UPPER-AIR RADIO SOUNDING SYSTEM IN NEPAL

With the aim to enhance the government’s capacity to mitigate climate-related hazards and to obtain accurate, precise and more reliable weather data, the Government of Nepal brought the concept of radiosounding in Nepal. 

The Department of Hydrology and Meteorology has recently equipped themselves with a radiosonde sensor that measures the various atmospheric parameters and transmits them by radio frequency to a ground receiver.

The project deals with the measurement of barometric pressure, temperature, humidity, wind speed and wind direction of the upper air with the help of radiosonde attached to a weather balloon.

Mahavir Shree International Pvt. Ltd. has installed the Upper-Air radiosonde system inside the premises of the Tribhuvan University, Central Campus, Kirtipur. The location is 200 meters east of the Central Department of Hydrology and Meteorology, Tribhuvan University. 

Mahavir Shree International Pvt. Ltd. has also provided 30 days of training to DHM staff in four different phases about the operation, maintenance and troubleshooting of the system. 

The ground station for receiving the sensor data, the generator for hydrogen generation and all other necessary components are placed inside a container. Similarly, the antennas are mounted above the container.

In this system, the initialized radiosonde is tied across a parachute and unwinder and released into the upper atmosphere with the help of a hydrogen-filled weather balloon. The ascending radiosonde continuously emits the atmospheric data in the frequency band of 402.1MHz. The ground located AT-OMNI antenna receives the signal emitted by the radiosonde and the GPS information is received by the AT-GPS antenna. The signal of both the antenna is then received by the ground station (GS-E). The data of the ground station is then passed to the computer where the software (Grawmet) converts raw data into a graphical representation. 

The graphs thus obtained are used by weather forecaster for forecasting the weather as the obtained atmospheric data is very precise and accurate. Also, airlines, researchers, surveyors can use this data as per their reference.

Normally the average height achieved by the balloon is 27.124 km whereas a maximum of 32 Km was recorded. The runtime integrated battery of radiosonde is a minimum of 140mins. 

Simultaneously, a Hydrogen generator is operated for 2 to 3 hours daily to produce hydrogen gas which is required to fill the weather balloon. The calibration of the hydrogen generator should normally be performed every 3 months.

Every early morning around 5:30 am – 5:45 am, the DHM staff is launching weather balloons and is sure that the weather forecasts will be more reliable and also hope that the situation can somewhat be controlled by pre-alert information raised due to climate change.