Validation of high‐resolution satellite rainfall products over complex terrain

TLDR

The study evaluates satellite rainfall products over two African sites—Ethiopia with complex terrain and Zimbabwe with less rugged topography. The authors assessed daily 0.25° satellite rainfall estimates from NOAA‑CPC RFE, TRMM‑3B42, CMORPH, PERSIANN, and NRL blended product against station networks in Ethiopia and Zimbabwe. The products accurately detect rainfall occurrence but poorly estimate rainfall amounts, with low correlations and high errors; performance was better over Zimbabwe, where CMORPH, TRMM‑3B42, and RFE performed relatively well, while over Ethiopia CMORPH and TRMM‑3B42 were superior.

Abstract

High‐resolution satellite rainfall products, at daily accumulation and 0.25° spatial resolution, are evaluated using station networks located over two different parts of Africa. The first site is located over Ethiopia with a very complex terrain. The second site, located over Zimbabwe, has a less rugged topography. The evaluated satellite rainfall products are the NOAA‐CPC African rainfall estimation algorithm (RFE), TRMM‐3B42, the CPC morphing technique (CMORPH), PERSIANN, and the Naval Research Laboratory's blended product. These products perform reasonably well over both regions in detecting the occurrence of rainfall. However, performances are poor in estimating the amount of rainfall in each pixel. The correlation coefficients are low and random errors high. The performance was better over Zimbabwe as compared with Ethiopia. Comparing the different products, CMORPH and TRMM‐3B42 showed a better performance over Ethiopia, while RFE, CMORPH, and TRMM‐3B42 preformed relatively better over Zimbabwe.