A high-resolution space-time model for precipitation combining remote sensing and in-situ measurements

Research Area:
Meteorology, Hydrology

We detect and monitor structures of rain fields covering spatial scales from tens of metres to hundreds of kilometres and temporal scales from minutes to months.

Specific efforts are put on the full exploitation of the polarization information for quantitative rain estimation in both rain and snow cases. Polarisation information based on differential phase and specific differential phase are used to correct reflectivities for both attenuation (especially large for X-Band) and beam blocking (a particularly serious problem for the Bonn radar). The local vertical profiles are used to estimate surface rainfall. For validation we exploit the strong overlap of the Bonn radar with an equivalent radar setup on the Sophienhöhe in the framework of the HGF monitoring effort TERENO.

We further develop a space-time precipitation model that optimally combines precipitation observations from different sources, which have in part vastly different spatial and temporal supports and error structures. The precipitation model describes transformed radar rain rates as thresholded Gaussian random fields and merges them with gauge mesurements. The final goal is the derivation of high-resolution area mean surface precipitation fields on a horizontal grid with a grid spacing of a few hundreds of meters and a temporal resolution of 5 minutes which are, on a larger scale, calibrated to aggregated gauge measurements, and which, on a small scale, reproduce the spatial characteristics as suggested by the radar images.

Cooperation partner:

• Dr. Alexander V. Ryzhkov, National Severe Storms Laboratory, Norman, Oklahoma, USA