The workshop will bring together experts working on land-atmosphere feedbacks and dry extremes at boundary layer scales and climate model scales to gain more insight into the two following research questions:

Q1 | Dry events: What is the effect of local and remote land-atmosphere feedbacks on the onset, evolution and termination of droughts and dry spells?

Current understanding of the physical factors influencing development of abnormally dry conditions suggests the key role of large-scale circulation features. However, an increasing number of studies show that land surface state and its immediate interaction with the atmosphere can play an important and direct role in the evolution of dry events locally or even remotely. In the former case, as soil dries out, less evaporation enters the atmosphere accelerating drying process even more. One consequence of that is the amplification of dryness conditions. Another, is a change in the local and remote land surface feedbacks on the boundary layer and, hence a change of the probability to form convection and precipitation locally. Little evidence exists on the relevance of land–atmosphere feedbacks on precipitation changes during droughts and dry spells.

Q2 | Drying trends: How does the contribution of land–atmosphere feedbacks vary as climate changes and to what degree it explains drying trends?

The second main aspect that will be considered in the workshop is the role of the land–atmosphere feedbacks in the observed and modelled positive global dryness trends. The simulations of climate models almost unanimously suggest a key role of soil moisture reduction in the strengthening of the dryness conditions with time via land–atmosphere interactions. However, the exact mechanisms underlying this relationship remain unclear. The effect of modified precipitation triggering via change of the local land–atmosphere feedbacks on boundary layer is suggested as one of the potential reasons but it has yet to be explored. As part of this problem, the lack of a direct collaboration between climate modelling community and the research carried out at boundary layer and daily scales further complicates the solution of the above problem.

TOOLS

– Open-access tools developed in the project –