Reducing the uncertainty on climate induced by land-atmosphere feedbacks

The length of the growing season of plants extended due to global warming during the last decades. The growing season will further extend with higher CO2 concentrations and warming in the future.

The phenological development of vegetation impacts the energy and water cycle through the albedo, the roughness length, and the turbulent fluxes of heat and CO2. This influences near-surface air temperature, precipitation and finally the boundary layer structure and cloud cover regime.

The phenophases, in turn, depend on the vegetation type, the net primary productivity, photoperiod, the ambient temperature and water availability. Warmer environmental conditions lead to an earlier start or later end of the growing season. Precipitation and available soil water influence the variability during the phenological stages. These vegetation-atmosphere interactions need to be accurately represented in climate models to improve projections and ultimately advise climate change mitigation.

The main research focus at CESR is on model development.

The phenological cycle is currently static in the regional atmospheric model COSMO/ICON and not connected to photosynthesis. This is the same for the climate mode of the model. Therefore, we implement a new phenology scheme connected to photosynthesis and vegetation growth for various vegetation types. Combined with the former, the land cover maps of atmospheric model need to be adjusted to account for different vegetation types and their variation with time.

Other tasks include sensitivity and uncertainty analyses regarding extreme events as well as the impact of seasonal and inter-annual varying phenology on local climate.

Project partners

Germany: German Weather Service

Switzerland: MeteoSwiss