Laser Radar (LIDAR) Applications

to

Weather and Climate Studies

Prof. Panuganti CS Devara

Amity Centre for Ocean-Atmospheric Science and Technology

(Amity COAST)

Amity University Haryana, Panchgaon (Manesar) Gurgaon

pcsdevara@ggn.amity.eduOther Contributors: Dedicated team at Indian Institute of Tropical Meteorology (IITM),

Pune, India

• Introduction

• Lidar Configurations

• Lidar Facilities

• Long-term Changes and Trends in Aerosol

Loading; Environmental Chemistry and

Pollution; Turbulence and Sate Variables;

Clouds and Climate

• Upcoming Lidar Programs in India for

Climate Studies

• Thoughts to Think Tank and Future Scope

OUTLINE

Lidar Configurations

• Bi-static, Helium-Neon Lidar

• Bi-static, Multi-wavelength Argon-ion Lidar

• Argon-ion Pumped Dye Lidar

• Mono-static Excimer DIAL

• TEA Pulsed CO2 Lidar

• Dual Polarization Micro Pulse Lidar (DPMPL)

• Doppler Wind Lidar

• Multi-Parameter Raman Lidar

Aerosol and Gas Profiling Facilities

(Active Remote Sensors)

Bi-static Argon-ion Lidar with Newtonian

Telescope Equipped with Detection and

Data Acquisition Systems

UV DIAL Ozone Profiler with Alt-

Azimuth Cassegrain Telescope Equipped

with Detection and Data Acquisition

Systems

LOS Raman Lidar with Double

Monochromator and Fiber Optic Coupling

Dual Polarization Micro Pulse Lidar with

Built-in Polarization Flipper

Multi-parameter

Raman Lidar Profiler

Portable Doppler Wind Lidar

Active Remote Sensing Facilities

Atmospheric Lidar Facilities and their Applications

* Helium-Neon Lidar (632.8 nm)

* Multi-wavelength Argon Ion Lidar (514.5, 501.5, 496.5, 488.0, 476.5 nm)

* Argon ion pumped Dye lidar [(570-655 nm (Rhodamin–6G) & 695-790 nm (Pyridin I)]

* Tunable Carbon dioxide lidar (9.2-11.8 m)

* Excimer-Raman DIAL lidar (308 nm & 353 nm)

* Dual Polarization Micro Pulse Lidar (532 nm)

The Argon ion lidar has been

@ Operated during the correlative measurement program of LITE

(Lidar In-space Technology Experiment) of NASA in September 1994 and now for

CALIPSO, upcoming Megha Tropiques

@ Operated extensively during the INDOEX, BoBMEX and ARMEX Campaigns.

@ Operating in conjunction with the overhead passes of IRS-P3/P4/P6

Twice-a-week observations of vertical profiles of aerosol concentration using the Argon ion

lidar have been in progress since October 1986. Using these multi-year data sets, tropospheric

aerosol climatology has been established and undertaken several studies.

Atmospheric AerosolsThe most complex and least well understood constituentsVaried chemical composition (both acid- and water-soluble)Dynamic size range from 10^-3 to 10^2 m diameter

TYPES: (i) Aitken Nuclei or Condensation Nuclei or Transient NucleiRadius <0.1 m [Play significant roles in Atmospheric Chemistryand Electricity]

(ii) Large or Accumulation-mode particles0.1 < radius < 1.0 m [Earth-Atmosphere Radiation Balance and Climate Change]

(iii) Giant or Coarse-mode particles > 1.0 m [Act as Cloud Condensation Nuclei or IceNuclei and are important for studies in Cloud Physics]

SOURCES

Natural: * Gas-to-Particle (Chemical Reaction of variety of particles)* Sea-spray (Marine or Maritime aerosols)* Wind-blown mineral dust particles from arid and semi-arid zones* Organic aerosols from trees and plants* Biological aerosols such as pollens and spores* Smoke emissions from burning of land biota* Stratospheric aerosols due to volcanic eruptions (direct particleand gas phase reactions)* Meteoric debris

Anthropogenic: * Industrial emissions, soot particles (carbonaceous)* Al2O3 and SO2 from aircrafts and rockets* Bio-mass and bio-fuel burning* Transport and vehicular emissions* Land-use pattern changes such as building constructional activities andagricultural activities

Photograph of the Lidar Laboratory with

Different Laser Systems

[A] [B] [C]

Multi-Wavelength Continuous Wave Argon-ion Lidar system.

