Mark G. Lawrence Max Planck Institute for Chemistry, Mainz, Germany

Cloud Processing of Trace Gases and Aerosols:

What are we missing / what should we do in the

future?

Mark G. Lawrence

Max Planck Institute for Chemistry, Mainz, Germany

Chemistry-Climate Interactions WorkshopSanta Fe, 10 February 2003

“At the Cleaners with Mark”

Mark G. Lawrence



“Doing the Laundry with Mark”

Mark G. Lawrence



Objectives

• Importance of clouds for atmospheric chemistry?

•Major outstanding issues?

• (Chemistry climate?)

Organized Picture of thewide range and complexity of

issues

TopicsBreak down into 2x2 different topics:

• Cloud type

– Shallow: • Stratiform, fair weather cumulus, and non-Cb

cirrus– Deep:

• Vertical motions exceeding 2-3 km: Cumulus convection (cu-congestus to MCSs and Hurricanes) and deep cirrus anvils (e.g., squall line)

• Chemical phase– Gases– Aerosols

Outline

• Shallow Clouds– Introduction/Effects– Issues

• Deep Clouds– Introduction/Effects– Issues

• Assessment of Priorities

Illustrations/Exampleslargely with MATCH results

Current studies often not explicitly listed

ISSUE

Importance (O3, AOT)

Difficulty (80-90% job)

G A G A

SHALLOW CLOUDS

Parameterization: Microphysics

Parameterization: Cloud Fraction

Liquid water chemistry: Role of internal/external mix

Liquid water chemistry: Uptake kinetics/amount

…

DEEP CLOUDS

Parameterization: Thermo/Location/Intensity

Vertical Transport: Entrainment

Vertical Transport: Detrainment

Vertical Transport: Downdrafts

…

Fill in withL/M/H

Fill in withL/M/H

Shallow Clouds

StratocumulusNorth

Atlantic

(From the Karlsruher Wolkenatlas)

StratocumulusGermany


Fair Weather CumulusKarlsruhe


Altocumulus LenticularisUtah


Processing air

Cirrus

New Mexico


New Mexico

Bolivia

Shallow Cloud Issues

• Parameterization

• Liquid Water Chemistry

• Ice Surface Chemistry

• Precipitation Scavenging

• Radiative Transfer / Photolysis Rates

Issues: Parameterization

• Microphysics– Currently mainly bulk schemes– Global models: mostly prognostic only for

total condensate, diagnostic for the rest – Cloud resolving models: typically bulk

schemes but prognostic for all condensate types

Large-ScaleProcesses

Cloud-ScaleProcesses

Control

Feedback


• Cloud cover– Diagnostic threshold (Slingo) schemes in

widest use– Often decoupled from microphysics,

though recent improvements…?– Always decoupled from advection (so far…)


Cloud-ScaleProcesses

Control

Feedback

Issues: Parameterization• Cloud cover – resolving cloud systems

<2% of rain cells (and <5% of clouds) exceed T42 (~105 km2), however…

From Wilcox, Thesis, 2002

Issues: Parameterization• Cloud cover – resolving cloud systems

…rain cells > T42 produce 70% of the total precipitationHouze/Mapes (Pacific):1% of clouds > 105 km2, but are 25% of total cloud cover

No coupling of clouds in one grid cell

with th

ose in the neighborin

g cells!


Issues: Liquid Water Chemistry

• Aerosols– Crucial for processing of all aerosol types

– Importance of internal/external mixtures (type, age, and size) and coating for determining hygroscopicity, nucleation, and optics?

– Collection/uptake of existing aerosols by droplets?

– Form of aerosols after evaporation (and evaporation process)?

– Coupling with gas phase chem (e.g., interaction of S and N cycles, halogen release, etc.)?

Issues: Liquid Water Chemistry

• Gases– Effects on O3 and HOx still under debate:

locally strong, globally moderate to weak

– Halogen and NMVOC reactions?

