CCMVal

Overview of CCMVal simulations
in support of WMO 2007


by Veronika Eyring, Doug Kinnison, and Ted Shepherd,
B. Boville, C. Brühl, N. Butchart, M. Chipperfield, M. Dameris, R. Garcia,
M. Giorgetta, E. Manzini, S. Montzka, A. Ravishankara, R. Salawitch, and G. Stenchikov

On behalf of the CCM Validation activity for SPARC (CCMVal)


General questions regarding the specifications of external forcings can be directed to Veronika Eyring, Doug Kinnison, and Ted Shepherd.
Please directly contact the appropriate scientists for questions regarding specific data sets (see below).

In order to facilitate the set-up of the CCMVal reference and sensitivity simulations,
CCMVal has established this website where the forcings for the proposed simulations are now ready for download.


Download Summary on CCMVal simulations in support of WMO 2007: Eyring, V., D. E. Kinnison, and T. G. Shepherd (2005), Overview of planned coupled chemistry-climate simulations to support upcoming ozone and climate assessments, SPARC Newsletter No. 25, 11-17.

(A) Proposed simulations within CCMVal  in the near term
(B) Reproducing the past: Forcings for a transient model simulation 1960 to present da
(C) Making predictions: Forcings for a transient model simulation from present day to 2100
(D) Model recommendations concerning the model set-up and the variables that should be stored in order to allow sophisticated inter-comparisons of chemistry, transport, dynamics and radiation in CCMs
(E) Current coupled chemistry-climate models
(F) References
(G)
Use of CCM results in the upcoming WMO/UNEP Scientific Assessment of Ozone Depletion
In addition to existing CCM simulations, the model results from the REF1, REF2, SCN1, and SCN2 simulations are planned to feature prominently in the 2006 WMO/UNEP ozone assessment. The runs into the future (REF2 and SCN2) will provide the basis for Chapter 6 of the assessment entitled ‘The ozone layer in the 21st century’. This chapter will also validate all 4 CCMVal model runs through historical (1980 or earlier to 2004) intercomparisons with observed ozone changes taken from Chapters 3 and 4 of the assessment. Chapter 5 of the assessment entitled ‘Climate-Ozone Connections’ will also make use of all 4 model simulations as illustrative case studies of the interactions between ozone and climate. The lead authors of these two chapters (Martin Dameris and Mark Baldwin for Chapter 5, Greg Bodeker and Darryn Waugh for Chapter 6) therefore strongly encourage the CCMVal community to submit the requested models data
to allow a more detailed assessment of the evolution of total ozone as soon as possible so that they can be used in the assessment. Download CCMVal Ozone Data Request
(H) Model intercomparison
A more detailed inter-comparison of CCM results and observations has successfully started. Model results from 10 European model groups that are participating in the European Integrated Project SCOUT-O3 and one model group from outside Europe (CCSR/NIES) have been obtained. The first phase of the inter-comparison will be based on existing runs. With the exception of total column ozone, only transient model simulations for the time period 1980 to 1999 will be compared (no time sliceexperiments). We would like to encourage other model groups to join in the inter-comparison and to send data. Please follow this link for data requests and formats.


(A) Proposed CCMVal Simulations

Some of the key questions that have been addressed by the WMO/UNEP Steering Committee are: (1) How well do we understand the past changes in stratospheric ozone (polar and extra-polar) over the past few decades in an environment where stratospheric constituents (including halogens, nitrogen oxides, water, and methane) were changing, as was the climate in this region? (2) What does our best understanding of the climate and halogens, as well as the changing stratospheric composition, portend for the future? (3) Given this understanding, what options do we have for influencing the future state of the stratospheric ozone layer?

In order to address question (1) and (2), we would propose the following two reference simulations:

REF 1: REPRODUCING THE PAST, Core time period 1980 to 2000

REF 1 is designed to reproduce the well-observed period of the last 25 years during which ozone depletion is well recorded, and allows a more detailed investigation of the role of natural variability and other atmospheric changes important for ozone balance and trends. This transient simulation includes all anthropogenic and natural forcings based on changes in trace gases, solar variability, volcanic eruptions, quasi-biennial oscillation (QBO), and sea surface temperatures (SSTs). SSTs in this run are based on observations. Depending on computer resources some model groups might be able to start earlier. We highly recommend reporting results for REF1 between 1960 and 2004 to examine model variability. Forcings for the simulation and a detailed description can be downloaded from the CCMVal website (http://www.pa.op.dlr.de/CCMVal/Forcings/CCMVal_Forcings.html). They are defined for the time period 1950 to 2004.

