Reflectivity and Precipitation Measurements
Previous modules described basic radar systems and principles and radar beam propagation through the atmosphere. In this module the influence of both radar and target characteristics on the intensity of the received signal will be examined.
The measurement of precipitation with radar is accurate only under strictly defined conditions. Thus, it is essential for users of weather radar data to understand how radar and precipitation characteristics affect observed reflectivity. Only with such understanding can a user properly interpret weather radar data.
The power being returned to the radar from a target is referred to as reflectivity. It is a measure of the efficiency of a target in intercepting and returning radio frequency energy. Thus, a weather radar system provides a value of "efficiency" with which targets in the atmosphere return the energy transmitted by the radar. And this efficiency is measured in terms of reflectivity.