{"id":1489,"date":"2013-07-14T09:47:44","date_gmt":"2013-07-14T01:47:44","guid":{"rendered":"https:\/\/gergely.imreh.net\/blog\/?p=1489"},"modified":"2013-07-14T09:47:44","modified_gmt":"2013-07-14T01:47:44","slug":"typhoon-soulik","status":"publish","type":"post","link":"https:\/\/gergely.imreh.net\/blog\/2013\/07\/typhoon-soulik\/","title":{"rendered":"Barometric recording of Typhoon Soulik"},"content":{"rendered":"

It all started a few weeks ago with Sparkfun<\/a> having “20%-off” day, when I got myself (among other things) a BMP085 barometric pressure sensor<\/a>. When it arrived, I have soldered some pins on it, and set it up with an Arduino Nano<\/a>, to have the readings off it easily.<\/p>\n

\"View
BMP085 barometric pressure sensor breakout board from Sparkfun<\/figcaption><\/figure>\n

Originally all I wanted is just some laid back pressure recording, so maybe I can use that to predict the weather a bit. “Pressure falls: bad weather comes, pressure rises: things will clear up”. I was recording for about a week, and nothing really noteworthy came out of that.<\/p>\n

Then it was the news, that the year’s first typhoon is on the way to Taiwan, and it was supposed to be a big one. Obvious that I will try to record the barometric pressure pattern of its passing, but wanted to make it more interesting and informative. More visual than just the timeseries plot of pressures.<\/p>\n

The Japanese Meteorological Agency<\/a>\u00a0(JMA) is a good place to watch for information about typhoons. They list path prediction, typhoon properties like strength, wind speeds, and central pressure, have satellite imagery.\u00a0Putting these together, two days before the typhoon arrived, I set up a script to download the satellite imagery as it became available.<\/p>\n

\"Satellite
The morning before the typhoon arrived<\/figcaption><\/figure>\n

The JMA publishes usually 2 satellite images in an hour for our North Western Quadrant (at :00 and :30), one of them covers the whole area, the other covers just the top 80% or so, leaving a dark band on the bottom. Nevertheless, matching up the pressure reading with the satellite pictures would be a good little project for this time.<\/p>\n

Friday came, the government gave the afternoon off, though it turned out no landfall happened till everyone supposed to be off anyways, just a bit of on-and-off rain. People stocked up on convenience store food (I now have a good supply of instant noodles:) and water, taped over their glass windows, take in their plants and BBQ equipment from outside – well, those who have planned.<\/p>\n

Around 10pm the big rain has arrived, here’s a video of how it looked from my window<\/a>. Went to sleep later, and got woken up around 3:30am by the rain having changed into pretty darn big wind. Here’s another video of the violent part of the typhoon<\/a> that time in the morning, that doesn’t even really do it justice. The houses around here are pretty tall, and I wonder if they have protected from the wind, or been artificial canyons channeling it. Some things got broken, though not as much as I expected – which is a very good thing.<\/p>\n

In the meantime by the power of the Internet I have checked out the pressure reading, how is it going a few miles away in the Taipei Hackerspace<\/a>, where I have left the barometric pressure sensor (the geolocation is\u00a025.052993,121.516981<\/a>)<\/p>\n

Here’s the entire recording of the approximately 2 days of typhoon. It was pretty okay weather in the start and end of the plot.<\/p>\n

\"Plot
Pressure reading during the passing of Typhoon Soulik, recorded at the Taipei Hackerspace<\/figcaption><\/figure>\n

The readings have been corrected to sea level (from about 20m height, where the Taipei Hackerspace is), should be good within 1hPa or less.<\/p>\n

The the pressure was indeed dropping like a rock, and the dip on the graph coincided with the most violent wind that woke me up.\u00a0According the JMA, the central area of the typhoon had pressures down to 950hPa, which means that core must have passed pretty close to here, having readings below 958hPa, though probably not directly, as it didn’t stay down there for long.<\/p>\n

I made a video syncing up the pressure reading and the satellite picture. The red dot on the video marks the recording location. (Watching it in full screen and HD makes it clearer.)<\/p>\n