SSTs in REF1 are prescribed as monthly means following the global sea ice and sea surface temperature (HadISST1) data set provided by the UK Met Office Hadley Centre (Rayner et al., 2003). This data set is based on blended satellite and in situ observations.

Both chemical and direct radiative effects of enhanced stratospheric aerosol abundance from large volcanic eruptions are considered in REF1. The three major volcanic eruptions (Agung, 1963; El Chichon, 1982; Pinatubo, 1991) are taken into account, i.e., additional heating rates and sulfate aerosol densities are prescribed on the basis of model estimates and measurements, respectively. A climatology of sulfate surface area density (SAD) based on monthly zonal means derived from various satellite data sets between 1979 and 1999 has been provided by David Considine (NASA Langley Research Center, USA). Details on how to represent the sulfate SAD before 1979 are described on the CCMVal web site.

The QBO is generally described by zonal wind profiles measured at the equator. While the QBO is an internal mode of atmospheric variability and not a “forcing” in the usual sense, at the present time most models do not exhibit a QBO. This leads to an underestimation of ozone variability, and compromises the comparison with observations. While some of the models internally generate a QBO, for the others it has been agreed to assimilate observed tropical winds. Assimilation of the zonal wind in the QBO domain can add the QBO to the system, thus providing for example its effects on transport and chemistry. Radiosonde data from Canton Island (1953-1967), Gan/Maledives (1967-1975) and Singapore (1976-2000) have been used to develop a time series of measured monthly mean winds at the equator (Naujokat, 1986; Labitzke et al., 2002). This data set covers the lower stratosphere up to 10 hPa. Based on rocket wind measurements near 8 degree latitude, the QBO data set has been vertically extended to 3 hPa. The software package to assimilate the QBO by a linear relaxation method (also known as “nudging”) as well as the wind data sets have been provided by Marco Giorgetta (MPI Hamburg, Germany).

The influence of the 11-year solar cycle on photolysis rates is parameterized according to the intensity of the 10.7 cm radiation of the sun (which is a proxy to the phase of the given solar cycle). The spectral distribution of changes in the observed extra-terrestrial flux is based on investigations presented by Lean et al. (1997) (see http://www.drao.nrc.ca/icarus/www/sol_home.shtml for details).

Recommendation: We recommend reporting results for REF1 between 1960 and 2004 to examine model variability. We will be conducting detailed model evaluation with data between 1980 and 2004 (i.e., during the satellite measurement period). Please check the list of model recommendations that is specified under (D). We encourage groups to run ensembles.

REF 2: MAKING PREDICTIONS, Core time period 1980 to 2025

REF 2 is an internally consistent simulation from the past into the future. The proposed transient simulation uses the IPCC SRES scenario A1B(medium) (IPCC, 2000). REF 2 only includes anthropogenic forcings; natural forcings such as solar variability are not considered, and the QBO is not externally forced (neither in the past, nor in the future). Sulfate surface area density is consistent with REF1 through 1999. Sulfate surface area densities beyond 1999 will be fixed at 1999 conditions (volcanically clean conditions). Changes in halogens will be prescribed following the Ab scenario (WMO, 2003; Table 4B-2). SSTs in this run are based on coupled atmosphere-ocean model-derived SSTs. Depending on computer resources some model groups might be able to run longer and/or start earlier. We recommend reporting results for REF2 until 2050. The forcings on the website are defined through 2100.

Fully coupled atmosphere-ocean CCMs
that extend to the middle atmosphere and include coupled chemistry, will use their internally calculated SSTs. CCMs driven by SSTs and sea ice distributions from the underlying IPCC coupled-ocean model simulation could use the model consistent SSTs. One constraint is to make the SST dataset consistent with the SRES greenhouse gas (GHG) scenario A1B(medium). All other CCM groups will run with the same SSTs, provided by a single IPCC coupled-ocean model simulation. These simulations have good spatial resolution, so the data-sets should be suitable for all the CCMs participating in the WMO/UNEP assessment.

