POET

During the meeting, each of the participants presented the work which has already been done and the work everyone is planning to do within each workpackage.

Workpackage 1: Distribution of ozone precursors from satellite data

John Burrows and Andreas Richter showed examples of distributions of NO₂ tropospheric columns measured by GOME in 1997. He discussed the strategy for comparing observations and model results: should we calculate the slant columns directly in the models for better comparisons?

The work planned in Bremen for the first year of the project will concern the improvement of the tropospheric NO₂ columns retrieval techniques, more specifically on the air mass factors. The data for 1997 should be ready for inclusion into the POET data base by the end of 2000.

The modellers should think about it, and tell the Bremen group what they would like to have in the data base. In 2001, the Bremen group will work on the ozone and CH₂O retrievals.

Cathy Clerbaux discussed the first CO tropospheric columns retrieved from the IMG/ADEOS satellite instrument. The measurements cover the June 16-19, 1997 period. In 2000, she and Juliette Hadji-Lazaro will concentrate on the retrieval of CO for April and January 1997, and will start the retrieval of tropospheric ozone columns from the same instrument.

Workpackage 2: Emission inventories

Jos Olivier discussed the development of the new EDGAR v3.0 data base, which will provide anthropogenic emissions for year 1995. The emissions factors used in the EDGAR v2.0 (1990 emissions) will be improved, when possible, and the new ship emissions inventory will be included. Lightning and aircraft emissions will also be updated.

The current Edgar v2.0 data base can be found at the following Web site:

http://www.rivm.nl/env/int/coredata/edgar

His group will start to work on time profile for the emissions, on a monthly or daily basis for specific days.

The data base provides currently emissions of kg hydrocarbons per time unit. However, most models need additional data to convert these numbers into molecules. Jos and Jean-Francois Müller will provide during the first year speciation factors for the hydrocarbons, and they will work together on the time profiles of the anthropogenic emissions.

Jos has written several papers describing the data base and its improvements. People interested by the papers can send him an email to receive these publications.

Jean-François described the work he recently started to update the algorithms used to calculate the global emissions of natural hydrocarbons, with a focus on isoprene and terpenes.

Stig described the emissions set used in the Oslo model, and focused primarily on biomass burning emissions.

Jos also noted that he would like to have a wish list provided by the modellers for emissions that are not yet available from EDGAR.

Jos proposed to have a small meeting of people working more particularly on biomass burning emissions (Jos, Jean-Francois, Stig, Claire, and Martin Schultz from Hamburg), who could meet in June to agree on a common distribution for biomass burning emissions to be used in the 4 models.

Workpackage 3: Intercomparison of CTMs

4 models are participating in POET: TOMCAT from Cambridge, OSLO-CTM2 from the University of Oslo, MOZART from CNRS in Paris, and IMAGES from BISA, Brussels.

Nick Savage presented the strategy for the intercomparison:

All models will first perform a first set of runs where the distribution of long-lived species such as radon will be calculated. Cambridge will send to the modeling groups the emissions to be used in all models, as well as the meteorological fields everybody should use. This first set of runs should be done before the summer, and a 2-days meeting will take place in Cambridge in July or in September to analyze the model results.

We will have to discuss more the way the comparisons will be done:

- which set of data should we use

- what diagnostics will we use for the intercomparison

- what definition of tropopause will we use

- what will be the best period to do accurate comparisons: data, spin up, El Nino, ...

- how to define a common emission database: speciation of hydrocarbons, diurnal/weekly/seasonal variation

- What informations should we put in the model database

We should also work on a description of the models, which should be sent to all the participants (or be included in the POET data base).

Inga Floisand gave us detailed informations of the POET data base. The ftp address will be:

zardoz.nilu.no (128.39.104.1)

directory: /nadir/projects/poet

NILU will send us a standard protocol, and we will have to discuss and agree about the conditions of access to the POET database.

The format we will use in the database is the CDF format, defined in the Web site:

http://nssdc.gsfc.nasa.gov/cdf/cdf_home.html

This format is binary format and platform independent.

We will have to define one person who is responsible for each topic.

We have defined for now 4 directories:

à Observations

à Isotopes

à Models

à Documents

Note : Just after the meeting, Inga sent a note indicating that the format used in the

NILU data base will become HDF. This will be discussed in more details at the next meeting.

Workpackage 4: Inverse modeling

Philippe Ciais detailed what he has already done with Jean-François on the inverse modeling of methane, and he proposed to continue this work by looking at the interannual changes in methane sources. This will also include an impact of OH changes with sensitivity studies.

Different models would be used, and data from the Aerocarb network, which provides regular measurements of CO₂, CH₄ and CO, could be used.

Claire showed preliminary results obtained for the inverse modeling of CO using the IMAGES model and data from the CMDL network.

The strategy for the development of the adjoints of IMAGES and MOZART was discussed by Claire and Jean-François. The adjoint generator TAMC will be used for these developments, which will start in May in collaboration with Thomas Kaminski (Max Planck Institut, Hamburg) who participated in the development of TAMC.

Workpackage 5: Isotopes

Carl Brenninkmeijer gave an overview of the CO and CH₄ isotopes measurements made by different groups. These data will be collected and will be made available in the POET data base. No systematic work has ever been done on the analysis of all the available data, and, during the first year of POET, the data will be analyzed more critically, in order to better understand what we can learn from isotopic data.

Not all the sources are known, and the missing parameters will have to be identified.

Carl should have a first database by September, and he will discuss the format with NILU.

Workpackage 6: OH/ozone precursors

Stig discussed the use of the Oslo model in this study. The Oslo group will define a strategy for establishing the emissions used in this workpackage.

Paul Monks (UK) has contacted us before the POET meeting. He is the coordinator of the TROTREP project: the goals of TROTREP are to understand the trends of CO, methane and ozone during the 2-3 previous decades. The work performed within WP 6 is very close to what will be done in TROTREP. John and Carl, who are going to the Eurotrac meeting will talk to Paul Monks in order to see how we could cooperate.

Workpackage 7: tagging of ozone

Nick showed how the tagging of stratospheric ozone has been performed in the TOMCAT model. The tagging of ozone formed by photochemical production is not straightforward: different possibilities were discussed. Everybody should think about it, and bring possible ideas at the meeting in Cambridge.

Summary by Nick: Think, think and think!

Workpackages 8 and 9:

These WP will start later. Stig said a few words on the definition of future scenarios, that will be based on IPCC scenarios.

Jos proposed to couple the IMAGES CTM with the emission model IMAGE developed at RIVM. This will be discussed in more details in a year from now.