Here are month and year average charts of local background radiation levels from November 2007 to 2018 for Caloundra, located in the Southern Hemisphere on the East coast of Australia. Historically, the recorded pre-Fukushima local background here was low, averaging around ~0.1 uSv/hr. This data has allowed the tracking of changes in local background levels, plus the detection of radioactive clouds passing through.
This community radiation monitoring station was created in response to detections of multiple radioactive clouds passing through after March 2011. Click these links to find detailed documented information on these significant detections in Australia, and New Zealand.
Here are two examples.
Australian Radioactive Cloud Detection
New Zealand Radioactive Cloud Detection
This short animation of Northern, and Southern Hemisphere air circulation, shows why we can get detections so far south. Wind direction can significantly influence the background levels here. Observations show that when the Southern Ocean air reaches this location, we see lower background averages. More Southern Ocean air reaches this location in the cooler months and winter, hence the significant seasonal variation in background levels showing in the average background level charts below.
The long term data collected here before and after Fukushima, has become a valuable resource. It has enabled the tracking of changes in background levels since the nuclear catastrophe. After the Fukushima nuclear catastrophe in 2011, the recorded data has shown an increase in local background levels, compared to pre-Fukushima levels. In 2015 there was a small decrease in post Fukushima average background levels. In 2016 and 2017 there were more increases in post Fukushima year average background levels at this location. As this monitoring station is located in the Southern Hemisphere, small increases here indicate there likely have been much greater background level increases in the Northern Hemisphere.
The GammaScout Alert Geiger Counter model pictured here, was used to log background level data once a week prior to the Fukushima Nuclear Catastrophe. After the Fukushima event it was set up to log background levels every minute, so the data collected after Fukushima is statistically much more accurate.
(Note: The reference monitoring station's GammaScout Geiger counter died on the 12th September 2018, RIP. The last full day average it recorded was on the 11th September 2018. The GammaScout was used as a reference for many years up until it stopped working.
Will be trialling different equipment for the local monitoring station, a SBT-10 pancake, using Theremino Geiger counter software. It has been worked out how to transfer the logged data form this new set up into the old charting system. As different monitoring equipment is now being used, the long term data charts will not have the same statistical accuracy.)
The dotted line through the monthly charts is the year average local background, and through the year chart represents the overall trend since Fukushima.
What does the chart colour code mean?
Click on charts to see larger version
Click on charts to see larger version
Click on charts to see larger version
The data logging of the older local GammaScout Alert Geiger counter stopped on March 14th 2011 for some reason. High demand at the time meant that the newly ordered GammaScout did not arrive until late November 2011. So there is a gap in the data collection from the middle of March 2011 to December 2011. The 2011 year average in this chart, represents the average of the collected data, up until March 2011.
