Doppler radar gives ‘near-perfect forecast’ of rains

LEGAZPI CITY—Weathermen and Bicol’s disaster officials are anticipating the activation of the state-of-the-art Doppler radar in Catanduanes after forecasters here successfully tested its capability to provide a “near-perfect forecast.”

The test, conducted by weather forecasters here at the break of day on Thursday, accurately predicted the rains that were then going to come to Albay that day, said Landrico Dalida Jr., chief of the Philippine Atmospheric, Geophysical and Astronomical Services Administration (Pagasa) in Bicol.

Dalida said weather forecasters underwent a three-week training from January 9 to 21, focusing on the maintenance, operation and interpretation of the radar pictures.

He said the training helped forecasters to become more confident in their forecasts, especially with regard to evaluating the rains.

Dalida said the “torture test,” or validation test, was successfully conducted on February 2, when forecasters accurately predicted heavy rains coming to Albay by 10 a.m. that day.

Dalida said that on that day, they predicted about 12-14 millimeter per/hour of heavy rains that would be pouring until early evening.

He said the results were sent to Albay Governor Joey Salceda and to Cedric Daep, chief of the Albay Public Safety and Emergency Management Office, and these were subsequently used to warn the people in the third district of Albay, especially those people living near the foot of Mount Mayon.

“So we are now starting to use its near-perfect forecast with regard to the rains but since the Doppler radar has not been turned over officially, we are not giving the results to the public but limited (the results) to the disaster managers of the province especially in Albay,” said Dalida.

The new Doppler radar in Bato town in Catanduanes, the first of three units being built in the country using the solid-state technology developed by Japanese engineers, is set to operate in March.

Salceda, chairman of the Bicol Regional Development Council, said that with the Doppler radar in place, forecasters would have longer lead time, estimated to be at least six hours, to determine the rain content of tropical cyclones and give disaster authorities time to decide and implement preventive measures.

He said that although rain gauges are good instruments to determine the rainfall rate, they do not tell the weathermen the amount of rain before it falls, something that the new Doppler radar can now do.

Dalida said this new technology uses the new S-band system that transmits electromagnetic waves as far as 420 kilometers away to determine rainfall intensity and coverage, wind velocity and speed.

The S band, according to Dalida, is defined as standard for radio waves with frequencies that range from 2 to 4 gegahertz. It is used by weather radar, surface ship radar, and some communication satellites, especially those used by National Aeronautics and Space Administration to communicate with the space shuttles and the international space stations.

By using the solid-state technology, he said the new Doppler radar would no longer use the US-made coaxial magnetron (a device use to emit power so the radar can detect clouds), which cost P3 million.

The new Doppler radar is more economical because of its low power consumption of 10 kilowatts as compared to the previous 500-kW power need of a magnetron, while maintaining accuracy and efficiency of the radar, he said.

“The most impressive characteristic of the recent Doppler radar is that aside from detecting the clouds, it penetrates the inside the clouds,” he said.

The new Doppler radar, he added, now determines the rainfall volume of the clouds, its intensity, wind velocity and speed, thus giving an early warning to the community where the clouds are going and how much rainfall these contain.

Dalida said this could help warn the local government units in advance so that preemptive evacuation could be done with minimal damage and fewer deaths or, at best, zero casualty.

Dalida explained that even with the new radar in Catanduanes, the Pagasa would still maintain the four Automated Weather Stations (AWS) in Tiwi and Libon towns and the cities of Legazpi and Tabaco, all in Albay.

He said the AWS and the Doppler would “work perfectly together as the Doppler serves as early monitoring while the AWS harmoniously confirms the data given off by the radar system.”