Published online: 21 October 2015
Ô Springer
Ocean Dynamics
DOI 10.1007/s 10236-015-0897-8
Uncertainty estimation for operational ocean forecast
products—a multi-model ensemble for the North Sea
and the Baltic Sea
Inga Golbeck * 1 • Xin Li 1 • Frank Janssen 1 • Thorger Brüning 1 • Jacob W. Nielsen 2 •
Vibeke Hu ess' • Johan Söderkvist 3 • Bjame Büchmann 3 • Simo-Matti Siiriä 4 •
Olga Vähä-Piikkiö 4 • Bruce Hackett 5 • Nils M. Kristensen 5 • Harald Engedahl 5 •
Ed Blockley 6 • Alistair Sellar 6 • Priidik Lagemaa 7 • Jose Ozer 8 • Sebastien Legrand 8 •
Patrik Ljungemyr 9 • Lars Axell 9
Received: 18 February 2015 /Accepted: 8 September 2015
© The Author(s) 2015. This article is published with open access at Springerlink.com
Abstract Multi-model ensembles for sea surface temperature
(SST), sea surface salinity (SSS), sea surface currents (SSC),
and water transports have been developed for the North Sea
and the Baltic Sea using outputs from several operational
ocean forecasting models provided by different institutes.
The individual models differ in model code, resolution,
boundary conditions, atmospheric forcing, and data assimila
tion. The ensembles are produced on a daily basis. Daily sta
tistics are calculated for each parameter giving information
about the spread of the forecasts with standard deviation, en
semble mean and median, and coefficient of variation. High
forecast uncertainty, i.e., for SSS and SSC, was found in the
Responsible Editor: Emil Vassilev Stanev
G3 Inga Golbeck
inga.golbeck@bsh.de
1 Bundesamt fur Seeschifffahrt und Hydrographie,
Hamburg, Germany
2 Danish Meteorological Institute, Copenhagen, Denmark
3 Defence Centre for Operational Oceanography, Ballerup, Denmark
4 Finnish Meteorological Institute, Helsinki, Finland
5 Norwegian Meteorological Institute, Oslo, Norway
6 Met Office, Exeter, UK
7 Marine Systems Institute at Tallinn University of Technology,
Tallinn, Estonia
8 Operational Directorate Natural Environment, Royal Belgian
Institute of Natural Sciences, Bmssels, Belgium
9 Swedish Meteorological and Hydrological Institute,
Norrkoping, Sweden
Skagerrak, Kattegat (Transition Area between North Sea and
Baltic Sea), and the Norwegian Channel. Based on the data
collected, longer-term statistical analyses have been done,
such as a comparison with satellite data for SST and evalua
tion of the deviation between forecasts in temporal and spatial
scale. Regions of high forecast uncertainty for SSS and SSC
have been detected in the Transition Area and the Norwegian
Channel where a large spread between the models might
evolve due to differences in simulating the frontal structures
and their movements. A distinct seasonal pattern could be
distinguished for SST with high uncertainty between the fore
casts during summer. Forecasts with relatively high deviation
from the multi-model ensemble (MME) products or the other
individual forecasts were detected for each region and each
parameter. The comparison with satellite data showed that the
error of the MME products is lowest compared to those of the
ensemble members.
Keywords Multi-model ensemble • Uncertainty estimates •
Ocean forecast • Baltic Sea • North Sea • Satellite data
1 Introduction
Several operational ocean forecasting models are currently
available for the North Sea and the Baltic Sea providing a
wide range of realizations for the uncertain future situation.
There is a strong demand to make the best out of the available
forecasts, e.g., for sea level warnings or oil drift forecasts. One
solution now commonly applied in weather forecasting is the
estimation of forecast uncertainties with the aid of ensemble
prediction systems (EPSs). There exist several different types
