cargese utls ozone and ozone trends 1 utls ozone and ozone trends d. fonteyn (my apologies) given by...

Cargese UTLS ozone and ozone trends 1

UTLS ozone and ozone trends

D. Fonteyn (My apologies)

Given by

W. Lahoz (My thanks)


Importance UTLS

• relatively large (but variable) ozone trends

• very high climate sensitivity

• crucial region modulating stratospheric entry of

tropospheric pollutants

• growing commercial aviation


Problems UTLS studies

• very complex region (dynamics and chemistry on a

variety of scales)

• high demands on modeling capabilities

• limited amount of satellite observations with large

uncertainties: rely on in-situ measurements


UTLS: combination of mixing and chemistry


Upper Troposphere:

• Emission of chemical species

• Ozone production

• Oxidation capacity

• Species influencing radiatif budget


Lower Stratosphere:

• Ozone destruction (ClOx, BrOx, NOx, heterogeneous

chemistry)

• Species influencing radiatif budget


Upper Troposphere – Lower Stratosphere Studies:

• STE: Stratosphere – Troposphere Exchange

• Dynamical processes

• Chemical processes

• Climate

• All Linked


Overview of ozone chemistry?

Huge task

Chemical processes are relatively well known

Tropospheric chemistry

Stratospheric chemistry

Coupling with emissions, dynamics, climate change

makes it extremely vast.


UTLS: ‘slow’ chemistry and ‘fast’ mixing


UTLS: distinct tracer relationships


Models & Observations:

Climatology: dynamical features present in species

distributions


>> Park et al, JGR 2004

Methane distribution at 136 hPa in July.

Maximum near Asian monsoon and secundary

maximum near North America


>> Park et al, JGR 2004



• Climatology

• Convective driven methane distribution, models agree

with observations, gradients do not agree

• Lightning NOx production: qualitative agreement but

not in vertical

Ozone ?


>> Kuell et al., JGR 2005

Detrended CFC 11 distribution at 100 hPa in

the TRACHT region during the time period

from 10–13 August 1997 as measured by

CRISTA (upper map) and modeled by

EURAD (interpolated to the CRISTA

measurement grid; lower map). The EURAD

data have a negative bias of about 20 pptv.

Dynamical features: a mid-latitude blocking

event characterized by an omega circulation

pattern with a persistent cutoff low at its

western wing.



• Satellite observations allow to detect dynamical effects

in CFC 11 distributions on an event basis.

• Event modelling in qualitative agreement


Models & Observations: shifting towards event chemistry

(UT):

Brunner D., et al., ACP, 2005

An evaluation of the performance of chemistry transport

models. Part 2: Detailed comparison with two selected

campaigns


>> Brunner et al., ACP 2005


>> OUTLINE

Composites of PEM-Tropics A time series. Measurements at 0–35 S and 400–200 hPa (about 7.2–12 km) only. Flight numbers are indicated at the top of each panel. Black: measurements.


>> OUTLINE

Composites of SONEX time series. Only measurements between 350 and 200 hPa are included.


Models & Observations: shifting towards event chemistry

(UT):

Senistivity to emissions, biomass burning, lightning,

aircraft …

Large model variability


Problems UTLS studies

• Other uncertainties, winds

• Bregman: mass conserving properties

• Comparing with MOZAIC aircraft campaign


>> Bregman, B., et al., ACP, 2003


Ozone UTLS trends

• Observations:

– LS ozone depletion related and “recovery”

– UT pollution effects

• VERY LONG term trends: models


>> WMO, 2002

Ozone decrease in lower stratosphere in

Northern Mid-latitudes. The period 1980 –

2000 shows less decrease than 1980 – 1996.


>> OUTLINE

Vertical discriminated deseasonalized ozone

evolution from ozonesondes NH.


>> MOZAIC trends, Thouret, V., et al., ACPD, 2005

Time series of ozone monthly means in the UT over the three selected regions Europe, Eastern US and Iceland.


>> OUTLINE

Time series of ozone monthly means in the LS over the three selected regions Europe, Eastern US and Iceland.


MOZAIC Ozone UTLS trends

Apparent discrepancies:

UT increase, high compared to literature

LS increase, decreased expected

Effect of period, effect of location


>> GAUSS, M., et al., ACPD, 2005

Very long term trend: 1850 – 2000

Chemical change induced:

Dynamical change induced:


A flavour of what to expect

cargese utls ozone and ozone trends 1 utls ozone and ozone trends d. fonteyn (my apologies) given by...

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