[H1] Compare JRA55-do / CORE / CM2 winds

[adele-morrison]

Plots maps of wind u/v across different forcing products. This will be useful to see how biased the CM2 winds are and if any CM2 years look more promising than others for forcing the ocean model.

[wghuneke]

Does someone know where the CORE dataset is saved on gadi?

[adele-morrison]

Maybe @PaulSpence?

[wghuneke]

Here a some figures of wind speed in different products. JRA and ERA5 are for the RYF time period (May 1990-April 1991), CORE is for NYF, CM2 is a 10 year average.

[wghuneke]

Here a comparison between CORE NYF and RYF:

[wghuneke]

This plot shows 10 yr mean and std winds in CM2-025:

[adele-morrison]

Nice. Difference plots between CM2 and JRA, and between CM2 and CORE would be useful to see just how much weaker the CM2 winds are in the DSW formation sites.

[wghuneke]

Here the difference plot. I interpolated the reanalysis fields onto the model grid.

The anomaly pattern is similar between the two with too weak winds in CM2 along the entire shelf in EA.

[adele-morrison]

Interesting. By my eyeballing, this looks like ~2 m/s too weak, compared with mean winds around the coast in JRA55-do of ~7m/s, so roughly 30% too weak at the margins. Probably we could expect the dynamics of applying too weak winds to be similar to our easterlies project. But this would be a much larger response, because we only did +/- 10% wind speed in our easterlies project.

I'm thinking it might not be such a useful exercise to force ACCESS-OM2-01 with CM2 output with too weak winds, or to run a coupled model with too weak winds. Any opinions from others?

Maybe we could apply some bias correction to the CM2 winds and then use them to force ACCESS-OM2-01?

[dkhutch]

To check if weak winds are responsible for a lack of DSW formation, I would say forcing ACCESS-OM2-01 with CM2 output is the most straightforward test. In terms of applying a bias correction to CM2, I would guess that this would involve adding a "flux correction" to the winds. In which case, the original winds are still operating and can't be fully controlled. Probably still feasible but the OM2 experiment is slightly cleaner.

On Wed, Mar 22, 2023 at 12:22 PM Adele Morrison @.***> wrote:

Interesting. By my eyeballing, this looks like ~2 m/s too weak, compared with mean winds around the coast in JRA55-do of ~7m/s, so roughly 30% too weak at the margins. Probably we could expect the dynamics of applying too weak winds to be similar to our easterlies project. But this would be a much larger response, because we only did +/- 10% wind speed in our easterlies project.

I'm thinking it might not be such a useful exercise to force ACCESS-OM2-01 with CM2 output with too weak winds, or to run a coupled model with too weak winds. Any opinions from others?

Maybe we could apply some bias correction to the CM2 winds and then use them to force ACCESS-OM2-01?

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[wghuneke]

Follow-up on the individual wind components. Both, the zonal and meridional winds are biased in amplitude, but the bias in the meridional wind might be more relevant in terms of DSW formation. The patterns itself agree well between the coupled model and reanalysis products.

[wghuneke]

[PaulSpence]

RE: "To check if weak winds are responsible for a lack of DSW formation, I would say forcing ACCESS-OM2-01 with CM2 output is the most straightforward test."

I'm a little behind ... are we trying to understand ack of DSW formation in CM2-025 or another model? What is the interest in the CM2 winds?

[wghuneke]

We're interested to understand why OM2-01 has DSW, so we can apply that knowledge to any other model. If we find that the CM2 winds would still produce DSW in the OM2-01 configuration, that would be great motivation to set up a CM2-01 version (which might happen anyway).

[PaulSpence]

Winds overall look weaker in CM2 on shelf.