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

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.

There’s no shortage of sandstone in the Sydney area, almost the entire extent of Garigal National Park sits on what’s known as the Hawkesbury Sandstone. The Sydney 1:100 000 Geological Sheet classifies it as “Medium to course-grained quartz sandstone, very minor shale and laminite lenses” I wanted to highlight two sandstone formations, both of which are a bit of a mystery as to how they form. I came across these formations on a trail run on a section of single track in Belrose that runs from the end of Ralston Ave down to the Bare Creek trail next to Bare Creek. The first formation is called tessellated pavement.

I’ve updated the climate pages with the latest data from the BOM. If this summer felt long and hot to you then you’re right. The graph shows the average summer high is the hottest it’s been for 5 years. Looking at the 1 year averages the cooling trend that started in 2014 has reversed and we’re warming again. As always the longer term 30 year averages still show a very clear and consistent warming trend. The warming acceleration that started in 2013 is continuing. Still no update from the BOM on sea level measurements, we’re stuck at the end of 2014 with that. Rainfall data shows no clear long term trend, we’re pretty much smack in the middle of the historical long term measurements.

We’re just coming out of what felt like a freezing cold winter, it seemed like it was bitter and dark for so long. But when it comes to accuracy human skin and brain cells are really terrible at remembering and comparing the weather. Lucky for us we have the data!

Cold and wet at the Mt Tomah botanical gardens

The BOM have updated their long term climate data again. This time we’re in for a treat, we have updates to temperature, sea level and rainfall. Looking at the maximum and minimum monthly temperature averages we have indeed had some cold months. The July average minimum of 8C is the coldest since 2002 when it was 7.9C, and looking back 30 years only 1995 was colder. The mean maximum for July was cool but many years have been cooler over the past 30 years. 2013 and 2014 were quite warm by comparison though, maybe that’s why it felt cold this year. As we’ve only got up to July we can’t compare moving averages yet. For sea levels the short term averages actually show a drop in 2014. The 5yr and above moving averages still show an unmistakable upward trend. Rainfall averages are up, I don’t recall it being particularly wet though, so much for memory.

I’ve updated the Sydney temperature and rainfall pages with the latest data from the BOM, we’re pretty much right up to date now, thanks BOM. Something has happened to their sea level pages though, their Fort Denison measurements have not been updated since the end of 2012. It’s the long term trends that are of most interest so nothing mind blowing in these updates, temperature continues to rise on almost all average time periods. I found it interesting that even after the “August of rain” most rainfall averages are still low when you look back over time.

The 2014 annular solar eclipse was meant to be a rare one, occurring once every 73 years. It was going to be about 50% in Sydney, not total but still impressive to watch. I left the arc welding helmet at home with instructions for the kids on how and when to use it to look at the sun. The goggles came with me to work. It was clear all day, but the clouds gathered near the horizon just as the sun dipped and the eclipse was due to start. Damn!

An igneous dyke is where molten magma has forced it’s way up into a crack between existing rocks. Dykes can extend for many kilometers in lines on the surface.  There’s a dyke marked on the Sydney 1:250,000 geological sheet that cuts across the M1 and old pacific highway just south of the Hawkesbury River. It’s mentioned in the “Geology along state highways” section of The Field Geology of NSW. I’ve tried to spot it many times while driving down the M1, I think I’ve seen it but it wizes by so fast it’s hard to be sure.

The BOM have updated some of their climate datasets, rainfall for Sydney now goes to December 2013, temperature to May 2013. I’ll keep updating as the graphs as the BOM releases more data!