Physical Climate Models Research Articles

A biosphere-atmosphere interaction model(BAIM) and its primary verifications using grassland data.

A Biosphere-Atmosphere Interaction Model (BAIM) for use within physical climate models was developed. BAIM has two vegetation layers and three soil layers, and predicts the temperature of each layer and moisture stored for each layer. In the presence of snow on the ground, the snow layer is divided into a maximum of three layers, and the temperature and the amount of snow and water stored in each layer are predicted. BAIM can estimate not only the energy fluxes but also the carbon dioxide flux between the land surface ecosystem and the atmosphere. The photosynthesis processes for C3 plants and C4 plants are adopted in the model. BAIM can also predict the accumulation and melting of snow on the ground, and the freezing and melting of water in the soil. Primary off-line verifications of BAIM in a snowless condition were made using point micrometeorological data observed at grassland. In general, fluxes simulated by the model agreed well with those observed. In particular, clear differences between results using the parameters for C3 plants and those using the parameters for C4 plants appeared in the net carbon dioxide fluxes. Sensitivity tests were conducted for the model to study the influence of variations in the values of parameters related to the property of vegetation. By changing the values of the parameters by ±50%, the maximum variations in the time-averaged fluxes were obtained. The values for net radiation flux, sensible heat flux, latent heat flux, and soil heat flux were about ±15W m-2, ±8W m-2, ±9W m-2, and ±1W m-2, respectively. The maximum variations in the time-averaged value of net carbon dioxide flux were about±5μmol m-2 s-1 for C3 parameters and±7μmol m-2 s-1 for C4 parameters. These maximum variation values are comparable to observation errors.

The regional hydrologic impacts of global climate change: the role of climate models

The requirement to increase understanding of the complex interaction between society and the environment is well documented. Dramatic evidence of the vulnerability of anthropogenic systems to short-term weather fluctuations abounds. Taking an historical perspective provides an equally impressive picture of the potential upheaval caused by longer term climate changes. However, the past (and present) may not provide an adequate analogue for the future. The greenhouse theory of climate change suggests that the changes in climate regime to be expected from enhanced atmospheric CO2 will be of similar magnitude to the glacial-interglacial mean temperature difference, but will occur in a fraction of the time. Consequently, considerable emphasis is being placed on the role of physical climate models in determining projections of future global and regional temperature and precipitation patterns. The latter climate changes will have important implications for the distribution (in time and space) of water, a principal natural resource and basic requirement for a variety of human activities. Consequently, climate models are being applied to the question of determining the regional hydrologie response to global climate change. The latter objective is a prerequisite to assessing the likely impacts on the water resources sector. This paper reviews current progress in achieving this aim and outlines some future research directions.

The regional hydrologic impacts of global climate change: the role of climate models

The requirement to increase understanding of the complex interaction between society and the environment is well documented. Dramatic evidence of the vulnerability of anthropogenic systems to short-term weather fluctuations abounds. Taking an historical perspective provides an equally impressive picture of the potential upheaval caused by longer term climate changes. However, the past (and present) may not provide an adequate analoque for the future. The greenhouse theory of climate change suggests that the changes in climate regime to be expected from enhanced atmospheric CO 2 will be of similar magnitude to the glacial-interglacial mean temperature difference, but will occur in a fraction of the time. Consequently, considerable emphasis is being placed on the role of physical climate models in determining projections of future global and regional temperature and precipitation patterns. The latter climate changes will have important implications for the distribution (in time and space) of water, a principal natural resource and basic requirement for a variety of human activities. Consequently, climate models are being applied to the question of determining the regional hydrologic response to global climate change. The latter objective is a prerequisite to assessing the likely impacts on the water resources sector. This paper reviews current progress in achieving this aim and outlines some future research directions.