[A]: Laser Source (Transmitter); [B]: Beam Director and

[C]: Telescope , Detection and Data Acquisition System (Receiver)

Newtonian telescope - Receiver part of the

Lidar System

Argon-ion lidar in operationLidar Dome Equipped with Cassegrain

Telescope and Data Acquisition Systems

Computer-controlled Bi-static Argon-ion Lidar

Intra-Seasonal Variations in

Aerosol Loading over Pune

Aer

oso

l C

olu

mn

Con

ten

t (X

10

6 C

m-2

)

October 1986 – September 2006

0 20 40 60 80 100 120 140 160 180 200 220 2400

306090

120150180210240270300330360390420450480510540

ACC

Regression fit

October 1986 - December 2006

Ae

ros

ol

co

lum

n c

on

ten

t (

X 1

06)

cm

-2

Month number

Long-term Changes and Trends in Aerosol Loading.

Dashed red line indicates polynomial regression fit

Time evolution of mixed and stable layer heights

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

500

1000

1500

2000

2500

3000V

en

tila

tio

n C

oeff

icie

nt

(m2 s

-1)

Month

Ventilation Coefft.

300

350

400

450

500

Mix

ed L

aye

r He

igh

t (m)

Mixing Depth

Variation of monthly mean mixed layer heights and corresponding

ventilation coefficients observed during 1986-2000 over Pune

Optical Layout of Laser Scintillometer

ClimateClouds

Aerosol-Cloud-Climate Interactions

Aerosols

Cloud Lidar Principle

Cloud Profiling using Argon-ion Lidar

BEAM EXPANDER

FILTER

BEAM SPLITTER

14" DIA.

SCHMIDT

CASSEGRAIN

TELESCOPE

/2 WAVE PLATE

POLARIZATION

FLIPPER

1 Hz to 5 KHz

ENERGY

METER

DPSS

LASER

PRINTER

COMPUTER

MONITOR

DEPOLARIZING

OPTICS

FILTERH.V.

PMT1

*

DUAL

CHANNEL

MULTI-

CHANNEL

SCALER

M

C

S1

M

C

S2

PMT2 -1500 V

PMT SUPPLY

FEEDBACK AND

VOLTAGE CONTROL

DUAL CHANNEL

PHOTON

COUNTER

Optical Layout of Dual Polarization Micro Pulse Lidar (DPMPL). Bore-sight

mechanism, Octopus and Pockels cell are some of the novel features of the system

Main Specifications of Dual Polarization Micro Pulse Lidar

(DPMPL)

Transmitter

Laser type: DPSS Nd:YAG

Laser wavelength: 532 nm

Laser Repetition Rate: 2 KHz

Laser Pulse Energy: 20 J/pulse

Laser Pulse Width: 18 ns

Laser Beam Expansion: > 20

Polarization Flipper: Alternate parallel and perpendicular

Polarization Switching: 1 KHz

Receiver

Telescope type: 30-cm (12 inch) Schmidt Cassegrain

Focal Ratio: f / 10

Filter Bandwidth: 0.6 nm

Detection: Dual Channel MCS with metal package

PMTs in photon count mode

FOV overlapping: Octopus (4 Quadrant PSD), High

Performance Remote Terminal Unit

Range Resolution: 30 cm

Dual Pol Micro Pulse Lidar (DPMPL)

Time evolution of Linear Depolarization Ratio (LDR)

observed in the night intervening between 30 and 31

December 2005. Smaller LDR values in the surface

layer almost from mid-night to early morning hours

indicate relatively more isotropic aerosol particles

than in the NBL over the experimental site.

Time

evolution

of NBL

and Residual

layer

and aerosol

plumes

Dual Polarization Micro

Pulse Lidar (DPMPL)

Typical profiles of nocturnal boundary layer and stratiform cloud evolution observed

with DPMPL during south-west monsoon 2008

Principle of

DIAL (DIfferential Absorption Lidar) or

DASE (Differential Absorption Scattering Energy) Technique

Block Diagram of XeCl (Xenon Chloride) Excimer Ozone Lidar System

Photograph Showing the Excimer Laser, Raman Cell and

Beam Expander-cum-Collimator

Photograph Displaying the Lidar Telescope, Detection and

Data Acquisition / Processing Systems

1x1012

2x1012

3x1012

4x1012

5x1012

6x1012

7x1012

8x1012

0

5

10

15

20

25

30-0.003 -0.002 -0.001 0.000 0.001 0.002 0.003 0.004 0.005 0.006

0

5

10

15

20

25

30

Altitu

de

(K

m)

Ozone Number Density (cm-3)

18 December 2003

1930 Hrs

Wind Gradiant (S-1)

Vertical distributions of DIAL ozone and their association with height gradients

of wind speed (open circles) derived from concurrent pilot-balloon observations

on December 18, 2003

10/11/03 20/11/03 21/11/03 25/11/03 27/11/03 28/11/03 29/11/03

180

200

220

240

260

280

300

320

340

360

380

400

To

tal C

olu

mn

Ozo

ne (

DU

)

