The Atmospheric Chemistry Experiment (ACE): Latest

ResultsPeter Bernath

Department of Chemistry, University of York

Heslington, York, UK

and

Department of Chemistry, Old Dominion University, Norfolk, VA (Aug. 2011)

The Shambles, Medieval York, UK

Norfolk Harbor, Norfolk, Virginia

ACE Mission is Applied Spectroscopy

Second edition now includes line strength formulas and their derivation for microwave (JPL), infrared (HITRAN) and electronic transitions plus light scattering.

ACE GoalsTo investigate the chemical and dynamical

processes that control the distribution of ozone in the stratosphere and upper

troposphere with a particular focus on the Arctic winter stratosphere.

To accomplish this, Temperature and pressure will be measured. ACE will measure the concentrations of

more than 30 molecules as a function of altitude.

Aerosols will be measured and quantified.

ACE Satellite

Bernath et al., GRL, 32, L15S01 (2005)

http://www.ace.uwaterloo.ca/

Solar Occultation

Advantages: 1.Radiance of sun gives higher S/N than emission2.Limb view gives longer path length ~500 km (lower detection limits) than nadir (but lower horizontal resolution)3.“Self-calibrating” so excellent long-term accuracy and precisionDisadvantages: 1.Modest global coverage2.Samples only free troposphere (>5 km or so)

Timeline (“faster, cheaper”)

Jan. 1998 Proposal to Can. Space Agency (CSA)

Feb. 2001 FTS and Imager CDR Mar. 2001 MAESTRO CDR Jun. 2001 Bus CDR Sept. 2002 S/C integration & test Mar. 2003 Instrument test (Toronto) May 2003 Final integration (DFL) Aug. 2003 Launch Sept. 2003 Commissioning Feb. 2004 Routine operations

First ACE data Feb. 2004, mission currently approved to March 2012. Mission had a planned 2-year lifetime – eighth anniversary Aug. 2011.

Curtis Rinsland

Instruments

Infrared Fourier Transform Spectrometer operating between 2 and 13 microns (750-4400 cm-1) with a resolution of 0.02 cm-1

2-channel visible/near infrared Imagers, operating at 0.525 and 1.02 microns (cf., SAGE II)

Suntracker keeps the instruments pointed at the sun’s radiometric center.

UV / Visible spectrometer (MAESTRO) 0.4 to 1.03 microns, resolution ~1-2 nm

Startracker

Optical Layout (ABB-Bomem)

Secondaymirror (6)

Field stop (5)

IR Filter(7)

Suntrackermirror (1)

Aperturestop (4)

PV MCTDetector

(18)

Glare stop(16)

Coolerwindow (17)

Outputcondenser

(14)

INTcorner-cubemirror (10)

End mirror(13)

INTcorner-cubemirror (11)

(12)

(9)

(12): Reflective coating(9): B/S coating

Beamsplit ter/compensatorassembly (8)

Primary mirror (3)

Fold mirror(22)

Lenses(23)

0.525 mimager (28)

1.02 mimager (26)

Dichroic(24)

Solarinput

Compensator

VIS/NIR-Quad CellDichroic

Quad Cell(21)

Lenses(20)

LaserMetrologyDetection

1.02 mfilter (25)

0.525 mfilter (27)

Beam splitter

Foldmirror(15) Laser Metrology Insertion

MAESTROInterface (2)

PV InSbDetector

Lens

Lens Glare stop

Dichroic

1.55 mfilter (19)

ACE-FTS (ABB-Bomem)

Interferometer-side Input optics-side

Integration to S/C Bus (DFL, Ottawa)

Pegasus XL Launch Vehicle (Aug. 12, 2003)

ACE Orbit- Global Coverage

650 km, 74° inclined circular orbit

Global Occultation Distribution

FTS – Decontamination Results

After 6 months operationAfter decontamination

Ryan Hughes

750-4400 cm-1

SNR>300 in

2 s scan

Occultation Sequence

NB: retrieved tangent height

ACE-FTS Version 3 SpeciesTracers: H2O, O3, N2O, NO, NO2, HNO3, N2O5, H2O2, HO2NO2, N2

Halogen-containing gases: HCl, HF, ClONO2, CFC-11, CFC-12, CFC-113, COF2, COCl2, COFCl, CF4, SF6, CH3Cl, CCl4, HCFC-22, HCFC-141b, HCFC-142b

Carbon-containing gases: CO, CH4, CH3OH, H2CO, HCOOH, C2H2, C2H4, C2H6, OCS, HCN as well as pressure and temperature from CO2 lines

Isotopologues: H218O, H2

17O, HDO, O13CO, OC18O, OC17O, O13C18O, 18OO2, O18OO, O17OO, N15NO, 15NNO, N2

18O, N217O, 13CO, C18O,

C17O, 13CH4, CH3D, OC34S, O13CS

Research species: ClO, acetone, PAN, HFC-23, etc.

Retrievals are entirely dependent on lab spectroscopy: HITRAN.

