Reduzierung des physikalischen Einschwingens an der Landoberfläche in einem Klimamodell

Siehe englischen Text unten:

Reducing the physical spin-up-time of the climate model land surface scheme JSBACH

Starting from an initial state, climate models usually need a certain time to reach an equilibrium state, which is characterized by conditions in which no significant shifts in temperature and other parameters occur. The elapsed time is called the spin-up-time. Under constant forcing (no forcing trends) and with common principal physical mechanisms, an Earth system model, climate model or land surface model is run until it reaches an equilibrium state. This process can be quite time consuming and creates computational costs, especially if different model configurations shall be tested. In an Earth System model, spin-up times related to the ocean and the carbon cycle can add up to hundreds or thousands of model years, but also land surface spin-up times for soil moisture and soil temperature can last several decades. Therefore it is highly desirable to speed up the spin-up process.

In this master project, the focus is on soil moisture and temperature spin-up within the JSBACH model, which is the land surface scheme of the MPI Earth System Model. Here, soil moisture and temperature are represented by five vertical soil layers over the global land areas, and as common for a land surface model, the initial state usually consists of arbitrarily chosen patterns of soil moisture and soil temperature.  The main question/task is on (finding) a method that accelerates the spin-up process, so that equilibrium is reached significantly faster (and thus less expensive). Approaches may rely on improving the initial conditions of temperature and moisture themselves, but may also consist of more mathematical, and thus more general, methods. The latter may be utilized for future applications with other state variables, such as, e.g., carbon pools. Experiments can be carried out with JSBACH in the offline mode. Later the results are supposed to be applied for the coupled atmosphere/land general circulation model ECHAM6/JSBACH. No changes in the model code are required for this task, as changes to the state variables can be done to the model output, which can then be used as input to the model again. (Anmerkung: Text ist in Englisch, weil es einfacher zu schreiben war.)

Stefan Hagemann, MPI-M, Schäferkampsallee 29, Raum 1.11, Opens window for sending emailEmail