Date

MICROTOPS

LIDAR

TOMS

Comparison of total ozone determined from Microtops, Lidar and TOMS

TEA Carbon Dioxide Tunable Laser System

Schematic of the Raman lidar set-up for LOS monitoring of

atmospheric NO2, CO2 and CH4. Corresponding shifted

wavelengths are 535, 554 and 605 nm at 515 nm

Photograph showing the receiver consisting of 25cm-diameter astronomical quality

Newtonian telescope fitted with Peltier-cooled Photo Multiplier Tube and holographic

grating-based double monochromator with fiber optic coupling of the Raman-Lidar

set up at IITM, Pune

LOS Raman Lidar

500 510 520 530 540 550 560 570 580 590 600 610 620

0.0

2.5

5.0

7.5

10.0

12.5

15.0

17.5

20.0

22.5

25.0

554 nm

(CO2)

535 nm

(NO2)

605 nm

(CH4)

515 nm

(Ar+)

Date:9/1/2006

Time:2032 Hrs

Scan range = 500-620nm

Spectral resolution of scan=2nm

La

se

r R

etu

rn S

ign

al S

tre

ng

th (

mV

)

Wavelength (nm)

Typical record of LOS Raman Lidar

Main Specifications of Doppler Wind Lidar

Compact (65 Kg) Doppler Wind Lidar. The system provides

3D wind field during all sky and weather conditions.

Height – Time evolution of signal-

to-noise-ratio recorded on

15/07/2010 . Cirrus cloud

signatures Up to 12 km can be

noted from the figure.

Height – Time evolution of

horizontal wind recorded on

15/07/2010. Wind structures

within the cloud up to 12 km

can be noted from the figure.

DOPPLER WIND LIDAR

Time-height cross-section of the noise-corrected Back-scattered signal strengthprofiles obtained with p (co-polarization) and s (cross-polarization) channelsof the DPMPL from around 2015 to 2200 LT on July 03, 2007. The gap in the recordcorresponds to drizzle for about 11 minutes. The delay (about 7 minutes) inrevival of cloud activity followed by this (recharging of atmosphere) over the sitemay be noted.

July 03, 2007

DPMPL Investigation of “Recharging of Atmosphere”

Date: August 9, 2007

0 km

5 km

Pune region

Total attenuated back scattered signal Perpendicular attenuated backscatter

Depolarization Pune region

Pune region

Cloud-Aerosol Lidar and Infrared

Pathfinder Spaceborne

Observations

(CALIPSO)

Validation Experiments on

9 and 11 August 2007

at IITM, Pune, India

using DPMPL

CALIPSO Validation

The low-level clouds observed with DPMPL and

CALIPSO at 02:30 hrs on 31 May 2008

Indian Lidar Network (I-Link)

Right now, a few Research Organizations and a very few Universities have

stationary/ mobile lidar systems for monitoring aerosols, gases and temperature in the

boundary layer, free-troposphere and stratosphere. In addition, a well-planned

program to establish country-wide network of micro pulse lidars for regular

monitoring of aerosols, pre-cursor gases and clouds up to the UTLS region has been

drawn. Some of these lidars are also being planned to be operated in conjunction with

ST Radars/Doppler Sodars for better characterization of aerosols and clouds in terms

of their radiative forcing in regional climate diagnosis and prediction programs.

Space Borne Lidar (SBL)

An ISRO project, as a National Program, called “Aerosol Cloud Climatology Laser

Radar in Mission to Space (ACCLAIMS)” has been undertaken to study the role of

aerosols, gases and clouds in the atmosphere-land-ocean interactions. The pilot

experiment has been successfully conducted to test the performance of the payload

“Backscatter Lidar” with the National Balloon Facility in Hyderabad.

Altitude: 600 km; No. of orbits per day: 15; Wavelengths: 532 and 1064 nm

Height resolution: ~ 30 m

SOME THOUGHTS AND FUTURE SCOPE

Laser Radar (LIDAR) technique augments humanity’s ability to

study aerosols, trace gas chemistry, clouds and state variables,

joining in-situ instruments in both complementary and unique ways

for environmental monitoring and climate studies. There is still

much work to be done to bring the field maturity.

Besides the stationary systems, new generation mobile profilers

need to be developed for multi-dimensional mapping of aerosols and

gases in different environments. Such systems in network mode will

play a vital role in the identification of sources/sinks and modeling of

the impacts of aerosols and gases on air pollution, hydrological cycle,

weather and climate.

Modeling techniques need to be developed for better laser sources

with wide tunability and more portability.

Thank

you

all

for

Attention