– Coupling with aerosol chem (e.g., SO2 oxidation, N2O5 hydrolysis)?

Issues: Ice Surface Chemistry

• Aerosols– Uptake/ageing of aerosols on ice?

Dependence on type/mixture?

• Gases– Halogen activation?

– HO2 + O3 (and other O3- or HOx-related reactions?)

– NMVOC reactions?

Issues: Precipitation Scavenging

• Aerosols– Major loss for all aerosol types

(some after processing)– Importance of aerosol type/mixture for

nucleation and collection?


• Gases– Major loss process for reactive nitrogen, odd hydrogen, VOCs,

and halogens– Water solubilities generally known (except VOCs)– Ice uptake/retention very poorly characterized– Kinetic uptake limitations difficult to model (generally

neglected)


• Example: Effect on soluble gases with a surface source

Based on Crutzen and Lawrence, J. Atmos. Chem., 2000

Hx in M/atm:

Hx = 0Hx = 103

Hx = 104

Hx = 105

Hx = 106


• Example: Effect on soluble gases with a surface source


Hx in M/atm:

Hx = 103

Hx = 104

Hx = 105

Hx = 106

Hx = 1010


• General– Precipitating fraction and stratiform/convective split– Preservation of information on scavenged areas– Slower sedimentation of smaller hydrometeors


• Precipitating fraction



• Preservation of Information / Artificial Mixing

t0 t0 + scav t0 + scav + adv t0 + t

Shorter t => worse artificial mixing!


• Slower sedimentation of smaller hydrometeors

From Lawrence and Crutzen, Tellus, 2000

Issues: Radiative Transfer

• Effects on Photolysis Rates (and heating rates…)

– Effect on OH and CH4 small to moderate (~10%)

– Already simulated rather accurately (Landgraf/Crutzen)

From Landgraf, Thesis, 1998

MATCH-MPICsimulation

Deep Clouds

Organized

Convection

Cumulus CongestusMiam

i

Karlsruhe(From the Karlsruher

Wolkenatlas)

Near Karlsruhe

Cumulonimbus with and without Anvil

(From the NOAA Gallery)

Supercell Cumulonimbus

(From Houze‘s Cloud Atlas)

Squall Line

Hurricane Floyd

Mass-Balance

Subsidence

Downdrafts

Deep Convection: Characteristics

Updrafts

Eigenschaften der Eigenschaften der KonvektionKonvektion

Precipitation and Precipitation and slower slower

SedimentationSedimentation

PrecipitatiPrecipitationon

Anvils Anvils (Ice)(Ice)

LightniLightningng

Deep Convection: Characteristics

Deep Cloud Issues

• Parameterization

• Vertical (dry) Transport

• Precipitation Scavenging

• Lightning NOx

• Several components to deal with:– Thermodynamics (T/t, Q/t, Q1, Q2)– Microphysics– Cloud Cover / Precipitation Swath– Mass Fluxes / Tracer Transport– Proper treatment in offline models

(pre-stabilized thermodynamic profiles)



Moist-ConvectiveProcesses

Control

Feedback


• Wide range of philosophies and closures

• Focus of testing on thermodynamics; Tracers (e.g., CO, CH3I) may provide powerful tests

• Mesoscale organization rarely considered– CEMs: delays in response to large-scale forcing– First attempts by Donner, others? – Relevance for tracer transport unknown, likely substantial


Moist-ConvectiveProcesses

Control

Feedback

Issues: Vertical (dry) Transport

• Updraft Effects – Transport to the UT:– O3 and O3-precursors– HOx reservoirs– Stratosphere-relevant gases (halogenated gases, COS)– Aerosols – esp. Dust, BC, OC, and Sulfate precursors– Clean air masses

Example:

Southern Asian CO

from MATCH-MPIC

Issues: Vertical Transport

?Entrainment intothe Ensemble

?

Tropopause

Mu

Z



Detrainment fromthe Ensemble

?

Mu

Z

?

Tropopause



Detrainment fromthe Ensemble

?

