Aura MLSmls.jpl.nasa.gov/joe/eos-mls-sci-obj.pdf · Aura pre-launch Science Team meeting 8 Jul 2004 Aura MLS The Microwave Limb Sounder (MLS) on Aura: Science Objectives presentation

FroidevauxFroidevaux: MLS Science : MLS Science -- 11

Aura pre-launch

Science Team

meeting8 Jul 2004

AuraAura

MLS

The Microwave Limb Sounder (MLS) on Aura: Science Objectives

presentation at 8 July 2004 Aura pre-launch meetingLucien Froidevaux

MLS Science Team

Jet Propulsion LaboratoryCalifornia Institute of Technology

[email protected]

CL #04-2325

The Microwave Limb Sounder (MLS) on Aura: Science Objectives

presentation at 8 July 2004 Aura pre-launch meetingLucien Froidevaux

MLS Science Team

Jet Propulsion LaboratoryCalifornia Institute of Technology

[email protected]

CL #04-2325

mailto:[email protected]

mailto:[email protected]


Aura pre-launch

Science Team

meeting8 Jul 2004

Overall Science Objectives of MLS- Fall under Objective 1.1 of NASA’s (2003) Strategic Plan:“To understand how Earth is changing, better predict change,

and understand the consequences for life on Earth.”

• Track recovery of the ozone layerespecially track chlorine and bromine chemistry, and resolve current issues in hydrogen chemistry

• Understand aspects of how composition affects climateespecially through water vapor in the upper troposphere

• Quantify aspects of pollution in the upper troposphereozone, carbon monoxide (CO), methyl cyanide (CH3CN),hydrogen cyanide (HCN); biomass burning injections

A more detailed discussion of these objectives follows

Overall Science Objectives of MLS- Fall under Objective 1.1 of NASA’s (2003) Strategic Plan:“To understand how Earth is changing, better predict change,

and understand the consequences for life on Earth.”

• Track recovery of the ozone layerespecially track chlorine and bromine chemistry, and resolve current issues in hydrogen chemistry

• Understand aspects of how composition affects climateespecially through water vapor in the upper troposphere

• Quantify aspects of pollution in the upper troposphereozone, carbon monoxide (CO), methyl cyanide (CH3CN),hydrogen cyanide (HCN); biomass burning injections

A more detailed discussion of these objectives follows

Microwave Limb Sounder (MLS): ScienceMicrowave Limb Sounder (MLS): Science


Aura pre-launch

Science Team

meeting8 Jul 2004

MLS Science Objectives: Ozone Chemistry - Bromine & ChlorineMLS Science Objectives: Ozone Chemistry - Bromine & ChlorineObjective: Quantify bromine & chlorine budgets, trends, & impact on ozone.MLS will measure spatial & temporal changes in stratospheric bromine monoxide (BrO), a key reactive bromine gas that destroys ozone.

> Total bromine ≈ 20 pptv (± ~ 20%): 150 times less than total chlorine.- Exact amount of bromine getting into the stratosphere is still under investigation.

> BrO in the lower stratosphere destroys O3 much faster (atom for atom) than ClO.- Reactive fraction BrO/Bry ≈ 0.5 in lower stratosphere » chlorine fraction in ClO.

Objective: Quantify bromine & chlorine budgets, trends, & impact on ozone.MLS will measure spatial & temporal changes in stratospheric bromine monoxide (BrO), a key reactive bromine gas that destroys ozone.

> Total bromine ≈ 20 pptv (± ~ 20%): 150 times less than total chlorine.- Exact amount of bromine getting into the stratosphere is still under investigation.

> BrO in the lower stratosphere destroys O3 much faster (atom for atom) than ClO.- Reactive fraction BrO/Bry ≈ 0.5 in lower stratosphere » chlorine fraction in ClO.

