Record breaking aerosol index values from Canada forest fires – “These are remarkably high values”

Desdemona Despair

By Colin Seftor
15 August 2017

(NASA) – I plan to post more about smoke from the fires burning both in Canada and Russia. But I did want to post this particular item.

Over the last couple of days, OMPS has recorded the largest aerosol index values ever seen since TOMS measurements started in 1978 for smoke over Canada. Here’s what the last couple of days looked like from VIIRS and with the OMPS AI overlaid (notice the scale).

On 13 August 2017, the maximum AI was a value of 39.9. That was topped by yesterday’s maximum value of 49.4. These are remarkably high values.

The AI calculation assumes a simple model of the atmosphere that essentially just includes Rayleigh scattering and some assumption about reflections off the surface (including clouds). The model usually works quite well (including handling clouds), so any deviation of the AI from zero indicates that the atmosphere doesn’t correspond to the model. That usually means the presence of aerosols like smoke and dust (or the presence of sun glint). Well, we certainly have smoke here. And the magnitude of the AI indicates that the simple model is not working well at all and that indicates some interesting conditions (including dense smoke high in the atmosphere).

Most of the smoke is (still) being generated by the fires burning in British Columbia, although some fires in the Northwest Territories are also contributing. [more]

Record Breaking Aerosol Index Values Over Canada

By Colin Seftor
18 August 2017

(NASA) – The massive, high altitude, and dense cloud of smoke still covers a huge area over Canada, and now a finger of that cloud has curled its way over New England. Here are the last 6 days.

You’ll notice that I’ve had to expand the scale once again; the largest aerosol index value recorded by OMPS now stands at 55.4, seen on 16 August 2017. Besides the sheer size of the cloud and the magnitude of the aerosol index, the persistence of the feature as well as the persistence of the extremely high values are amazing. Here are the maximum AI values for the last 6 days:

12 August: 17.2
13 August: 39.9
14 August: 49.4
15 August: 49.7
16 August: 55.4
17 August: 47.2

It will be interesting how long this event lasts (and how far the smoke travels).

Very Smoky Skies Persist Over Canada and, Now, New England