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
Contents
Background
Model tools
Analysis of control run
Preliminary results from climate projection
Conclusions
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
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)
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
Model domain
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
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
Sea surface temperature average for March 1978
BCM ROMS Climatology
Sea surface salinityaveraged over August 1978
BCM ROMS Climatology
Volume averaged temperature
Averaged sea surface temperature
Temperature – northern North Sea
Volume averaged salinity
Averaged sea surface salinity
Salinity – northern North Sea
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
Atlantic inflow
Results from downscaling of the
A1B scenario
Integrated temperature scenario
1972-95 vs. 2072-95
Downscaled inflow to the North Sea
20C3M vs. A1B
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.
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:
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 %