AMMA-UK: Work Package 5

Centre for Atmospheric ScienceUniversity of Cambridge

Glenn CarverAndrew RobinsonNicola Warwick

(pretending to be John Pyle and Neil Harris)

Centre for Atmospheric ScienceUniversity of Cambridge

Work packages

WP5.1 Use observations of the convective outflows in the TTL regions to analyse the chemical and dynamical processes occurring in such outflows.

WP5.2 Use modelling techniques to assess global transport and impacts of species from WAM & estimate impacts on lower stratosphere.

OWP5 TTL chemistry balloons. Two stratospheric balloons deployed during SOP2 to gain observations of the TTL region in the vicinity of the MCS events.

WP4.5 Investigate global impact on burden of ozone of biogenic emissions from the WAM region.

p-TOMCAT Chemical Transport Model

p-TOMCAT is a global offline chemical transport model Includes a fairly detailed gas-phase / photolysis tropospheric

chemistry scheme. Also includes parametrizations for cloud mixing, boundary layer

mixing, wet & dry deposition, emission inventories for surface and aircraft & lightning emissions.

Driven by ECMWF analyses (operational and ERA40) Standard configurations are 6x6 degree and 3x3 degree

horizontal resolutions with 31 levels Used for many studies of tropospheric chemistry; including

budget studies, field campaign support roles. Recent technical development has seen a move to much higher

resolutions.

Tropical Tropopause Layer tracer studies

Work done by James Levine (Cambridge)

Motivation Study troposphere to stratosphere transport to determine (any)

preferred regions of entry. Planning of SCOUT-O3 tropical campaigns

Studies used tracers in p-TOMCAT designed to allow the exchange of TTL air to lower strat. to be quantified.

TTL regions

1 = Africa 5 = C. Pacific2 = Indian O. 6 = E. Pacific3 = Indonesia 7 = S. America4 = W. Pacific 8 = Atlantic

Release of trop. tracers

T-tracers released one box below the tropopause

(weighted-average of min-T and 2 PVU surfaces)

Conversion to strat tracers

T-tracers converted to S-tracers as a function of TTL origin and entry into the stratosphere

Entry into the stratosphere

Tropopause: min-T and 2 PVU

2000-01

Entry into the stratosphere

Tropopause: min-T and 2 PVU

1997-8

High Resolution Chemical Modelling

Motivation

Emission datasets have global resolution of 1 degree or better : how does this impact on CTM simulations?

Improved representation of long-range transport and comparison with observations

Improved comparisons with aircraft data

Major technical changes to p-TOMCAT to achieve 1x1 and 0.5x0.5 degree global horizontal resolutions with full chemistry

High resolution chemical modelling

NO2 around model’s tropospause.

Taken from short test run of the 0.5x0.5 version of p-TOMCAT.

Transport and chemistry only.

High resolution chemical modelling

QuickTime™ and aPNG decompressor

are needed to see this picture.

NO2 has strong diurnalvariation. Destroyed by sunlight

Resolution

640 x 320

0.56 degree

Approx. 60km at equator

Aircraft .v. model comparisons

Achieving a quantitative comparison of model .v. aircraft data is difficult because of the difference in scales

Fiona O’Connor used high resolution advection to demonstrate this improved comparisons with aircraft data

Ozone and CO were advected (no chemistry) for short periods using horizontal resolutions of 1x1 and 3x3 degrees for comparison with ACTO flights.

In most cases there was significant improvement in the comparison, due to the improved representation of the synoptic situation in the model

Aircraft .v. model comparison

3x3 degrees

Aircraft .v. model comparison

1x1 degrees

Aircraft .v. model comparison

3x3

1x1

Improvements to p-TOMCAT (1)

Addition of Isoprene (Paul Young / Guang Zeng) Mainz Isoprene Scheme (MIM) (Pöschl et al., 2000)

~40 isoprene-related reactions and 16 isoprene-related species:

Emission inventory from GEIA

Sensitivity studies using the Met. Office Unified Model

Current chemistry scheme: NOx-CO-CH4-NMHCs (52 species)

The MIM C5H8

ISO2

OH

MACRO2

OH

NALD

OH

OH

HACETMGLYCH3CO3

NO

ISON

NO3

MACRISO2HOH

NOHO2

MACRO2H

MPAN

OH

HO2

± NO2

CH3C(O)OOH / CH3C(O)OH

PAN OH

HO2

± NO2

OHOH / NO3

HCHO + CO + NO2

OH

Isoprene-Related Species

1. C5H8 - isoprene2. ISO2 - hydroxy-peroxy radicals from C5H8+OH3. ISOOH - beta-hydroxy hydroperoxides from ISO2+HO24. ISON - hydroxy-alkylnitrates from ISO2+NO and alkyl nitrates from C5H8+NO35. MACR - methacrolein and MVK and other C4-carbonyls6. MACRO2 - hydroxy-peroxy radicals from MACR+OH7. MACROOH - hydroxy-hydroperoxides from MACRO2+HO28. MPAN - peroxymethacrylic nitric anhydride and other higher peroxyacyl nitrates9. HACET - hydroxyacetone and other C3-ketones10. MGLY - methylglyoxal and other C3-aldehydes11. NALD - nitrooxy-acetaldehyde (from decomposition of ISON)12. MeCOOOH - peroxyacetic acid13. MeCOOH - acetic acid14. HCOOH - formic acid15. PAN16. acetyl radical (MeCO3)

