Quantifying the effect of irrigation on non-local aspects of the atmosphere

Many decades of research through modeling case studies and field work have shown the influence of soil moisture on the atmosphere. One result is the initiation of convection along the boundary separating the heterogeneous land. More recently, research has been focused on the impact of irrigation in arid regions, which can result in cumulus cloud formation due to moistened soils. Across the irrigated area, the sensible heat flux is reduced and the latent heat flux is increased forming a boundary that can create a local circulation and modification of the nearby cloud distribution. More generally, such changes can result in deep, moist convection with sufficient soil moisture and atmospheric instability.

This study uses the WRFV3.3 model to establish a strategy to quantify the input of moisture needed from irrigation to lead to the formation of cumulus clouds, precipitation, and the subsequent downstream evolution of these perturbations that might affect the atmospheric state on larger scales. Different flow regimes (e.g. pre-frontal, post-frontal) are tested to understand the particular perturbation growth mechanisms that might be responsible for inadvertent weather modification, and the frequency with which they occur.