Regional issues of changing storm surges and sea level - what is done at the Institute for Coastal Research @ HZG

First CLISAP/KlimaCampus Workshop on Sea Level Variability and Change

27 May, 2013

Institute of Coastal Research @ HZG

• The Institute of Coastal Research deals with the issue of long-term change of the

geophysical coastal environment, mainly in the North Sea and Baltic Sea.

• Long term = several decades, homogeneous quality

into the past, mainly 1948 onwards

as projections into the future: until 2100

• Parameter: Sea level, storms, surges, waves, currents

• Researchers:

Ralf Weisse, Frauke Albrecht, Iris Grabemann, Lidia Gaslikova, Hans von Storch,

Katja Worth (North Sea) and Iris Grossmann (Elbe)

Eduardo Zorita, Birgit Hünicke (Baltic Sea)

• In cooperation with BALTEX, TU Siegen, FSK Norderney, BAW, KLIFF, U Szczecin

and others 2

North Sea

3

• Usage of CoastDat data set, a downscaling effort, using a cascade of

- NCEP/NCAR reanalysis (beginning in 1948),

- CLM-atmospheric LAM (earlier REMO) forced with spectral nudging,

- dynamical models of hydrodynamics and waves (with BAW)

- empirical models for estimating local changes (Elbe)

• Analysis of homogenized sea level data (in cooperation with U Siegen)

• Discussion of significance of results of coastal defense planning with various

stakeholders with responsibility for the North Sea coast; part of AKÜST-KLIFF

assessment of different adaptation strategies to increasing extreme sea levels;

operationalization in www.kuestenschutzbedarf.de by Norddeutsches Klimabüro

• Usage of estimates for commercial applications, in particular planning for wind

farming, shipping and other cases.

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Temporal development of intra-seasonal 99%ile of high tide levels AFTER subtraction of annual mean high tide

and mean annual high tide

in Esbjerg (Denmark) and Den Helder (The Netherlands)

until 1995.

Sea level changes different at different locations, because of different drivers, and different dynamics.

Mean and extreme sea level changes

Mean sea level changes in the German Bight

Different methods yield

comparable results after 1924

For this time interval there is little

difference between VM and EOF

approach

correlation 0.996;

trends 1.64 mm/yr (VM)

1.74

mm/year (EOF)

RMSL from different methods

black – VM method (Wahl et al. 2011);

green – EOF method (Albrecht et al. 2011)

Regionale Meeresspiegeltrends

Beschleunigung des (globalen)

Meeresspiegelanstiegs?

Verschiedene Methoden führen zu

ähnlichen Ergebnissen

Gegenwärtige dekadische Trends

sind relativ hoch

Aber nicht ungewöhnlich im Vergleich

zu früheren Perioden

37-jährige Trends des regionalen Meeresspiegels

schwarz – VM Methode;

grün – EOF Methode;

rot – Cuxhaven

(Albrecht et al. 2011)

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Extreme sea level changes

Extreme sea levels increased over the

past 100-150 years in the North Sea

Primarily as a result from a rise in mean

sea level

Meteorologically induced components

(waves, storm surges) show pronounced

variation on time scales of years and

decades but no substantial long-term trend

Variations in storm surge and wave climate

consistent with those in storm activity over

the North Sea

Annual mean high water and linear trend 1843-2012 at

Cuxhaven, Germany (bottom) and corresponding difference

between annual 99-percentile and annual mean high water

levels (top); In addition an 11-year running mean is shown in

the upper panel.

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The case of the Elbe and Hamburg

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Difference of maximum heights in Hamburg and Cuxhaven

Storm surges in Hamburg elevated because of modifying the river Elbe – both coastal defense and shipping channel deepening

Storm surges in Hamburg in the past

Possible and plausible future changes in regional storm surge climate

Changes in extreme

storm surge levels

2071-2100 ./. 1961-

1990

(Woth et al. 2006; Woth

2005)

Here 99.5 percentile

based on half hourly

values; this compares

to 99 percentiles

derived from hourly

values

Contour lines show

99.5 percentile storm

surge residuals from

respective control

runs

Future changes in regional storm surge climate

A1B B2

1.Realisation

2.Realisation

After Gaslikova et al. 2012

Projected changes in storm surges in the German Bight

Scenario Woth et al. (2006) Gaslikova et al. (2012) Weisse et al. (2012)

A2 30 cm -- -

A1B - 15 cm 18 cm

B2 20 cm - -

B1 - 15 cm -

Maximum changes along the German Bight coast at the end of the 21st century

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Summary of knowledge about change of storm surge heights (per 2009)