Recommendation:
We encourage groups to run ensembles.

Sensitivity experiments :

SCN 1 (REF 1 with enhanced BrOy): An additional simulation is being developed to represent the known lower stratospheric deficit in modeled inorganic bromine abundance. This simulation will be identical to REF 1, with the exception of including source gases abundances that will increase the burden of BrOy. A detailed description of SCN1 can be found here --> DOWNLOAD pdf-file  (Contact for questions: Ross Salawitch).

SCN 2 (REF 2 with natural forcings): A sensitivity simulation defined similar to REF1, with the inclusion of solar variability, volcanic activity, and the QBO in the past. Future forcings will include a repeating solar cycle and QBO, under volcanic clean aerosol conditions. SSTs will be based on REF2.

  Table 1: Summary of proposed CCMVal scenarios. 

Scenario

Period

Trace Gases

Halogens

SSTs

Background & Volcanic  Aerosol

Solar Variability

QBO

Enhanced Bry

REF1

1980-2004

If possible 1960 to 2004

OBS
GHG used for WMO/UNEP 2002 runs. Extended until 2004

OBS

used for WMO/UNEP 2002 runs.

OBS

HadISST1

 

OBS

Surface Area Density data (SAD)

OBS

MAVER data set, observed flux

OBS or internally generated

-

REF2

1980-2025

If possible until 2050

OBS + A1B(medium)

OBS + Ab scenario from WMO/UNEP 2002

Modeled SSTs

 

Constant SADs
(1999 background aerosol for entire period)

Not included
Please use average solar flux for the entire REF2 period

Only internally generated

-

 

 

 

 

 

 

 

 

 

SCN1

1980-2004

OBS

OBS

used for WMO/UNEP 2002 runs

OBS

OBS

OBS

OBS or internally generated

Included

Based on Salawitch et al. (2005)

SCN2

1980-2025

OBS + A1B(medium)

OBS + Ab scenario from WMO/UNEP 2002

Modeled SSTs
(same as in REF2)

Constant SADs
 
(1999 background aerosol for entire period)

OBS in past and repeating in future

OBS / repeating in future or internally generated

-



(B) Reproducing the past: Observed forcings for a transient model simulation 1960 to present-day

B1. Greenhouse Gases 1959 to present day (CO2, CH4, N2O)

GHG used for WMO/UNEP 2002 runs and updated until 2004. The file gives surface volume mixing ratios of CH4 (ppbv), N2O (ppbv) and CO2 (ppmv)
DOWNLOAD --->    Monthly mean data set 1959 to 2000 based on WMO (2003) and extended until 2004 (24 kB).

(Contact for questions:
Doug Kinnison and Stephen Montzka)


B2.   Halogens (1950 to present day)

UNEP/WMO Scientific Assessment of Ozone Depletion: 2002
Chapter 1: Controlled substances and other trace gases
Scenarios from Archie McCulloch (Marbury Techn. Cons.), John Daniel (NOAA/AL), Steve Montzka (NOAA/CMDL), and Guus Velders (RIVM/LLO), September 21, 2001 (Version 3)

DOWNLOAD ---> Monthly mean data set (1959 to 2000) based on WMO (2003) and extended until 2004 (66 kB).

(Contact for questions: Doug Kinnison and Stephen Montzka)


B3.   Sea Surface Temperatures 1950 to present day

Sea Surface Temperature prescribed as monthly means following the global sea ice and sea surface temperature (HadISST1) data set provided by UK Met Office Hadley Center (Rayner et al., 2003).
The data is available without charge, but please read the terms and conditions before using it. The UK Met Office Hadley Center also asks you to register before downloading the data.
DOWNLOAD Hadley Centre Sea Ice and SST data set (HadISST) --->   http://www.hadobs.org/: Follow the link "Marine Data" and "HadISST - Globally complete sea-ice and sea-surface temperature"


B4.   Solar Cycle 1951-2000

The influence of the 11-year solar cycle on photolysis rates is parameterized according to the intensity of the 10.7 cm radiation of the sun (data available at: http://www.drao.nrc.ca/icarus/www/daily.html).  The spectral distribution of changes in extra-terrestrial flux is based on investigations presented by Lean et al. (1997).

