A soil temperature and energy balance model for integrated assessment of Global Change impacts at the regional scale

The investigation of the impact of Global Change on the basic
resources on which life, and man, depends, is the main objective of
the environmental science community at the beginning of the 21st
century. Advances in information technology, new methods of
spatially distributed data retrieval and increased understanding of
the physical, chemical and biological processes in the Earth system
facilitate integrative models of the dynamic processes under
change. Together with the integration of deep actors models from
social and economical sciences into a common model framework,
scenario runs based on inputs from Regional Climate Models (RCMs)
and constrained by prognoses of the future developments in
demography, economy and human behaviour are now possible. The
objective of the integrative project GLOWA-Danube is the
development of such a modelling system and its application on the
mesoscale catchment of the Upper Danube river with an area of about
77,000 km2. The decision support system DANUBIA is designed for
plausible predictions of the impact of changes in climate, human
behaviour and land use on the future of the water and related
matter cycles. DANUBIA is able to assist knowledge-based management
decisions, by predicting the effects of adaptation and mitigation
strategies on the natural resources of the Upper Danube basin. The
closure of the water, energy, nitrogen and carbon cycles in the
soil-vegetation-atmosphere system relies on the adequate
representation of all processes involved and their interaction. To
close the energy cycle in the soil-vegetation-atmosphere system and
provide valuable input data for biochemical models of soil nitrogen
and carbon transformation, this thesis presents the Soil Heat
Transfer Module (SHTM) together with an energy balance algorithm of
the soil surface for regional scale simulations. SHTM combines
simplified physical algorithms for the computation of the actual
temperature in the upper soil layers and a dynamic lower boundary
condition to represent Climate Change conditions. Changes in soil
moisture and soil freezing are explicitly taken into account. The
surface ground heat flux as the driving force of the model is
provided by an explicit solution of the soil surface energy balance
and a snow-soil coupling algorithm, respectively. This thesis
shows, that the soil temperature and energy balance modules
developed as extensions of PROMET (PROcesses of Matter and Energy
Transfer) are ready to bridge the gap between regional scale (up to
100,000 km2) application and the requirement of physical process
models in predictive, coupled modelling systems like DANUBIA.