Transactions on Ecology and the Environment vol 28, © 1999 WIT Press, www.witpress.com, ISSN 1743-3541
The Influence of Coastal Processes
on Aerosol Composition, Air Chemistry
and Marine Eutrophication
Invited contribution from the coordinator of subproject CAPMAN
G.L. Geernaert
National Environmental Research Institute, P.O. Box 358, DK-4000 Roskilde, Denmark
Introduction
The coastal zone represents a key area for intensive study of environmental,
ecological, and societal interactions. Most of the world's population lives
within 30 km of the coastline, and most of the pollution is generated in this
domain. To sustain coastal societies, human activities are dedicated to intensive
agriculture, fisheries, recreation, and a host of commercial and industrial
activities.
From an atmospheric sciences viewpoint, the coastal zone presents challenges
to the interpretation of measurements, the construction of high performance
models, and policy development. One encounters extremely inhomogeneous
and nonstationary conditions, which limits easy application of the governing
transport equations and chemical budgets. The coastal zone contains complex
geometries separating land and sea, the presence of mountains which steer the
flows, and "hot spots" of air pollution and effects. Efforts to construct policy
options for coastal zone management and emissions reduction protocols require
detailed, accurate, high resolution information on the full suite of human
activities and impacts. For the sake of definition, we define the coastal zone to
be a swath of land and sea extending the extent of a land and sea breeze, i.e.
around 50 km both inland and seaward from the coastline.
The processes governing air pollution transport, transformation, and effects in
coastal regions must account for orography, irregular coastlines, three
dimensional sea breezes, internal boundary layers, emissions, and chemical
reactions. The marine side of the coastline is a significant governing factor
influencing these processes. Marine aerosols, humidity, and trace gases
associated marine eutrophication are among the more important types of
Proceedings ofEUROTRAC Symposium '98
Editors: P.M. Borrell and P. Borrell
© 1999: WITPRESS, Southampton
Transactions on Ecology and the Environment vol 28, © 1999 WIT Press, www.witpress.com, ISSN 1743-3541
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G.L. Geernaert
species to consider in the coastal zone, in particular in reference to policies
governing recreation, health, and fisheries management. In addition to
windspeed, temperature, and clouds, there is dramatic spatial and temporal
variability of the concentrations for these species. The physical aspects of
meteorological transport, and the chemical mechanisms associated with
pollutants and thermodynamic variabilities, must be well accounted for, in
describing both the concentrations and impacts of local air pollution.
The CAPMAN subproject
In order to make progress in the science of coastal air pollution, and in order to
integrate scientific achievements into effect studies, the EUROTRAC
subproject CAPMAN was created. The Coastal Air Pollution Meteorology and
Air-Sea Nutrient Exchange subproject represents a web of atmospheric
scientists who support the following overall aim: to improve our knowledge of
atmospheric physical and chemical processes in coastal regions which govern
the atmospheric transport, transformation and exchange of nutrients with the
coastal sea.
CAPMAN is framed by four scientific objectives:
Objective 1.
Extend the understanding of atmospheric dynamics and
chemical transformation in coastal circulations, by emphasising: (a) the role
of strong inhomogeneities in chemical transformation processes; (b)
downscaling and upscaling of models; and (c) mixing and transport caused
by internal boundary layers, sea breezes, and jets.
Objective 2.
Extend the understanding of aerosol mass closure and the
role of organics, by emphasising: (a) determination of aerosol budgets based
on their physical and chemical transformation; (b) determination of the
mass closure relationships in coastal regions; and (c) determination of the
flux of organics.
Objective].
Extend the understanding of the physical and chemical
processes governing air-sea exchange of nutrients and the related
parameters and compounds over the coastal sea, with emphases to
determine: (a) the chemical mechanisms governing air-sea nutrient
exchange; (b) the role of surface wave state and fetch relationships on
deposition velocities; (c) the role of air mass modification and windspeed
accelerations; and (d) the relative importance of the point and area source
contributions to fetch-dependent flux.
Objective 4.
Extend our understanding of source-receptor relationships at
various sites in the coastal zone, with emphases to determine: (a) the
Transactions on Ecology and the Environment vol 28, © 1999 WIT Press, www.witpress.com, ISSN 1743-3541
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importance of source locations on coastal nitrogen loads; and (b) optimum
reduction strategies to control nutrient input levels.
These four objectives will utilise nested models, including both Eulerian and
Lagrangian types, and dedicated field campaigns will be carried out which
combine measurements and modelling.
