Characterization of Aerosols using

Aerosol Optical Depth (AOD) over

Pakistan by exploring MODIS,

CALIPSO and AERONET Data

Lokhaze Ali

PhD Student NUST

+2.50C

+1.50C

+1.90C

Ref: Dr. G Rasul (PMD),

2014

Pakistan 2050

The Deciding Factors

for Climate Change:

• Temperature

• Precipitation

• Wind Speed

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Weather Systems Tracks

2010, 2011 & 2014

3Ref: Dr Hanif (PMD), 2014

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Aerosols

Least Understood Components

Aerosols play animportant role in ourclimate system by meansof their direct and indirectimpacts, yet, they are stillone of the leastunderstood componentsof the global climatesystem…Intergovernmental Panelon Climate Change(IPCC) 2007, 2013…

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IPCC 2013

Fifth Assessment Report - AR5

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IPCC 2013

Fifth Assessment Report - AR5

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Aerosols• Aerosols are minute

particles suspendedin the atmosphere

• Adverse effect onhuman health inurban environments

• Effective pathwaysfor deposition ofpollutants

• Scatter and absorbradiation impactingheat balance of theatmosphere

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Aerosols can alter Cloud Properties

• Aerosols act as tiny “seeds”called Cloud CondensationNuclei (CCN's)

• Clouds form when enough water vapor condenses

• Aerosols play a critical role

• Without aerosols in the air,there would be far fewerclouds

• High amounts of aerosols,clouds will have moredroplets than normal

• Droplets are smaller and more numerous, clouds last longer

• Clouds owe their existence to Aerosols 9#Aerosols

Remote Sensing

Clouds & Aerosols

• Nucleation

• Hydrophilic/Hydr

ophobic Aerosols

• Size/Shape/Distri

bution of

Aerosols

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Saharan Dust

• Dust from Sahara Desert

• Transported across the AtlanticOcean

• Supplies iron to the underlyingocean surface waters

• Occasionally limits visibility inFlorida and the Caribbean

• Possibly fertilizes the Amazonbasin

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Saharan Dust (Pink Color) travelling

from Lybia to Italy and Greece

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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

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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

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

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Aerosol Optical Depth

Deep Blue AOD• Deep Blue AOD at 550

nm for MODIS calculatesAOD over bright areassuch as deserts where thestandard MODIS AODalgorithm does not work.

• Surface Reflectancegreater than 0.15 and forcoarse particles

• Lower surface reflectance in the blue part of the visible spectra than in the red part

(Ref: Dr. Farrukh Chishtie(IST), 2015)

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Aerosol Robotic Network

AERONET

• Sunphotometer is usedto measure theextinction of direct beamspectral solar radiation

• AERONET serve asvalidation tool forsatellite aerosol product

• Robots with a datalogger, datatransmission device,batteries, solar panels,and antenna for datatransmission

• Karachi & Lahore

Robotic Arm tracking

the Sun

AERONET Pad#Aerosols 17

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

clouds and aerosols18#Aerosols

CALIPSO

(Cloud Aerosol Lidar and Infrared

Pathfinder Satellite Observations)• Cloud-Aerosol Lidar with

Orthogonal Polarization (CALIOP)

• CALIOP is a two-wavelength polarization-sensitive lidarthat 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

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Arizona Fires June 3, 2011

A-Train Constellation

• A-Train of satellites circlesEarth, about eight-sixteenminutes elapse between thetimes when the first satellite(Aqua) and the last (Aura)pass over any given spot.

• String of satellites stretchesacross 3,000 kilometers

• CloudSat flies in front ofCALIPSO, only around 93.8kilometers

• Distance corresponds to anaverage delay of only 12.5seconds between lidar andradar measurements

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Vertical Profile of AtmosphereCALIPSO/Aeronet Sunphotometers/Ground Based Lidars

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Monthly and Seasonal AOD

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CALIPSO - Data Availability Site

NASA

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Selection of Path

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Precipitation Outlook - PMD

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CALIPSO over Pakistan

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CALIPSO Data

2-9-2014

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Pakistan Floods 2014

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Fog - WorldView

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Sensor : AVHRR

Satellite : METOP-1

Date : 30-12-2014

Time : 16 : 25 : 00 GMT

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CALIPSO Comparison

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Dust Storm 2nd April 2015

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Dust Storm 3rd April 2015

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Sensor : MODIS

Satellite : TERRA

Date : 03-04-2015

Time : 06 : 10 : 30 GMT

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Dust Storm 3rd April, 2015

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Dust Storm 4th April 2015

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Dust Storm 5th April 2015

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Dust Storm 2nd -7th April 2015

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02-04-2015 03-04-2015 04-04-2015

05-04-2015 06-04-2015 07-04-2015

Dust Storm 2nd -15th April 2015

AOD 550 nm (Deep Blue)

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2nd-8th April 2015

2nd-15th April 2015

HYSPLIT Model

Backward Trajectory

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2nd April 2015 8th April 2015

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 Datahttp://www-calipso.larc.nasa.gov/products/kmz_exp/index.php

• NASA EOSDIS WorldViewhttps://earthdata.nasa.gov/labs/worldview/

• GIOVANNI (The Bridge between Data & Science http://giovanni.gsfc.nasa.gov/giovanni/

• GIOVANNI Air Qualityhttp://gdata1.sci.gsfc.nasa.gov/daac-bin/G3/gui.cgi?instance_id=Air_Quality

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