Truth

-90 -45 0 45 90Latitude

10

1

Pre

ssu

re / h

Pa

Retrieved

-90 -45 0 45 90Latitude

-8 -4 0 4 8 12 16 20 Day - night BrO / pptv

Simulated MLS retrieval of Simulated MLS retrieval of zonal mean zonal mean BrOBrO (~ 23 (~ 23 -- 45 km) 45 km) (Day(Day––Night) monthly averageNight) monthly averageCan infer Can infer BrBry (total (total

inorganic bromine)inorganic bromine)and other Br species and other Br species

from from BrOBrO & other & other Aura data (HOAura data (HO22, NO, NO22) )

+ models or + models or correlations correlations

(e.g., between (e.g., between BrBry and tracers) and tracers)

→ constrain models of Br chemistry and sources of bromine in the stratosphere.

hhνν,, ClOClO, O, O

HOBrHOBr

BrClBrCl

HOHO22hhνν

ClOClO

measured measured by MLSby MLS

Bromine gases & chemical Bromine gases & chemical cycles in the stratospherecycles in the stratosphere

BrBr BrOBrO

hhνν

HBrHBr

BrONOBrONO22

HOHO22

OHOH

hhνν

OO3

NONO22


Aura pre-launch

Science Team

meeting8 Jul 2004

MLS Science Objectives: Ozone Chemistry – Bromine & ChlorineMLS Science Objectives: Ozone Chemistry – Bromine & Chlorine

Objective: Quantify bromine & chlorine budgets, trends, & impact on ozone.Objective: Quantify bromine & chlorine budgets, trends, & impact on ozone.

Valuable HALOE HCl data global avg. Cl (at 55 km) vs surface Cl (with 5 yr lag).(James M. Russell III and John Anderson, Hampton Univ., private communication).MLS will provide daily global profiles of HCl to track chlorine loading and recovery (upper stratosphere)+ chlorine partitioning variations and trends (throughout stratosphere and under depleted ozone conditions).Other useful quantities: ClO/HCl ratio, related Aura data (e.g., HIRDLS ClONO2).

Source Gases for chlorine & bromine Atmospheric Chlorine (Cl) loadingDecreases (per international regulations)Decreases (per international regulations)in total surface sources for bromine and in total surface sources for bromine and chlorine gases should be reflected (a few chlorine gases should be reflected (a few years later) in total stratospheric Br & years later) in total stratospheric Br & ClCl..

Surface measurements (symbols) and Surface measurements (symbols) and predictions (lines). Figure is updated predictions (lines). Figure is updated

from WMO Report No. 47 (2003). from WMO Report No. 47 (2003). ((S. S. MontzkaMontzka, NOAA CMDL, private communication)., NOAA CMDL, private communication).

CFCCFC--1212


Aura pre-launch

Science Team

meeting8 Jul 2004

MLS Science Objectives: Ozone Chemistry – Hydrogen ChemistryMLS Science Objectives: Ozone Chemistry – Hydrogen ChemistryObjective: Resolve issues in hydrogen chemistry

- Hydrogen chemistry is dominant mechanism of ozone destruction at the highest and lowest altitudes in the stratosphere

Objective: Resolve issues in hydrogen chemistry- Hydrogen chemistry is dominant mechanism of ozone destruction at the highest and lowest altitudes in the stratosphere

adapted from Conway et al., GRL (2000)

OH:OH: Models are inconsistent with Models are inconsistent with previous OH data in altitude region previous OH data in altitude region where chemistry seems fairly simple where chemistry seems fairly simple -- mainly need to know OH, HOmainly need to know OH, HO22, O, O33, , HH22O, all measured by MLS. O, all measured by MLS.

HOHO22:: BalloonBalloon--borne and groundborne and ground--based measurements of HObased measurements of HO22 yield yield larger than expected abundances larger than expected abundances (by ~30%). (by ~30%).

Chemistry or Data Issue ?

““The The HOHOxx dilemma”dilemma”

Chemistry or Data Issue ?

heig

ht (k

m)

heig

ht (k

m)

OH density (10OH density (1077 cmcm--33))

MAHRSI shuttle-based OH

data (1997)

models

MLS OH precision (monthly zonal mean)

Column OH:Column OH: GrdGrd--based col. shows based col. shows large variability large variability (Mills et al., GRL, 2002).(Mills et al., GRL, 2002).InterannualInterannual changes at Table changes at Table MtnMtn., ., CA, are larger than the expected CA, are larger than the expected combined effects of Ocombined effects of O33, H, H22O, and O, and solar flux solar flux (Mills et al., JGR, 2003).(Mills et al., JGR, 2003).The combination of groundThe combination of ground--based based and MLS measurements will help and MLS measurements will help to understand these variations.to understand these variations.

