Meteorological tsunamis on Meteorological tsunamis on the Pacific coast of North the Pacific coast of North

AmericaAmerica

Fine I.V.Fine I.V..1,2.1,2, Thomson R.E., Thomson R.E.11 , Rabinovich A.B. , Rabinovich A.B.1,31,3

1 Institute of Ocean Sciences, Sidney, Canada

2 Heat and Mass Transfer Institute, Minsk, Belarus

3 Shirshov Institute of Oceanology, Moscow, Russia

ContentsContents1. Introduction: Tsunamis and meteotsunamis1. Introduction: Tsunamis and meteotsunamis

2. Observations:2. Observations: - 9 December 2005- 9 December 2005 - 13 July 2007- 13 July 2007

- 26 February 2008- 26 February 2008

3. Model: Energetic of the wave generation, major 3. Model: Energetic of the wave generation, major mechanisms and effectsmechanisms and effects

4. Conclusions4. Conclusions

“Rissaga” waves in Ciutadella Harbour (Menorca I.) 15 June 2006

More than 40 damaged boats. Total loss: ~ 30 mln euros.

(Montserrat, Vilibic, and Rabinovich, 2006)

Vela Luka, Croatia, 21 June 1978

134 o 132 o 130 o 128 o 126 o 124 o 122 o

46 o

48 o

50 o

52 o

54 o

Prince RupertLangara

Bella Bella

Port Hardy

Winter Harbour

Pacific Ocean Neah Bay

Seattle

Tacoma

Victoria

La Push

Patricia Bay

Point Atkinson

Tofino

Longview

British Columbia

WA

La Push

Neah BayVictoria

Tacoma

Longview

Seattle

BamfieldPat. Bay

Tofino

Observational sites on the coast of British Columbia and Washington State

December 2005

Friday Harbor

Tacoma

Cherry Point

Toke Point

09/12 06 121812

Seattle

Port Townsend

Port Angeles

Neah Bay

10 c

m

WA Stations

6-min data

Sea

leve

l

Tsunami-like event recorded on 9 December 2009 on the coast of British Columbia

There were no seismic activity nor strong storm in the region.

December 2005

09/1206 12 18

La Push

Se

a le

vel (

cm)

06 12 18 10/12 06

-5

5

0

1

-1

0

2

Air

pre

ssur

e (h

Pa

)

1035

1030

1025

1020

Re

sid

ual

air

pre

ssur

e (h

Pa

)

Original

Residual

Later we found an atmospheric pressure record at La Push showing that the event was forced by an abrupt jump of atmospheric pressure (~2 mb).

12 13 14 15July 2007

Seattle (WA)

Patricia Bay (BC)

Neah Bay (WA)

Port Angeles (WA)

Victoria (BC)

Friday Harbor (WA)

Cherry Point (WA)

10

cmS

ea

leve

l All records have a clear arrival time.

Sea level

Tsunami-like event on 13 July 2007 recorded at tide gages of the WA and BC coast in the Golf area.

12 13 14 15July 2007

Seattle (WA)

Patricia Bay (BC)

Neah Bay (WA)

Port Angeles (WA)

Victoria (BC)

Friday Harbor (WA)

Cherry Point (WA)

10

cmS

ea

leve

l

12 13 14 15July 2007

1010

1015

1020

5 hP

aA

tmo

sph

eri

c p

ress

ure

(h

Pa)

(a)

(b)

T34

Seattle

Tacoma

Longview

Neah Bay

La Push

T31

T18

T20

All records have a clear arrival time.

Atmosphreric disturbances were on nigth time of 13 July and repeated on 15 July 15 with less intersity.

Sea level Atmospheric pressure

Tsunami-like event on 13 July 2007 recorded at tide gages of the WA and BC coast in the Golf area.

Strait of Georgia

VancouverIsland

PB11:26

Vic11:06

SaanichInlet

Thetis I

TI~12:00

Juan de Fuca Strait

49°N

48'

36'

24'

12'

124°W 123°W12' 24' 36' 48' 09 12 15

Time (UTC hrs)

13/07/200711:26

11:06

Se

a le

vel

10

cm

Patricia Bay (BC)

Victoria (BC)

(b)(a)

We analyzed atmospheric pressure records and found the event was forced by disturbance moving northward with speed about 23 m/s

-10h -8h -6h -4h -2h 0h 2h 4h 6h 8h 10h

Time of July 13, 2007

1200

1300

1400

1500

1600

1700

1800

1900

Pre

ssur

e, (

kPa-

1000

)*10

0

a62a134a228a62

2h 3h 4h 5h 6h

Time of July 13, 2007

1300

1400

1500

1600

1700

1800

Pre

ssur

e, (

kPa-

1000

)*10

0

Additional high resolution microbarograph records in the Greater Victoria Area confirmed the previous estimates.