Mu

Z

??

Tropopause

??


• Updraft Effects – Importance of Detrainment Region:

MATCH-MPIC O3:

Detrain-top----------

Base run


?

Downdrafts

• Strength

• Feeder Regions

( Organization)

• Entrainment

• Detrainment

?

Significance of downdrafts?


Mass-Balance Subsidence

• In same model column?

• As part of circ. cells (Hadley, Walker)?

Issues: Vertical Transport• Role of Subsidence, Balance with Updrafts:

From Lelieveld and Crutzen, Science, 1994


MATCH-MPIC O3:

Base run----------

No Conv Transp


Trop. Total Ozone (Tg)Run MATCH-MPIC1 MOGUNTIA2

No Convection 293 315

With Convection 328 (+12%) 253 (-20%)(Base Run)

1 This Study (when conv. precip is also turned off => 297 Tg)2 Lelieveld & Crutzen, Science, 1994 (only conv. transport turned off)

Cause for difference??


Degree/Amount ofPenetration into the TTL

(tropical tropopause layer)?


Penetration into the Stratosphere?• Tropical?• Extratropical?• Induced STF?


• Scavenging Effects:– Major loss process for all aerosol types (some after processing)

– Major loss process for reactive nitrogen, odd hydrogen, and VOCs

– Important for stratosphere-relevant gases (soluble halogenates)


Amount/Distribution?

Based on a MATCH simulation with NCEP reanalysis data


Precipitation Swath?

Core/Anvil, Intensity?

Origin of scavenged air?

} }}


Kinetic Uptake Limitations


• Uptake in/on ice

• Retention in supercooled droplets upon freezing

Issues: Precipitation Scavenging• Importance of retention in ice and kinetic uptake limits


Hx in M/atm:

Hx = 103

Hx = 104

Hx = 105

Hx = 106

Hx = 1010

Ice

Issues: Precipitation Scavenging• Importance of retention in ice

30 min 45 min 60 min

WRF - (Preliminary!)

Insoluble

Soluble

Degassed

Issues: Precipitation Scavenging• Importance of retention in ice WRF -

(Preliminary!)


Artificial Mixing(preservation of info)

Issues: Lightning NOx


Influence on NOx and O3

(MATCHResults)

O3 Ratio:with/withoutLightning

NOx Ratio:with/withoutLightning


• Global Amount

• Regional Distribution

• Vertical Distribution

• Charge Separation

• NOx Production Mechanism


Global Amou

nt

REFERENCE(type of estimate)

P(NO)(1016 molecules

J-1)

P(NO)(1025

Molecules flash-1)

F(102 flashes s-1)

G(NO)(Tg (N) year-1)

Lawrence et al. (1995)(review)

- 2.3 (1-7) 1 (0.7-1.5) 2 (1-8)

Kumar et al. (1995)(observations)

0.5 1 2

Ridley et al. (1996)(observations)

- 1 2-5

Levy et al. (1996)(theoretical)

- - - 3-5

Price et al. (1997)(observations)

10 - 0.7-1 12.2 (5-20)

Price et al. (1997)(theoretical)

10 - - 13.2 (5-25)

Wang et al (1998)(laboratory)

- 3.1 0.3-1 2.5-8.3

Nesbitt et al. (2000)(observations)

- 0.87-6.2 0.57 0.9

Issues: Lightning NOx• Regional Distribution

MATCH-MPICOTD

Extratropics - underestimated

Tropics - overestimated

Flashes/km2/Month

Overarching Issues

Major Overarching Issues

• Do we need to unify/combine stratiform and convective cloud parameterizations?

• Do we need to keep separate cloudy and cloud-free variables for each grid cell?

• How do we include the effects of mesoscale organization?

• How do we properly compare CEM studies with 1D versions from global models?

• Which geographical regions need the most attention?

