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1st INTERNATIONAL ASTRA CONFERENCE“ARE WE PREPARED TO COPE WITH CLIMATIC CHANGE?CONSEQUENCES OF THE WINTER STORM 2005”MAY 18-20, 2006Klaipeda (Lithuania)

Consequences of the winter storm 2005 in Estonia; possible changes in mean and extreme sea levels due to climate change

Ülo Suursaar, Estonian Marine Institute, Univ. of Tartu(ASTRA - Are Kont group)

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Structure of the presentation:

• Gudrun (winter storm 2005) meteorology• Gudrun sea level• Hydrodynamic modelling of Gudrun impacts

• Past sea level trends 1923-05 (aver., max, min) • Influence of climate change on sea level• Influence on hydrodynamic processes• Further sea level developments, return periods__________________________* This on-line version is due to technical considerations a shorter version of the original 39-slide presentation, given at Klaipeda.

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The presentation is based on published/submitted papers:

Suursaar, Ü., Kullas, T., Otsmann, M., Saaremäe, I., Kuik, J., Merilain, M. 2006. Cyclone Gudrun in January 2005 and modelling its hydrodynamic consequences in the Estonian coastal waters. - Boreal Environment Res., 11, 2, 143-159.

Suursaar, Ü., Jaagus, J., Kullas, T. 2006. Past and future changes in sea level near the Estonian coast in relation to changes in wind climate. - Boreal Environment Res., 11, 2, 123-142. [see: http://www.borenv.net]____________________

Tõnisson, H., Orviku, K., Jaagus, J., Suursaar, Ü., Kont, A., Rivis, R. 2006.

Coastal Damages on Saaremaa Island, Estonia, Caused by the Extreme Storm and Flooding on January, 9 2005. – Journal of Coastal Research (submitted).

Suursaar, Ü., Sooäär, J. 2006. Decadal variations in mean and extreme sea level values along the Estonian coast of the Baltic Sea. – Tellus A (submitted).

Suursaar, Ü., Kullas, T. 2006. Influence of wind climate changes on mean sea level and current regime in the coastal waters of West Estonia, the Baltic Sea. – Oceanologia (submitted).

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Cyclone “Gudrun/ Erwin” 09.01.2005, 06.00 UTC

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Cyclone track and SSP (air pressure, Ruhnu)

970

980

990

1000

1010

1020

0 1 2 3 4 5 6 7 8 9 10 11 12

Air

pres

sure

(hP

a)

(a) SSP at Ruhnu (hourly averages)

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New highest surge (+275 cm) in recorded history at Pärnu

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Windforcing:

mean 28 msgusts 38 msSWWNW

Pärnu level response:275 cm(in tideless sea)

0

10

20

30

40

0 1 2 3 4 5 6 7 8 9 10 11Time (days from 1 January 2005)

Win

d s

pe

ed

(m

/s)

0

90

180

270

360

Win

d d

ire

ctio

n (

de

gre

es)

Wind gusts 1h average

(a) Ruhnu wind Wind direction

0

50

100

150

200

250

0 1 2 3 4 5 6 7 8 9 10 11 12

Time (days from 1 January 2005)

Sea

leve

l (cm

)

(b) Pärnu sea level

275 cm, 9 January 2005

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Surge height depends on - background Baltic sea level before the event- cyclone trajectory (i.e. wind speed and direction). For Pärnu the most dangerous trajectories lie between the red arrows.

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2D hindcast modelling of sea level and flows

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2D hindcast modelling of sea level and flows:24 km3 water entered the Gulf of Riga, strong flushing, coastal erosion, etc.

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0

6

12

18

24

0 1 2 3 4 5 6 7 8 9 10 11 12Time (days from 1 Jan. 2005, 00:00 GMT)

Cu

mu

late

d tr

an

spo

rt (

km ³

) .

Irbe St. Suur St.

Soela St. Hari St.

(c) Cumulated flows in the straits

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The areas of potential inundation in Pärnu City (45 000 residents) in case of 1.5, 2.5 and 3.5 m sea level rise.

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Storminess in Estonia (at Vilsandi Island) data compiled by J.Jaagus, see also Suursaar et al., 2006b

0

10

20

30

40

50

1948 1953 1958 1963 1968 1973 1978 1983 1988 1993 1998 2003

Time (years)

Sto

rm d

ays

.

0

5

10

15

20

25

30

Max

. w

ind

spee

d (m

s -1)

b

number of storm days

max. wind speed

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Sea level and surge statistics in EstoniaTide gauges: 3-4 mareographs + tide poles

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Pärnu trends 1923-2005:annual mean, max, min

-120

-60

0

60

120

180

240

300

1920 1930 1940 1950 1960 1970 1980 1990 2000Year

Sea

leve

l (cm

)

Pärnu tide gauge(uplift 1.5 mm/yr)

Mean: rise by trend 9 cm

Max: rise by trend 26 cm

Min: rise by trend 11 cm

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Pärnu trends 1924-03, summer/ wintera Pärnu, Apr.-Oct.

-40

-30

-20

-10

0

10

20

30

1924 1934 1944 1954 1964 1974 1984 1994 2004

Sea le

vel (

cm) .

b Pärnu, Nov.-March

-30

-20

-10

0

10

20

30

40

1924 1934 1944 1954 1964 1974 1984 1994 2004

Sea le

vel (

cm) .

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Ristna trends (West-Estonian Archipelago): summer/ winter Uplift 2.8 mm/yr

c Ristna, Apr.-Oct.

-40

-30

-20

-10

0

10

20

30

1950 1960 1970 1980 1990 2000

Time (years)

Se

a le

vel (

cm)

d Ristna, Nov.-March

-40

-30

-20

-10

0

10

20

30

1950 1960 1970 1980 1990 2000

Time (years)

Se

a le

vel (

cm)

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List of further figures:

•Seasonality in sea level (and NAO) trends•Seasonal structure of correlations: NAO/ Sea level/ Storminess•Seasonal structure of Pärnu max, mean and min sea levels•11 year running averages and corrected linear trendlines•Results of 2D modelled sea levels, Gulf of Riga•Modelled influence of changes in westerlies•Change in flow regime (cumulated fluxes) due to enhanced •S, SW, E winds at Järve (Saaremaa Island): •annual bottom stress could increase 2-3 fold•Return periods based on Pärnu max sea level data 1923-2005

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Pärnu hourly data histogram,

n=369 071, ca 15%=50 000, nout =ca 19h

0.0001

0.001

0.01

0.1

1

10

100

-150 -100 -50 0 50 100 150 200 250Sea level classes (cm)

Pro

babi

lity

(%)

1961-January 2005n=369 071

1961-January 20052 storms (19h) excl.n=369 052

c)

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Thank you