current work on methane and tropospheric bromine daniel j. jacob

Current work on methane and tropospheric bromine

Daniel J. Jacob

with Kevin Wecht, Alex Turner, Melissa Sulprizio, Johan Schmidt

Global methane trend (IPCC AR5)

UCIAGAGENOAA

Building a methane monitoring system for N America

EDGAR emissionInventory for methane

Can we use satellites together with suborbital observations of methane to monitor methane emissions on the continental scale and test/improve emission inventories?

Methane emission inventories for N. America: EDGAR 4.2 (anthropogenic), LPJ (wetlands)

N American totals in Tg a-1

Previous top-down constraints from surface/aircraft observationshave suggested factor of 2-3 underestimate in US emissions

AIRS, TES, IASI

Methane observing system in North America

Satellites

2002 2006 2009 20015 2018

Thermal IR

SCIAMACHY 6-day

GOSAT3-day, sparse

TROPOMI GCIRI 1-day geoShortwave IR

Suborbital

CalNex

INTEX-A

SEAC4RS

1/2ox2/3o grid of GEOS-Chem chemical transport model (CTM)

High-resolution inverse analysis of methane emissions in North America

GEOS-Chem CTM and its adjoint1/2ox2/3o over N. America

nested in 4ox5o global domain

Observations

Bayesianinversion

Optimized emissionsat 1/2ox2/3o resolution

Validation Verification

EDGAR 4.2 + LPJa priori bottom-up emissions

Testing GEOS-Chem methane backgroundwith HIPPO aircraft data across Pacific

GEOS-ChemHIPPO

Latitude, degrees

Jan09 Oct-Nov09 Jun-Jul11 Aug-Sep11

Alex Turner and Kevin Wecht, Harvard

Time-dependent boundary conditionsare optimized iteratively as part of the inversion

Met

hane

, ppb

v

Optimization of methane emissions using SCIAMACHY data for Jul-Aug 2004

Concurrent INTEX-A aircraft mission allows validation of SCIAMACHY, evaluation of inversionSCIAMACHY column methane mixing ratio XCH4 INTEX-A methane below 850 hPa

INTEX-A validation profiles H2O correction to SCIAMACHY data

Kevin Wecht, Harvard

D. Blake(UC Irvine)

C. Frankenberg(JPL)

SCIA

MAC

HY

INTEX-A

XCH4

Optimized selection of emission clustersfor adjoint inversion of SCIAMACHY data

Optimal clustering of 1/2ox2/3o gridsquares

Correction factor to bottom-up emissions

Number of clusters in inversion1 10 100 1000 10,000

34

28

Optimized US anthropogenic emissions (Tg a-1)

posterior cost function

Native resolution 1000 clusters

SCIAMACHY data cannot constrainemissions at 1/2ox2/3o resolution;use 1000 optimally selected clusters


North American methane emission estimatesoptimized by SCIAMACHY data (Jul-Aug 2004)

1700 1800ppb

SCIAMACHY column methane mixing ratio Correction factors to priori emissions

Livestock Oil & Gas Landfills Coal Mining Other0

5

10

15US anthropogenic emissions (Tg a-1)

EDGAR v4.2 26.6

EPA 28.3

This work 32.7


GOSAT methane column mixing ratios, Oct 2009-2010

Retrieval from U. Leicester

Preliminary inversion of GOSAT Oct 2009-2010 methane

Nested inversionwith 1/2ox2/3o resolution

Correction factors to prior emissions (EDGAR 4.2 + LPJ)

Alex Turner, HarvardNext step: clustering of emissions in the inversion

Testing the information content of satellite datawith CalNex inversion of methane emissions

CalNex observations GEOS-Chem w/EDGAR v4.2

0.1 1 3

Correction factors to EDGAR(analytical inversion)

1800 2000ppb

May-Jun2010

State of California Los Angeles Basin0

0.51

1.52

2.53

3.5CA Air Resources BoardEDGAR v4.2Santoni et al. Lagrangian (STILT) inversionGEOS-Chem inversion

Emis

ssio

ns, T

g a-1


2x underestimateof livestock emissions

S. Wofsy (Harvard)

GOSAT observations are too sparseto spatially resolve California emissions

GOSAT data (CalNex period))Correction factors to methane emissions from inversion

GOSAT (CalNex period) GOSAT (1 year)

CalNex aircraft data

GOSAT(CalNex)

GOSAT(1 year)

Degrees of Freedom for Signal (DOFS) in inversion of methane emissions

15 0.55 1.4

Each point =1-10 observations

0.5 1.5


Potential of TROPOMI and GCIRIfor constraining methane emissions

TROPOMI (global daily coverage) GCIRI (geostationary 1-h return coverage)Correction factors to EDGAR v4.2 a priori emissions from a 1-year OSSE

A priori CalNex TROPOMI GCIRI TROPOMI+GCIRI

DOFS 15 10 14 17

California emissions (Tg a-1) 1.9 3.2 2.9 3.0 3.1

0.2 1 5


Working with stakeholders at the US state level

State-by-state analysis of SCIAMACHY correction factors to EDGARv4.2 emissions

with Iowa Dept. of Natural Resources

State emissions computed w/EPA tools too low by x3.5;now investigating EPA livestock emission factors

with New York Attorney General OfficeState-computed emissions too high by x0.6,reflects overestimate of gas/waste/landfill emissions

Melissa Sulprizio and Kevin Wecht, Harvard

Hog manure?

