Greetings!
When checking PM10 product in both global and EU forecast, I noticed they are quite different in some regions (I noticed north of Africa for example). Let me show you an example:
This is what global forecast for 2023-11-21T03:00 UTC (base time 2023-11-21T00:00 UTC) looks like (notice north of Africa reaching around 300 ug/m3):
And this is what EU forecast looks like for same time with same base time (not a slightest hint of raised values in the north Africa coast region):
Is it because north of Africa is too close to the edge of EU forecast domain or are these products showing different data. I noticed that EU chart is labeled CAMS European ground-level PM10 forecast, while global chart is labeled CAMS particulate matter forecasts. Does it mean that EU product is surface (ground-level) only and global product is whole atmosphere column? I tried to find this in both product documentations (EU, global) with no luck. Or am I missing something completely?
With regards, Filip
Hi Filip,
The CAMS regional forecast chart is showing quite coarse colour scaling to reflect the thresholds used to calculate the Air Quality Index following the EEA definition, which is why you don't see much enhancement. For the PM10 forecast with a more regular colour scale please see https://atmosphere.copernicus.eu/charts/packages/cams_air_quality/products/europe-air-quality-forecast-regulated?base_time=202311210000&layer_name=composition_europe_pm10_forecast_surface&originating_centre=85_2&projection=opencharts_europe&valid_time=202311211200. There are some differences in the emissions sources between the CAMS global and regional forecasts, which means they won't be identical but they should show some of the same features.
I hope this helps,
Mark
Hi Mark,
thank you for link to better chart (with same spatial projection). This shows even greater difference between regional and global forecast. For example border between Morocco and Algeria is blue and darker in global forecast (meaning more than 200ug/m3) while regional forecast doesn't go higher than 40ug/m3.
While indeed some features are in both forecasts (for example north of Italy, west of Germany or central Tunisia), many are not.
Am I simply wrong to assume that regional forecast for Europe is higher resolution version of global forecast? And comparing them directly doesn't make much sense?
Since regional forecast is median of ensemble of many models, it might very well be the case.
Thank you, Filip
PS: similarly surface carbon monoxide looks also quite different (aside from using different units)
Hi Filip,
The CAMS European regional forecasts are not produced by the same system as the CAMS global forecasts and are not simply a higher resolution version of the same forecast. I have summarised the main differences below and further details can be found on the website:
- CAMS global forecasts are generated by the ECMWF Integrated Forecast System and are initialised from an analysis which assimilates all available satellite observations.
- CAMS regional forecasts are generated by higher resolution regional air quality models (11 different models are used and also combined as an ensemble median forecast) which take their lateral boundary conditions from the CAMS global forecast. No satellite data are currently assimilated but there is an analysis which assimilated in situ surface measurements available from EEA.
- The emissions inventories are also different between the global and regional forecasts (see documentation at https://atmosphere.copernicus.eu/anthropogenic-and-natural-emissions).
I hope this helps,
Mark
This helps very much, thank you
