SWING: Stable water isotope intercomparison group

Experiment S1B

The SWING experiment S1B has been defined as a 134-years simulation with varying SST from the HadISST data set, period 1870-2003 (for the GissE Model: 1880-2000). All other boundary conditions were set to the specific years, accordingly.

For more detailed information about the different simulation experiments, please contact Martin Werner (Echam4), Gavin Schmidt (GissE) or Jospehine Brown (MUGCM).

The different GCM model grids have been interpolated to a common 2x2 degree grid for comparison reason.
Both monthly and daily GCM output values have been included in the SWING database.

(1) Monthly data

Monthly values of the following surface and atmospheric GCM model variables are available:

Variable	Dimension	Echam4	GissE	MUGCM
2m temperature	2D	x	x	x
surface pressure	2D	x	x	-
sea level pressure	2D	x	x	x
10m wind speed	2D	x	x	x
precipitation (H216O, H218O, HDO)	2D	x	x	x
surface flux (H216O, H218O, HDO)	2D	x	x	x
temperature	3D	x	x	x
zonal wind	3D	x	x	x
meridional wind	3D	x	x	x
specific humidity (H216O, H218O, HDO)	3D	x	x	x

Download

All monthly data files are found here.

(2) Daily data

Daily values of the following surface GCM model variables are available:

Variable	Dimension	Echam4	GissE	MUGCM
2m temperature	2D	x	x	x
sea level pressure	2D	x	x	x
10m wind speed	2D	x	-	x
zonal wind at 10m	2D	x	x	x
meridional wind at 10m	2D	x	x	x
precipitation (H216O, H218O, HDO)	2D	x	x	x
surface flux (H216O, H218O, HDO)	2D	x	x	x
specific humidity at 2m (H216O, only)	2D	x	x	x

Download

All daily data files are found here.

Important Remarks

2D variables represent surface values (if not indicated otherwise).
3D Variables are stored on the following pressure levels: 100, 250, 500, 700, 850, and 1000 hPa
The given unit of daily specific humidity values in the GissE and MUGCM NetCDF Files is wrong. It says [m/s] but values are given in [kg/kg], like in the Echam4 NetCDF data files.
For the MUGCM, the daily temperatures, specific humidity values, zonal and meridionl winds are given for the lowest model level, not for 2m above surface. In addition, the 10m temperature values have been included in the MUGCM NetCDF files.
For the MUGCM, daily evaporation rates (EVP) are given instead of daily (net) surface fluxes (SFL).
To convert values (e.g., PRTH218O) to conventional "delta" notation, use the formulations
```
   deltaD   = ((HDO/H2O)  /(modelStandardRatio) - 1)*1000
   delta18O = ((H218O/H2O)/(modelStandardRatio) - 1)*1000
```
where modelStandardRatio refers to the appropriate value given above for each specific model and isotope species as below. The variables "H2O" are total water (meaning sum of all species).
```
  Echam4:  H218O: 2.0052e-3  /  HDO: 1.5576e-4
  GissE:   H218O: 2.2280e-3  /  HDO: 3.2900e-4
  MUGCM:   H218O: 2.0052e-3  /  HDO: 3.1152e-4
```
(Explanation: While Echam4 and MUGCM are using isotope mole ratios, the GissE Model is using isotope mass ratios. For the HDO in Echam4 results, the values in the model are for D/H rather than HDO/H2O.)