Climate update

I’ve recently updated the Sydney temperature, sea level and rainfall pages to include the latest data available from the BOM. In case you’ve not seen these before a quick explanation:

The BOM provides long term weather observations for the Observatory Hill weather station going back as far as 1859. It’s an amazing resource, when graphed over time you start to see some cool trends emerge. I’ve set it up so you can graph the raw observations or select to see moving averages from 6 months up to 30 years. For the shorter time periods the observations can be all over the place, even the 10 year averages fluctuate up and down but selecting the 30 year averages show clear trends. Except for rainfall! In Sydney at least it’s all over the place with no clear trend over the last 160 years, there are 10yr or so patterns that i think correspond to El Nino and La Nina events.

Anyway, go check them out

Sydney Temperature

Sydney Sea Level

Sydney Rainfall

Steel Blue Sawfly Larvae

While running in the rain I came across this group of sawfly larvae moving together en masse in the middle of the trail. I’m glad I spotted them, a misplaced foot could really have ruined their day!

This group of Steel Blue Sawfly Larvae was wriggling its way across a wet bush trail

I’ve seen these guys before, they are commonly known as spitfires due to their habit of regurgitating a thick yellow irritating fluid when they feel threatened. I stopped to take a few photos while my running partner caught up. She was a bit grossed out but fascinated too. I touched a few of them, they are soft and squishy, the hairs on their body are nowhere near as spiky as they look. When I got too close they would all start raising their tails and thumping them back to the ground, it was quite a sight!

We said our goodbyes and left them where we found them, I hope they got where they were going to safely.

See my previous post on Sawfly Larvae for more info.

Smoke pollution from a local hazard reduction fire

Saturday morning after the hazard reduction burn. The smoke was choking, PM2.5 levels were close to 1000 µg/m3 for 4hrs

After last years terrible fire season I got interested in particulate matter air pollution from smoke and other sources and It’s effect on health. Inspired by this post I ended up buying some parts so that I could put together my own PM2.5 and PM10 detector. There are plenty of ready made detectors you can buy but I figured if I made my own I’d be able to customise it and add functionality that you’d normally have to pay a premium for. It’s also a lot of fun to build these projects and learn along the way!

Last Friday there was a planned hazard reduction burn in our area carried out by NSW RFS, Fire and Rescue NSW and the NSW National Parks and Wildlife Service. We got some advance warning from a friend in the RFS so were expecting it. This would be the first proper test of my PM detector!

The core of the detector is an old Raspberry Pi2. For the actual pollution measurement I used a SDS011 particulate matter detector. I also had a tiny little OLED display left over from another project that was used for a simple screen. I wrote some Python code to read the pollution values from the detector, display them on the screen and also post them to an online data recording platform. Initially I used code from the the raspberrypi.org post to read values from the detector. It worked but it was simplistic. It had the detector and the fan running around the clock even though I was only taking a reading every 5 minutes. After learning that the SDS011 has a limited operational life of 8000 hours I decided to take a different approach. By issuing commands to the detector it’s possible to only switch it on when making a reading and then switch it off again. The SDS011 is a popular part and there were already several Python libraries out there that handled the low level details, perfect! I went with Ivan Kalchev’s py-sds011 Running the detector, screen and Python code required some setup and configuration of the Raspberry Pi, I automated this using Ansible so the details would be saved and could then quickly be rerun again as needed. Here’s what I did

OK, back to the fire. The burn was over a 33ha area of nearby bushland with the closest point only 2 streets away. As it started on the Friday morning huge plumes of smoke appeared, for most of the day air quality at our house actually was fine. All the smoke went straight up into the sky. At around 5pm that changed.

This is a snapshot of recorded PM2.5 (orange) and PM10 (dashed) values from inside my closed house from 12pm Friday Oct 2nd 2020 – 12pm Saturday. You can find live values here

I had the detector running inside the house with all windows closed. PM2.5 levels quickly rose to about 300, the smell was awful and it became very hazy, ash was dropping from the sky. It was still like this when I went to bed.

At 4am Saturday morning I was woken with a sore throat and a heavy feeling in my chest, I got up and the whole house was full of smoke, the indoor PM2.5 reading was almost 1000 at that point! I got up put on a mask and went for a walk around the streets and through to bush to take some photos. The air must have cooled overnight and brought the smoke down with it. It was pretty interesting that it was not evenly distributed, some streets were thick with it others relatively clear.

View towards our place from across the valley. The smoke had settled in some places while other areas were relatively clear
Down at the river. This is how it normally looks
Before sunrise
A Lyrebird spotted through the smoke
This was the point the smoke was thickest, visibility was around 50m

The smoke started to clear at around 8am, levels dropped rapidly over the next hour then by 10am it was on the way to normal.

As bad as it was it was over reasonably quickly and it was important to get the burn done to reduce the chances of an out of control fire. The PM numbers were sobering though, even short term exposure to elevated PM2.5 results in increased mortality from cardiac arrest, especially for people over 65 and other vulnerable members of the community. Smoke from the 2019/2020 summer fires killed almost 450 people, more than 10x the fires themselves.

The NSW government provides hourly, daily and monthly pollution data. The nearest monitoring station is at Macquarie Park is 6.5km away, on the day of the smoke it measured virtually no elevation above normal background levels for PM2.5 or PM10.

I’m going to try to keep my detector running full time and make the readings public, here are the live daily and weekly stats.

Links and further info

Grey Goshawk

Grey Goshawks are a frequent visitor to the area, up until now I’ve not been able to identify or get a good photo of one. Last week I heard the sound of a screeching flock of cockatoos off in the distance, as they got closer the sound got louder. They were swooping and swerving making a huge racket, in front of them was a hawk! It looked like they were chasing it away! A few days later I spotted it sitting in a tree out the back and managed to get these photos.

Very lucky to spot this guy out the back. I don’t know if it’s male or female, the information I found suggests they looks the same although the female is much larger than the male
This Grey Goshawk was spotted out the back, it was looking around for something and didn’t stay still for long
After flying off in pursuit of something I though that was the last I would see of it, but I spotted it again through a gap in the trees in the distance

Grey Goshawks are a medium size bird of prey, local ones have a grey back and upper wings, with a white belly. They have large yellow talons and a yellow, black tipped hooked beak. They prey on mammals like rabbits, possums and bats, also reptiles and insects. Their most common prey is other birds, no wonder the cockies were chasing it away.

References and further reading