stratospheric chemical-climate variability during the 20th century andreas fischer, stefan...

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.


HYDE database

Land Use Change DatasetLand Use Change Dataset

1700 1990

- 20 vegetation classes on 0.5° x 0.5° grid- 8 years: 1700 / 1750 / 1800 / 1850 / 1900 / 1950 / 1970 / 1990

Pasture land

Crop land

Mapping to ECHAM


1 Urban

… …

9 Upland Tundra

… …

96 Deciduous Tree Crop

Surface Background Albedo

Surface Roughness Length

Leaf Area Index

Vegetation Ratio

Forest Coverage

Field Capacity

ECHAM vegetation classes(Hagemann et al. 2002)

HYDE vegetationclasses

Considered land surface parameters

Forest coverage


IGBP datasetat 1 km resolution

Original in ECHAM4 HYDE mapped to ECHAM

Procedure:

Look-up-table

……

……

Number densityrmod

Surface Area Density

scaling factor Interpolation of the extinction to the 8spectral bands of ECHAM using Mie calculations (look-up-table)

T, wts, sigma fixed

extinction at 1E-4

GISS data 1850 – 1999 (Sato et al., 1993)

Stratospheric Aerosol DatasetStratospheric Aerosol Dataset

Input:- Effective radius as a function of latitude- Optical Depth (@ 550nm) as function of latitude and 4 altitude levels

Output:- Surface Area Density, Number Density- Extinction Coefficients, Single Scattering Albedo and Asymmetry Factors for 8 spectral intervals

Surface Area Density (1850-1999, global mean, 100hPa)

Stratospheric Aerosol DatasetStratospheric Aerosol Dataset

SAGE dataset 1979-2002

GISS dataset 1850-1999

[um

2/c

m3]

Sea Level Pressure HadSLP2 (climatology 1901 – 1909)

Climate 1901 - 1909Climate 1901 - 1909

Summer (JAS)

Winter (JFM) Spring (AMJ)

Autumn (OND)

[hPa]

Sea Level Pressure SOCOL (climatology 1901 – 1909)

Climate 1901 - 1909Climate 1901 - 1909

Summer (JAS)

Winter (JFM) Spring (AMJ)

Autumn (OND)

[hPa]

Total Ozone SOCOL (Zonal Mean, 1901 – 1909)

Climate 1901 - 1909Climate 1901 - 1909

40 and 100 hPa Temp. Anomaly SOCOL (versus climatology 1901–1909)

Climatic effects after Santa Maria 1902Climatic effects after Santa Maria 1902

JFM 1903

JFM 1904

Temp at 40 hpa Temp at 100 hPa

[K][K]

Surface Air Temp. Anomaly SOCOL and Obs. (versus climatology 1901 – 1909)


JFM 1903

JFM 1904

SOCOL HadCrut

[K]

100 hPa GPH Anomaly Reconstructions (versus climatology 1901 – 1909)


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.


Surface Air Temperature Anomaly with respect to climatology 1901 - 1909


AMJ 1903

OND 1902 JFM 1903

JFM 1904

40hPa Temp. Anomaly SOCOL (versus climatology 1901–1909) and SAD


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)


AMJ 1903

OND 1902 JFM 1903

JFM 1904

Sea Level Pressure Anomaly HadSLP (versus climatology 1901–1909)


AMJ 1903

OND 1902 JFM 1903

JFM 1904

100hPa Ozone Anomaly with respect to climatology 1901 - 1909


OND 1902 JFM 1903

Vegetation Ratio


before after

IGBP datasetat 1 km resolution

100hPa Temperature Anomaly SOCOL (versus climatology 1901–1909)


AMJ 1903

OND 1902 JFM 1903

JFM 1904

100hPa GPH Anomaly SOCOL (versus climatology 1901–1909)


AMJ 1903

OND 1902 JFM 1903

JFM 1904

100 hPa GPH Anomaly Reconstructions (versus climatology 1901 – 1909)


AMJ 1903

OND 1902 JFM 1903

JFM 1904

stratospheric chemical-climate variability during the 20th century andreas fischer, stefan...

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