10h 11h 12h 13h

T ime of July 13, 2007, GMT

170

180

190

Pa

tba

y

-1000

0

1000

2000

a124

Comparison of the tide gauge record at Patricia Bay and atmospheric pressure record at the nearby microbarograph station.

Sea level and atmospheric variations started almost simultaneously

The direction and the speed of the moving atmospheric disturbances are in good agreement with the direction and speed of the jet stream in the area of interest.

25 26

February, 2008

Tofino (BC)

Patricia Bay (BC)

Neah Bay (WA)

Port Angeles (WA)

Victoria (BC)

Friday Harbor (WA)

Cherry Point (WA)

20 c

mS

ea le

vel

Point Atkinson (BC)

27 28 29 30Time (hours)

1028

1029

1030

1031

1032

Pre

ssur

e(m

b)

LAPW1_BNEAH_BSEATTLE_BTACOMA_B

02 04 06 08 10 12

Tsunami-like event on 26 February 2008 recorded at tide gages of the WA and BC coast in the Golf area.

The direction (toward east-north) and the speed (~30 m/s) of the moving atmospheric disturbances are also in good agreement with direction and speed of the jet stream in the area of interest.

ModelModel

Similarly to a seismological tsunami, a Similarly to a seismological tsunami, a meteotsunami is forced by a term in the mass meteotsunami is forced by a term in the mass conservation equation conservation equation

tP

gh

t

gt

A

1)( u

u),( yxPA

),,( tyx

Energy generationEnergy generation

dxdyhgE

dxdytP

tE A

22

21

u

Wave energy is generated due to the hysteresis effect.

In a stationary case, when the atmospheric disturbance moves with a constant velocity, the wave energy is not generated.

However, in a non-stationary case the energy is generated permanently feeding propagating waves.

Proudman resonanceProudman resonance

gh

UF

FF

gP

UtxPP

A

AA

,1

)(

2

20

0

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

F

n=8n=4n=2

edisturbancofscalel

widthbaL

lLn

sin

/

Bathymetry map of the central part of the area

“Supersonic” (red) and “subsonic” (blue) areas for U=30 m/s

The areas of the active energy generation

30 m/s20 m/s

Meteotsunami modelling: The disturbance moves to the north

-3

-2

-1

0

1

2

3

Pat Bay

v=60 km/h, T=10 min

-3

-2

-1

0

1

2

3

Sidney

-3

-2

-1

0

1

2

3

Victoria

0 1 2 3 4 5-3

-2

-1

0

1

2

3

Sooke

-3

-2

-1

0

1

2

3

Pat Bay

v=60 km/h, T=20 min

-3

-2

-1

0

1

2

3

Sidney

-3

-2

-1

0

1

2

3

Victoria

0 1 2 3 4 5-3

-2

-1

0

1

2

3

Sooke

Simulated records at specific locations

-50 -40 -30 -20 -10 0 10 20 30 40 50-50

-40

-30

-20

-10

0

10

20

30

40

50

00.050.10.150.20.250.30.350.40.450.50.550.60.650.70.750.80.850.90.951

The total generated energy (over the entire region) is nearly isotropic. The atmospheric speed is the major factor

The simulated energy as function of atmospheric parameters

ConclusionsConclusions 1. Meteotsunamis are relatively frequent phenomena on 1. Meteotsunamis are relatively frequent phenomena on

the west coast of the US and Canada.the west coast of the US and Canada. 2.Meteotsunami in the area are mainly caused by fast 2.Meteotsunami in the area are mainly caused by fast

moving (20 – 30 m/s) atmospheric disturbances of 1-3 moving (20 – 30 m/s) atmospheric disturbances of 1-3 mb with periods of ~5 min – 2 hrs.mb with periods of ~5 min – 2 hrs.

3. High atmospheric activity (small-scale disturbances 3. High atmospheric activity (small-scale disturbances and buoyancy waves) may last hours and even days. and buoyancy waves) may last hours and even days. The speed and direction of the disturbances correlate The speed and direction of the disturbances correlate well with the speed and direction of the atmospheric jet well with the speed and direction of the atmospheric jet stream.stream.

4. Mountains and instability conditions (occurring mainly 4. Mountains and instability conditions (occurring mainly the night time in summer) are additional important the night time in summer) are additional important factors stimulating the process.factors stimulating the process.

5. The efficiency of the wave energy generation is 5. The efficiency of the wave energy generation is related to the Proudman resonance; with the related to the Proudman resonance; with the atmospheric disturbance speed of 20-30 m/s most atmospheric disturbance speed of 20-30 m/s most of energy is generated at depths of 40-90 m.of energy is generated at depths of 40-90 m.

6. The direction and peak period of the atmospheric 6. The direction and peak period of the atmospheric disturbance propagation are the secondary factors disturbance propagation are the secondary factors influencing the total amount of energy generated in influencing the total amount of energy generated in the area. For some sites these factors can play the the area. For some sites these factors can play the crucial role. crucial role.

Thank you!Thank you!