Observations of Storms off the West Coast in 2012 from Seafloor Data
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Observations of Storms off the West Coast in 2012 from Seafloor Data David Atkinson, UVic Dept. of Geography Steve Mihaly, ONC Dilumie Abeysirigunawardena, ONC Martin Heesemann, ONC 2013 CSAS State of Ocean Workshop February 20, 2013. Series of storm events, Jan 19 – 26, 2012:

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Observations of storms off the west coast in 2012 from seafloor data


Observations of storms off the west coast in 2012 from seafloor data

  • Series of storm events, Jan 19 – 26, 2012: Seafloor Data

  • Synoptic overview

  • La Perouse traces

  • ONC Folger Passage (Deep) data:

    • surface waves

      • Start with annual variance and comparison, 2011 vs 2012

        • BPR power spectra trace, late summer period

      • spring period close-up

      • storm period close-up

    • ADCP currents

      • storm event response

    • oxygen

      • storm event response


Observations of storms off the west coast in 2012 from seafloor data


Observations of storms off the west coast in 2012 from seafloor data

January 19 2012 00Z Seafloor Data

  • Typical progression:

  • - “parent” system moves off jet

  • into GoA

  • Dynamically linked systems

  • generated, moved towards

  • coast and to NE

  • -Support from aloft =

  • rapid increases in strength

M


Observations of storms off the west coast in 2012 from seafloor data

January 19 2012 06Z Seafloor Data

  • La Perouse Bank buoy

  • Direction

  • Wspd,Hs

M

6,4


Observations of storms off the west coast in 2012 from seafloor data

January 19 2012 12Z Seafloor Data

M

10,4


Observations of storms off the west coast in 2012 from seafloor data

January 19 2012 18Z Seafloor Data

M

7,3

1


Observations of storms off the west coast in 2012 from seafloor data

January 20 2012 00Z Seafloor Data

M

6,2.5

1


Observations of storms off the west coast in 2012 from seafloor data

January 20 2012 06Z Seafloor Data

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1

11,3


Observations of storms off the west coast in 2012 from seafloor data

January 20 2012 12Z Seafloor Data

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1

15,3


Observations of storms off the west coast in 2012 from seafloor data

January 20 2012 18Z Seafloor Data

M

1

15,4


Observations of storms off the west coast in 2012 from seafloor data

January 21 2012 00Z Seafloor Data

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1

16,5


Observations of storms off the west coast in 2012 from seafloor data

January 21 2012 06Z Seafloor Data

960

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1

12,4

2


Observations of storms off the west coast in 2012 from seafloor data

January 21 2012 12Z Seafloor Data

960

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1

11,4

2


Observations of storms off the west coast in 2012 from seafloor data

January 21 2012 18Z Seafloor Data

M

11,5

2


Observations of storms off the west coast in 2012 from seafloor data

January 22 2012 00Z Seafloor Data

M

10,6

2


Observations of storms off the west coast in 2012 from seafloor data

January 22 2012 06Z Seafloor Data

M

11,6

2


Observations of storms off the west coast in 2012 from seafloor data

January 22 2012 12Z Seafloor Data

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2

977

18,6


Observations of storms off the west coast in 2012 from seafloor data

January 22 2012 18Z Seafloor Data

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977

2

20,7

3


Observations of storms off the west coast in 2012 from seafloor data

January 23 2012 00Z Seafloor Data

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2

977

22,9

3


Observations of storms off the west coast in 2012 from seafloor data

January 23 2012 06Z Seafloor Data

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2

10,7

3


Observations of storms off the west coast in 2012 from seafloor data

January 23 2012 12Z Seafloor Data

M

7,6

4

3


Observations of storms off the west coast in 2012 from seafloor data

January 23 2012 18Z Seafloor Data

M

4

9,4

3


Observations of storms off the west coast in 2012 from seafloor data

January 24 2012 00Z Seafloor Data

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4

5

10,4


Observations of storms off the west coast in 2012 from seafloor data

January 24 2012 06Z Seafloor Data

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4

5

14,4


Observations of storms off the west coast in 2012 from seafloor data

January 24 2012 12Z Seafloor Data

M

4

5

14,6


Observations of storms off the west coast in 2012 from seafloor data

January 24 2012 18Z Seafloor Data

4

967

5

972

13,6


Observations of storms off the west coast in 2012 from seafloor data

January 25 2012 00Z Seafloor Data

4

964

968

5

12,5


Observations of storms off the west coast in 2012 from seafloor data

January 25 2012 06Z Seafloor Data

4

964

5

968

15,6


Observations of storms off the west coast in 2012 from seafloor data

January 25 2012 12Z Seafloor Data

4

5

10,8


Observations of storms off the west coast in 2012 from seafloor data

January 25 2012 18Z Seafloor Data

5

4

8,8


Observations of storms off the west coast in 2012 from seafloor data


Observations of storms off the west coast in 2012 from seafloor data

Max sustained wind ~23m/s Seafloor Data

(gust 30m/s)