Interannual variations in OH col. abundance Table Mountain, CA(S. Sander et al., JPL, private communication)O

H C

olum

n A

nom

aly

(10

OH

Col

umn

Ano

mal

y (1

01313/c

m/c

m22 ))


Aura pre-launch

Science Team

meeting8 Jul 2004

Objective: Use measurements of radicals and source species to provide critical global tests of ozone chemistry.Objective: Use measurements of radicals and source species to provide critical global tests of ozone chemistry.

MLS Science Objectives: Ozone Chemistry – Chemical CyclesMLS Science Objectives: Ozone Chemistry – Chemical Cycles

• MLS monthly zonal mean distributions for OH, HO2, ClO & BrO above ~ 20 km.

• HIRDLS & TES measure NO2.

• Aura instruments will also measure the radical-generating molecules (H2O, N2O, CFCs, O3) in the ‘same’ air mass (within 15 minutes).

• Can use model radical values on daily basis and average over a month to compare with monthly Aura observations of these radicals.

• MLS monthly zonal mean distributions for OH, HO2, ClO & BrO above ~ 20 km.

• HIRDLS & TES measure NO2.

• Aura instruments will also measure the radical-generating molecules (H2O, N2O, CFCs, O3) in the ‘same’ air mass (within 15 minutes).

• Can use model radical values on daily basis and average over a month to compare with monthly Aura observations of these radicals.

Total Total LossLoss

OOxx

HOHOxx

NONOxx

ClOClOxx

BrOBrOxx

Importance of Chemical Cycles for O3 Loss (updated from Osterman et al., GRL, 1997)

MLS data combined with the ensemble of Aura products will critically test the completeness of known chemistryover a range of heights and for all seasons.


Aura pre-launch

Science Team

meeting8 Jul 2004

Objective: Refine understanding of lower stratospheric winter polar ozone loss and track its variations

Objective: Refine understanding of lower stratospheric winter polar ozone loss and track its variations

• Measured and modeled Arctic O3loss rates do not ‘match’ in January

• Measured and modeled Arctic O3loss rates do not ‘match’ in January

MLS Science Objectives: Ozone Chemistry – Polar ProcessesMLS Science Objectives: Ozone Chemistry – Polar Processes

Arctic avg. O3 change (Manney et al., JGR, 2003)

(Rex (Rex et al., et al., GRL, GRL, 2003)2003)

• Uncertainties remain in quantifying the relative contributions of transport and chemical processes in O3 loss (for polar regions and globally).

• Uncertainties remain in quantifying the relative contributions of transport and chemical processes in O3 loss (for polar regions and globally).

… but do in late winter.… but do in late winter.

• Improvements (over UARS MLS) include better spatial and temporalcoverage, resolution, precision, and additional constituents.

• Improvements (over UARS MLS) include better spatial and temporalcoverage, resolution, precision, and additional constituents.

• Further explore issues regarding denitrification & dehydration and their relationship to O3 loss in both hemispheres.

• Track interannual & longer-term variations, especially in Arctic, where temperatures may be near a threshold for larger ozone losses or a delay in recovery (tied to H2O, polar stratospheric clouds, and climate change).

• Further explore issues regarding denitrification & dehydration and their relationship to O3 loss in both hemispheres.

• Track interannual & longer-term variations, especially in Arctic, where temperatures may be near a threshold for larger ozone losses or a delay in recovery (tied to H2O, polar stratospheric clouds, and climate change).

In addition to polar OIn addition to polar O33 loss studies, loss studies, we plan to:we plan to:

OO33 estimated chemical lossestimated chemical loss

UARS MLS OUARS MLS O33 datadata

OO33 change (at ~20 km) from transportchange (at ~20 km) from transport

19931993

OO33

Cha

nge

(C

hang

e ( p

pmv

ppm

v ))

00

--11

LS OLS O33 loss rate loss rate from from sondesonde datadata

0 0 Day of yearDay of year 9090


Aura pre-launch

Science Team

meeting8 Jul 2004

MLS Science Objectives: Water Vapor and ClimateMLS Science Objectives: Water Vapor and ClimateObjective: Understand processes controlling stratospheric humidityObjective: Understand processes controlling stratospheric humidity

• How is H2O removed before entering the stratosphere?

