Tropical Convection, Cirrus, and Nitrogen Oxides Experiment




of a project under the RTD Programme of the European Commission, DG RTD-I.2,

”Energy, environment, and sustainable development”,

Key Action: 2 (Global Change, Climate and Biodiversity)


Project duration:   1 June 2002 – 31 May 2005


The project TROCCINOX (Tropical Convection, Cirrus, and Nitrogen Oxides Experiment) will investigate the impact of tropical deep convection on the distribution and the sources of trace gases, cloud and aerosol particles focusing on processes in the upper troposphere and lower stratosphere.


General objectives of TROCCINOX are:

  • to improve the knowledge about lightning-produced NOx (LNOx) in tropical thunderstorms by quantifying the produced amounts, by comparing it to other major sources of NOx and by assessing its global impact, and
  • to improve the current knowledge on the occurrence of other trace gases (including water vapour) and particles (ice crystal and aerosols) in the upper troposphere and lower stratosphere in connection with tropical deep convection as well as large scale upwelling motions

Map of locations and flight route planned for the TROCCINOX field campaign. Set-up of the aircraft will be in Seville (Spain). Transfer flights to and from Recife via the Cape Verde Islands will provide meridional cross-sections. Bauru in Brazil is envisaged as location for an IOP with ground-based observing systems involved. The circle indicates the approximate range of local aircraft operations.

The field study  addresses these problems on different spatial scales. Two aircraft (Geophysica and Falcon)  probe the atmosphere during the transfer flights (large scale) to a tropical destination. During two intense measuring campaigns at the tropical site(s) the aircraft operations are  co-ordinated with detailed ground-based observations of thunderstorms or other relevant atmospheric parameters on a local scale. Satellite data will serve to establish the link between local and global-scale parameters.


For  the first TROCCINOX field experiment during February and March 2004 just the Falcon was deployed to Brazil. The measurements were closely co-ordinated with the HIBISCUS balloon campaign. The EU-project (5´th FP) HIBISCUS is following similar aims as TROCCINOX performing bolloon-borne chemical measurements in the upper troposphere and lower stratosphere. Both were based at Bauru (State of São Paulo, Brazil). Strong support from local partners is given here. The IPMET (Instituto de Pesquisas Meteorológicas) as the local Institute of Meteorological Research is highly interested in questions of tropical convection, weather forecast and hydrological research. It operates a network of weather radars thus providing good information on thunderstorms. The IPMET is part of the UNESP (University of the State of São Paulo). The Brazilian TroCCiBras project additionally contributes the INPE-Bandeirante aircraft probing the chemical composition of the lower atmosphere.


Both TROCCINOX aircraft, the Geophysica and the Falcon, are participating in the second field campaign during January and February 2005. Again, the experiment is based in the State of São Paulo and the Brazilian Bandeirante aircraft is  participating once more. IPMET contributes the radar network information and DLR deployes additionally a new lightning detection system.


The large range of scales addressed in the proposed study requires a variety of models to be applied to the inherent problems, each to a special aspect of the project. Modelling will cover the growth of ice crystals and aerosol particles, the effects of clouds on the radiative transfer, chemistry and transport of trace gases, precipitation formation, lightning and the related NOx-production, and the global scale climatic impacts of deep tropical convection.


Moreover, new experimental evidence will not only enable the improvement of existing parameterisations but also offer the opportunity to develop and test new ones. Using such new or refined process or distribution descriptions, it will be the final aim of the proposed project to reduce the still large degree of uncertainties of climate system understanding within the limits of the problems addressable in the present study.



Scientific Questions 

  • What is the impact of tropical deep convection on the balance and distribution of NOx and other trace gases?
  • How do troposphere-stratosphere exchange processes contribute to the amount of water vapour entering the stratosphere?
  • What is the effect of tropical deep convection on the formation and distribution of aerosol particles?
  • What are the origins of cirrus clouds in the tropics and how do cirrus clouds affect air composition?
  • How do tracer correlations across the sub-tropical barrier look like quantitatively and what does that mean for transport between the tropical and mid-latitudinal stratosphere?




  • TROCCINOX-Summary  (pdfdoc )
  • TROCCINOX Project Information (Summary, Objectives, Workplan) (pdfdoc)


For further information contact 


Prof. Dr. Ulrich Schumann, DLR, Institute of Atmospheric Physics, 82230 Oberpfaffenhofen,

Germany, (project co-ordination)



Dr. Hartmut Höller,  DLR, Institute of Atmospheric Physics, 82230 Oberpfaffenhofen,

Germany, (project co-co-ordination)



Dr. Claus Brüning, European Commission, DG RTD-I.2,  B-1049 Brussels, Belgium, (EU scientific officer)


(Oberpfaffenhofen, July 2002)

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