SMOKE: ocean source


I’m searching how to make ocean inventory for my ocean emission list. The ocean source has the same FIPS code and different x, y coordinates. Which type should I choose (area source or point source) ? If I choose area source, then the variation over ocean would disappear since all points in ocean have the same FIPS code.


Thank you.

Are you talking about for commercial marine vessels? If so, you can either use a nonpoint inventory with appropriate spatial surrogates to spatially allocated the emissions to your grid cells. Recently, EPA has been using a pseudo-gridded FF10 point source inventory for CMV – where the CMV emissions within a grid cell are emitted from a point at the center of the grid cell and plume rise can be applied (the big ships can emit at vertical layers higher than layer 1). It depends how you are constructing your inventory whether the point or surrogate-based approach is better. EPA FF10 inventories are hourly, but you could do daily or annual/monthly depending on how you want to temporally allocate the emissions.

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Yes, commercial marine vessels is right. I will try to use FF10 point source inventory. Thank you for comment.

Dear eyth.alison,

When I treated commercial marine vessels as point source, I met some problem. I have no information about STKDIAM, STKTEMP, and STKVEL (required). How should I set them easily?

If I should treat commercial marine vessels as area source, I have to assign different FIPS code to each row of emission list (so many FIPS code).

Best regards,

We use a standard set of stack parameters by – one for large (C3) vessels and one for smaller (C1C2) vessels.

For C1C2: The stack parameters used for cmv_c1c2 are a stack height of 1 ft, stack diameter of 1 ft, stack temperature of 70°F, and a stack velocity of 0.1 ft/s. These parameters force emissions into layer 1.

For C3: A set of standard stack parameters were assigned to each release point in the cmv_c3 inventory. The assigned stack height was 65.62 ft, the stack diameter was 2.625 ft, the stack temperature was 539.6 °F, and the velocity was 82.02 ft/s.

For point sources, you are giving the sum of all emissions in the grid cell. The FIPS needs to be specified but is only used for summary purposes as the location is specified by the lat-lon coordinates. You could put all in the same FIPS if you wanted to. SMOKE may require unique IDs for the sources, but you can make them concatenated grid cell numbers if you like e.g., 105203

For area sources, you would need to provide a spatial surrogate to allocate the emissions to the grid cells for each specified FIPS code. Off the coast of the US, we have some FIPS codes used close to the coast, but others farther away cover large areas of the ocean and the spatial surrogate allocates the emissions to specific cells. We have used both the point and area source approach at various times. Our recent inventories are as point because our inventory is developed from AIS transponder locations.

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