Study on a rainfall intensity retrieval model for short links

Rainfall retrieving via commercial microwave links is a new rainfall monitoring method. With the development of communication technology, high-density commercial microwave link networks can provide higher spatial resolution rainfall retrieval results. At present, the power-law model has been widely used to study the relationship between microwave attenuation and rainfall rate. The model has high inversion accuracy for links over 1 km in length, but there is a significant overestimation when retrieving short links (length<1 km). In response to this issue, this paper studies the long-term rain attenuation calculation formula provided in the ITU-R P.530-16 recommendation, and established the corresponding rainfall retrieval model. The model was validated in Gothenburg, Sweden, and the rainfall retrieval results of the P.530-16 model and the power-law model are compared and analyzed. The results show that compared to the power-law model, the P.530-16 model is more stable and accurate in retrieving rainfall intensity over short links, with a 55.3% increase in coefficient of determination, a 76.2% decrease in normalized root mean squared error, and a 92.4% decrease in relative error of rainfall depth. The results of this paper provide a solution to the problem of overestimation when inverting rainfall over short links.