Wave height peaks >8m

Note direction shifts



Observations of storms off the west coast in 2012 from seafloor data

Annual: 2011 variance

log


Observations of storms off the west coast in 2012 from seafloor data

Annual: 2011 variance

log

More energetic,

more variable

winter season

Less energetic/variable

summer season


Observations of storms off the west coast in 2012 from seafloor data

Annual: 2011 variance

log

February – activity appeared to be winding down

- Kicked back in for an active March


Observations of storms off the west coast in 2012 from seafloor data

Annual: 2012 variance

log


Observations of storms off the west coast in 2012 from seafloor data

Annual: 2012 variance

Similar in general form to 2011 – winter active, summer quieter

log


Observations of storms off the west coast in 2012 from seafloor data

Annual: 2012 variance

Timings – 2011 winter ended fairly suddenly; 2012 dragged out

log


Observations of storms off the west coast in 2012 from seafloor data

Annual: 2012 variance

Timings – both years – late July/August very quiet, September sees increasing activity

log

July/Aug.

Sept.


Observations of storms off the west coast in 2012 from seafloor data

First three weeks of September 2012 locally were (very) storm free

Observed energy can not be local.


Observations of storms off the west coast in 2012 from seafloor data

Use a running spectral power plot of Folger BPR data to assess wave dispersion

- angled tracks between 25s-10s indicate long period waves arriving well before shorter

= wave trains pumped out by distant storms

Relative

power

Wave

Period

Sept 1

2012

Sept 7

2012

Sept 14

2012

Sept 21

2012


Observations of storms off the west coast in 2012 from seafloor data

Annual: 2012 assess wave dispersion

Late Jan. Stormy period – most active single week in 2012

log


Observations of storms off the west coast in 2012 from seafloor data

Spring: 2011 assess wave dispersion

Closer look at variance traces for stormy period

log

spring

JAN 01

FEB 01

MAR 01


Observations of storms off the west coast in 2012 from seafloor data

Spring: 2011 assess wave dispersion

log

spring

  • Note pattern – waves often exhibit rapid onset, slow decline

  • Cordillera blocks eastern progression of storms

  • move in fast, but stall and die slowly

JAN 01

FEB 01

MAR 01


Observations of storms off the west coast in 2012 from seafloor data

Spring: 2011 assess wave dispersion

log

spring

  • Note pattern – waves often exhibit rapid onset, slow decline

  • Cordillera blocks eastern progression of storms

  • move in fast, but stall and die slowly

JAN 01

FEB 01

MAR 01


Observations of storms off the west coast in 2012 from seafloor data

Spring: 2011 assess wave dispersion

log

spring

Can also observe fairly regular synoptic timing

3 – 7 days between events in mid-latitudes at this time of year

JAN 01

FEB 01

MAR 01


Observations of storms off the west coast in 2012 from seafloor data

Spring: 2012 assess wave dispersion

Similar general pattern but a higher level of activity persisted

- no February slow-down as in 2012

log

spring

Storm period

JAN 01

FEB 01

MAR 01


Observations of storms off the west coast in 2012 from seafloor data

Stormy period: Jan 19-27, 2012 assess wave dispersion

Three peaks in local activity, two major (22-23rd and 26th)

log

storms

JAN 18

JAN 21

JAN 24



Observations of storms off the west coast in 2012 from seafloor data

Stormy period: Jan 19-27, 2012 assess wave dispersion

ADCP current vector data, daily averages, filtered

North

South

East

West


Observations of storms off the west coast in 2012 from seafloor data

Stormy period: Jan 19-27, 2012 assess wave dispersion

Direction maintained,

Speed dropped off

ADCP current vector data, daily averages, filtered

North

South

Rapid wind shift

Bottom return

current

East

West


Observations of storms off the west coast in 2012 from seafloor data

Stormy period: Jan 19-27, 2012 assess wave dispersion

ADCP current vector data, daily averages, filtered

Upper ~40m

entrained during

these events

North

South

Possible Barkley

Sound outflow?

East

West



Observations of storms off the west coast in 2012 from seafloor data

Stormy period: Jan 19-27, 2012 assess wave dispersion

Oxygen data at 94m


Observations of storms off the west coast in 2012 from seafloor data

Stormy period: Jan 19-27, 2012 assess wave dispersion

Oxygen data at 94m compared with ADCP vector currents


Observations of storms off the west coast in 2012 from seafloor data

Stormy period: Jan 19-27, 2012 assess wave dispersion

Presumably return flow at depth draws from oxygenated upper flow

Oxygen data at 94m compared with ADCP vector currents

Upwelling?

(SE flow)


Observations of storms off the west coast in 2012 from seafloor data

Summary assess wave dispersion

- 2012 – surface forcing from Folger BPR:

- more active and longer winter/spring

- quiet mid-July/Aug,

- Sept showed activity due to distant storms

- Strong storm period in late Jan

- Folger data show in general

- very high resolution overview of wave activity

- spectral tracks great for ID storm distance

- depth of entrainment of surface water

- indications of overturning flow due to storm-surge forcing/

interactions with Barkley Sound and bathy

- resulting oxygenation at depth

- short lived upwelling events ?


Observations of storms off the west coast in 2012 from seafloor data


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