Analysis of the potential of CML data for nowcasting forecasts in Poland

The growing network of telecommunication stations and commercial microwave links (CMLs) in last years has opened a window into a new way of rainfall estimation. This is a relatively new approach in precipitation estimation field, and it gives reasonably good results, and so have become a valuable source of precipitation information which can successfully supplement other existing observations. The potential of CMLs lies in their high temporal resolution (reaching one minute) and high abundance, so they are increasingly used for short‐term forecasting (nowcasting). Like any type of data, data from commercial microwave links are subject to quality control to isolate non-functioning stations and those links that systematically give erroneous results. Such a pilot analysis and quality control was recently carried out on 66 CMLs from the Opole Voivodeship, Poland. It was analysed to what extent the precipitation derived from CML attenuation data is useful in estimation of the precipitation field with the high temporal and spatial resolution required in nowcasting models. Several methods were used to estimate precipitation field based on data from available links. The CML-based estimates were compared to point observations from manual rain gauges and multi-source precipitation fields using daily and half-hourly accumulations. The analyses conducted show that the CML-based precipitation fields are much worse than radar-derived estimates. At the same time, they had slightly poorer reliability than spatially interpolated telemetric rain gauge data and significantly higher reliability than satellite estimates. There is seen potential for precipitation forecasting using CML data, for example in regions where there is no weather radar. But on the other hand there a challenge to validate data in regions where there is no ground-truth data available.