Improvements to p-TOMCAT (2)

Addition of Bromine (Xin Yang / Nicola Warwick) Bromine chemistry scheme: gas-phase and heterogeneous reactions

on cloud particles and background aerosols

Br emissions from biogenic bromocarbons and sea-salt aerosol

Aim: to determine the influence of bromine chemistry on tropospheric ozone

BrO

Br

BrONO2

HOBr

Br2

O3

NO, OH, RO2, BrO

NO2

HO2,RO2

HO2, RO2, HCHO, RCHO

hv

hv, OH

hv

hv

Ocean/land

BrNO2

CH3Br, CHBr3,CH2Br2, CH2BrCl,CHBr2Cl, CHBrCl2

OH hv

NO2 hv

hv

HBrOH

BrO

HBr, HOBr, Br2

wet or dry deposition

Bromine cycling scheme used in the p-TOMCAT model

Br

Cloud particles/ aerosols

Sea-salt

Heterogeneous or aqueous reactions ??

Particles

hv

~0.62 TgBr/yr

~3.1 TgBr/yr

Emissions of BromoformGlobal CHBr3 Flux

(GgCHBr3/yr)Derived from: Reference

210 Loss rate and global average concentration (0.4 pptv)

WMO, 1999

300 Tropical atmospheric measurements and calculated lifetimes

Dvortsov et al., 1999

220 Reviews of algal halocarbon emissions and biomass estimates

Liss and Carpenter, 2000

826 Published concentration data, global climalogical parameters and information on coastal and biogenic sources

Quack and Wallace, 2003

Bromine Source Studies

Top-down estimates of bromoform emissions depend on location of emission:

latitude (lifetime)

local/non-local source

Vertical Profiles of Bromoform

Red – Scenario 3 (400 Gg/yr) Red – Scenario 4 (595 Gg/yr)

Modelled Zonal Mean Total Bromine

Zonal mean total organic and inorganic bromine in emission Scenario 6 (595 Gg CHBr3 / yr)

Impact of bromine chemistry on tropospheric ozone

Figure by Xin Yang

Objectives

(1) Define the scope of the chemistry (in collaboration with Leeds/UEA)

(1) Include additional organics (e.g. isoprene, halocarbons)

(2) Others? (e.g. oxygenates)

(3) WAM emissions?

(2) Define range of model experiments

(1) Verification of new chemistry

(2) Comparisons with measurements (high res. simulations)

(3) Budget studies (global transport studies of emissions – impact on O3 in troposphere and lower stratosphere)

Acknowledgements

p-TOMCAT: Glenn Carver, Fiona O’Connor, Nick Savage

TTL tracer studies : James Levine, Nick Savage

High resolution modelling : Glenn Carver

Aircraft / model comparisons : Fiona O’Connor

Aircraft campaign support : James Levine, Peter Cook, Nick Savage, Fiona O’Connor

1 'O(3P)' 1 'FM' 'Ox' F F F 'Atomic oxygen (ground state)' 'pptv' 2 'O(1D)' 1 'FM' 'Ox' F F F 'Atomic Oxygen (excited state)' 'pptv' 3 'O3' 1 'FM' 'Ox' T F F 'Ozone' 'ppbv' 4 'NO' 1 'FM' 'NOx' T F F 'Nitric Oxide' 'pptv' 5 'NO3' 1 'FM' 'NOx' T T F 'Nitrate Radical' 'pptv' 6 'NO2' 1 'FM' 'NOx' T F T 'Nitrogen Dioxide' 'ppbv' 7 'N2O5' 2 'TR' ' ' T T F 'Dinitrogene Pentoxide' 'ppbv' 8 'HO2NO2' 1 'TR' ' ' T T F 'Peroxynitric Acid' 'ppbv' 9 'HONO2' 1 'TR' ' ' T T F 'Nitric Acid', 'ppbv'10 'OH' 1 'SS' ' ' F F F 'Hydroxyl Radical' 'pptv'11 'HO2' 1 'SS' ' ' F T F 'Hydroperoxyl Radical' 'pptv'12 'H2O2' 1 'TR' ' ' T T F 'Hydrogen Peroxide' 'ppbv'13 'CH4' 1 'TR' ' ' F F T 'Methane' 'ppbv'14 'CO' 1 'TR' ' ' T F T 'Carbon Monoxide' 'ppbv'15 'HCHO' 1 'TR' ' ' T T T 'Formaldehyde' 'ppbv'16 'MeOO' 1 'SS' ' ' F T F 'CH3OO' 'ppbv'17 'H2O' 1 'CF' ' ' F F F 'Water Vapour' 'ppbv'18 'MeOOH' 1 'TR' ' ' T T F 'CH3OOH' 'ppbv'19 'HONO' 1 'TR' ' ' T T F 'HONO' 'ppbv'20 'C2H6' 1 'TR' ' ' F F T 'Ethane' 'ppbv'21 'EtOO' 1 'SS' ' ' F F F 'EtOO' 'ppbv'22 'EtOOH' 1 'TR' ' ' T T F 'EtOOH' 'ppbv'23 'MeCHO' 1 'TR' ' ' T F T 'CH3CHO' 'ppbv'24 'MeCO3' 1 'SS' ' ' F F F 'Acetaldehyde' 'ppbv'25 'PAN' 1 'TR' ' ' T F F 'Peroxyacetyl Nitrate' 'ppbv'26 'C3H8' 1 'TR' ' ' F F T 'Propane' 'ppbv'

