
V= Horizontal visibility in km
3.1 MODIS (Moderate Resolution Imaging Spectroradiometer)
MODIS is a sensor with a broad observational scope that captures daily Earth observations on
a global scale. MODIS aboard the Terra (formerly EOS AM-1) and Aqua (formerly EOS PM1) satellites. Terra's orbit around the Earth is scheduled such that it crosses the equator from
north to south in the morning, while Aqua crosses the equator from south to north in the
afternoon. Terra MODIS and Aqua MODIS view the entire earth's surface every 1 to 2 days.
MODIS ensures the ongoing collection of data, which is crucial for comprehending changes in
the Earth's environment, that are occurring over extended periods or in the short term. MODIS
measures aerosols, which have a direct and indirect impact on the climate. These aerosols
18
include various substances such as dust, sea salt, volcanic discharges, forest fire smoke, and
specific forms of pollution
Spatial Resolution: 250 m (bands 1-2), 500 m (bands 3-7), 1000 m (bands 8-36) (URL2).
During March 2001, a sandstorm swept through the Taklimakan and Gobi Deserts in western
China and Mongolia, transporting a dust cloud into eastern China. This dust cloud converged
with industrial pollution from southeast Asia. The left image, depicting true colors, reveals a
brownish-yellow haze resulting from the amalgamation of aerosols. On the right, the image
represents the ratio of small (depicted in green) to large (depicted in red) aerosols. Small
particles indicate pollution, while large particles signify dust.
Figure 3.0.1.The left image displays a brownish-yellow haze resulting from a mixture of
aerosols, while the right image depicts the proportion of small aerosols (green) to large
aerosols (red). Small particles indicate pollution, while large particles indicate dust. This
indicates the movement of a dust cloud from the Taklimakan and Gobi Deserts towards
western China (URL3)
3.2 AERONET (AErosol RObotic NETwork)
AERONET consists of a network of sun photometers situated on the ground, used for the
measurement of various atmospheric aerosol characteristics. AERONET collaboration offers
worldwide data on spectral aerosol optical depth (AOD), inversion results, and atmospheric
19
precipitable water in a variety of aerosol environments. The Version 3 AOD information is
categorized into three data quality levels: Level 1.0 (unprocessed), Level 1.5 (screened for
clouds and quality-controlled), and Level 2.0 (quality-assured) (URL4).
Figure 3.2 The WRF-Chem model domain is depicted, showcasing (a) the topography and
(b) the spatial distribution of dust emissions averaged from April 13 to 25, 2010. AERONET
sites are marked with black circles, and a black triangle indicates the site where the time series
of WRF-Chem dust emissions is presented in (c) for the same period the dust emiision., (b)
illustrates the location of the Thar Desert (bounded by solid black lines) and the CALIPSO
satellite overpass (grey line) within the model domain on April 20, 2010.
Kumar et al., 2014 used AERONET version 2 data with level 2 cloud-screened and qualityassured measurements of aerosol optical depth (AOD) at 500 nm, Ångström exponent
(measured between 440 and 870 nm), and single scattering albedo (SSA) at 675 nm were
obtained from seven locations within the model's region of interest. These data were utilized to
investigate the effects of the dust storm on aerosol optical characteristics and to compare them
with the WRF chem model.
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3.3 NOAA HYSPLIT
The Hybrid Single-Particle Lagrangian Integrated Trajectory model (HYSPLIT) is a
computational tool employed for calculating the paths of air parcels, helping predict the distance
and direction of travel for air masses, including the movement of air pollutants. (URL5)
Back trajectory analysis, using NOAA HYSPLIT-4, is employed to identify the source of dust,
as demonstrated by studies like (Begum et al., 2011; IWASAKA et al., 1983; Kim et al., 2015).
Figure 3.3 The 5-day retrograde paths originating from (a) May 9, 2001, (b) May 20, 2002,
and (c) May 27, 2002, at altitudes of 500, 1500, and 2500 meters above the surface
respectively (Dey, 2004)
To investigate the involvement of transportation in the dispersion of dust particles across the
Indo-Gangetic basin during dust events, (Dey, 2004) have employed the Hybrid Single-Particle
Lagrangian Integrated Trajectory (HYSPLIT) model developed by the National Oceanic and
Atmospheric Administration (NOAA) in the United States. This model is utilized to calculate
3-day trajectories, providing insights into the movement and transport patterns of dust particles
in the specified regions of Indo-Gangetic Planes.
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Chapter 4
Summary
Dust is a common aerosol in the atmosphere, plays a significant role in various environmental
and health aspects. As suggested by Prospero (1999), dust from sources like the Sahara Desert
has far-reaching impacts. This literature review explores the impact of dust storms on air
pollution, focusing on global dust sources, transport pathways, and the methods used to quantify
dust events. Dust is composed of various microscopic particles and it has both positive and
negative effects on the environment, including fertilizing ecosystems and influencing climate,
while also posing health risks and contributing to air pollution. Johnston et al. (2011) found that
dust events in Sydney, Australia, were associated with a 15% increase in non-accidental
mortality at a lag of three days, highlighting the health consequences of dust storms.
Dust events vary in duration and intensity. The primary component of dust is quartz, and dust
but it also contains pollutants, organic matter, and microorganisms. Environmental and climatic
factors, such as low rainfall and prolonged drought influence dust storm frequency.
The major global dust sources are concentrated in arid regions, with the most active belt
extending from North Africa to Asia. The literature review outlines the significant dust transport
routes and how dust from sources like the Sahara travels globally, impacting climate, ocean
fertility, and air quality in various regions. There are various factors contribute to increased dust
storm events, including low rainfall, changes in agriculture practices, urbanization, and
anthropogenic activities. The review also explores approaches for quantifying dust, including
the use of satellites like MODIS, AERONET, and NOAA HYSPLIT for trajectory analysis.
In summary, dust storms are intricate phenomena with multifaceted impacts. They affect air
quality, human health, and disease transmission, as well as the Earth's climate and ecosystems.
Research on dust events and their consequences continues to provide valuable insights into the
complex interplay of dust, air quality, and environmental systems. Understanding these intricate
relationships is vital for addressing the challenges posed by dust storms and their implications
for both local and global environments.
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