Date post: | 31-Dec-2015 |
Category: |
Documents |
Upload: | denis-gordon |
View: | 217 times |
Download: | 0 times |
Analysis of a 1950-1999 simulation Analysis of a 1950-1999 simulation with prognostic ozone in ARPEGE-Climatwith prognostic ozone in ARPEGE-Climat
Jean-François Royer, Hubert Teysseidre, Jean-François Royer, Hubert Teysseidre, Hervé Douville, Sophie TytecaHervé Douville, Sophie Tyteca
Meteo-France, CNRM, ToulouseMeteo-France, CNRM, Toulouse
• Importance of ozone• Overview the ARPEGE-Climat ozone parameterization• Presentation of the forced simulation• Mean seasonal cycle• Interannual variability• Reproduction of the ozone hole• Conclusions and perspectives
Importance of ozone
• Absorption of UV and IR radiation• Complex tropospheric and stratospheric chemistry• Long term trends observed in total ozone• Stratospheric ozone depletion over the South Pole
(ozone hole) since the 1970s• Many studies have shown evidence of the impact of
anthropic perturbations on atmospheric chemistry (CFCs, NOx, CH4, CO …)
• Stratospheric trends due to the inverse greenhouse effect
• Impact of stratospheric cooling on ozone photochemistry and ozone catalytic destruction by chlorine compounds
• WMO/UNEP Scientific Assessment of Ozone Depletion (1998, 2002)
Purpose of the presentation
• To document the capacity the ARPEGE-Climat GCM, that includes a ozone as a prognostic variable with a simple parameterization of its photochemistry, to reproduce the main characteristics of ozone distribution
• To evaluate its capacity at simulating its observed long term evolution in response to SST, greenhouse gas forcing, and changing composition of the atmosphere
• To identify the impact and signature of anthropic perturbations on the evolution of the ozone layer
Description of the simulations
• ARPEGE-Climat version 3
• Dynamics and resolution:• Semi-lagrangian version with ozone transport• T63 linear grid (128x64 points)• 45 levels in the vertical
• Physical parameterizations• State-of-the-art GCM physics (convective and large-scale
precipitation, interactive clouds, turbulence, land surface processes ISBA)
• ECMWF (Fouquart, Morcrette) radiation scheme (every 3 hours) with major greenhouse gases (CO2, CH4, N20, O3, CFC-11 and CFC-12)
• Sulfate Aerosols: direct and indirect effects (Boucher and Lohman parameterization implemented by Hu RM et al 2002)
• prognostic computation of ozone concentration
The forced simulation
• Aerosols concentrations (J Penner)• The sea surface temperatures (SSTs) are specified according to the
observed monthly means (Reynolds analyses) over the period 1960-2000
• Ozone transport and simplified photochemistry • Derived from the 2D zonal model MOBIDIC
– (MOdel of BI-DImensional Chemistry)
300
310
320
330
340
350
360
370
1950 1960 1970 1980 1990 2000
Year
pp
mv
CO2
1100
1200
1300
1400
1500
1600
1700
1800
1950 1960 1970 1980 1990 2000
Year
pp
bv
CH4
280
290
300
310
320
1950 1960 1970 1980 1990 2000
Year
pp
bv
N2O
0
100
200
300
400
500
600
700
1950 1960 1970 1980 1990 2000
Year
pp
tv
CFC11 CFC12*
•50 year simulation starting in 1950 •Observed GHGs:
•CO2•CH4•N2O•CFC11•CFC12+(others)
Climate statistics
MOBIDICMOBIDICStratosphericStratospheric
chemistrychemistry
Observed SSTs(monthly-mean)
Sea-ice
ISBALand surface
CO2 CH4N2O CFCs
ZonalAverages(10 years)
ARPEGE-ClimatAGCM
Cl
Zonal-mean coefficients for O3 parameterization
Aerosols
The 2D photochemical model MOBIDIC[Cariolle, CNRM, 1984 ; Teyssèdre, UPS, 1994]
• 2 dimensions (latitude, pressure)
• thermodynamical forcings from ARPEGE-Climat (T, v*, w*, Kyy, Kyz, Kzz)
• stratospheric chemistry : 56 species, 175 reactions
• studies of atmospheric impact (supersonic aircraft)
for ozone linear parametrisation :
• chemical equilibrium => (P-L) ; rO3 ; T ;
• +/- 10% perturbation => new equilibrium : (P-L) / rO3 ; (P-L) / T ;
(P-L) /
linearised ozone chemistry[Cariolle and Déqué, JGR, 1986]
rO3 / t = (P-L)
+ (rO3 - rO3
) (P-L) / rO3
+ (T – T) (P-L) / T
+ ( – ) (P-L) /
- Khet (Cly (year))2 rO3
from 3D GCM from 2D photochemical model ( , p)
(P-L) : ozone production-loss term rO3 : ozone mixing ratio
T : temperature : ozone column above gridpoint
Khet : heterogeneous chemistry Cly (year) : total chlorine for given year
Validation of the resultsComparison of the climate of the 60s and 90s
• Maps of the differences between 20-year mean simulated distributions for two different periods
– 1950-1969
– 1980-1999• Total ozone column (DU= Dobson Units ~ mm O3 at STP)
• Ozone concentration (volume mixing ratio in ppmv)
•Validation of the ozone distribution
–Comparison with UGAMP 5-year ozone climatology 1985-1989
Monthly, 2.5° x 2.5°, 47 levels(Li and Shine, 1995)
Available at BADC
ARPEGE-Climat
Difference from 1950-1969 mean: colour scale
20-year mean 1980-1999: isolines
September
1950 19501999 1999
10 hPa 10 hPa
surface surface
ozone
Ozone column temperature
temperature
Montly anomalies with respect to 1950-1969 global averageMontly anomalies with respect to 1950-1969 global average
1950 19501999 1999
Conclusions
• The ozone transport and simple parameterization of its sources and sinks is able to reproduce the geographical and seasonal distribution patterns of total ozone column
• The vertical distribution of ozone in the stratosphere is simulated realistically
• In response to the increase of CFCs the model simulates a reduction of ozone in the upper stratosphere due to its increased destruction by released chlorine
• This leads to a cooling in the upper stratosphere due to the reduction of UV absorption
• However due to the tropospheric response the total ozone column increases slightly, which is not in agreement with observations
Conclusions (2)
• The heterogeneous chemistry parameterization is able to reproduce the destruction of ozone by PSCs in the South Polar vortex at the begining of Austral spring
• Though the structure of the simulated ozone hole is realistic its intensity is too weak
• Need to revise and adjust the destruction coefficient for heterogeneous chemistry to improve the efficiency of the parameterization in future C20C simulations