DESCRIPTION OF THE ACID DEPOSITION SCENARIOS
Recent policy measures to control emissions of sulphur and nitrogen
combounds into the atmosphere are expected to lead to reductions
in deposition over Finland and in acid loading of ecosystems and inland
waters. Will these trends continue for all acidifying combounds in the
extended future under alternative emissions scenarios? How much will
the patterns of deposition be modified by possible changes in the
amospheric circulation due to climate change?
Summary information about the methods used to derive the acid deposition scenarios
|Underlying global drivers
||1990 and 1998
||Emission modelling, deposition modelling
||DAIQUIRI, EMEP/MSC-W, IMAGE, MESSAGE
||59°30'N 70°30'N × 19°E 32°E (spherical sector covering Finland)
|Main input data
||SRES-based sulphur and nitrogen emissions, transport matrix derived from climatological data
||sulphur deposition, total wet and dry, unit: gm-2year-1
nitrogen deposition, total wet and dry, unit: gm-2year-1
||regular raster grid with 1/4° longitude × 1/8° latitude resolution
The global long-term energy and emissions scenarios are from the IPCC Special Report on Emissions Scenarios (SRES), which described four scenario families (Nakicenovic, 2000). Each family assumes different global and regional driving forces of environmental change. In order to develop sulphur and nitrogen oxides scenarios for FINSKEN, scenarios were adopted from each scenario family in order to obtain a wide range of possible futures. As this study focuses on Europe, results from the two integrated assessment models used in the SRES work that were developed in Europe, IMAGE and MESSAGE, were selected for the analysis. A1, A2 and B2 scenarios were taken from the MESSAGE model (Nakicenovic et al., 2000).
Three variations of the A1 scenario were considered: a balanced mix of fossil and nonfossil fuels in the A1B scenario, the fossil fuel intensive A1C scenario and the technologically advanced, nonfossil fuel dominated A1T scenario. In addition, draft SRES A1 and B1 scenarios were taken from the IMAGE model (Alcamo et al., 1998 - version 2.1.2). These scenarios were modified in a parallel EC-funded project AIR-CLIM (Alcamo et al., 2002) to account for recent air pollution control policies.
Long-range transboundary air pollution in Europe is modeled with the Lagrangian Acid Deposition Model developed and employed by the Meteorological Synthesizing Centre-West of the UN/ECE EMEP programme (EMEP/MSC-W, 1998). The EMEP model is a receptor-oriented Lagrangian-type trajectory model. Along the trajectories, differential equations describing the mass balance for pollutants take into account emissions, chemical reactions and deposition. The model uses a horizontal grid size of 150 km x 150 km covering the whole of Europe, and it has one vertical layer of variable height corresponding to the atmospheric mixing layer. The model calculates concentrations and depositions as grid square averages and as country-allocated import-export budgets. The source-receptor matrices calculated from the results of the EMEP Lagrangian transport model are incorporated in the DAIQUIRI (Deposition, AIr QUality and Integrated Regional Information) deposition model available at SYKE (Syri et al., 1998, Kangas & Syri, 2002).
DAIQUIRI calculates deposition estimates on a horizontal grid size of 1/4 x 1/8 degrees (appr. 14 km in Southern Finland) covering the whole of Finland.
The figure describes the model linkages used in the derivation of deposition scenarios for Finland.
Alcamo J., Kreileman E., Leemans R. (eds) 1998. Global Change Scenarios of the 21st Century. Results from the IMAGE 2.1 model. Elsevier Science, London.
Alcamo J., Mayerhofer P., Guardans R., van Harmelen T., van Minnen J., Onigheit J., Posch M., de Vries B. 2002. An integrated assessment of regional air pollution and climate change in Europe: findings of the AIR-CLIM project. Environmental Science & Policy 5: 257-272.
EMEP/MSC-W, 1998. Transboundary air pollution in Europe. EMEP/MSC-W Status report 1998. EMEP/MSC-W, Oslo, Norway.
Kangas L. & Syri S. 2002. Regional nitrogen deposition model for integrated assessment of acidification and eutrophication. Atmospheric Environment 36:1111-1122
Nakicenovic N. (ed.) 2000. Special Report on Emission Scenarios. A Special Report of Working Group III of the Intergovernmental Panel on Climate Change. Cambridge University Press, United Kingdom.
Syri S., Johansson M. & Kangas L. 1998. Application of nitrogen transfer matrices for integrated assessment. Atmospheric Environment 32 (3): 409-413.
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