Script to calculate global volume mean temperature and same valid for salinity

[abhisheksavita]

…same valid for salinity.

[rmholmes]

Hi @abhisheksavita, this looks good overall and runs fine on my setup. Here are some comments:

• It would be great if you could include a bit more documentation explaining what you are doing at each step. For example, please add a description below the title of what the notebook does. Also, can you explain what the weighting function is doing.
• Please remove the code blocks that only contain commented code.
• Your Volume_mean_temp is computed twice. Please remove cell 12.
• Can you also explain what you are doing in the final code block with the plotting. Why compare the unweighted and weighted means?

I note also that the global averaged temperature and salinity variables are also included in the output of most runs in ocean_scalar.nc as the temp_global_ave and salt_global_ave variables (you could check your calculation by also plotting these variables on the time series plot). However, this script is useful to show how those are calculated.

[rmholmes]

Once you've made your changes all you have to do is commit them and then push them back up to your global_TS_Change branch on github and this pull request will be automatically updated.

[rmholmes]

Looks good @abhisheksavita. Runs fine. Thanks. Interesting that there is a difference between the offline and online calculation (although it's in the fifth decimal place for temperature). I guess this is coming from the neglect of temporal correlations at time-scales less than your monthly average offline diagnostics as I mentioned in COSIMA/access-om2#142