Evaluating Satellite Precipitation Error Propagation in Runoff Simulations of Mountainous Basins

This study investigates the error characteristics of six quasi-global satellite precipitation products and their
error propagation in flow simulations for a range of mountainous basin scales (255–6967 km2) and two different
periods (May–August and September–November) in northeast Italy. Statistics describing the systematic
and random error, the temporal similarity, and error ratios between precipitation and runoff are presented. Overall, strong over-/underestimation associated with the near-real-time 3B42/Climate Prediction Center morphing technique (CMORPH) products is shown. Results suggest positive correlation between the systematic error and basin elevation. Performance evaluation of flow simulations yields a higher degree of consistency for the moderate to large basin scales and the May–August period. Gauge adjustment for the different satellite products is shown to moderate their error magnitude and increase their correlation with
reference precipitation and streamflow simulations. Moreover, ratios of precipitation to streamflow simulation error metrics show dependencies in terms of magnitude and variability. Random error and temporal dissimilarity are shown to reduce from basin-average rainfall to the streamflow simulations, while the systematic error exhibits no clear pattern in the rainfall–runoff transformation.