TABLE OF CONTENTS Our atmosphere is a major environmental issue; radar is one of the key research tools.
The atmosphere would not appear to be a very promising radar target at first sight, and it is perhaps surprising to discover that there are a considerable number of radars dedicated to observing and investigating the atmosphere at all altitudes. There are three main areas in which atmospheric radars are used, and these are now outlined.
Hazard avoidance Most airliners carry a weather radar in the nose to look ahead and give a warning of severe weather on a display inside the cockpit. Pilots may then take avoiding action within the limits set by their flight lane. Airports prone to severe storms are now also installing ground-based weather radars to give warnings of severe down-draughts, which are a danger to aircraft taking off and landing. At present, strong down-draughts during thunderstorms cause about one aircraft crash every 18 months in the USA alone.
Forecasting Radar maps of rainfall are a familiar sight on televised weather forecasts, but the radars supplying this information also provide other data useful for forecasting. The main data source for weather forecasts remains satellite images, aircraft measurements and the radiosonde balloon flights, which are equipped with instruments to measure temperature, pressure and humidity. However, radar continues to make increased contributions to weather forecasting, and there are plans to replace balloons with a network of stratospheric-tropospheric (ST) radars, which are described in Sec. 9.3. (The balloons themselves are...