27 'n-PrOO' 1 'SS' ' ' F F F 'n-PrOO' 'ppbv'28 'i-PrOO' 1 'SS' ' ' F F F 'i-PrOO' 'ppbv'29 'n-PrOOH' 1 'TR' ' ' T T F 'n-PrOOH' 'ppbv'30 'i-PrOOH' 1 'TR' ' ' T T F 'i-PrOOH' 'ppbv'31 'EtCHO' 1 'TR' ' ' T F F 'EtCHO' 'ppbv'32 'EtCO3' 1 'SS' ' ' F F F 'EtCO3' 'ppbv'33 'Me2CO' 1 'TR' ' ' F F T 'Acetone' 'ppbv'34 'MeCOCH2OO' 1 'SS' ' ' F F F 'CH3COCH2OO' 'ppbv'35 'MeCOCH2OOH' 1 'TR' ' ' T T F 'CH3COCH2OOH' 'ppbv'36 'PPAN' 1 'TR' ' ' T F F 'PPAN' 'ppbv'37 'MeONO2' 1 'TR' ' ' F F F 'CH3ONO2' 'ppbv'38 'O(3P)S' 1 'FM' 'Sx' F F F 'Stratospheric Ground State Atomic Oxygen' 'ppbv'39 'O(1D)S' 1 'FM' 'Sx' F F F 'Stratospheric Excited State Atomic Oxygen' 'ppbv'40 'O3S' 1 'FM' 'Sx' T F F 'Stratospheric Ozone' 'ppbv'41 'NOXS' 1 'TR' ' ' T F F 'Stratospheric NOx' 'pptv'42 'HNO3S' 1 'TR' ' ' T T F 'Stratospheric Nitric Acid' 'ppbv'43 'NOYS' 1 'TR' ' ' T T F 'Stratospheric Reactive Nitrogen Species' 'ppbv'44 'SPECH' 1 'TR' ' ' F F F 'Advected Specific Humidity' 'g/g'45 'PT' 1 'TR' ' ' F F F 'Advected Potential Temperature' 'K'46 'ISOPRENE' 1 'TR' ' ' F F T 'Isoprene' 'ppbv'47 'C2H4' 1 'TR' ' ' F F T 'Ethene' 'ppbv'48 'C2H2' 1 'TR' ' ' F F T 'Ethyne' 'ppbv'49 'H2' 1 'CT' ' ' F F F 'Hydrogen' 'ppmv'50 'CO2' 1 'CT' ' ' F F F 'Carbon dioxide' 'ppmv'51 'O2' 1 'CT' ' ' F F F 'Oxygen' 'ppmv' 52 'N2' 1 'CT' ' ' F F F 'Nitrogen' 'ppmv'

Current p-TOMCAT Species

Global Bromoform Distribution - Surface

bromoform/pptv bromoform/pptv

Scenario 3 (400 Gg/yr) Scenario 4 (595 Gg/yr)

Creating an Emission Dataset for Methyl Bromide

Six model emission scenarios:

Methyl Bromide Seasonal Cycles

Measurements from NOAA/CMDL (Montzka et al., 2003)

CHBr3 Emissions (GgCHBr3/yr/km2)

Dataset 1: 826 Gg/yr distributed according to Q&W (2003)

Dataset 2: 210 Gg/yr distributed according to Q&W (2003)

Total Global Emissions:

71% in coastal regions

29% in open ocean

Tracer expt: sensitivities

• Sensitivity to level of T-tracer release: insensitive

Sensitivity to dates of T-tracer release?

Continued emission vs. release at start of run?

Differentiation between types of TST Sensitivity to definition of the tropopause?

Sensitivities to model resolution and convection?