CAPMAN focusses on three regions, each with different meteorological,
chemical, and/or geographic characteristics. These are:
* the relativelyflatNorth Sea coastal zones of the Netherlands and Germany,
which are adjacent to heavily populated coastal regions;
* the irregular coastline with complex topography of southern France and
adjacent sections of Italy, with lower population density than along the
Dutch section of the North Sea; and
* the northern Adriatic Sea with its characteristic meteorological flow
patterns and variability of emissions.
There are also other regions which have sites for specific process studies
related to the goals of CAPMAN and which are included in this subproject.
For example, the coastal region of Sweden on the Baltic side and coastal
Portugal are included among these, and the Marmara Sea is a candidate region
for future studies.
Because coastal regions have a high degree of nonstationarity and
inhomogeneity, which often exceeds the limits of many present theories, the
performance of many commonly used meteorological and chemical models in
coastal regions is weak at best. Innovative aspects are therefore a necessity to
include in CAPMAN to guarantee success and impact. The research tasks in
CAPMAN include a strong emphasis on extending theory in order to account
for coastal inhomogeneities, and extend and/or develop measurement
technologies which can be used to determine deposition and fluxes in
inhomogeneous conditions. The newly developed relaxed eddy-accumulation
flux sampling system will be exploited, and improved methods to use
dissipation techniques to a wider variety of constituents have a high priority.
Model integration techniques will be carried out, utilizing nested, downscaling,
upscaling, and resolution-variable approaches.
In the North Sea, the use of ferries between Germany and England is already
incorporated into the measurement strategy to complement the time series of
measurements collected during intensive operation periods on the Noordwijk
Dutch platform (during summer 1998 and summer 1999). The North Sea
Studies are framed under the EU project ANICE, and additional investigators
Transactions on Ecology and the Environment vol 28, © 1999 WIT Press, www.witpress.com, ISSN 1743-3541
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G.L. Geernaert
from both Europe and the USA are attached to the project using national
funding. Development of a nested Lagrangian/Eulerian model system to handle
coastal inhomogeneities is also included in ANICE. ANICE is also benefiting
from parallel process studies currently being carried out in the Baltic Sea,
under the frame of the EU project BASYS.
In the western Mediterrean studies, an experiment was carried out during the
spring 1998, called FETCH, in order to improve our understanding of the
dependence of atmospheric state variables on the governing processes, and to
document the surface flux characteristics as a function of distance from the
coastline. FETCH utilised ships and buoys.
Experiments to be carried out in 1999 in the North Sea and Mediterranean
regions will consider aircraft as an additional platform. Future experiments in
the Adriatic will capitalise on the advances and lessons learned from a variety
of international scientific studies, in particular those from BASYS, ANICE,
and FETCH.
CAPMAN currently involves 17 principal investigators from 8 countries.
Roughly 34 man years of effort are dedicated within these participanting
contributions.
Interactions within EUROTRAC
CAPMAN is a domain-oriented subproject which captures a cross-disciplinary
set of scientific issues. Improved knowledge of meteorological processes, better
emission inventories, a wider set of chemical reactions and mechanisms,
modelling, surface exchange processes, and aerosol science are all subjects
which play significant roles in CAPMAN. Interactions are therefore foreseen
with GENEMIS, CMD, SATURN, GLOREAM, TROMEDA and AEROSOL,
in workshops and future projects designed by CAPMAN investigators. In
addition, due to its coastal nature, CAPMAN has linkages to international
groups which promote research in coastal regions, e.g. ELOISE, CoOP, IGBP
and LOICZ.
Final Remarks
As a subproject which represents a growing field with the need for creativity
and innovation, an open invitation is given to the broad scientific community to
participate. The study of coastal zones, development of flux sampling
technologies and analysis methods, surface exchange processes in
inhomogeneous media, high resolution modelling, and coastal chemical
mechanisms, are all central to CAPMAN. We also solicit policy and system
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analysts to participate in the subjects of risk assessment and system design
specifications for policy options. We envision CAPMAN's strengths to be not
only in the scientific advances to be made, but also in the integration of science
with policies which focus on coastal marine management.
Acknowledgements
All principal investigators of CAPMAN are acknowledged for providing the
strategy development and scope of this subproject. The steering committee is
especially acknowledged, i.e. Gerrit de Leeuw, Soren Larsen, Kevin Noone,
and Serge Despiau. Lise Lotte Geernaert is acknowledged for the design of a
logo, and Kim Pilegaard is acknowledged for allowing me to use his "cap"
during the conference presentation.