Area-to-point with hour-specific FF10

Hi there, I wonder if anyone has ever run SMOKE with hour-specific area source FF10s together with an area-to-point text file. My understanding is that the area-to-point file is used to predetermine the amounts of emissions at listed lat/lon locations, so that no spatial fractions will be drawn from surrogate files. My concern, though, is whether the area-to-point fractions will ever be applied to the hour-specific FF10s, especially when FF10_AVEDAY_ANNINV_YN is set to Y to obtain emissions solely from them.
Feedback, recommendations, etc, will be greatly appreciated.


We haven’t done hourly processing with area sources of any kind (with or without area-to-point). In theory using area to point should work because gridding and temporalizing are independent processes. Although we note that we have been trying to get away from area-to-point. So, we recommend converting you hourly inventory to point pre-SMOKE and just running them as point like the EPA platform does for CMV or ptegu, because we know that works.

Thank you for your suggestion, Alison.

I began with point source FF10 containing over 2 million records, derived from AIS of ocean-going vessels. They were put to run inline, thus both stack groups and emissions files were generated. But because of the shear data size, the stack groups file encountered netCDF -40 error (HDF5-related).

So, I’m thinking about deriving area-to-point text files and aggregating the point sources to area sources at FIPS level. Hopefully, this approach that creates gridded netCDF will not get the same error.

Out of curiosity, why would you want to move away from the area-to-point approach? Is that because FIPS totals have been calculated from too many SCC’s?


We may be able to provide you the code that we use to grid the AIS-related emissions to point sources in the center of the grid cells.

That is how we are using the dense AIS data in our platform – hourly ‘gridded’ point sources. Would that code help you?

Thanks for offering. I’m reconsidering the hour-specific point source approach, though this time I’ll let go of individual ship names and use grid cell coordinates as facility ID’s. I’ll revise my code then.

Thanks again.