This session addresses two sub-topics: the small scale variability of precipitation, and the atmospheric water cycle. It adopts a PICO format which aims at employing the most modern and captivating environment of scientific exchange (i.e., a 2-minute oral presentation, nicknamed "2-minute madness", followed by an interactive poster presentation on dedicated touch-screens, https://egu2019.eu/guidelines/pico_presenter_guidelines.html).

Precipitation variability: from drop scale to lot scale

The understanding of small scale spatio-temporal variability of precipitation from seconds in time and drop scale in space to 5 minutes in time and 1 km in space is essential for larger scale studies, including more and more hydrological applications, especially in highly heterogeneous areas (mountains, cities). Nevertheless grasping this variability remains an open challenge. An illustration of the range of scales involved is the ratio between the effective sampling areas of the commonly used point measurement devices (rain gauges and disdrometers) and weather radars, which is greater than 10^7! This session will bring together scientists and practitioners that aim at bridging this scale gap and improving the understanding of small scale precipitation variability, both liquid and solid, as well as its consequences at larger scales.
Contributions addressing one or several of the following issues are especially targeted:
- Novel measurement devices, combinations of devices (both in situ and remote sensors), or experimental set ups enabling to grasp small scale precipitation variability;
- Novel modelling or characterization tools of small scale precipitation variability relying on a wide range of approaches (e.g. scaling, (multi-)fractal, statistic, deterministic, numerical modelling);
- Precipitation drop (or particle) size distribution and its small scale variability, including its consequences for rain rate retrieval algorithms for radars and other remote sensors;
- Physical processes leading to the small-scale rainfall variability
- Examples of hydrological applications where small scale precipitation variability input is required.


The atmospheric water cycle: feedbacks, management, land-use and climate change

Traditionally, hydrologists have always considered precipitation and temperature as input to their models and evaporation as a loss. However, more than half of the evaporation globally comes back as precipitation on land. Land-use changes alter, not only, the local water cycle, but through atmospheric water and energy feedbacks also effect the water cycle in remote locations.
This session aims to:
- show applied studies using fundamental characteristics of the atmospheric branch of the hydrologic cycle on different scales. These fundamentals include, but are not limited to, atmospheric circulation, humidity, residence times, recycling ratios, sources and sinks of atmospheric moisture, energy balance and climatic extremes.
- investigate the remote and local atmospheric feedbacks from human interventions such as irrigation and deforestation on the water cycle, precipitation and climate, based on observations and coupled modelling approaches.
- explore the implications of atmospheric feedbacks on the hydrologic cycle for land and water management. Can we favourably alter atmospheric hydrology and precipitation by means of ground based interventions of changing land cover, and thus changing evaporation, albedo and surface roughness?