Greenland climate characteristics in HadCM3

• Main Authors: Ridley, J. K., Huybrechts, Philippe, Gregory, J. M., Lowe, J. A.
• Format: Conference Object
• Language: unknown
• Published: 2003
• Subjects: Greenland; ice core; Ice Sheet
• Online Access: https://epic.awi.de/id/eprint/8999/; https://hdl.handle.net/10013/epic.19514

The HadCM3 AOGCM has been coupled to a 3D dynamic model of the Greenland ice sheet, which includes a visco-elastic solid Earth model. Once every year the AOGCM provides the ice sheet model with precipitation and temperature anomalies which it uses in order to calculate ablation, ice dynamics and basal rebound. A new orography and fresh water fluxes are passed back to the OAGCM to be utilised over the subsequent year. The water from the melting of calved Icebergs is applied evenly to the sea region adjacent to Greenland whilst runoff enters the ocean through 'river' outlets. A multiple century experiment starting from the present day ice sheet with an atmospheric CO2 concentration of four times pre-industrial levels is being undertaken to determine the rate of ice ablation and the impact of ice sheet changes on simulated sea level, and oceanic and atmospheric circulation. The effect of orographic changes in the ice sheet on its own mass balance is also of interest. The results from the first 180 years of the simulation indicate that the modelled surface air temperature over Greenland in the 4xCO2 climate is around 8 degrees warmer than in the pre-industrial control, compared with a global mean difference of 5 degrees. Precipitation is increased by 33% in the 4xCO2 experiment but the rate of ablation rises by 640%, causing a direct sea-level rise of 5mm per year. To understand the mechanisms of change we will examine the spatial patterns of temperature and precipitation anomalies for the model control and 4xCO2 experiments and compare them with data from anomalously warm years determined from in situ (ice core) data.