GFS diagnostic AOD output is not at exact 550nm

[zhanglikate]

Description

In the current GFS code, the diagnostic AOD output is not at exact 550nm, however, a band average covering 550nm. Most of the observation AOD data is at exact 550nm wavelength, so this is not consistent wavelength when compare with the observation AOD. It would better to update it by calculating the exact 550nm AOD instead of current AOD of band average covering 550nm. Also the AOD of band average covering 550nm is much high than that of exact 550nm AOD by update to 20%, especially over the fire regions. This would cause high bias for AOD evaluation when compare with observed AOD from satellite or in situ measurement.

Some related experiments can be found at: https://docs.google.com/presentation/d/1d7l2ZlQmIDAGr9xZX4sWVpoQPiM_ipZ0X3n9c1_jIu4/edit#slide=id.p

Solution

I have modified the code to calculate the exact 550nm AOD to replace the current AOD of band average covering 550nm.

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