• MLS H2O in tropical tropopauselayer (TTL) will have better vertical resolution than UARS MLS + expect longer time series.- Synergies with planned aircraft campaigns (which can also measure total H2O).

• How is H2O removed before entering the stratosphere?

• MLS H2O in tropical tropopauselayer (TTL) will have better vertical resolution than UARS MLS + expect longer time series.- Synergies with planned aircraft campaigns (which can also measure total H2O).

• Does tropical deep convection hydrate or dehydrate the TTL?

• MLS measurements that can be made in the presence of cirrus will help answer this question.

• Does tropical deep convection hydrate or dehydrate the TTL?

• MLS measurements that can be made in the presence of cirrus will help answer this question.

HG model initialized with MLS 147 hPa H2O

47

00

68

Corr. MLS V7.02 measurement

47

UARS MLS 100 UARS MLS 100 hPahPa HH22OOWinter (DJF) 1992/1993Winter (DJF) 1992/1993

00

68

147147

147147

100100

6868

100100

6868hPa

hPa

19921992 1993199319911991

HG Model HHG Model H22OO

UARS MLS HUARS MLS H22OO

Figures fromFigures from Read et al. (JGR, 2004)Read et al. (JGR, 2004)

H2O in the TTL from UARS MLS compared to Holton & Gettelman (HG)

“cold trap” model

Dry

M

oist

D

ry

Moi

st


Aura pre-launch

Science Team

meeting8 Jul 2004

• Quantify the water vaporfeedback in climate change

• MLS upper tropospheric H2O data should help better predict the surface temperature rise from increasing CO2 emissions.

• Quantify the water vaporfeedback in climate change

• MLS upper tropospheric H2O data should help better predict the surface temperature rise from increasing CO2 emissions.

• Understand intra- and interannual changes

• MLS can observe changes in upper tropospheric Relative Humidity from El Niño & other variations.

• Understand intra- and interannual changes

• MLS can observe changes in upper tropospheric Relative Humidity from El NiñoNiño & other variations.

UARS MLS tropical UT (215 UARS MLS tropical UT (215 hPahPa)) HH22O: O: Correlation with El NiñoCorrelation with El Niño

Waters et al. (J. Waters et al. (J. AtmosAtmos. . SciSci. 1999). 1999)

No feedbackNo feedback(fixed H(fixed H22O abundance)O abundance)

Constant RHConstant RH(positive)(positive)feedbackfeedback

ModelModel

MLS MLS HH22O (215 O (215 hPahPa)) vsvs Sea Surface TSea Surface T

MinschwanerMinschwaner & & DesslerDessler (J. Climate, 2004)(J. Climate, 2004)

MLS Science Objectives: Water Vapor and ClimateMLS Science Objectives: Water Vapor and ClimateObjective: Better quantify water vapor relationship to climateObjective: Better quantify water vapor relationship to climate

Change in SST (Kelvin)Change in SST (Kelvin)

Cha

nge

in

Cha

nge

in R

elR

el. H

umid

ity (%

). H

umid

ity (%

) Points: ~ 6 yrs of MLS dataPoints: ~ 6 yrs of MLS data


Aura pre-launch

Science Team

meeting8 Jul 2004

MLS Science Objectives: Water Vapor and Climate - CloudsMLS Science Objectives: Water Vapor and Climate - Clouds

Objective: To accurately measure global cloud Ice Water Content → improve climate models

Ice Water Content distributionIce Water Content distributionJan.Jan.--March 1992March 1992

Based on UARS MLS data Based on UARS MLS data (Wu et al., submitted)(Wu et al., submitted)

UARS MLS data UARS MLS data (Wu et al., submitted)(Wu et al., submitted)

ClearClear--sky distributionsky distribution

Cloud distributionCloud distribution

33

22

11

00

IWC IWC (mg/ m(mg/ m33))

More detailed statisticsMore detailed statisticsHistogram of cloud occurrence Histogram of cloud occurrence for different ice water contentsfor different ice water contents

(how does (how does this vary ? this vary ? -- versus versus time, time, region) region)

30S30S--30N 100 30N 100 hPahPa data (from 1993)data (from 1993)

• Inaccuracy in knowledge of cloud Ice Water Content: worse than 100%!- require assumptions about ice particle properties (e.g., sizes, shapes).

