This repository calculates the F2x, lambda and EffCS from the HadGEM3-GC3.1-LL abrupt-2xCO2 simulation, which will be part of our submission to CFMIP3/CMIP6.
Note: These are not our official CMIP6 numbers since the simulation has not yet gone through internal scientific review. Do not use without informing me.
Tim Andrews
Met Office Hadley Centre.
December 2019.
The abrupt-2xCO2 simulation runs from Jan 1850 through to Dec 1999, i.e. 150 years, following CFMIP protocols (Webb et al., 2016; GMD). It runs parallel to the piControl, i.e. branched from 1st Jan 1850.
Included in the data files are global-annual-mean timeseries tas and radiative flux data from the piControl and abrupt-2xCO2 simulation. The code used to create them converts standard CMIP6 type diagnostics into TOA radiative fluxes: Net, LW clear-sky, LW CRE, SW clear-sky and SW CRE. CRE (cloud radiative effect), is the difference between all-sky and clear-sky. All fluxes are positive downwards. Mappings from standard CMIP6 diagnostic names are as follows:
| name | Mapping Routine |
|---|---|
| NET | PP_FF('a-b-c',rsdt,rlut,rsut) |
| LWcs | PP_FF('a*b',-1.0,rlutcs) |
| LWcre | PP_FF('a*(b-c)',-1.0,rlut,rlutcs) |
| SWcs | PP_FF('a-b',rsdt,rsutcs) |
| SWcre | PP_FF('(a-b)-(c-d)',rsdt,rsut,rsdt,rsutcs) |
To ensure consistency between processing, please use the piControl data given here alongside the abrupt-2xCO2 simulation, rather than the piControl on the ESGF. They ought to be almost identical, except perhaps for LW fluxes since our ESGF submission includes a small adjustment to account for the boundary layer timestep. This should not impact differences, i.e. abrupt-2xCO2 minus piControl.
The data files have been produced using idl_create_data.pro.
| Filename | Description |
|---|---|
HadGEM3-GC31-LL_abrupt-2xCO2_r1i1p1f3_gn_1850-1999_GlobalAnnualMean.csv |
Global-annual-mean tas and radiative flux timeseries from abrupt-2xCO2 |
HadGEM3-GC31-LL_piControl_r1i1p1f1_gn_1850-1999_GlobalAnnualMean.csv |
Global-annual-mean tas and radiative flux timeseries from piControl |
Gregory plot: See Figure_GregoryPlot.pdf. Created with idl_gregoryplot.pro.
The F2x, lambda and EffCS (gregory plot on 150yrs) in comparison to abrupt-4xCO2 are:
| Simulation | F2x (Wm-2) | Lambda (Wm-2 K-1) | EffCS (K) |
|---|---|---|---|
| abrupt-2xCO2 | 3.43 | -0.70 | 4.9 |
| abrupt-4xCO2 | 3.49 | -0.63 | 5.5 |
The abrupt-4xCO2 values are documented in: Andrews, T., Andrews, M. B., Bodas‐Salcedo, A., Jones, G. S., Kulhbrodt, T., Manners, J., et al (2019). Forcings, feedbacks and climate sensitivity in HadGEM3‐GC3.1 and UKESM1. Journal of Advances in Modeling Earth Systems, 11. https://doi.org/10.1029/2019MS001866.