Background

program Description

Paramaribo station and its Inauguration!

news and Events and beautiful Places in Suriname

some Measurements and Results

Background

Currently, rapid population growth and industrial development, along with deforestation, are changing the environment in tropical countries. The effect of these changes on atmospheric composition and climate are however quite uncertain as the governing physical processes of the tropical atmosphere are only partly understood. Although the tropical atmosphere occupies about half the volume of the global atmosphere, systematic observations of relevant atmospheric parameters in this region are relatively scarce. This is mostly due to the inaccessibility of the tropical forests and the vast oceans spanning this part of the globe, as well as the lower priorities given to these observations by developing countries. However, awareness of this problem is rising, and we are very happy to contribute to a better understanding with the program RADChiS.

the Name:

RADChiS stands for " Research on Atmospheric Dynamics and Chemistry in Suriname", and is really named after the Suriname-born Radjesh Oemraw, a colleague and friend of mine with whom I once shared an office. Often, while enjoying our coffee breaks, he would tell about his adventurous youth in Suriname - and so this researh idea was born. Cees van Scherpenzeel, a former KNMI employee now retired, provided us with good scientific arguments to draft a first proposal. Cees obtained his knowledge of the Tropics through an extended stay in Suriname during the late sixties, where he cooperated with the Suriname Meteorological Service (MDS) to establish an extensive observation network under the World Weather Watch (that's what WWW then stood for!) program. Now Cees has drafted a plan to revitalize this network again, which hopefully will soon be implemented. All this planning would be to no avail if Cor Becker, Head of the MDS, had not shown the enthusiasm and undertaken countless initiatives to realise the implementation of the program in Suriname.

the Program:

The RADChiS program outline is quite straightforward: to establish an obervation site in Surinam where the dynamical and chemical features of the tropical atmosphere can be studied. The program will run for 4 years (and hopefully much longer if financing allows!) during which the following routine measurements are performed:

continuous total ozone, UV and Umkehr measurements with a Brewer MKIII spectrophotometer,

ozone, temperature, moisure and wind profiles during weekly balloonsonde releases.

the Participants:

RADChiS is a research initiative from KNMI and the Suriname Meteorological Service (MDS), with the Institute for Marine and Atmospheric Research in Utrecht (IMAU) and the Max Planck Institute in Mainz (MPI-Mainz) involved as research partners and program co-participants. The personnel directly involved with, or appointed under RADChiS are:

KNMI: Hennie Kelder (principal investigator and program leader) and Paul Fortuin (post-doc and project coordinator),

MDS: Cor Becker (Head MDS) and the operator group: Cheryll Ashruf, Walter Brewster, Roland Lansdorf, Dennis Rodrigues and Etto Zerp,

IMAU: Jos Lelieveld (principal investigator) and Wouter Peters (Ph.D. student),

MPI-Mainz: Paul Crutzen (principal investigator).

the Financing:

The program was approved for funding by the Netherlands Organisation for Scientific Research (NWO), for a period of 4 years starting September 1998. Financial aid for the program comes from the following institutes:

NWO (The Netherlands Organisation for Scientific Research): personnel, research and material costs;

NIVR (Netherlands Institute for Aviation and Space Reseach): material and consumable costs for the purpose of satellite validation,

SRON (Netherlands Foundation for Space Research): costs of ozone sondes for the purpose of satellite validation,

WMO (World Meteorological Organisation) generously granted the program a VCP (Voluntary Cooperation Program) status, through which membership countries can volunteer to support and participate in the progam and through which import of materials can be done duty-free,

MDS: costs involved with supporting and housing the program equipment,

KNMI: material plus consumable costs, training and expertise costs,

Additional financial aid is still actively sought to cover the high expenses, and also to possibly expand the scientific span of the program and support its observations further into the future.

The site is located in Paramaribo, the capital of Suriname at the northern coast of South America. Although it lies on the south-western edge of the city, it is still in a relatively pristine environment due to its close proximity to the ocean and to the Amazone forest, which stretches all the way past the southern boarders of Suriname.

