气象雷达的应用：测量降水

Radar is an English transliteration of Radar. It originates from the abbreviation of radio detection and ranging. It means “radio detection and ranging”. That is to say, target is detected and their spatial position is determined by radio method. Therefore, radar is also known as “radio positioning”. Radar is an electronic device that detects targets by means of electromagnetic waves. Radar emits electromagnetic wave to illuminate the target and receives its echo. From this, the information of distance, range change rate (radial velocity), azimuth and altitude from the target to the emitter of electromagnetic wave can be obtained.
There are many kinds of radar, and the classification method is very complicated. Generally military radar. Usually, it can be classified according to the use of radar, such as early warning radar, search and warning radar, guidance and command radar, gun-aiming radar, altimetry radar, battlefield surveillance radar, airborne radar, radio altimetry radar, radar fuze, weather radar, navigation control radar, navigation radar, anti-collision and IFR radar, etc. In daily life, we often know the weather forecast of the next day, sunny or rainy days, and even how much rainfall can be measured by radar. This depends on weather radar.
Meteorological radar is a radar specially used for atmospheric detection. The high-altitude wind radar, which belongs to active microwave atmospheric remote sensing equipment and radio sounding instrument, is only a special equipment for positioning displacement balloon, and is not generally considered as such radar. Meteorological radar is one of the main detection tools for warning and forecasting medium and small-scale weather systems, such as typhoons and rainstorm clouds. Conventional radar devices consist of directional antennas, transmitters, receivers, antenna controllers, displays and photographic devices, electronic computers and image transmission.
Meteorological radar is an important means of meteorological monitoring, which plays an extremely important role in sudden and disastrous monitoring, forecasting and warning. Since the advent of weather radar, precipitation estimation has been the target of detection. In the past 30 years, radar meteorologists in China have developed a variety of rain gauge calibration radar precipitation estimation algorithm B, trying to use real-time rainfall gauge data to calibrate the precipitation estimated by radar, improve the accuracy of precipitation estimation, and achieved good results. A set of radar quantitative precipitation estimation system (QPEGs) is formed step by step. Based on the data processing and quality control algorithm of PPS, the system integrates various calibration methods of rain gauge, which can effectively improve the accuracy of radar precipitation estimation. In 2003, 2005 and 2006, on average, the hourly precipitation estimated by QPEGS system is less than 50%, the daily precipitation error is less than 40%, and the process precipitation error is less than 30%. The accuracy of precipitation estimation is related to the number of calibrated precipitation stations, precipitation type, rainfall area and the relative position of radar. Although the influence of distance on precipitation estimation is taken into account in data processing and algorithm design of QPEGS system, the evaluation shows that distance and precipitation estimation accuracy are significantly correlated. The farther the distance is, the lower the accuracy of precipitation estimation is (Table 3). Rainfall station density and radar echo initial field have a win-win effect on precipitation estimation accuracy. When the density of rainfall station is insufficient, in order to ensure the accuracy of radar precipitation estimation, it is necessary to make radar echo initial field reflect the real precipitation field. Due to the limitation of detection environment, if the radar echo initial field is not ideal, more rainfall is needed. Station calibration radar estimates precipitation field.