SO&P: HadCM3 Global-mean sea level

Important notes regarding the HadCM3 data:

• Do not redistribute data to others outside the SO&P project.
• Hadley Centre will require co-authorship and need to know from the start what analyses you are using the HadCM3 data for. Please contact Simon Tett (see SO&P participants table) and keep him informed.
• To ensure collaboration between SO&P partners, please refer to the list of ongoing/planned model-data comparisons. Please contact others who have listed an interest in the same area, to initiate collaboration. To add your planned areas of model-data work to the list, email Tim Osborn.
• A small climate drift, unrelated to the external forcings, is present in the HadCM3 simulations. This drift has been removed from the time series made available here - see Gregory, Lowe and Tett (2005) for details. The drift was removed by reference to the HadCM3 control simulation, also available here.
• Please inform Tim Osborn of any errors that you find in the data.

HadCM3 Global-mean sea level (mm)

Variations in global-mean sea level have been estimated from the HadCM3 simulations as reported by Gregory, Lowe and Tett (2005) (see SO&P publications for reprint). There are a number of components of sea level variability:

• Thermal expansion of the oceans. This has been calculated from the HadCM3 simulated ocean temperatures.
• Change in mass of glaciers and small ice-caps. This component has been estimated using a simple glacier mass balance under various assumptions.
• Change in mass of the Greenland and Antarctic ice sheets. Estimates of this component have not been made.
• Change in mass of glaciers/ice-caps around the fringes of Greenland and Antarctica. Estimates of this component have not been made.
• Changes in mass of soil moisture and seasonal snow cover. HadCM3 simulated values for this component indicate that it is negligible and, therefore, no data have been included for this component.

The data provided below are from the Gregory, Lowe and Tett (2005) calculations. The nat and all time series have already been corrected for drift in the control simulation and for the estimated response to the initial step-change in forcing at the beginning of the nat simulation. These correction time series will also be made available soon.

The data series have arbitrary zero values. For the purposes of the plots shown below, the nat series have been adjusted to equal zero in 1500 and the all series have been adjusted to equal the nat values in 1750. The time series in the data files have not been adjusted in this way.

Total sea level variations are obtained by summing the glacier/ice-cap and ocean thermal expansion components. The anhtropogenic signal is estimated by differencing the all and nat data.

ALL, NAT and ANTHRO (=ALL-NAT)	Data
	Annual nat (glacier/ice-cap component) all (glacier/ice-cap component) nat (ocean thermal expansion component) all (ocean thermal expansion component)

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Important notes regarding the 'all' simulation:

• The vegetation cover was incorrectly set to present-day, rather than pre-industrial, during the 'nat' simulation. The 'all' simulation should start smoothly from the 'nat' simulation in 1750, but because of the sudden change from present-day to 1750 vegetation there is a step-change between the two simulations. Simon Tett will be calculating some correction fields for each variable, which can be applied to the 'nat' simulation data to remove the vegetation error effects.
• The stratospheric ozone depletion used as a forcing in the 'all' simulation was too strong by a factor of around 2. This may affect some variables (e.g. Antarctic atmospheric circulation) in the final 3 decades of the simulation. Simon Tett is considering a re-run of these final decades.

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Last updated: October 2005, Tim Osborn