I have a question regarding the actual unit of the num_a4 parameter.
From what I’ve observed, num_a4 typically has a unit of
(particles/cm²/s) × (molecules/mole) × (g/kg).
However, when I looked into the source code used to generate BC emissions—such as the script at:
https://svn.code.sf.net/p/codescripts/code/trunk/ncl/emission/createBC_US-Russia.ncl —I noticed it uses the "smoke" parameter, which has units of molec/cm³/s. This value is then multiplied by "(MW_bc / mass_particle)", where the units are (g/mole) × (particles/kg). This results in a final unit of
(particles/cm³/s) × (molecules/mole) × (g/kg).
The discrepancy I’m concerned about is the volume versus area component—cm³ versus cm²—between the derived unit and the expected unit. I’d really appreciate any clarification you can provide on this issue.
Best regards,
Nattanan
From what I’ve observed, num_a4 typically has a unit of
(particles/cm²/s) × (molecules/mole) × (g/kg).
However, when I looked into the source code used to generate BC emissions—such as the script at:
https://svn.code.sf.net/p/codescripts/code/trunk/ncl/emission/createBC_US-Russia.ncl —I noticed it uses the "smoke" parameter, which has units of molec/cm³/s. This value is then multiplied by "(MW_bc / mass_particle)", where the units are (g/mole) × (particles/kg). This results in a final unit of
(particles/cm³/s) × (molecules/mole) × (g/kg).
The discrepancy I’m concerned about is the volume versus area component—cm³ versus cm²—between the derived unit and the expected unit. I’d really appreciate any clarification you can provide on this issue.
Best regards,
Nattanan