• Can reduce these uncertainties in the future by analyzing multi-frequency measurements from MLS, the A-train (e.g., CloudSat), & other instruments.

• Inaccuracy in knowledge of cloud Ice Water Content: worse than 100%!- require assumptions about ice particle properties (e.g., sizes, shapes).

• Can reduce these uncertainties in the future by analyzing multi-frequency measurements from MLS, the A-train (e.g., CloudSat), & other instruments.


Aura pre-launch

Science Team

meeting8 Jul 2004

MLS Science Objectives: Tropospheric PollutionMLS Science Objectives: Tropospheric Pollution

MLS will measure the following upper tropospheric species (+ H2O):- Ozone (tropospheric pollutant & important greenhouse gas in UT) - CO (a good tracer of anthropogenic pollution) - CH3CN & HCN, biomass burning tracers. MLS sensitive only to largeenhancements above background. [UARS MLS detected enhancement in CH3CN from forest fire, injected into lower stratosphere (Livesey et al., 2004).]

These data complement tropos. data from TES, OMI, HIRDLS, aircraft - Expect pollution + long-range transport in UT

(e.g., from convection, warm conveyor belts, ‘pollution train’).- Couple to goals of INTEX aircraft/ground campaigns (2004 & 2006).

Objective: Quantify aspects of pollution in the upper tropospherObjective: Quantify aspects of pollution in the upper tropospheree

How are OHow are O33 and CO correlated? and CO correlated? How do models and data compare?How do models and data compare?

Intercontinental pollution transport Intercontinental pollution transport illustrationillustration(CO biomass burning component only) (CO biomass burning component only)

(Q. Li, JPL, private communication., 2004)(Q. Li, JPL, private communication., 2004)

Simulated CO, OSimulated CO, O33 (Li et al., JGR, sub., 2004)(Li et al., JGR, sub., 2004)

Caveats:Caveats: MLS sensitivityMLS sensitivity (~20, 30 (~20, 30 ppbvppbv for CO, Ofor CO, O33 at 200 at 200 hPahPa & worse at lower alt.)& worse at lower alt.)++ sampling issuessampling issues need useful need useful ‘‘averagingaveraging’’ (+ validation) of the MLS UT data.(+ validation) of the MLS UT data.


Aura pre-launch

Science Team

meeting8 Jul 2004

Summary and Acknowledgements

MLS will contribute to important areas of atmospheric research:[Thanks for inputs to this talk mainly from those listed below]

● Ozone Chemistry- Bromine and chlorine [N. Livesey, S. Montzka, J. Russell]- Hydrogen Chemistry [H. Pickett, S. Sander]- Chemical Cycles [H. Pickett, R. Salawitch]- Polar Processes [G. Manney, M. Santee]

● Water Vapor and Climate- Water Vapor [W. Read]- Cloud Ice [D. Wu]

● Tropospheric Pollution [M. Filipiak, Q. Li]

Thanks to Joe Waters and the whole MLS team (at JPL and

Edinburgh University), the Aura Project, JPL, and NASA

for helping get us to this stage & the eagerly awaited Aura launch.

Summary and Acknowledgements

MLS will contribute to important areas of atmospheric research:[Thanks for inputs to this talk mainly from those listed below]

● Ozone Chemistry- Bromine and chlorine [N. Livesey, S. Montzka, J. Russell]- Hydrogen Chemistry [H. Pickett, S. Sander]- Chemical Cycles [H. Pickett, R. Salawitch]- Polar Processes [G. Manney, M. Santee]

● Water Vapor and Climate- Water Vapor [W. Read]- Cloud Ice [D. Wu]

● Tropospheric Pollution [M. Filipiak, Q. Li]

Thanks to Joe Waters and the whole MLS team (at JPL and

Edinburgh University), the Aura Project, JPL, and NASA

for helping get us to this stage & the eagerly awaited Aura launch.

Microwave Limb Sounder (MLS): ScienceMicrowave Limb Sounder (MLS): Science

Documents

Aura MLSmls.jpl.nasa.gov/joe/eos-mls-sci-obj.pdf · Aura pre-launch Science Team meeting 8 Jul 2004 Aura MLS The Microwave Limb Sounder (MLS) on Aura: Science Objectives presentation