Significant drivers of changing storm surge heights

Recent changes 1967-2008

Possible changes until 2030

Possible changes until 2100

Global mean sea level rise ca. 2 dm ca. 1 – 2 dm ca. 2 – 8 dm

Meteororological short term effects (storms)

none ca. 0 – 1 dm ca. 1 – 3 dm

Regional and local sea level change

ca. 2 dm So far unknown So far unknown

waves none So far unknown So far unknown

tides Regionally very different

So far unknown So far unknown

bathymetry Regionally very different

So far unknown So far unknown

See: GKSS, 2009 : Nordseesturmfluten im Klimawandel .GKSS Wissenschaftler fassen aktuellen Forschungsstand zusammen.

www.kuestenschutzbedarf.de

www.kuestenschutzbedarf.de

www.kuestenschutzbedarf.de

www.kuestenschutzbedarf.de

Maps in the Internet highly misleading …

Hünicke, 2012

Baltic Sea

1800 1850 1900 1950 2000

-300

-200

-100

0

100

200

300

1800 1850 1900 1950 2000

-300

-200

-100

0

100

200

300

1800 1850 1900 1950 2000

-300

-200

-100

0

100

200

300

1800 1850 1900 1950 2000

-300

-200

-100

0

100

200

300

STOCKHOLM

KRONSTADT

SWINOUJSCIE KOLOBRZEG

PSMSL*, TU Dresden (2005)PSMSL* (2005)

Ekman (2003)

Bogdanov et al. (2000)

* Permanent Service for Mean Sea Level

(Woodworth and Player, 2003)

Zeitserien beinhalten Trend verursacht durch post-

glaziale Landhebung und evtl eustatischen

Meeresspiegeländerungen

Winter (DJF) Anomalien

Hünicke, 2012

Glacial isostatic vertical movement

9

0

5

-1 mm/yearRosentau et al., 2007

To get the relative sea level

change, the crustal movement has

to be subtracted. Tis movement is

in the Baltic Sea region very strong

as a response of the melting of the

earlier ice sheets.

Hünicke, 2012

Gauge series - detrended

1800 1850 1900 1950 2000

-300

-200

-100

0

100

200

300

1800 1850 1900 1950 2000

-300

-200

-100

0

100

200

300

1800 1850 1900 1950 2000

-300

-200

-100

0

100

200

300

1800 1850 1900 1950 2000

-300

-200

-100

0

100

200

300

STOCKHOLM

KRONSTADT

SWINOUJSCIE KOLOBRZEG

PSMSL*, TU Dresden (2005)PSMSL* (2005)

Ekman (2003)

Bogdanov et al. (2000)

* Permanent Service for Mean Sea Level

(Woodworth and Player, 2003)

Winter (DJF) Anomalien

Trend wird als linear angenommen und durch

subtrahieren des linearen Langzeit-Trends von jeder

Wasserstands-Zeitserie abgezogen

3. Datensätze

Hünicke, 2012

Warnemünde

1900 1920 1940 1960 1980 2000

Stockholm

RE: 0.56

SLP + precipitation

RE: 0.57

RE – relative error in

validation period (1900-1950)

Variations of relative sea level in DJFObservations and estimates by regression

-80 -60 -40 -20 0 20 40 60 80 Stockholm

Warnemünde

-80 -60 -40 -20 0 20 40 60 80

mm

1900 1920 1940 1960 1980 2000

RE: 0.48

SLPSL

Recorded sea level after subtraction of linear trendEstimated trends, using

SLP„ + precipitation„ + „ + temperature

RE: 0.11

1900 1920 1940 1960 1980 2000

Stockholm

Warnemünde

SLP+ precip+temp

RE: 0.67

RE: 0.81

Hünicke, 2012

Summary for Baltic Sea

The observational record discloses clear long-term variations, mostly uniform in the Baltic Sea Basin during the 20th century.

The atmospheric circulation has a significant influence on the variations of sea level in the Baltic Sea. The NAO is an important contributor, but only part of the forcing.

Additionally, precipitation and temperature variations relate to variations of regional sea level, in particular in summer.

Determination of long-term trends beyond glacio-isostastic rebound is difficult to achieve, as the space-time pattern of the rebound is qualitatively similar to the expected climate change signal.

Work done by Birgit Hünicke.

Hünicke, 2012

Overall summary

• The Institute of Coastal Research is engaged in describing geophysical

change of the environment in the North Sea and Baltic Sea regions.

• Efforts are underway to build homogeneous data sets (CoastDat) describing

this past and current change, as well as possible and plausible changes in

the future (next 100 years; climate)

• Efforts are underway to determine the most plausible mix of drivers behind

tehse changes.

• The results are brought into the science-stakehodler interaction of HZG and

CLiSAP.

• About 10 people involved in the ongoing work, which is associated both with

CLiSAP as well as the HGF-programme PACES with AWI.24