Question about MOZBC time handling

[Naser Mohammadzadeh]

Hello everyone,

I have a question regarding my understanding of MOZBC.

Suppose I want to run a model for a 1-day simulation with hourly outputs (00–23 UTC). My input data are as follows:

• CAM-Chem: 03, 09, 15, 21 UTC

• WACCM: 00, 03, 09, 15 UTC

I would like to clarify how MOZBC handles these time steps:

1. Does MOZBC only update the boundary conditions at the available input times, or does it perform temporal interpolation to provide values for all intermediate hours?

2. According to the WACCM documentation, the output is described as 6-hourly. However, the available times (00, 03, 09, 15 UTC) do not follow a strict 6-hour interval. In particular, the gap between 15 UTC and the next 00 UTC is 9 hours.

Could you please explain how this should be interpreted?

Thank you in advance.