MANTRA balloon FTIR measurements of stratospheric species at mid-latitude summertime: comparisons with the Canadian Middle Atmospheric Model

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MANTRA balloon FTIR measurements of stratospheric
species at mid-latitude summertime comparisons
with the Canadian Middle Atmospheric Model

• S. M. L. Melo, CSA, Canada
• C. McLandress, P. Fogal, T. Shepherd, and K.
  Strong
• Department of Physics, University of Toronto,
  Canada
• Jack McConnel, Kirill Semeniuk, York University
• Jonathan Davies, Environment Canada
• R. Blatherwick, Department of Physics, University
  of Denver, USA

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How well do we know what controls mid-latitude
stratospheric ozone?

• S. M. L. Melo, CSA, Canada
• C. McLandress, P. Fogal, T. Shepherd, and K.
  Strong
• Department of Physics, University of Toronto,
  Canada
• Jack McConnel, Kirill Semeniuk, York University
• Jonathan Davies, Environment Canada
• R. Blatherwick, Department of Physics, University
  of Denver, USA

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Outline

• - Ozone budget at mid-latitudes
• - MANTRA
• Justification for using CMAM
• Long-lived species
• O3 and T
• Discussions

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IPCC Special Report on Ozone and Climate, 2005
O3, like water vapour and CO2, is an important
and naturally occurring greenhouse gas
At the same time, changes in climate could impact
O3 in a number of different ways.
- any changes in O3 abundance could have an
impact on climate.
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IPCC Special Report on Ozone and Climate, 2005

• Globally, O3 has decreased by roughly 3 since
  1980
• Currently, there is no unequivocal evidence from
  measurements in the atmosphere that the onset of
  O3 recovery has begun
• Recovery of O3 layer is a complex issue it
  depends not just on the extent to which the ODSs
  are replaced but also on emission of gases that
  impact the climate system directly
• Stratospheric O3 depletion has lead to a cooling
  of the stratosphere (over mid-latitude
  0.6K/decade)
• Future temperature changes in the stratosphere
  could either enhance or reduce stratospheric O3
  depletion, depending on the region
• O3 abundance in the Northern Hemisphere
  mid-latitudes and Arctic is particularly
  sensitive to dynamical effects (transport and
  temperature)
• Statistical and modelling studies suggest that
  changes in stratospheric circulation regimes can
  have an impact on surface climate patterns

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Mid-Latitude Ozone Trends

• Total ozone deviations w.r.t. 1964-80 average,
  adjusted for seasonal effects and smoothed
  (1964-2001).
• Global mean total column ozone for 1997-2001
  was 3 below the 1964-1980 average
• NH decrease is 3
• SH decrease is 6

WMO Ozone Assessment 2002, adapted from Fioletov
et al. (JGR 2002)
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• Ozone vertical profile trends

• Range of model results at 40-45 km
• uncertainties in T, CH4 trends
• Underestimate NH trends at 10-25 km
• uncertainties in H2O trends, bromine, vortex
  chemistry and mixing, role of dynamics

WMO Ozone Assessment 2002
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Mid-Latitude Ozone Loss

• In contrast with the polar ozone destruction,
  which is attributed to anthropogenic emissions of
  CFCs, the origin of mid-latitude ozone decline
  still remains an open question.
• Proposed mechanisms
• In situ chemistry, involving heterogeneous
  reactions on aerosols/clouds,
• Changes in the intensity of the Brewer-Dobson
  circulation leading to an effect on diabatic
  descent,
• Transport of ozone-poor air or and PSC-activated
  air from the polar vortex toward mid-latitudes.

• Marchand et al., JGR 2003 model analysis
  estimates total polar air contribution is usually
  between 20 and 40 of the total O3 loss
  (45N-50N). Can be as much as 50 during large
  vortex intrusions.

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The MANTRA Campaigns

• Balloon mission to study the changing chemical
  balance of the mid-latitude stratosphere
• Supported by the Canadian Space Agency and the
  Meteorological Service of Canada (all flights),
  CRESTech (1998), NSERC (2002, 2004)
• Science Team from U of Toronto, MSC, York U, U of
  Waterloo, U of Denver, CNRS Service dAéronomie,
  Scientific Instrumentation Ltd.
• Four campaigns conducted at Vanscoy, SK (52?N,
  107?W)

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• Instruments of interest here balloon-based SPS,
  SAOZ, and DU-FTS, the ground-based UT
  Spectrometer and the sondes.
• In this work we report on vertical profiles of T,
  O3, NO2, N2O, CH4, and HCl concentrations .
• Campaigns 1998, 2000, 2002, and 2004

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MANTRA 1998 The one that got away
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MANTRA CMAM

• Canadian Middle Atmosphere Model (CMAM) is a
  spectral General Circulation Model (GCM)
• Using CMAM profiles output at the grid point
  closest to Vanscoy
• to complement the MANTRA measurements
• to compare correlations of long-lived species
  (indicators of transport)
• to validate representation of processes in CMAM
• to test assumptions about variability of species,
  and the extent to which some can be constrained
  from knowledge of others

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Late summer
Comparison of NCEP/NCAR (1970-2001), UKMO
(1993-2002) and CMAM (24 years) long-term means
of zonal wind velocity over Vanscoy.

• The green curve is NCEP/NCAR data
• Blue is UKMO
• Red is CMAM (WMO).
• Taken from Wunch et al., A-O in press.

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MANTRA CMAM T (sondes)
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MANTRA CMAM T (sondes)
10-20 km the averaged temperature profiles agree
with the model within 2 . - within the model
inter-annual variability.

• CMAM
• Below 14 km
• cold bias (2 6 km)
• Above warm bias

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MANTRA CMAM O3 (Sondes)

• Measurements
• - consistent in 2002
• depletion in the peak alt. 1998

CMAM 10-20 km positive bias ? - within the
variability
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Long-lived species (FTS) - 1998 campaign CMAM
(WMO)
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Long-lived species (FTS) - 1998 campaign CMAM
(V7)
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35 ozone depletion
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- Local O3 loss
HCl heterogeneous chemistry on top of clouds?
HCl ClONO2 -gt Cl2 HNO3 HCl HOCl -gt Cl2
H2O H2O ClONO2 -gt HOCl HNO3 HCl HOBr -gt H2O
BrCl requires cirrus clouds or cold aerosols
at 25 km?
Non-polar latitudes proposed by Hofmann and
Solomon, 1989 - Smith et al, 2001 has shown
evidence that this would not be the case!
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Arctic vortex processed air?

• - Hess and Holton, 1985 remains of polar vortex
  could persist a long time as "frozen" in the mean
  summertime flow
• Evidence shown by Newman et al., 1996 (ER-2
  dataset)
• Orsolini, 2001 chemical transport model
  predict that some "fossil" of polar vortex
  subsist even in August in stratosphere
• Durry and Hauchecorne, 2005 present evidence
  CH4 and H2O measurements.

Orsolini, GRL, 2001
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Summary

• Objective
• Analyze MANTA dataset in terms of O3 chemistry
  at mid-latitudes
• Use CMAM to complement measurements
• Results
• measurements indicating that the adoption of a
  lower vertical eddy diffusion coefficient
  improved model
• O3 and T measurements and model in general
  agreement
• lower levels of HCl measured in 1998 may be
  linked to depletion of O3 in the peak altitude
  region fossil from Arctic vortex?
• Paper drafted and now under revision still
  work in progress!

THANKS!