Stratospheric Chemical-Climate Stratospheric Chemical-Climate Variability during the 20th Variability during the 20th century century Andreas Fischer, Stefan Brönnimann, Eugene Rozanov, Nico Zeltner, Stefan Krähenmann CLIVAR Climate of the 20th century workshop, IACETH, 15-03-2007
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Stratospheric Chemical-Climate Variability during the 20th century Andreas Fischer, Stefan Brönnimann, Eugene Rozanov, Nico Zeltner, Stefan Krähenmann.
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Stratospheric Chemical-Climate Stratospheric Chemical-Climate Variability during the 20th centuryVariability during the 20th century
Andreas Fischer, Stefan Brönnimann, Eugene Rozanov, Nico Zeltner, Stefan Krähenmann
CLIVAR Climate of the 20th century workshop, IACETH, 15-03-2007
Stratospheric Chemical-Climate Variability during the Stratospheric Chemical-Climate Variability during the 20th century20th century
Table of Contents
• Motivation
• SOCOL Model / Model set-up
• Boundary Conditions - Land Use Change - Stratospheric Aerosol Data
• Chemistry Climate Features 1901 - 1909
• Conclusion
Stratospheric Chemical – Climate Variability • Stratosphere subject to a large dynamical variability, including the interannual-to-decadal scale (Solomon, 1999)
• Volcanic Eruptions, Solar Variability, ENSO, and other parameters affect stratospheric climate and ozone to a large degree (see Robock 2000; Hood 2004; Brönnimann 2007)
• Stratospheric interannual-to-decadal variability affects climate at the ground and vice versa (Shindell et al., 2001; Baldwin et al., 2001)
• Therefore interesting to investigate the mechanisms leading to stratospheric climate variability and to understand the processes modulating them. Chemistry Climate Model as an ideal tool
MotivationMotivation
Climate and Stratospheric Ozone during the 20th centuryClimate and Stratospheric Ozone during the 20th century
March Monthly mean temperature (30hPa, NP, 1956 – 2004)(Labitzke et al. 2004)
Chemistry Climate Modelling (CCM) • Most CCM studies focus on the past 25 years (Satellite period), focusing on anthropogenic influences (greenhouse effect and stratospheric ozone depletion) and major volcanic eruptions (El Chichon, Pinatubo)
• Only a few CCM simulations go back to 1950s (Shindell et al., 1998; Dameris et al., 2004)
• However, to represent natural variability of the stratosphere, it is essential to cover longer time periods. Low-frequency variability can be related to climate modes, such as AMO, IPO and to solar variability. Also, much larger variations than during the past 50 years occurred earlier (e.g. strong El Niño 1940-42, Brönnimann et al., 2004, or volcanic eruption of Krakatoa)
MotivationMotivation
Trying to fill this gap by simulating the whole 20th century by means of the CCM SOCOL 9 Ensemble Members with most realistic forcing
CCM Solar Climate Ozone Links (SOCOL) • General circulation model MA-ECHAM-4 coupled to chemistry-transport model MEZON (Rozanov et al., PMODWRC, Davos)
• Spectral model with T30 horizontal truncation
• 39 levels, from surface to 0.01 hPa
• Time step for dynamics and physics: 15 min; for radiation and chemistry: 2 hours
• Simulation of 60 chemical species; Reactions: 135 gas-phase, 52 photolysis and 16 heterogeneous reactions on/in sulfate aerosol
• Coupling between chemistry and GCM by ozone, water vapor, N2O, CH4, CFCs
• SOCOL can be run on normal PCs
SOCOL ModelSOCOL Model
Model Setup • Horizontal transport of substances with Semi-Lagrangian Scheme; Vertical transport with Prather Scheme
• Use of Family Transport Concept for Chlorine, Bromine, and Nitrogen containing species: Transport Cly, Bry, and NOy individually and as family in order to conserve total mass
• Mass fixer of O3 applied only for latitude band 40°S – 40°N; better agreement with observations and with a accurate transport scheme (Prather-Scheme)
• Spin up performed with off-line CTM-version for 10-yr long run simulation. Driven by temperature, water vapour, and daily circulation from a previous SOCOL 25yr time-slice simulation (Egorova 2005).
• 100yr transient simulation started in January 2007. Full output expected by end of August.
SOCOL ModelSOCOL Model
Boundary conditions
Land surface changeSea Ice
GHG / ODS / NOx / CO
Solar irradiance
Sea surface temperature
Stratospheric aerosols
SOCOL
Tropospheric aerosols
Quasi-biennial Oscillation
Reconstruction, Brönnimann et al.
HadISST, Rayner et al.
HadISST, Rayner et al.HYDE database
Lean et al.
WMO/GISSEDGAR-HYDE GADS climatology
GISS data, Sato et al.
Stratospheric Chemical-Climate Variability during the Stratospheric Chemical-Climate Variability during the 20th century20th century
Climatic effects after Santa Maria 1902Climatic effects after Santa Maria 1902
JFM 1903
JFM 1904
SOCOL Reconstructions
[m]
Conclusion
• 20th century runs by the CCM SOCOL provides useful insights in causes and processes related to interannual-to-decadal variability. Boundary Conditions have been successfully compiled for the whole century
• The SOCOL simulation compares reasonably well with HadSLP data for the first decade of the century
• For the winter month after Santa Maria eruption: the meridional gradient of Temperature at 40 hPa is increased whereas at 100 hPa the gradient of temperature and geopotential height strongly varies with longitude in the SOCOL simulation.
• Observational Surface Air Temperature show a anomalous warming over Europe and North America in winter 1903, consistent with previous studies about tropical eruptions. SOCOL reproduces some of these features, but magnitudes are often underestimated.
• In winter 1904 Temperature and Geopotential Height Anomalies are almost reversed compared to one year before in both, simulation and observational datasets.
Stratospheric Chemical-Climate Variability during the Stratospheric Chemical-Climate Variability during the 20th century20th century
Surface Air Temperature Anomaly with respect to climatology 1901 - 1909
Climatic effects after Santa Maria 1902Climatic effects after Santa Maria 1902
AMJ 1903
OND 1902 JFM 1903
JFM 1904
Surface Air Temperature Anomaly with respect to climatology 1901 - 1909
Climatic effects after Santa Maria 1902Climatic effects after Santa Maria 1902
AMJ 1903
OND 1902 JFM 1903
JFM 1904
40hPa Temp. Anomaly SOCOL (versus climatology 1901–1909) and SAD
Climatic effects after Santa Maria 1902Climatic effects after Santa Maria 1902
JFM 1903
JFM 1904
[K] [um2/cm3]
Temperature Surface Area Density
Latitude
Latitude
Pre
ssur
eP
ress
ure
Sea Level Pressure Anomaly SOCOL (with respect to climatology 1901–1909)
Climatic effects after Santa Maria 1902Climatic effects after Santa Maria 1902