Consider when the rain occurs

Rain during stopped periods and rain during rotation do not create the same relative impact condition. Annual aggregation hides that coincidence. A useful screening question is whether available precipitation and operating evidence share a relevant time basis. A remote rain gauge can also differ from conditions at the rotor. Those gaps should remain uncertainty, rather than be filled with an invented universal correction.

Distinguish amount from impact severity

Droplet size and relative velocity affect the physical event at the surface. NREL-hosted research discusses precipitation and blade impact conditions, but large-turbine examples cannot supply a damage rate for a small rotor. Equal rainfall depth need not mean equal impact histories or equal coating response. The actual blade geometry, operating speeds and protection system are needed before attempting a component-specific erosion assessment.

A site with frequent low-intensity rain during idle periods can present a different impact history from one with concentrated rain during higher-speed operation. This comparison explains why equal totals are insufficient; it does not establish which site is worse without actual matched evidence.

Choose the next evidence investment

Ask whether event-resolved weather and operating data would change a protection or maintenance decision, or whether the available information supports only broad screening. A laboratory test should be interpreted with its represented impacts and substrate, not converted from rainfall total into years of life. No MARSTON rain-erosion limit, output penalty or coating endurance is established here; a responsible specialist must define the useful assessment scope.