Large EDGAR source from gas+landfillsis just not there

0 1 2correction factor

Now on to bromine…

Bromine chemistry in the atmosphere

Tropopause (8-18 km)

Troposphere

Stratosphere

Halons

CH3Br

CHBr3

CH2Br2

Sea salt

Br BrO BrNO3

HOBrHBr

O3

hv, NO

hv

OH

Inorganic bromine (Bry)

BryOH, h

debrom

inatio

n

deposition

industry plankton

Stratospheric BrO: 2-10 ppt

Tropospheric BrO: 0.5-2 ppt

Thule

GOME-2 BrO columns

Satellite residual[Theys et al., 2011]

BrO

co

lum

n,

101

3 c

m-2

VSLS

http://www-as.harvard.edu/chemistry/trop/news.html

Mean vertical profiles of CHBr3 and CH2Br2

From NASA aircraft campaigns over Pacific in April-June

Vertical profiles steeper for CHBr3 (mean lifetime 21 days) than for CH2Br (91 days),steeper in extratropics than in tropics

Parrella et al. [2012]

Model comparison to HIPPO organobromine data

No bias for CHBr3, CH3Br; 10% low bias for CH2Br2

Johan Schmidt, Harvard

CHBr3 CH2Br2 CH3Br

ObservedGEOS-Chem

Global tropospheric Bry budget in GEOS-Chem (Gg Br a-1)

SURFACE

CHBr3

407

CH2Br2

57CH3Br

Marine biosphere Sea-salt debromination(50% of 1-10 µm particles)

STRATOSPHERE

TROPOSPHERE

7-9 ppt

Liang et al. [2010] stratospheric Bry model (upper boundary conditions)

56

36

Bry

3.2 ppt

Volcanoes

(5-15)

Deposition

lifetime 7 days

1420

Sea salt is the dominant global source but is released in marine boundary layerwhere lifetime against deposition is short; CHBr3 is major source in the free troposphere Parrella et al. [2012]

Tropospheric Bry cycling in GEOS-Chem

Gg Br [ppt]

Global annual mean loadings in Gg Br [ppt], rates in Gg Br s-1

• Model includes HOBr+HBr in aq aerosols with = 0.2, ice with = 0.1• Mean daytime BrO = 0.6 ppt; would be 0.3 ppt without HOBr+HBr reaction


Comparison to seasonal satellite data for tropospheric BrO[Theys et al., 2011]

model

model

• TOMCAT has lower =0.02 for HOBr+HBr than GEOS-Chem, large polar spring source from blowing snow

• HOBr+HBr reaction critical for increasing BrO with latitude, winter/spring NH max in GEOS-Chem

(9:30 am)


Effect of Br chemistry on tropospheric ozoneZonal mean ozone decreases (ppb) in GEOS-Chem

• Two processes: catalytic ozone loss via HOBr, NOx loss via BrNO3

• Global OH also decreases by 4% due to decreases in ozone and NOx


Bromine chemistry improves simulation of 19th century surface ozone

• Standard models without bromine are too high, peak in winter-spring; bromine chemistry corrects these biases

• Model BrO is similar in pre-industrial and present atmosphere (canceling effects)


Atmospheric lifetime of Hg(0) against oxidation to Hg(II) by Br

Hg(0) + Br ↔ Hg(I) → Hg(II)Br,OH

• 2-step Hg(0) oxidation (Goodsite et al., 2004; Donohoue et al., 2006)

Emission Deposition

• GEOS-Chem Br yields Hg(0) global mean tropospheric lifetime of 4 months, consistent with observational constraints

• Br in pre-industrial atmosphere was 40% higher than in present-day (less ozone), implying a pre-industrial Hg(0) lifetime of only 2 months

Hg could have been more efficiently deposited to northern mid-latitude oceans in the past


More recent model comparisons to BrO observations

TORERO - CU AMAX-DOAS over the SE Pacific (R. Volkamer, CU Boulder)

OMI tropospheric BrO from cloud slicing (S. Choi, SSAI/NASA GSFC)


Upper tropospheric BrO is severely underestimated by GEOS-Chem: major implications for tropospheric ozone, Hg

ObservationsGEOS-Chem

MAM

DJF

Model vs. observed ozone in upper troposphere

TOREROHIPPO

Model doesn’t underestimateozone transport from stratosphere- but stratospheric Bry/O3 ratio could still conceivably be too low


Model vertical profiles over SE Pacific A

ltit

ud

e, k

m

HBr, BrNO3 are major reservoirs in upper troposphere; should they cycle more efficiently to radicals?


Heterogeneous bromine chemistry

currentlyin GEOS-Chem

to be included in GEOS-Chem


Can heterogeneous chemistry correct the model underestimate of BrO in UT?Stay tuned! Any other ideas?

current work on methane and tropospheric bromine daniel j. jacob

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