Requirements to Observational Systems for a Better Quantification and Understanding of Hydroclimate Extremes

Abstract:

We address issues associated with requirements to different observing systems necessary for a better understanding and prediction of hydroclimate extremes. Although hydroclimate extremes result from many factors that sometimes act together, water is a central component of these extremes via either its excess or scarcity. Quantitative description of precipitation extremes is based upon different types of metrics, from simplified extreme indices to sophisticated estimates involving consideration of probability density functions. However, their applicability is critically dependent on the type and characteristics of data used. We will consider different data sources, namely in-situ rain gauge and pluviometer measurements, satellite data from different missions and also reanalyses and model data output mostly for European continent. For in-situ measurements we will analyse how the quality of observations and the density of the networks may affect estimates of extreme precipitation in different regions. In particular, we will demonstrate capabilities of daily precipitation grids built from relatively coarse resolution and very high resolution data for capturing characteristics of specific extreme events and long-term variability in the intensity of extremes. Of a special attention will be consideration of precipitation extremes associated with prolonged wet episodes and associated requirements for the data record completeness. Finally, when considering estimates of extreme precipitation based on satellite and model data, we will address the issue of scaling of extreme precipitation, which put serious quantitative and qualitative constrains on assessment of climatologies and climate variability in the intensity and frequency of hydroclimate extremes.