Priorities

ISSUE



G A G A

SHALLOW CLOUDS

Parameterization: Microphysics L/M H H H

Parameterization: Cloud Fraction M H L/M L/M

Liquid water chemistry: Role of internal/external mix

- H - H

Liquid water chemistry: Uptake kinetics/amount L/M L/M L L/M

Liquid water chemistry: Aerosol processing details - H - H

Liquid water chemistry: Effects on O3/HOx L/M - M -

Liquid water chemistry: Halogens / NMVOCs L/M - H -

Liquid water chemistry: Gas-aerosol coupling L/M H H H

Ice surface chemistry L/M ? H H

Precipitation scavenging: Amount/Fraction M H M/H M/H

Precipitation scavenging: Ice uptake/retention M M(?) H H

Precipitation scavenging: (Liquid) kinetic limitations M M M M

Precipitation scavenging: Artificial mixing M H M/H M/H

Photolysis rates L L L L

DEEP CLOUDS

ISSUE



G A G A

DEEP CLOUDS

Parameterization: Thermo/Location/Intensity H H M/H M/H

Vertical Transport: Entrainment M/H M M/H M/H

Vertical Transport: Detrainment M/H M M/H M/H

Vertical Transport: Downdrafts L L M M

Vertical Transport: Subsidence – connection to LS circ

M/H M H H

Vertical Transport: Penetration into the TTL M/H L/M M/H M/H

Vertical Transport: Penetration into the Strat / STE L/M L M/H M/H

Precipitation scavenging: Amount/Distribution /Swath M H M/H M/H

Precipitation scavenging: Ice uptake/retention M M(?) H H

Precipitation scavenging: (Liquid) kinetic limitations M M/H H H

Precipitation scavenging: Artificial mixing M H H H

Lightning NOx: Amount M - M -

Lightning NOx: Distribution M - L/M -

Extras

(type of estimate)

REFERENCEP(NO)

(1016 molecules J-1)P(NO)

(1025 Molecules flash-1)

F(102 flashes s-1)

G(NO)(Tg (N) year-1)

Tuck (1976) (theoretical)

- 1.1 5 4

Chameides et al.(1976) (theoretical)

3-17 6-14 4 18-41

Noxon (1976)(field observations)

- 10 5 37

Chameides (1979) (theoretical)

8-17 16-34 4 47-100

Dawson (1980) (theoretical)

- 0.8 5 3

Hill et al. (1980) (theoretical)

- 1.2 1 0.9

Levine et al.(1981)(laboratory )

5 ± 2 0.5 5 1.8 ± 0.7

Kowalczyk (1981) - - - 5.7

Peyrous and Lapeyre (1982)(laboratory)

1.6 3.2 4 9.4

Drapcho et al. (1983)(field observations)

- 40 1 30

Franzbau et al. (1989)(field observations)

- 300 1 220

Sisterson (1990)(theoretical)

- 8.2 2 12

Liaw et al. (1990) - - - 81


• Precipitation Swath

• Core/Anvil fraction

• Uptake in/on ice

• Retention in supercooled water upon freezing

• Kinetic uptake limitations

• Preservation of information (artificial mixing)

(From the NOAA Gallery)

Tornadoes

Hail

Lightning


• Distribution/Intensity of deep convection

Based on a MATCH simulation with NCEP reanalysis data

From Lawrence and Crutzen, Tellus, 2000

Issues: Lightning NOxInfluence on NOx and O3

O3 Ratio:with/withoutLightning

NOx Ratio:with/withoutLightning

500 hPa

MATCH-MPIC

Einfluss der vertikale Verteilung von Blitzen

Verhältnisder Stickoxide:Amboss/gesamt Wolke

Verhältnisdes Ozons:Amboss/gesamt Wolke

Dru

ck (

hP

a)D

ruck

(h

Pa)

Vertical distribution: Implications for tropospheric chemistry.

Ratios of zonal averages for NOx, and O3 for July 1997.

NOx O3

Pick/base Pick/base

Mark G. Lawrence Max Planck Institute for Chemistry, Mainz, Germany

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