<![CDATA[How are air quality pollutants pollutants measured?]]>Pollutant levels, such as that for SO2, are given in units of mass/volume (i.e. densities). These must ultimately be measured using physical sensors somehow, correct?

And if so, at what height are these sensors placed at? And by extension, up to what altitude are these pollutant levels valid for (ex. 200m above the ground? 500m? 1km? etc.)

]]>https://community.windy.com/topic/11220/how-are-air-quality-pollutants-pollutants-measuredRSS for NodeSun, 08 Mar 2026 07:22:28 GMTSun, 09 Feb 2020 21:21:55 GMT60<![CDATA[Reply to How are air quality pollutants pollutants measured? on Wed, 12 Feb 2020 05:43:19 GMT]]>We can see the anomaly in SO2 actual from the NASA data itself: https://so2.gsfc.nasa.gov/pix/special/time_sres/time_series.html

This clearly shows some crazy spikes right then and there for Eastern Asia. Look at the scale, ffs, its off the charts:

https://so2.gsfc.nasa.gov/pix/special/time_sres/china_so2pca_pbl_ts_plot.png

And there's also a weird data hole around Feb 2 (0 everywhere).

Doesn't mean we know what it was from, but it cannot be denied that there are/were crazy spikes in SO2 over that region recently.

]]>https://community.windy.com/post/39782https://community.windy.com/post/39782Wed, 12 Feb 2020 05:43:19 GMT<![CDATA[Reply to How are air quality pollutants pollutants measured? on Mon, 10 Feb 2020 09:38:51 GMT]]>@jyscao
Seems that Windy uses NASA data for SO2.

FFF68C0B-4F7D-410D-AB9D-FBD78BEAE438.jpeg

On website press the small clock in right low corner of your screen to get information about all layers.

DACDA071-97A3-4089-A407-417DBEE4119E.jpeg

]]>https://community.windy.com/post/39596https://community.windy.com/post/39596Mon, 10 Feb 2020 09:38:51 GMT<![CDATA[Reply to How are air quality pollutants pollutants measured? on Mon, 10 Feb 2020 08:59:42 GMT]]>@idefix37 thanks for the info, it's really helpful.

The altitude of the chemical plumes detected by satellite depends on the pollutants type but probably more than 1 km.

The pollutant I'm specifically interested in is sulfur dioxide (SO2). And I'd like to be able to get a maximally accurate estimate (with error bounds if possible) for altitude ranges that the stated densities are valid for.

This is the SO2 forecasts from Copernicus: https://atmosphere.copernicus.eu/charts/cams/sulphur-dioxide-forecasts

And this is from NASA: https://so2.gsfc.nasa.gov/

Judging by the recency of data and spatial resolution, I presume windy.com uses data from Copernicus for emitted SO2. If that's indeed the case, do you know I might access the raw SO2 data from either Copernicus or Windy?

]]>https://community.windy.com/post/39590https://community.windy.com/post/39590Mon, 10 Feb 2020 08:59:42 GMT<![CDATA[Reply to How are air quality pollutants pollutants measured? on Sun, 09 Feb 2020 22:58:09 GMT]]>@jyscao
Air pollutants on Windy are measured by satellites. So the sensors are placed on satellites at high levels. Data are provided by Copernicus or NASA.

https://en.m.wikipedia.org/wiki/Remote_sensing

https://www.esrl.noaa.gov/csd/groups/csd3/instruments/lidar/

The altitude of the chemical plumes detected by satellite depends on the pollutants type but probably more than 1 km.

]]>https://community.windy.com/post/39554https://community.windy.com/post/39554Sun, 09 Feb 2020 22:58:09 GMT