Validation of satellite rainfall monitor (SRM) estimates against automated rain gauge observations in the Cagayan de Oro River Basin, Philippines
Paper Details
Validation of satellite rainfall monitor (SRM) estimates against automated rain gauge observations in the Cagayan de Oro River Basin, Philippines
Abstract
Accurate rainfall monitoring is essential for flood forecasting in the Philippines, where intense precipitation and limited ground-based instrumentation pose major challenges. Satellite rainfall products can help address these gaps, but their performance must be evaluated before operational use. This study assessed the accuracy of the Satellite Rainfall Monitor developed by PHIVOLCS using observations from automated rain gauges in the Cagayan de Oro River Basin in northern Mindanao for 2019–2020. The reliability of the rain gauge network was first examined by comparing gauge measurements with data from the El Salvador Synoptic Station operated by PAGASA. Normalized gauge values showed strong temporal agreement with synoptic observations, indicating that the network effectively represented regional rainfall patterns. Using these validated observations, the uncorrected satellite product was found to exhibit substantial systematic biases. The satellite estimates captured only about half of the observed rainfall magnitude and showed poor predictive performance. Moderate to heavy rainfall was consistently underestimated, while light rainfall tended to be overestimated. These results highlight important limitations for operational flood monitoring, as underestimation of high-intensity rainfall may reduce the effectiveness of early warning systems. The validation framework and quantified bias characteristics presented here provide a basis for developing correction methods to improve the suitability of satellite-derived rainfall estimates for flood forecasting applications in the Philippines.
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Elgin Joy N. Bonalos*, Johniel E. Babiera, Peter D. Suson, 2025. Validation of satellite rainfall monitor (SRM) estimates against automated rain gauge observations in the Cagayan de Oro River Basin, Philippines. J. Biodiv. Environ. Sci., 27(6), 79-90.
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