Institute for Marine and Atmospheric research Utrecht
Atmospheric Dynamics and the hydrological Cycle
In this project precipitation and temperature projections for the Rhine basin are further analysed. A new reference precipitation data set is constructed and used for bias correction of a variety of climate model outputs. (C.S. Photiadou, A.H. Weerts (Deltares), B.J.J.M. van den Hurk)
Feedbacks between climate and anthropogenic land use change may affect regional projections of future climate and land use characteristics. In current IPCC protocols, land use change is provided as a forcing to GCM simulations, without allowing climate effects to feedback on the land use change. In this project the magnitude of the strength of this feedback is explored. The first step is to run a global land use model LPJmL and explore the sensitivity of modelled NPP to climatic droughts, a possible feature in which strong feedbacks may exist. (Laura Batlle-Bayer, Bart van den Hurk)
Here a conceptual model has been constructed of the land-atmosphere system, building on earlier versions found in literature including vertical gradients of atmospheric moisture convergence, radiation effects and soil processes. With this model, driven by reanalysis data, time scale analysis of land-atmosphere interaction are being carried out. (Helio Camargo, Bart van den Hurk, Aarnout van Delden)
The response of vegetation to climate may alter the surface characteristics (vegetation cover, carbon uptake, water use efficiency) dramatically, certainly in areas where strong climatic constraints on vegetation growth and strong potential climatic effects of vegetation change are co-existent. For a case area in the Western Sahel a conceptual vegetation-climate model is built to explore effects of different vegetation growth strategies on this vegetation-climate feedback. (Vincent Yun, Bart van den Hurk, Henk Dijkstra)
This research project is concerned with the interaction between radiation and dynamics, taking into account also the energy transformations that occur in connection with the water cycle. The changing atmospheric carbon dioxide concentration is perturbing the radiation budget of the atmosphere. This perturbs the large scale atmospheric circulation, i.e. the strength and position of the jets. The atmospheric circulation, in turn, changes the radiation budget. This interaction is studied with "process models" using the concept of potential vorticity. Changes in the pattern and intensity of heating lead to changes in potential vorticity distribution. Potential vorticity inversion is used to connect these changes to circulation changes. (Aarnout van Delden, Yvonne Hinssen, Theo Opsteegh, Wouter de Geus, Maarten Ambaum, Chris Bell, Peter Siegmund)
(Aarnout van Delden, Alwin Haklander, Pieter Groenemeijer, Jeroen van Zomeren)
(Aarnout van Delden, Sander Tijm and Bert Holtslag)