Analyzing the influence of irrigation on convection – Case study for Northern Italy using convection-permitting simulations

Land management practices modify the land surface by changing its biogeophysical and biogeochemical properties, leading to heterogeneous surface and soil conditions. One example for this is irrigation, which is widely used to overcome unsuitable climatic conditions in agriculture to protect plants from water stress. Irrigation leads to a heterogeneous and time-varying soil moisture distribution. Soil moisture conditions are known to feedback with the atmosphere. Previous studies analyzed the soil moisture-precipitation feedback and focused on the development conditions of convection. However, uncertainties in the magnitude and sign of this feedback remain due to the representation of convection in the climate model. Therefore, convection-permitting simulations are crucial to understanding the link between soil moisture and convection.

In our study, we investigate this link by taking into account sudden soil moisture changes through irrigation and the resulting heterogeneity of soil moisture distribution. Our aim is to understand how irrigation influences development conditions for convection in the atmosphere. For this purpose, we conduct convection-permitting simulations at high resolution with a focus on the Po valley in Northern Italy. We use the non-hydrostatic version of the regional climate model REMO which in our setup is interactively coupled to its mosaic-based vegetation module iMOVE. For REMO-iMOVE we developed and implemented a new irrigation parameterization based on a fractional approach which makes it suitable for the representation of heterogeneous soil moisture distribution.

We will present the effects of irrigation on the development of convection in the Po valley by analyzing selected atmospheric variables from simulations with and without irrigation.