What makes this site particularly interesting from a scientific viewpoint is the fact that the Inter-Tropical Convergenze Zone (ITCZ) - a cloudy band near the Equator where tropospheric air from the two Hemispheres converges - migrates twice a year over Surinam. The ITCZ here is well discernable, as can be illustrated with rainfall statistics over Paramaribo. These show a distinct increase during the months when the ITCZ lies overhead (December-January, April-July), with dry seasons in between. Hence this station supports the study of atmospheric features associated with the Northern as well as the Southern Hemisphere, and in addition, the features which are unique to the ITCZ itself:

A further advantage of the site is the relatively flat orography on this part of the South American continent, leaving the background atmosphere relatively unperturbed as it is advected by the easterly trade winds over this location. This is especially useful for tracing the atmospheric composition, measured at the ozonesonde site, back to its regions of origin.

the Research:

The research objectives of RADChiS can be roughly divided into two categories:

Atmospheric transport and dynamics in the Tropics
Since the ECMWF observational network is not very dense over the South-American continent and over the tropical Atlantic Ocean, it may be expected that the representation of meteorological processes that are relevant for tracer transport models is not as good as e.g. over Europe. Tracer transport studies, for example with intermediately long-lived HCFCs, will be carried out to test the model performance. Particular attention will be paid to:

the role of deep convection, associated with cumulonimbus (Cb) clouds, on transport between the boundary layer and the upper troposphere/lower stratosphere;

dynamics of equatorial waves and their role in vertical advection of tracer species and in influencing the Quasi-biennial Oscillation (QBO);

the role of the large scale circulation on the transport of species to and from the equator, in both the troposphere and stratosphere;

the interaction between various dynamical features in the Tropics (i.e., between convection, equatorial waves, QBO, large scale circulation);

tracing the recorded balloon profile back to the various source regions at different altitudes, using back-trajectories;

determine the ozone budget, i.e., to quantify the separate roles of ozone transport vs. ozone production (stratospheric intrusions, lightning, photochemistry in NO-rich areas) and ozone destruction (dry deposition, photochemistry in NO-poor areas). This will be done, first for the observation area, later for the Tropics.

Atmospheric chemistry in the Tropics
The model transport and chemistry will be tested through comparisons with experimental data from previous campaigns (GTE/TRACE-A, ABLE 2A and 2B), from the concurrent LBA-CLAIRE campaign, as well as the ozone profiles from the RADCHIS observation program. Specific items that will be addressed are:

model optimization to represent hydrocarbon chemistry and South-American industrial and forest emissions. The role of convection in the vertical redistribution and chemistry of ozone and its short-lived precursors will be quantified;

chemical processes in marine air and the possible role of multiphase processes. This includes heterogeneous processes on sea salt aerosols and cloud chemistry in the marine boundary layer;

chemistry during the mixing of continental and marine air in the coastal zone. Interesting processes may occur when naturally or anthropogenically enriched air flows from the continent to the marine boundary layer. For example, NOy-rich air can get into contact with chlorine containing air parcels. Night-time radical chemistry and heterogeneous processes that involve chlorine activation are interesting aspects;

extrapolation of the regional to the global scale. The nested model will be used to study the role of southern American emissions in the tropical and global troposphere and the effects on large-scale ozone distributions. In general, it will be studied how the chemical composition in the tropical troposphere may have changed in the past and might change in the future. It will be evaluated what the consequences are for oxidation and radiation processes and how these link to climatic aspects.

Validation of satellite measurements in the Tropics
In the field of remote sensing, the Suriname ozonesonde and total ozone observations will provide the first regular ground-based validation of satellite ozone measurements in the Tropics, e.g., for the GOME instrument, and the future SCIAMACHY and OMI instruments, respectively onboard the ERS-2, ENVISAT (launch 1999) and METOP (launch 2002) satellites. The KNMI has gained experience with DOAS (Differential Optical Absorption Spectroscopy) retrieval of total ozone, and is currently involved in the validation of GOME measurements based on observations by Brewer and Dobson instruments located at several points at Northern midlatitudes, and at only one point in the Southern Hemisphere: Lauder, in New Zealand. KNMI has taken the lead in validating future SCIAMACHY measurements of total ozone and ozone profiles. GOME crosses a given spot on the equator once every 3 days, future SCIAMACHY once every 6 days, so the sonde launches in Surinam can be planned accordingly.

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