Climate Change

The Independent

21 Dec. 2006

Greenhouse Gases (IPCC)

1. CO2

2. CH4

3. N2O4. Halocarb.5. Trop. O3

6. Strat. H2O“Indirect Greenhouse Gases (GHGs)”1.CO2.NOX

3.VOCsAll can be measured by solar occultation IR spectroscopy.

ACE-FTS CO2 line near 61 km

Note: results are plotted on the raw measurement grid (unapodized).

ACE-FTS measures CO2, main greenhouse gas, but…

Temperature from relative CO2 line intensities; pressure from CO2 line absorption, assuming a constant CO2 concentration.

CO2 Profiles from ACE-FTS

Normal ACE retrieval uses constant CO2 VMR to get T, p and tangent heights. Use N2 continuum instead and then retrieve CO2 VMR in 5-25 km altitude range.

Foucher et al., ACP 9, 2873 (2009)

Lafferty et al., Appl. Opt. (1996)

ACE-FTS results for the 40°N-60°N latitude band

Foucher et al., ACP 11, 2455 (2011)

ACE 9-10 km (red)CARIBIC (blue)

CO2 Profiles from ACE for the 50°N-60°N latitude band

May 2006

July 2006

ACE (red)Carbontracker (blue)Flexpart (purple)

ACE CO2 trend 50°N-60°N latitude

Helpful to add observed CO2

profile information to total column

observations.

Atmospheric CCl4

G

From Geoff Toon; Note line mixing in CO2 Q-branch

CO2 line mixing H2O non-Voigt line shapes

First Global CCl4 Distribution

70S 60S 40S 20S 0 20N 40N 60N 80N

10

15

20

25

30

10

10

20

2020

30

30

40

40

50

50

60

60

70

70

8080

90

90

100

100

110

110

120130

120

20

120

Latitude (in degree)

Alt

itu

de

(in

km

)

2004-7 Latitudinal Distribution for CCl4 (in ppt)

0

20

40

60

80

100

120

N. Allen et al., ACP 9, 7449 (2009)

CCl4 produces Cl2CO peak in stratosphere

Atmospheric Phosgene, Cl2CO

Toon et al., GRL 28, 2835 (2001)ν5 (C-Cl antisymmetic

stretching mode) at849 cm-1

observed with MkIVballoon-borne FTS.

Global Distribution of Phosgene, Cl2CO

Latitude (in Degrees)

Alt

itu

de

(in

Km

)

2004-2005-2006 COCl2 Volume Mixing Ratio (in pptv)

-80 -60 -40 -20 0 20 40 60 800

5

10

15

20

25

30

35

40

0

10

20

30

40

50

60

D. Fu et al., GRL 34, L17815 (2007)

-10 0 10 20 30 400

5

10

15

20

25

30

Volume Mixing Ratio (in pptv)

Alt

itu

de

(in

km

)

85oS-60oS

60oS-30oS

30oS-30oN

30oN-60oN

60oN-90oNWilson et al. 1988Kindler et al. 1995

50oN-80oN

0o-90oN

0o-85oS

Cl ClC

Oװ

Halogen Budget and Trends

Species Global Warming Potential(20 year time horizon)

Carbon Dioxide 1Methane 72

Nitrous Oxide 289CFC - 11 6,730CFC - 12 11,000

CFC - 113 6,540Carbon Tetrachloride 2,700

HCFC - 22 5,160HCFC - 141b 2,250HCFC - 142b 5,490HFC - 134a 3,830

Sulphur Hexafluoride 16,300Carbon Tetrafluoride

(PFC - 14) 5,210

Retrievals v. 3.0: CFC-11, CFC-12 , CFC-113, HCFC-22, HCFC-141b, HCFC-142b, CCl4, CH3Cl, CF4, SF6, (HFC-134a), F2CO, ClFCO, Cl2CO, HCl, HF, ClONO2, (ClO)

A. Brown and C. Boone

SF6

HCFC-142b (CH3CClF2)

HCFC-22 (CHClF2)

CFC-12 (CCl2F2)

ACE solar spectrum (F. Hase): 224782 spectra added, improvement over ATMOS, no telluric lines, but 0.02 cm-1 vs 0.01 cm-1 resolution (resolution largely determined by width of solar lines) and 750-4400 cm-1 vs 600-4800 cm-1.

CO, Δv=1

OH

CO Δv=2

CH, NH, OHACE Solar Spectrum http://

www.ace.uwaterloo.ca/

Used in Leicester for IASI CO retrievals

Confusion Limit

OH v=2-1 P1(2.5)

OH v=1-0 P1(6.5)

Every bump is an atomic or molecular line: confusion limit!

IR NH Spectra

Lab: Hollow cathode emission

ACE Solar

ATMOS Solar

Improved vibration-rotation and pure rotation IR spectroscopy:OH, Bernath & Colin JMS 257, 20 (2009)NH, Ram & Bernath JMS 260, 115 (2010)CH, Colin & Bernath JMS 263, 120 (2010)

Air Quality and Biomass Burning

VOCs and Air Quality

Volatile Organic Compounds (VOCs) lead to the production of tropospheric ozone, a pollutant & GHG.