DOWNLOAD --->  Data Set for transient model simulations (maver_1951-2000.dat) (25.2 kB).   (Contact for questions: Christoph Brühl)

Recommendation: Use observed flux (column 3 in maver_1951-2000.dat)

10,7 cm solar flux from http://www.drao.nrc.ca/icarus/www/maver.txt
More explanation see http://www.drao.nrc.ca/icarus/www/sol_home.shtml


B5.   Assimilated Quasi-Biennial Oscillation (QBO)

The QBO has been assimilated in several studies with the aim to study QBO effects on the dynamics and/or chemistry. Often the assimilation procedures assume a certain idealistic meridional structure of the QBO jets and force the model to follow the externally given vertical zonal wind structure within the QBO domain. Even simple relaxation methods (see for example Giorgetta et al., 1999) can provide fairly realistic QBO structures, and the GCM will generate the secondary meridional circulation of the QBO and the related temperature signal. This can provide a significant improvement for certain experiments. The method implies nearly no costs compared to the costs of the GCM integration.

Care must be taken with regard to the effect of the QBO on vertical momentum fluxes, as provided by resolved vertically propagating waves or parameterized gravity waves, and the resulting vertical dynamical coupling between the QBO and the semiannual oscillation ( SAO). If the QBO is assimilated, then its shear layers will act immediately as a filter on vertically propagating waves, resolved or parameterized. Hence wave mean-flow interaction will be intensified in the QBO domain and reduced at higher levels. This may lead to a substantial reduction of the zonal momentum fluxes passing the stratopause towards the mesosphere, with consequences for instance for the circulation above the QBO domain. This may cause changes for example in the SAO compared to the SAO in a simulation without QBO assimilation.

The QBO is described by zonal wind profiles measured at the equator.

QBO data sets provided by Marco Giorgetta (Contact for questions: Marco Giorgetta )


B6.   Volcanic eruptions and aerosol loading

Surface Area Density data (SAD)  WMO2002 SAD dataset put together by David Considine, LaRC. This data set is based on SAGE and SAM data.  
Monthly zonal mean surface area density climatology derived from various satellite data.

DOWNLOAD --->
SAD data set 1979 to 1999 (1.8 MB) provided by David Considine (Contact for questions: David Considine)
For the time period 1999 to 2004, please use 1999 values.
For the time period previous to 1979, please use 1979 values. For the years 1963 to 1966 you might wish to add delta SADs for the eruption of Agung that have been used in a transient simulation with E39/C (Dameris et al., 2005). These data will be made available on request. Please contact
Martin Dameris.

Heating rates from volcanic aerosols:  A set of heating rates has been compiled by Gera Stenchikov.

In addition to the larger eruption (Agung, 1963; El Chichon, 1982; Pinatubo, 1991) smaller ones like Feranadina and Fuego are included. The fortran program "hrates_ascci.f"
reads ASCII all-sky zonal mean aerosol heating rates (K/day, filename=hrates.ascii) and net surface radiative forcing (W/m2, filename=sfc_forcing.ascii). Forcing calculation were conducted using volcanic aerosols from (Sato et al., JGR, 98, 22987, 1993) and GISS ModelE radiative routines and climatology (Schmidt et al., J. Climate, 2005, in press). Surface radiative forcing is negative corresponding to cooling caused by volcanic aerosols. The data sets are monthly mean from January 1950 to December 1999 for all-sky conditions. Spatial grids both in pressure and latitudes are defined in the program. You have to interpolate these data sets to your spatial grid.
The right way to use these data sets to mimic effect of volcanic eruptions would be to apply heating rates to the atmosphere and cooling flux to the surface.
Heating rates and surface forcing would characterize the entire volcanic effect that is: Stratospheric warming and Tropospheric-surface cooling. If you are focusing on the stratospheric processes you could use only aerosol heating rates. That should not cause any problem.

    DOWNLOAD --->    hrates_readascii.f, hrates.ascii, sfc_forcing.ascii
   
    Please contact Gera Stenchikov if you have any further questions on the use of the heating rates and surface radiative forcing.

B7.   Anthropogenic Emissions of NOx etc. (important only for models with tropopsheric chemistry)

We propose to use EDGAR for the past between the time period 1950 to 1995, e.g. because this allows us to be comparable to the IPCC-ACCENT simulations.

