A review of the firsts in meteorological history: the "Luyang Silver Pearl" you don't know

In 1996, my country's first new generation weather radar was built in Hefei. From the start of construction in 1997 to its full completion in 1999, this 128-meter-high "Luyang Silver Pearl" witnessed the "acceleration" of the development of Anhui's meteorological industry and became an important force in the province's meteorological disaster prevention and mitigation.

What is the meaning of "big ball"?

The building where the "big ball" is located is the tower of Anhui Meteorological Observatory, which is known as the "Luyang Silver Pearl" in Hefei. It is my country's first domestically produced S-band Doppler weather radar. After more than 20 years of development, my country has built 242 weather radars and put them into operation.

The "big ball" has a diameter of 11.8 meters. Its exterior is made up of 86 pieces of fiberglass. Its interior is a parabolic antenna with a diameter of 8.5 meters. The "big ball" is the protective cover for the parabolic antenna of the Doppler weather radar.

It can monitor the changes of various cloud and rain weather phenomena in real time, generate radar echo images, and then invert meteorological products, effectively monitor disastrous weather such as heavy rain, typhoons, and severe convection, and can also quantitatively estimate precipitation. It plays an important role in meteorological disaster prevention and monitoring, flood control and drought relief, and ecological civilization construction.

How does weather radar work?

Radar is the abbreviation of Radio Detection and Ranging (RADAR), which detects and locates targets by transmitting and receiving electromagnetic waves. Electromagnetic waves are transverse waves with different polarization states. Those vibrating in the horizontal direction are called horizontally polarized waves, and those vibrating in the vertical direction are called vertically polarized waves.

The single polarization radar in the new generation of weather radar is a horizontal polarization radar, while the dual polarization radar after technological upgrading is a radar with polarization diversity function, which can detect with horizontal polarization and vertical polarization separately or simultaneously, and compare the detection results to obtain polarization parameters.

The big ball mentioned above is usually called the "clairvoyant" for observing clouds and measuring rain. It is based on the Doppler effect, which monitors the relative movement speed of cloud and rain particles according to the Doppler effect of electromagnetic waves. Under certain conditions, by observing these changes, we can know the vertical speed of the cloud, horizontal wind speed, turbulent movement, and airflow evolution characteristics.

Why is the radar antenna cover designed as a sphere?

The radar radome is an important part of the radar. The radome is equipped with a radar antenna for transmitting and receiving electromagnetic waves. It performs a three-dimensional scan every 6 minutes. After receiving and processing the returned electromagnetic wave signals, it can generate precise monitoring and early warning products for severe weather such as heavy rain and severe convection in Hefei and surrounding areas.

The shape of the radar antenna is a rotating parabolic pot cover, which rotates 360 degrees in a plane around the center of the antenna at a set elevation angle, and the motion trajectory it forms is conical. Therefore, the antenna cover is designed to be spherical. In addition, the radar antenna cover is made of fiberglass, and its main function is to resist wind and rain, and protect the normal operation of the radar equipment inside it, while having little effect on the radar's transmission and reception of electromagnetic wave propagation. The spherical appearance not only saves raw materials, but also effectively reduces wind resistance and ensures the safe operation of equipment. (Written by Zhu Yazong and Fang Yan from the Secretariat of the Anhui Meteorological Society, and Zhu Pengfei, Director of the Hefei National Weather Radar Station, reviewed by Dong Debao from the Anhui Atmospheric Detection Technology Support Center)