Presenting data is like telling a story. When we look at a graph of our water quality data, it tells us a story about the health of Casco Bay. Seeing the same data in a different kind of graph can help us see another perspective, another side of the story. 

This graph compares 2022 daily mean temperatures (the blue line) to historic temperature data (the gray line and shaded area) from our Yarmouth Continuous Monitoring Station. Additional graphs in this style for other water quality data — including dissolved oxygen, pH, salinity, and more —   recorded at our Yarmouth station can be found here. 

Staff Scientist Mike Doan is using a new kind of graph to present data from our Continuous Monitoring Station in Yarmouth. “This style of graph is one that climate scientists like to use to present long term data sets,” says Mike. “Using it helps us compare data from a single year to the historic range of conditions we’ve seen at our Yarmouth station.” 

The Yarmouth station is one of our three Continuous Monitoring Stations in Casco Bay. These stations use high-tech oceanographic equipment to collect data on multiple water quality parameters and help us assess how the Bay may be changing. Our stations located off Harpswell and in Portland Harbor were launched last spring. Our Yarmouth station was launched in 2016. With over six years of data from that station, we can compare data from a specific year to the historic range of conditions we have recorded there.  

To illustrate this point and get us all thinking about what these data can reveal about the health of Casco Bay, consider the graph below and the information it presents.

This graph compares 2021 daily mean temperatures to historic temperature data recorded at our Yarmouth Continuous Monitoring Station. 

Daily Means 2021: the green line represents the mean water temperature at the Yarmouth station for every day in 2021. A “mean” is just another word for an average.

Daily Means 2016 – 2021: the dark gray line represents the mean water temperature at the Yarmouth station for every day between 2016 – 2021. In other words, this dark gray line represents the daily average water temperature over the past six years. 

Range of Daily Means 2016 – 2021: The gray shaded area represents the range of daily mean water temperatures at the Yarmouth station between 2016 – 2021. It helps us to visualize the difference between the highest and lowest daily average temperature recorded at the station. The top of the gray shaded area represents the highest daily average temperature and the bottom represents the lowest daily average temperature recorded on any given day over the past six years. 

Mike says that 2021 was one of the hottest years we have seen at the Yarmouth station. “This graph shows us just how hot the year was. We can see that for much of 2021, the green line is close to the top of our historical range of temperature values,” explains Mike. “In the context of the past six years, 2021 was a particularly warm year for the Bay.”

What do you see in these new graphs?

Let us know by emailing keeper [at] cascobay [dot] org and visit this page of our website to see our latest data on salinity, dissolved oxygen, pH, and other parameters from the Yarmouth station presented in this new style of graph.