is there any future atm forcing that I can use for CAM

Hi, all,

I plan to do a future run for CAM, as MERR2 is reanalysis data, I can not find a suitable atm forcing for the future.
Not sure, do you have any experiences about this?



Best
Ru

Hi Ru,

Future scenario simulations are recommended to run with "free-running" meteorology, i.e. dynamics calculated inline by CESM.

Best,
Rebecca

rrbuchholz said:

Hi Ru,

Future scenario simulations are recommended to run with "free-running" meteorology, i.e. dynamics calculated inline by CESM.

Best,
Rebecca

Click to expand...

Hi, Rebecca,

What you mean is first run an AMIP/fully coupled simulation to get the atm forcing for the future, then nudged CAM to this atm forcing

or directly run a free-running run for the future with land-atm coupled.

For the first solution, not sure if I can use FHIST (even though it is for the past) by setting SST for the future, e.g, 2050-2060.

Best
Ru

Hi Ru,

It depends of what type of experiment you want to perform, there are several ways to run a future scenario. Here are some points from a discussion we had previously with another user:

• Generally future simulations use free-running meteorology, but if you want to match an existing simulation, you can nudge to model output, if you have saved meteorology from a previous run.
• Running with free-running meteorology (FCHIST) is not any more expensive than nudging if you run with specified SSTs (F-case). What is expensive is running fully coupled with the ocean model (B-case).
• Fixed SSTs, I think exist for some scenarios and periods.
• To run a fully coupled simulation, you probably want to use a WACCM6 case that has been run for various scenarios, which has been fully spun-up. Since a fully coupled simulation has a lot of variability from the ocean, it may be difficult to tease out any chemistry effects.
• Note that even when nudging there can be small changes in the meteorology when emissions are changed due to the cloud-aerosol interactions.
  There are a couple papers about this linked on this page:
  Meteorology for physics-based nudging - CAM-Chem - wiki.ucar.edu

Best,
Rebecca