The EDGAR data sets for EDGAR-HYDE (1890-1970), EDGAR v2 (1990), EDGAR v3 (1995) are consistent and can be downloaded from the EDGAR website.
The data sets contain emissions of CO, NOx, NMVOC, SO2, CO2, N2O and CH4.
Please note that the GHGs (CO2, N2O and CH4) in CCMVal are already defined and we recommend to use the GHGs as specified under B1.

Reference EDGAR 1890-1970, 1990, 1995:
J. A. van Aardenne et al, A 1° x 1° resolution data set of historical anthropogenic trace gas emissions for the period 1890-1990, 2001.

To download the data, please go to the EDGAR website (www.rivm.nl/edgar ) for the time period 1950 to 1995.

Furthermore, for the year 2000  we would recommend to use the data that have been defiend for the IPCC-ACCENT simulations and to interpolate linearily between 1995 and 2000.
Emissions for the year 2000 have been put together by Frank Dentener and David Stevenson and can be downloaded from the following website: http://www2.nilu.no/farcry_accent/index.cfm?objectid=F978B37B-BCDC-BAD1-A6205238588A0C03&flushcache=1&showdraft=1

Reference 2000:
F. Dentener, D. Stevenson, J. Cofala, R. Mechler, M. Amann, P. Bergamaschi, F. Raes, R. Derwent: The impact of air pollutant and methane emission controls on tropospheric ozone and radiative forcing: CTM calculations for the period 1990-2030, Atmos. Chem. Phys. Discuss., 4, 8471-8538, 2004.


B8.   Other issues

Impact of new HCFCs (141B, 142B) (Contact for questions: Rolando Garcia and Doug Kinnison)

e.g. instead of including HCFCs explicitly, we could instead use MCF, HCFC22 and CH3Cl as "surrogates", as follows:
    MCF --> MCF + 2/3 * HCFC141B
    HCFC22 --> HCFC22 + 1.0 * HCFC142B

This approach was used in the WMO1998 2D model assessment. These surrogates have similar tropospheric and stratospheric lifetimes as the omitted HCFCs.



(C) Making predictions: Forcings for a transient model simulation from present day to 2100


C1. Greenhouse Gases 2001-2100 (CO2, CH4, N2O)

For REF2, SCN2:
COMMENT: The chapter of the next IPCC assessment (AR4) that includes the greenhouse gases will use the scenarios B1 (low case), A1b (medium), and A2 (high)

Since the IPCC AR4 results will be aligned with these selected scenarios, we suggest to use the medium A1b scenario.
The file gives surface volume mixing ratios of CH4 (ppbv), N2O (ppbv) and CO2 (ppmv).
For the model simulation, please use scenario A1b (medium).

DOWNLOAD --->     
Monthly mean data set 1959 to 2050 based on IPCC GHG scenario A1b (medium)   (46 kB)

(Contact for questions:
Doug Kinnison)

C2.   Halogens  2001-2100

For REF2, SCN2:

UNEP/WMO Scientific Assessment of Ozone Depletion: 2002
Chapter 1: Controlled substances and other trace gases
Scenarios from Archie McCulloch (Marbury Techn. Cons.), John Daniel (NOAA/AL), Steve Montzka (NOAA/CMDL), and Guus Velders (RIVM/LLO), September 21, 2001 (Version 3)

For the model simulation, please use scenario  -> B2

DOWNLOAD ---> Monthly mean data set (1959 to 2050) based on WMO (2003), Table 4B-2 (130 kB)
This scenario is essentially the same (except for a few small deviations) as the baseline scenario Ab described in Tables 1-13 and 1-16 of Chapter 1 of the WMO 2003 report.  

