• Weather radar allows precipitation to be detected and measured over a wide area. The radar sends out pulses, some of which are reflected back to the radar by precipitation. The echo signal received is related to the reflectivity of the precipitation, and hence to the precipitation rate (mm/hour).
• There are two radars in the Republic of Ireland, at Dublin and Shannon Airports. Data from the two are used to create an Ireland composite image.
• Images (every 15 minutes) are archived from April 1997.
• Images are colour coded to indicate rainfall intensities.

Radar Rainfall Accumulations: View Sample Radar Accumulation Image

• Weather radar data can be used for computing total rainfall accumulations over large areas such as river basins. Such data are increasingly used for flood prediction, water supply and irrigation management.
• Accumulation products from the Shannon and Dublin Radars are available for hourly, 3 hourly, 6 hourly and 24 hourly accumulation periods.
• Two product types are available:
  • 75 Km range made from the PAC products. These incorporate several corrections including topography and rainfall attenuation.
  • 240Km range product made from the pseudo CAPPI Rainfall products.
• These have an extended range but have no additional corrections. Accuracy falls off at longer ranges. The accuracy of these Accumulation products has not been determined. It is estimated to be between 50% to 70%. However the accuracy varies with the type of precipitation, showers, rain, drizzle, and the distance from the radar. Beyond 100km from the radar the accuracy falls off dramatically.