To estimate initial soil water content for crop simulations, the implemented approach is to start a pseudo crop simulation starting with a full soil moisture profile long before the actual crop simulation. Using this approach, recharge of the soil moisture by rainfall and water use of the pseudo crop will help to find a more representative estimate of the soil moisture level when the actual crop simulation for the year of interest starts.
The pseudo crop simulation has been implemented by a simplified model which only implements leaf area index dynamics, root growth and evapotranspiration. For root growth and evapotranspiration modules from WOFOST were taken and parameterized for a typical cereal crop. The leaf dynamics are described by the Canopy Structural Development Model (CSDM, Koetz et al., 2005) which describes LAI growth and senescence by a combination of a logistic and exponential curve. The difference with the original CSDM is that the pseudo crop uses the day number as its internal state to calculate LAI, while in the original version a temperature accumulation is used. Finally, a loose coupling to the soil water balance has been established which allows switching the crop simulation on and off while still keeping the integrity of the soil moisture balance intact. At the end of the pseudo crop run, the amount of available soil moisture is updated in the SOIL_INITIAL_WATER table (WAV parameter). Thereafter, the BIOMA crop simulation is run, using more realistic initial soil water content.
The ISW is developed in python. To be able to run the package in parallel, it is connected to a tasks administration system that should be configured before estimating initial soil water content. Each instance of ISW picks up a pending task. Once picked up, it cannot be handled by another instance. Together all instances handle the pending tasks one by one until all tasks of the task list are finished. The tasks can be created by the COPdate package as in the operational production line for the RUK window, or inserted during a manual set-up as in the operational production line for the EUR window.
Required objects inside the oracle schema where the ISW is applied (e.g. CGMS14RUK):
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