(Contact for questions: Doug Kinnison)

C3.   Sea Surface Temperatures 1980 to 2100 for the "Making Prediction" simulation

REF2, SCN2 both based on the same modeled SSTs:
The focus of the future simulation is NOT a model-model intercomparison. Rather we would like to make the best shot at predicting the future. REF 2 is a simulation that focuses on consistency and that follows the  IPCC simulations. In any case one constrait is to make the SST data set consitstent with the GHG scenario. Essentially we are asking the modeling groups to make their best prediction. Therefore, having consistent SST in future(and past of the making prediction simulation) is not necessary.
However, it would be desirable, if at least a subset of model groups uses the proposed SSTs (
HadGEM1 simulation) that can be downloaded following the link under (c) below.

a.       Fully coupled atmosphere ocean CCMs with the atmosphere extending to the middle atmosphere, with coupled chemistry, use their internally calculated SSTs (probably beyond the possibilities for most groups).

b.      CCMs driven by SST and sea ice of the underlying IPCC coupled-ocean model simulation could use the model consistent SSTs. One constraint is to make the SST data set consistent with the GHG scenario. However, if preferred, they could also decide to use the SSTs defined under (5c).

c.       All other CCM groups might wish to run with equal SSTs: We propose to use the modeled SSTs from a Hadley Centre coupled ocean-atmosphere model (HadGEM1) simulation
for the full time period (1980 to 2025 or longer) based on the chosen GHG scenario.

      SST and ice datesets have  been derived using output from UK Met Office HadGEM1 simulations using IPCC SRES scencario AIB performed for the IPCC fourth assessment report.  The HadGEM1 simulations  had historical anthropogenic forcing from December 1970 to November 1999 (simulation started December 1859) , and followed the SRES A1B scenario from December 1999 to December 2099.  Volcanic stratospheric aerosols and solar irradiance were constant. The data was transformed from the HadGEM1 grid to the same 1x1 degree grid used for the HadISST1 dataset.  The fields are monthly means.

DOWNLOAD HadGEM data set--->   http://www.hadobs.org/. Under "Other Resources" click on "SST and sea-ice from HadGEM for 1970-2100".
(Contact for questions: Neal Butchart)


C4.   Solar Cycle 2001-2085

For REF2:
Solar variability is not included in reference simulation REF 2.
We recommend to use average solar flux for the entire REF2 period.

For SCN2:
Solar variability is included in SCN2.
DOWNLOAD ---> Data Set for transient model simulations (maver_2001-2085.dat) (Contact for questions: Christoph Brühl)
Recommendation: Use observed flux (column 3 in maver_2001-2080.dat), which is a continuation of observed 11-year cycle.


C5.   Assimilated Quasi-Biennial Oscillation (QBO)

For REF2:
The QBO is not included in reference simulation REF 2 (neither in the past, nor in the future).


For SCN2:

The QBO is described by zonal wind profiles measured at the equator.

QBO data sets are provided by Marco Giorgetta (Contact for questions: Marco Giorgetta )


C6.   Volcanic Eruptions and aerosol loading

For REF2 and SCN2:
Volcanic eruptions are not included in reference simulation REF 2 and SCN2.
For aerosol loading, please use 1999 from the
WMO2002 SAD dataset put together by David Considine, specified under B6.


C7.   Anthropogenic Emissions of NOx etc. (important only for models with tropopsheric chemistry)

We recommend to linearily interpolate the emissions from 2000 to 2030 and to keep the emissions constant between 2030 and 2100.

For the year 2000  and 2030 we would recommend to use the data that have been defiend for the IPCC-ACCENT simulations and to interpolate linearily between 1995 and 2000.
Emissions for the year 2000 and 2030 have been put together by Frank Dentener and David Stevenson and can be downloaded from the following website: http://www2.nilu.no/farcry_accent/index.cfm?objectid=F978B37B-BCDC-BAD1-A6205238588A0C03&flushcache=1&showdraft=1

Please note that the GHGs (CO2, N2O and CH4) in CCMVal are already defined and we recommend to use the GHGs as specified under B1.


(E) Current coupled chemistry-climate models

see http://www.pa.op.dlr.de/CCMVal/CCMVal_ParticipatingCCMs.html

(D) Model Recommendations

Concerning the model set-up and the variables that should be stored in order to allow sophisticated inter-comparisons of chemistry, transport, dynamics and radiation within the CCM, we would recommend the following:
  1. Chemistry update: we recommend to use chemical kinetics from JPL 2005. JPL05 Tables are for use in WMO Ozone Assessment – Not for General Distribution. The recommended rate data and cross sections are based on laboratory measurements (Contact for questions and comments: Stanley P. Sander).
  2. If possible, please store the following variables:

