Recap of last year's wildfire smoke season

It has been awhile since I posted, and I really don't want this blog to wither. But the absence has been for good reason. Last summer, I went on maternity leave and had high hopes of working on this blog during my "time off." That didn't happen. I made a few drafts, but never sat down and finished any draft. So, I wanted to do a recap of last season as I start thinking about 2019.

Below is a plot showing the number of days when there was a fire and the number of days when there was smoke in the atmospheric column for the wildfire season (May - October) of 2018. A couple of notes, I'm using satellite products here that I have "gridded." This doesn't represent the number of fires, but the number of days when there was fire in that grid (a defined area). A grid could have multiple fires at the same time and fires could burn for multiple days. But, it gives you a sense of where fires were occurring. For the smoke plot, this is again from a satellite product. It notes when there was smoke in the atmospheric column, so this does not equate necessarily with surface air quality. Also, this satellite smoke product is only for daytime, so it doesn't show plumes at night, and it might miss very small plumes. But, again, it gives you a sense of where smoke was. I also like to compare these to different years to kind of get a sense of severity (you can look back at my analysis of 2017).

Maps showing the number of days with a fire (left) in a gridbox or smoke plume (right) in a gridbox for May - October 2018. These are created using the Hazard Mapping System Fire and Smoke Product. 

What these plots show is that there were lots of fires in the Southeast, which is normal. These are generally smaller fires, and many of the fires are prescribed fires. If you compare to the smoke plot, you can see that these fires aren't creating a lot of smoke. Most of the smoke comes for the large fires in the Pacific Northwest and Canada. These fires create large plumes that can travel long distances and impact a lot of the US. But again, this is smoke in the atmospheric column, not necessarily at the surface.

To see the impact on surface air quality, we can look at the PM!d2.5!n measurements in Fort Collins. The following is a time series of the 24-hour (daily) average.

Concentrations were pretty high last summer, and we had a lot of days with smoke. Early in the summer, we had smoke from some local fires (Wyoming and Colorado). Later in the summer, we had smoke transported from the Northwest.

Smoke plumes on 14 June 2018, 29 June 2018, and 1 July 2018. Note the different scales (first picture is zoomed in on Northern Colorado).

On the plot, the two days with the highest concentrations were 20 August 2018 and 24 August 2018. Even though I was on maternity leave, I was still taking smoke pictures as you can see below. You can tell just from comparing the pictures (and seeing how much the foothills were obscured) that concentrations were higher on the 24th of August.

Looking west from Galway Dr. in Laporte, CO on 20 August and 24 August 2018. 

We can again use the HMS product to determine where this smoke originated. On the 20th, there were fires all over the Northwest and plumes coming from all over. In Fort Collins, surface concentrations were lower overnight and then ramped up and stayed high throughout the day (shown in the hourly time series below).

HMS Smoke Plumes and Fire Locations for morning, early afternoon, and late afternoon on 20 August 2018.

Hourly PM!d2.5!n in Fort Collins, CO for 19 August - 22 August 2018. 

On the 24th, smoke was also coming from fires in the Northwest and Canada. The plumes were pretty broad, covering a large portion of the western US, but there weren't as many as on the 20th.

HMS Smoke Plumes and Fire Locations for morning, early afternoon, and late afternoon on 24 August 2018.

The WE-CAN field campaign (https://www.eol.ucar.edu/field_projects/we-can) was happening during this time period, and they actually sampled a lot of these plumes on their flights. It will be pretty interesting to see all that they learned about smoke and air quality!