Surface Heat Budget over the North Sea
in Coupled Climate Simulations
C. Dieterich, S. Wang, S. Schimanke, M. Gröger, B. Klein, R. Hordoir,
P. Samuelsson, Y. Liu, L. Axell, A. Höglund, H.E.M. Meier
ESA-SOLAS-EGU, 30. October 2014
Atmosphere-Ice-Ocean Model RCA4-NEMO
• EURO-CORDEX setup for
RCA4
• Resolution: 0.22◦ , 40 levels
• Flux-coupled every 3 hours
to NEMO-Nordic
• Resolution: 2 naut. miles,
56 levels, 5 ice classes
• Boundary conditions: GCM
or reanalysis data
• Runoff: E-HYPE reanalysis
data
Ensemble of scenarios with RCA4-NEMO
Source of uncertainty / variability
Annual SST biases ERA40 / Historical
Validation ERA40 hindcast against MUDAB database
T: std dev 1.1/1.1◦ C; rms err 1.3◦ C
S: std dev 0.92/1.05 g/kg; rms err 0.5 g/kg
O(5000) datapoints during 1999 to 2008
6-hourly wind speed 1989 to 2006 at MARNET
Climatological heat fluxes ERA40 / Historical
Momentum and freshwater fluxes ERA40 / Historical
Annual SST and T2M changes far future - recent past
Changes in atmosphere ocean temperature difference
S = short wave + long wave
L = latent + sensible heat flux
S(t) = S̄ + Ŝ cos ωt
L(t) = −k(Ts − Ta )
S̄ = 50W/m2 ; Ŝ = 100W/m2
(Ts − Ta ) = 1◦ C; k = 50W/m2◦ C
Prandle and Lane, 1995
[W/m2 ]
past
future
change
S̄
60
62
+2
L̄
-70
-69
+1
S̄ + L̄
-11
-8
+3
T2M - SST and non-radiative heat flux changes
Annual radiative and net heat flux changes
Conclusions
• First ensemble with coupled RCM for North Sea and Baltic Sea
• Spatial variability of uncertainties offers insight in model sensitivity
• RCA4-NEMO hindcast compares fairly well with observations
• Downscaled historical periods are from the same distributions as
the observed ones
• Validation of RCA4-NEMO scenarios is ongoing
• Heat exchange over the North Sea shifts under warmer conditions
Ensemble of scenarios with RCA4-NEMO
experiment
historical
RCP 4.5
RCP 8.5
ERA40
1961 - 2010
MPI-ESM-LR
1961 - 2006
2006 - 2099
2006 - 2099
EC-EARTH
1961 - 2006
2006 - 2099
2006 - 2099
GFDL-ESM2M
1961 - 2006
2006 - 2099
2006 - 2099
HadGEM2-ES
1961 - 2006
2006 - 2099
2006 - 2099
IPSL-CM5A-MR
1961 - 2006
2006 - 2069
2006 - 2079
• 5 different GCMs
• 2 different scenarios
• 1 RCM
RCA4-NEMO RCP8.5 and RCP4.5 ensemble
RCA4-NEMO RCP8.5 and RCP4.5 ensemble