1. Downscaling Future Climate Scenarios for the North Sea 2006 ROMS/TOMS Workshop, Alcalá de Henares, 6-8 November Bjørn Ådlandsvik Institute of Marine Research and Bjerknes Centre for Climate Research

2. Contents Background Model tools Analysis of control run Preliminary results from climate projection Conclusions

3. Motivation Norway's two largest export industries, petroleum activity and fisheries, are based on the continental shelves and are heavily influenced by climate. It is therefore important to develop future climate scenarios for shelf sea climate. Global ocean models are not yet adequate for shelf sea dynamics; lack of resolution and/or physics

4. Dynamical downscaling Force a shelf sea model with atmospheric input and lateral boundary conditions from an AOGCM. Control run: CMIP 20C3M, (1970-1999) Future scenario: SRES A1B, (2070-2099)

5. Bergen Climate Model (BCM) Atmospheric model: ARPEGE Ocean Model: MICOM Coupler: OASIS One of four European models in IPCC AR4 Reference: Furevik et al., 2003

6. Model domain

7. Model setup Atmospheric forcing  Daily averaged BCM surface fluxes Ocean lateral boundary forcing  Monthly averaged BCM fields  8 tidal constituents  Boundary scheme: FRS + Flather Fresh water  Climatological run-off modulated by BCM precipitation  Baltic = large river, salinity = 18  Relaxation of Sea Surface Salinity towards BCM

8. Model setup Atmospheric forcing  Daily averaged BCM surface fluxes Ocean lateral boundary forcing  Monthly averaged BCM fields  8 tidal constituents  Boundary scheme: FRS + Flather Fresh water  Climatological run-off modulated by BCM precipitation  Baltic = large river, salinity = 18  Relaxation of Sea Surface Salinity towards BCM

9. Sea surface temperature average for March 1978 BCMROMSClimatology

10. Sea surface salinity averaged over August 1978 BCMROMSClimatology

11. Volume averaged temperature

12. Averaged sea surface temperature

13. Temperature – northern North Sea

14. Volume averaged salinity

15. Averaged sea surface salinity

16. Salinity – northern North Sea

17. Important climate process transporting heat and salt into the North Sea Important climate variable for ecological effects as it controls import of nutrients and zooplankton from the Norwegian Sea To high degree controlled by regional wind field Atlantic Inflow to the North Sea

18. Atlantic inflow

19. Results from downscaling of the A1B scenario

20. Integrated temperature scenario 1972-95 vs. 2072-95

21. Downscaled inflow to the North Sea 20C3M vs. A1B

22. Conclusions I BCM does a good job with integrated values for the North Sea Some problems due to low resolution but also isopycnal coordinates on shallow shelf sea. Downscaling works technically, with a factor ten in resolution.

23. Conclusions II Downscaling provides added value by improving the BCM results where most needed  Improved regional details, incl. Coastal Current  Improved Atlantic Inflow  Improved winter temperature  Improved vertical structure, incl. surface salinity:

24. Conclusions III Future scenario:  Warming of the North Sea, maximum in winter Yearly mean: BCM +1.0°C, ROMS +1.4°C  Increasing Atlantic Inflow, max increase in August Yearly mean: +0.2 Sv = +15 %