Formaldehyde in the Troposphere

Directly emitted: biomass burning, incomplete combustion, industrial emissions, emissions from vegetation

Secondary product: oxidation of most anthropogenic and biogenic hydrocarbons (including methane and isoprene)

Important role in HOx and NOy radical cycling Influence the oxidative capacity of the atmosphere Effect on the tropospheric O3 budget

Important test species in evaluating our mechanistic understanding of tropospheric oxidation reactions

Surface, aircraft, and satellite measurements

HCHO tropospheric columns (GOME, SCIAMACHY, OMI, GOME-2) used for inferring isoprene emissions

HCHO contribution to the spectrum

0,0

0,2

0,4

0,6

0,8

-0,05

0,00

0,05

2778,0 2778,2 2778,4 2778,6 2778,8

-0,05

0,00

0,05

Observed spectrum

without HCHO HCHO contribution

HCHO contributionwith HCHO

0,0

0,2

0,4

0,6

0,8

-0,10-0,050,000,050,10

2780,8 2780,9 2781,0 2781,1 2781,2 2781,3 2781,4 2781,5 2781,6-0,10-0,050,000,050,10

Observed spectrum

HCHO contributionwithout HCHO

HCHO contributionwith HCHO

6 spectral windows selected in 6 spectral windows selected in the range 2735 - 2830 cmthe range 2735 - 2830 cm-1-1 ::

2739.85 ; 2765.65 ; 2778.4 ; 2739.85 ; 2765.65 ; 2778.4 ; 2781.2 ; 2812.25 ; 2826.672781.2 ; 2812.25 ; 2826.67

Perrin et al., JQSRT 110, 700 Perrin et al., JQSRT 110, 700 (2009)(2009)

0,2

0,4

0,6

0,8

-0,05

0,00

0,05

2826,2 2826,4 2826,6 2826,8 2827,0-0,05

0,00

0,05

Observed spectrum

HCHO contributionwithout HCHO

HCHO contributionwith HCHO

Dufour et al., ACP 9, 3893 (2009)

Formaldehyde Seasonal Zonal Means

Atmospheric Dynamics: Asian Summer Monsoon Anticyclone

At 13.5 km in altitude, HCN is high over Tibet because of rapid lofting of polluted air from India and China during summer; it is lower over the Pacific Ocean because of deposition and destruction in the ocean. Randel et al., Science 328, 611 (2010).

(model)(Obs)

Fox News

Molecular Spectroscopy Facility at Rutherford

Appleton Lab

Bruker IFS 125 HR, with short path and long path coolable cells

Ethane, Propane and Acetone (3 micron region)

Harrison et al., JQSRT 111, 357 (2010)

Harrison & Bernath, JQSRT 111, 1282 (2010)

Harrison et al., JQSRT, 112, 53 (SW region) and 457 (LW region)(2011)

Harrison et al., JQSRT (2011)

Acetone Measurements

ν5 and ν16 1365 cm-1 CH3 deform. bands

~195 K

~197 K

↑ acetone

Methane Near Acetone Q-branch at 1365 cm-1

• ACE spectrum near 15 km for occultation sr10063.

• Residuals for all of the measurements in the occultation between 8 and 25 km are shown on a common plot.

• The bottom panel plots the residuals when a combination of line mixing and speed dependence is used for the CH4 lines.

Acetone Retrievals (Boone)• Narrow microwindow 1364.7

- 1367.1 cm-1 covering the Q-branch.

• Line mixing and speed-dependent Voigt parameters derived from ACE spectra.

ACE Partners (Selected)• Canada- K. Walker, J. Drummond, K. Strong, J.

McConnell, W. Evans, T. McElroy, I. Folkins, R. Martin, J. Sloan, T. Shepherd, T. Llewellyn, etc.

• USA- NASA launched ACE: C. Rinsland, L. Thomason (NASA-Langley), C. Randall (U. Colorado), M. Santee, L. Froidevaux, G. Toon, G. Manney (JPL), etc.

• Belgium- supplied CMOS imager chips: R. Colin, P.-F. Coheur, M. Carleer (ULB), D. Fussen, M. DeMaziere (IASB), M. Mahieu, R. Zander (Liege), etc.

• UK- J. Remedios (Leicester), P. Palmer (Edinburgh), M. Chipperfield (Leeds), etc.

• France- C. Camy-Peyret, C. Clerbaux, C. Brogniez, G. Dufour, D. Hauglustaine (Paris)

• Japan- M. Suzuki (JAXA), Y. Kasai• Sweden- G. Witt (Stockholm)

Funding: CSA, NSERC, NERC, ...

ESA-NASA ExoMars Trace Gas Orbiter

JPL will send a “copy” of ACE-FTS (called MATMOS) to Mars in 2016 to look for organic signatures of life (e.g., methane).