institute of atmospheric physic beijing, china 30 august 2010 differential absorption lidar to...

Institute of Atmospheric PhysicBeijing, China

30 August 2010

Differential Absorption Lidar to Measure Tropospheric Ozone Variations

Shi Kuang1, Mike Newchurch1, John Burris2, Steve Johnson3

1University of Alabama in Huntsville2NASA-Goddard Space Flight Center3NASA-Marshall Space Flight Center

kuang@nsstc.uah.eduhttp://nsstc.uah.edu/atmchem

o Introductiono Lidar hardwareo Measurement exampleso Future designo Conclusion

2Institute of Atmospheric physicBeijing, China , August 2010

The common techniques to measure ozone profile: ozonesonde satellite lidar.

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NOAA, NASA, United Nations Environment Programme, WMO, “Scientific Assessment of Ozone Depletion: 2002”.

o Strength: well-characterized, low up-front cost, good vertical resolution, OK for cloudy sky, simultaneous T/P/RH.o Weakness: long preparation time, drifting with wind.

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Introduction

UAHuntsville 2010 earth day launch

Measuring O3 up to 35km~5m/s rising rate, ±10% uncertainty,100-m vertical resolution

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Introduction

11-year and >600 ozonesonde profiles at Huntsville, AL, U.S.A.

O3 mixing ratio (top) and RH (bottom)

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Introduction

o Strength: good for column O3, global distribution o Weakness: low vertical resolution (several km), cloud contamination

Liu et al. 2005

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Introduction

o Strength: continuous measurement, high temporal resolutiono Weakness: cloud contamination, expensive, can’t measure surface for ground-based

JPL-Table Mountain Facilityhttp://tmf-lidar.jpl.nasa.gov/index.htm

ground-based, aircraft-based, mobile

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Introduction

o Provide high-resolution ozone observation needed by atmospheric modeling, satellite validation, and air quality studies.

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Introduction

P

RR1 R2

On

Off

σ

λλon λoff

Δσ

)ln(2

1][

)()(

)()(

33

21

21

RonRoff

RoffRon

O PP

PP

RO

O3 DIAL Equation

TelescopeLaser

R

Backscattering Medium

Transmitter (266, 280-292, 308, 316, 351, 355nm for O3)

Receiver (telescope and aft optics)

Detector (photomutiplier (PMT) or avalanche photodiode (APD))

Signal processing (photoncounting or analog)

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10

Typical composition

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1

11

285 291

Nd:YAG pumped Dye laser

4

16” Telescope

Aft Optics

Licel

Computer

PMT

Nd:YAG pumped Dye laser

4” Telescope

5

2

3

30Hz, 6 or 3mJ/pulse

RAPCD-DIAL configuration

Alt (km)

2

4

6

8

0

10

Ch1

Ch2

Ch5

Web server

Measurement range

Lidar hardware

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Introduction

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Lidar hardware

PumpDye laser

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Lidar hardware

16’’ Newtonian telescope16’’ Newtonian telescope 4’’ customized small telescope4’’ customized small telescope

PMT

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sonde

500ppbv

CloudCloud Cloud

1. Intense STE (~500ppbv at 7km) to reach top of the PBL (~2km) within 48 hours

Ozone lidar measurements with a 10-min temporal resolution and ~500-m vertical range resolution from 27 to 28 April 2010.

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Measurement examples

Apr. 23, 2010 Apr. 27, 2010 May 1 2010

Dry stratospheric air

Tropopause

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Measurement examples

May 7

May 3, 2010 May 4, 2010

EPA surface O3

Sonde, 11:30

May 6 (high PBL O3)May 5

89ppbv, highest during 2010 so far

Local time

Aloft ozone in the PBL generally explains the daily surface maximum value although large differences between the surface and upper-air O3 often exist especially during nighttime.

18Hey!!

Lidar observation, Aug. 4, 2010

Lidar convolved with OMI kernel

18

The 3rd Asia Pacific Radiation Symposium

Seoul, South Korea25-28 August 2010

Convolution of lidar ozone measurements between the surface and 10 km altitude at Huntsville, AL during August 4, 2010 with OMI ozone averaging kernel and a priori indicates that OMI is unable to capture the highly variable ozone structure in PBL, but captures a significant portion of the mid-tropospheric layer

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1. shift one dye laser to 316 and add two Raman-shifted lasers at 289 and 299 so that we can extend the observations to upper troposphere.

2. Apply dual-DIAL (289/299, 299/316) retrieval technique to further reduce aerosol interference in the lower troposphere.

Schematic diagram of the future transmitters, wavelength pairs, and their measurement ranges.

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On1-off1

On2-off2

1( ) 2( ) 1 2 1 2( ) ( ) ( ) ( ) ( )1 2

3 3 1( ) 2( )

13 { [ ln ln ] [ 3 3 ] [ 3 3 ]}

2( )on r on r b b e e

r r r r rO O off r off r

P PdO C O C O O C O

C dr P P

+

-Cx

Dual-DIAL Eqn.

Dial Eqn.

0 0

1 1

2 2

( )

( )off on

off on

C

[Kovalev and Bristow 1996, Wang et al. 1997]

Future plan

)(1

ln2

1ln

2

13 )()(

3)(

)(

3)(

)(

3)( roffron

Oroff

ron

Oroff

ron

Or dr

d

P

P

dr

dO

er

br

sr OOO )()()( 333

1)(

1)(

1)(

1)( 3333 e

rbr

srr OOOO

2)(

2)(

2)(

2)( 3333 e

rbr

srr OOOO

No assumption for lidar ratio and Angstrom!

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2-m Raman cell for future transmitter (289/299nm)

Future plan

Big Sky (Quantel) 266 pump laser

Raman gas cell

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Future plan

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1. Lidar measures high spatio-temporal ozone variations associated with different dynamic and photochemical processes from PBL to upper troposphere.

2. The ozone variations and structures sometimes are closely correlated with aerosol and sometimes not.

3. Nocturnal residual ozone layers often exist decoupled from the surface.

4. The lidar observations will be very helpful for addressing the ozone variability captured by geostationary satellites and forecast with regional air-quality forecasts.

Kuang, S., et al. (2010), Differential Absorption Lidar (DIAL) to measure sub-hourly variation of tropospheric ozone profiles, IEEE Trans. Geosci. Remote Sens., in press.

Liu, X., K. Chance, C. E. Sioris, R. J. D. Spurr, T. P. Kurosu, R. V. Martin, and M. J. Newchurch, "Ozone profile and tropospheric ozone retrievals from Global Ozone Monitoring Experiment: Algorithm description and validation," J. Geophys. Res., 110, p. D20307, 2005.

NOAA, NASA, United Nations Environment Programme, WMO, “Scientific Assessment of Ozone Depletion: 2002”, World Meteorological Organization Global Ozone Research and Monitoring Project - Report No. 47

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