The Philippine Radar Network

By Irene Crisologo

In analyzing rainfall from thunderstorms or typhoons, we must know how much rain fell in different areas of the country. For this, we have what we call rain gauges, the most common is the tipping bucket type. For this type of rain gauge, a funnel collects the rain and directs it to a seesaw-like container which tips when it reaches a certain amount of precipitation, sending electrical signals to the receiver. The number of tips is converted to rain rate, and these data are then transmitted to a remote collection station every 10 minutes.

Tipping bucket rain gauge

Tipping bucket rain gauge. (http://0.tqn.com/d/weather/1/0/w/0/-/-/Rain-gauge-animation.gif)

An ideal rain gauge network would be dense and spaced at least 20 kilometers apart. However, this is difficult to achieve due to financial and topography constraints. Currently, we have around 220 automated rain gauges (ARG) from the Department of Science and Technology- Advanced Science and Technology Institute (DOST-ASTI) that cover the whole country. Some areas have denser rain gauge networks than others, some areas have none.

 DOST-ASTI ARGs

The DOST-ASTI Philippine Rain Gage Network consists of about 200 automated rain gauges.

Since rain gauges are considered as point data, small scale rain such as convective currents or thunderstorms can be easily missed. For example, in the image below, the rain gauges say that there is no rain in the area, but the person in the middle would say otherwise.

2

Small scale rainfall such as thunderstorms can be easily missed by rain gauges.

And these isolated rain showers and thunderstorms are a common occurrence in our country. They have limited horizontal extent – they are not very widespread. It can be raining over San Juan but not Mandaluyong or Quezon City.

3

Isolated rainshowers and thunderstorms.

In the recent years, the PAGASA acquired several Doppler Weather Radars. These instruments send out electromagnetic signals which hit objects that are in the way. These objects reflect the electromagnetic signals, and the receiver for the radar listens for these reflections.

radarops

Electromagnetic signals that hit objects get reflected back to the radar transmitter. (http://www.srh.noaa.gov/jetstream/doppler/images/radarops.gif)

The most important objects that the radar signal detects are the clouds. With Doppler radars, not only do the signals tell the locations of precipitation but it can also tell the amount of rain the clouds bring. And compared to rain gauges, weather radars have a higher resolution. Each data point of the radar can be thought of as an individual rain gauge – it’s like having lots of rain gauges side-by-side in a dense network.

radarloc

Radars can tell the location of rain clouds and how much rain it bring.

The extent of Philippine RADARs is 200 km from the station covering 360 degrees, with a spatial 1 km2.  It’s like having a rain gauge every 1 km in all directions within the radar coverage.

radar high reso

With high resolution radar data, it’s like having a very dense and equally spaced rain gauge network.

Currently, we have six operational  radars: Baguio, Subic, Tagaytay, Mactan, Hinatuan, and Tampakan.

PH doppler

The six operational Doppler Radars from PAGASA.

For a closer look, here are the coverage of each Doppler Radar:

Baguio Radar Coverage

Baguio Radar CoverageSubic Radar CoverageSubic Radar Coverage

Tagaytay Radar Coverage

Tagaytay Radar Coverage

Cebu Radar Coverage

Cebu Radar Coverage

Hinatuan Radar Coverage

Hinatuan Radar Coverage

Tampakan Radar Coverage

Tampakan Radar Coverage

With the Radar Network, we can monitor weather systems even before it arrives in our area.

Habagat_doppler_subic

Doppler images of the small-scale cyclone that hit Metro Manila on the night of July 29, 2013.

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Irene Crisologo is a Science Research Analyst of Climate X, a project that predicts rainfall in the Philippines. Climate X is one of the eight component projects of the NOAH Program

9 Comments:

  1. Hi,

    I just want to know why Catanduanes Doppler Radar is not on the list. Thanks

    • Hi Gilbert,

      You are right, we do have the Catanduanes Doppler Radar. However, we currently do not have access to the raw data. The list you see in this blog entry only includes those we have access to. We are still waiting for the PAGASA to supply the real-time raw data. I believe they are still setting up the connections for data transfer. As soon as we get the raw data, we will include it in the website.

      In the meantime, PAGASA uploads the images produced by the Catanduanes Radar in this site:
      http://www.slprsd-pagasa.com/doppler_virac.php

      However, right now it is not updating in real-time.

  2. Antonio L. Fernandez

    I am in touch with an LGU in Sibuyan Island. It appears that no Doppler radar covers the island. I also understand that the PAGASA has only one weather station in the province and it is located in Romblon Is. Would it therefore be a wise thing for an LGU to invest in rainfall gages and river flow gages as flood mitigation measure? What other hardware would be useful?

    • Dear Antonio,

      Although at present it is not updated, it looks like Sibuyan Island is covered by the Virac doppler radar. However, the NOAH website still does not include the Virac radar because we are still in the process of exploring this new data format (Virac is operated by a different system than the ones in the website).

      However, additional rain gages and sensors would definitely help, as these serve as the ground truth for all other remotely sensed data such as radar data. And it would also aid in decision making if sensors are placed in the upstream areas. If heavy rainfall fell upstream, and a drastic increase in water levels were also observed upstream, then you get an idea how much water is expected downstream where flooding might occur.

  3. Ryan Jose Calubad

    Hi.

    Some facts are quite misleading. According to this site, there 6 radar sites in operation here in the Philippines. But as I see in other websites there are already 11, 13, 16 Doppler radars. I would just like to ask the ff:

    1. How many Doppler radar have been acquired as of this moment?
    2. Of these acquired, radars, how many were installed?
    3. Where are these radars designated?
    4. Of these installed radars, how many were used to access raw data?

    Hoping for a response. Thank you.

    • Hi Ryan,

      Thank you for the questions, and sorry that the reply is 3 years late. >_<

      I hope you are still interested to know the answers to your questions.

      1-2. There are currently 12 radar stations in the Philippines. There are plans on building more, I think two will be in Palawan.

      3. The radars are installed in the following locations:
      Basco, Batanes
      Aparri, Cagayan
      Baler, Aurora
      Baguio, Benguet
      Subic, Zambales
      Tagaytay, Cavite
      Virac, Catanduanes
      Iloilo, Iloilo
      Guiuan, Eastern Samar
      Mactan, Cebu
      Tampakan, South Cotabato
      Hinatuan, Surigao del Sur

      4. The access to raw data varies from time to time, depending on the transmission of data from the radars. Sometimes the radar needs maintenance, or is damaged (like in the case of Guiuan radar because of Typhoon Yolanda or the case of Baler radar because of Typhoon Lando). Baguio radar has been under repair for quite some time, that's why there are no updates from there. The radars with available real-time updates can be seen in the NOAH website.

      If you have any other questions, feel free to ask!

      Cheers,
      irene

  4. Kristine Carnicer

    Hello!

    Is it possible to ask for the data for the Doppler radar data that covers Davao City? I am currently doing a study on the rainfall data and atmospheric water vapor of Davao City.

    Thank you very much.

    • Hi Kristine. The Doppler data streamed through the NOAH website is directly from PAGASA. Kindly contact them regarding the data. Thank you.

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