Characterization of Aerosols using Aerosol Optical Depth (AOD) over Pakistan by exploring MODIS, CALIPSO and AERONET Data
1. Characterization of Aerosols using
Aerosol Optical Depth (AOD) over
Pakistan by exploring MODIS,
CALIPSO and AERONET Data
Lokhaze Ali
PhD Student NUST
2. +2.50C
+1.50C
+1.90C
Ref: Dr. G Rasul (PMD),
2014
Pakistan 2050
The Deciding Factors
for Climate Change:
• Temperature
• Precipitation
• Wind Speed
2#Aerosols
5. Aerosols
Least Understood Components
Aerosols play an
important role in our
climate system by means
of their direct and indirect
impacts, yet, they are still
one of the least
understood components
of the global climate
system…
Intergovernmental Panel
on Climate Change
(IPCC) 2007, 2013…
#Aerosols 5
8. Aerosols
• Aerosols are minute
particles suspended
in the atmosphere
• Adverse effect on
human health in
urban environments
• Effective pathways
for deposition of
pollutants
• Scatter and absorb
radiation impacting
heat balance of the
atmosphere
8#Aerosols
9. Aerosols can alter Cloud Properties
• Aerosols act as tiny “seeds”
called Cloud Condensation
Nuclei (CCN's)
• Clouds form when enough
water vapor condenses
• Aerosols play a critical role
• Without aerosols in the air,
there would be far fewer
clouds
• High amounts of aerosols,
clouds will have more
droplets than normal
• Droplets are smaller and
more numerous, clouds last
longer
• Clouds owe their
existence to Aerosols 9#Aerosols
11. Saharan Dust
• Dust from Sahara Desert
• Transported across the Atlantic
Ocean
• Supplies iron to the underlying
ocean surface waters
• Occasionally limits visibility in
Florida and the Caribbean
• Possibly fertilizes the Amazon
basin
11#Aerosols
12. Saharan Dust (Pink Color) travelling
from Lybia to Italy and Greece
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13. Arctic from 1913 to 2012
• Greenhouse gas
warming alone three
degrees Celsius in
the Arctic over the
last 100 years
• Actual observed
warming is around
1.2 degrees Celsius
• Aerosols offset about
60 per cent of the
warming
13#Aerosols
14. Levels of Data
Level 1B Level 2 Level 3
Calibration to
Radiance
Aerosol
Retrieval
Algorithm
Spatial & Temporal
Averaging
Ref: Pawan Gupta (NASA), 2015 #Aerosols 14
15. Aerosol Optical Depth (AOD)
Aerosol optical depth is a
measure of radiation
extinction due to scattering
and absorption by aerosol
particles in the atmosphere.
• Particles (dust, smoke,
pollution)
• Dimensionless number
• Amount of aerosol in the
vertical column of
atmosphere over/below
the observation location
15#Aerosols
16. Aerosol Optical Depth
Deep Blue AOD
• Deep Blue AOD at 550
nm for MODIS calculates
AOD over bright areas
such as deserts where the
standard MODIS AOD
algorithm does not work.
• Surface Reflectance
greater than 0.15 and for
coarse particles
• Lower surface reflectance
in the blue part of the
visible spectra than in the
red part
(Ref: Dr. Farrukh Chishtie
(IST), 2015) #Aerosols 16
17. Aerosol Robotic Network
AERONET
• Sunphotometer is used
to measure the
extinction of direct beam
spectral solar radiation
• AERONET serve as
validation tool for
satellite aerosol product
• Robots with a data
logger, data
transmission device,
batteries, solar panels,
and antenna for data
transmission
• Karachi & Lahore
Robotic Arm tracking
the Sun
AERONET Pad
#Aerosols 17
18. The Lidar
• Lidar (light detection and
ranging) is an active
remote sensing technique
for observing the
distribution of molecules
and particles in the
atmosphere as a function
of height by means of the
light they backscatter from
a laser beam.
• The CALIPSO spacecraft
uses an innovative lidar
and imaging system to
reveal the secrets of 18#Aerosols
19. CALIPSO
(Cloud Aerosol Lidar and Infrared
Pathfinder Satellite Observations)
• Cloud-Aerosol Lidar with
Orthogonal Polarization
(CALIOP)
• CALIOP is a two-wavelength
polarization-sensitive lidar
that provides high-resolution
vertical profiles of aerosols
and clouds
• CALIOP utilizes three
receiver channels: one
measuring the 1064 nm
backscatter intensity and
two channels measuring
orthogonally polarized
components of the 532 nm
backscattered signal
#Aerosols 19
Arizona Fires June 3, 2011
20. A-Train Constellation
• A-Train of satellites circles
Earth, about eight-sixteen
minutes elapse between the
times when the first satellite
(Aqua) and the last (Aura)
pass over any given spot.
• String of satellites stretches
across 3,000 kilometers
• CloudSat flies in front of
CALIPSO, only around 93.8
kilometers
• Distance corresponds to an
average delay of only 12.5
seconds between lidar and
radar measurements
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21. Vertical Profile of Atmosphere
CALIPSO/Aeronet Sunphotometers/Ground Based Lidars
21#Aerosols
41. Important Data Links
• AERONET (Aerosol Robotic Network)
http://aeronet.gsfc.nasa.gov/
• LAADS Web (Level 1 and Atmosphere Archive and
Distribution System)
http://ladsweb.nascom.nasa.gov/data/search.html
• CALIPSO - KML/KMZ Data using Expedited Data
http://www-calipso.larc.nasa.gov/products/kmz_exp/index.php
• NASA EOSDIS WorldView
https://earthdata.nasa.gov/labs/worldview/
• GIOVANNI (The Bridge between Data & Science
http://giovanni.gsfc.nasa.gov/giovanni/
• GIOVANNI Air Quality
http://gdata1.sci.gsfc.nasa.gov/daac-
bin/G3/gui.cgi?instance_id=Air_Quality
#Aerosols 41