    • Total ozone
    • Mean age of air tracer: Conserved tracer with linearly increasing concentration, SF6 or CO2 in order to calculate mean age of air. More details on how to include a mean age of air tracer can be found at http://www.jhu.edu/~eps/faculty/waugh/ccmval/ccmval_meanage.html. Darryn Waugh recommends a CO2 run rather than basic linearly increasing tracer (or stratospheric uniform source tracer) (Contact for questions: Darryn Waugh).
    • Passive Ozone Tracer: 
      The model runs should include a tracer to diagnose polar chemical ozone loss in winter and spring. As most models will advect (and integrate) O3 as part of the 'odd oxygen' (Ox=O3 + O(3P) + O(1D)) family we will call this the 'passive Ox tracer'. This will be a global tracer which is reset during each polar winter (i.e. twice per year). Given the relatively slow transport and long chemical lifetime (without PSC processing etc) of O3 in the polar regions this will provide a useful diagnostic over the timescale of a few months in the lower stratosphere.

      The model tracer should be set equal to your advected 'odd oxygen' tracer on December 1 and June 1 every year. Then, the tracer is simply advected without any further chemical change. If your advection scheme stores other variables for each tracer (e.g. higher order moments) remember to set these equal to that of the chemically integrated Ox tracer too. If your model advects members of the Ox family separately, then we suggest you set the passive Ox tracer equal to the sum of these species. The passive Ox tracer should be ouput according to the other instructions. The re-initialisation dates are selected so that we diagnose most of the chemical loss over the course of the winter, some of which would be missed by a later date (Contact for questions: Martyn Chipperfield).

    • Tracer fields (e.g. N2O, CH4, O3, NOy, H2O)
    • CO
    • Actinic fluxes
    • Photolysis rates of O3 and NO2
    • For chemistry evaluation: 2D monthly-mean zonal-mean chemical fields for the full period (Jan 1980 - Dec 1999) and 3D chemical fields for three years (1999, most stable (coldest) NH vortex and most unstable (warmest) NH vortex over the time period 1990 to 1999; 31 pressure levels defined in ICD) as snapshots twice a month (Day 1 and Day 15), output at fixed time (12 UTC). In addition 2D fields of solar zenith angle at the 3D output day/time (12 UTC). Output full chemical consituents: O3, T (temperature), U (zonal wind component), V (meridional wind component), H2O, CH4, Cly, Bry, O3s (passive odd oxygen tracer), NOy, N2O,CO, HNO3, density, CFC11, sulfate aerosol surface area, PSC Type I and Type II surface areas; O(3P), O(1D), OH, HO2, NO, NO2, N2O5, ClO, ClONO2, HCl, HOCl, Cl2O2, OClO, H2O2, HBr, HOBr, BrONO2, BrO, BrCl, Br, Br2. For CCMVal SCN1 in addition: CHBr3, CH2Br2 (Contact for questions: Martyn Chipperfield, Ross Salawitch and Veronika Eyring).

      These fields will provide the data to test the chemistry schemes. The instantaneous (3D) output will be used to compare models with a standard photochemical box model and then with overall datasets from in-situ (e.g. ER-2) data. These fields will also be used to investigate the models’ treatments of polar processing in the Arctic – hence the request for 1 common year (1999) and your model’s extreme Arctic years in the 1990-1999 period. The 2D fields will be used for a comparison with satellite climatologies and for an overview comparison during the whole period (e.g. as aerosol levels change). Certain fields (e.g. PSC monthly surface area will also be an indication of temperature variability).

    • Heating rates
    • Gravity wave tendencies
    • TEM diagnostics (includes EP-fluxes, EP-divergence, residual circulation (w*, v* and streamfunction))

  1. Correct chemical initialization and spin-up (at least 5 years)

  1. Software diagnostic tools should be provided to the community (e.g. equivalent latitudes, TEM diagnostic) in order to allow more complex comparisons.

(F) References


Austin, J. et al., 2003: Uncertainties and assessments of chemistry-climate models of the stratosphere, Atmos. Chem. Phys., 3, 1-27.

Anderson, J.L. et al., 2004: The new GFDL global atmosphere and land model AM2/LM2: Evaluation with prescribed SST simulations, J. Climate, in press.

Austin, J., 2002: A three-dimensional coupled chemistry-climate model simulation of past stratospheric trends, J. Atmos. Sci., 59, 218-232.

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Last modified:  July 6, 2005
by Veronika Eyring