6 major objectives have been determined for the AGACC-II project:

Objective 1: Derive new information about important greenhouse gases.

Objective 2: Enlarge the range of atmospheric trace gases that can be detected from the ground.

Objective 3:Advance our expertise in the field of aerosol remote sensing above Ukkel.

Objective 4: Study African emissions.

Objective 5: Interact with satellite, modelling communities and spectroscopists.

Objective 6: Integrate our data in regional and global assessment reports.

Hereafter follows a short description of our objectives.

1. Derive new information about important greenhouse gases in the atmosphere.

These gases are:

• Carbon dioxide (CO₂)
• Methane (CH₄)
• Nitrous oxide (N₂O)
• Carbon tetrafluoride (CF₄)
• Carbon tetrachloride (CCl₄).

Our activities:

• Study long-term trends of these greenhouse gases over Europe, thanks to our historical records at Jungfraujoch.
• Initiate measurements of the same greenhouse gases in the near-infrared spectral range at Ile de La Réunion. This will give us the possibility to become affiliated to the TCCON network. 
• Link historical and present data in the midinfrared spectral range and the new data in the near-infrared, by having a campaign simultaneous measurements in both spectral ranges at Ile de La Réunion to support the interpretation of the historical and current greenhouse gas measurements at Ile de La Réunion and the Jungfraujoch.

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2. Enlarge the range of atmospheric trace gases that can be detected from the ground using FTIR spectrometry, both at Jungfraujoch and Ile de La Réunion.

In AGACC-II, we will investigate a suite of direct greenhouse gases and organic compounds that affect the oxidizing capacity of the troposphere. This will enable us to establish representative organic chlorine and fluorine budgets which is very important in the context of Montreal and Kyoto Protocols.

The proposed species are:

• methylchloride (CH₃Cl)
• methanol (CH₃OH)
• formaldehyde (H₂CO)
• acetone ((CH3)₂CO)
• PAN (peroxyacetyl nitrate), C₂H₃NO₅
• HFC-134a (CFC substitute)

Following molecules will be investigated in the laboratory, to improve the quantitative spectroscopic parameters :

• ethylene (C₂H₄)
• ethane (C₂H₆)

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3. Advance our expertise in the field of aerosol remote sensing to enhance our understanding of the aerosol characteristics above Ukkel and to estimate their direct radiative forcing.

Total aerosol optical density can be obtained with Brewer, MAXDOAS, and CIMEL sun photometer data.

Aerosol extinction vertical profiles in the lowest layers of the atmosphere can be retrieved with the MAXDOAS technique.

We would like to derive additional aerosol optical parameters :

• single scattering albedo 
• phase function

We will use an aerosol lidar which will provide vertical profiles of the backscatter ratio and the height of the planetary boundary layer.

During a campaign in Ukkel, we will combine the data from the
different instruments, and from the CIMEL sun photometer, to characterize the aerosol load above Ukkel. The data will be combined with modeling results (CHIMERE and trajectory modeling) to study the aerosol sources.

We will also include the aerosol data in radiative transfer calculations in
order to evaluate their impact on the direct radiative forcing.

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4. Study African emissions

Why?

Satellite observations indicate large uncertainties on these emissions and therefore a critical need exists for additional measurements, in particular from the ground.

How?

We plan to install a MAXDOAS instrument in Bujumbura (Burundi), for the measurement of aerosol and several ozone precursors like glyoxal (OCHCHO), formaldehyde, and tropospheric nitrogen dioxide (NO₂).

Using the observations at Ile de La Réunion and Lagrangian dispersion modeling (FLEXPART), we will also study the transport from Africa to the Indian Ocean.

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5. Interact with satellite, modelling communities and spectroscopists

Our data will be very useful for global and regional chemistry-climate models.

Our laboratory and field data will be delivered to international databases (HITRAN and GEISA for laboratory data ; NDACC and TCCON for field data)

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6. Integrate our data in regional and global assessment reports.

Why?

These results will appeal directly to policy makers and will be relevant for environmental policies for monitoring of atmospheric composition changes:

• Long-term trends of greenhouse gases
• Aerosol direct radiative forcing above Ukkel
• Organic chlorine and fluorine budgets

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