Winter Lead Convection

The Study of Environmental Arctic Change (SEARCH) and the Barrow

Cabled Observatory

Presentation at Science and Education Opportunities for an Arctic Cabled Seafloor Observatory

February 7-8, 2005

Jamie Morison Polar Science Center, University of Washington

morison@apl.washington.edu

SEARCH Motivation

The Arctic has been characterized in recent decades by a complex of

significant, interrelated, pan-Arctic changes (Unaami).

Examples• Decreased sea level atmospheric pressure,• Increased air temperature over most of the Arctic, • More cyclonic ocean circulation and rising coastal sea level,• Warmer Atlantic waters, • Reduced sea ice cover,• Warming of permafrost• The physical changes of Unaami impact ecosystems and society.

Complex of change appears related to a spin up of the Northern Hemisphere atmospheric Polar Vortex.

Complex of Arctic change is a possible component of climate change.

Motivates a program of long-term observations, analysis, and modeling

Implementation Strategy at SEARCH Web site:Implementation Strategy at SEARCH Web site:http://psc.apl.washington.edu/search/index.html

Current Activities atCurrent Activities athttp://psc.apl.washington.edu/search/Activities/activities.html

Eight SEARCH Activities Areas include:Eight SEARCH Activities Areas include:- DTO: Distributed Terrestrial Observatories - DMO: Distributed Marine Observatories- LAO: Large-scale Atmospheric Observatories- DQU: Detecting and Quantifying Unaami and Other Modes of Variability- LGC: Linkages and Global Coupling- ASR: Arctic System Reanalysis- SEI: Social and Economic Interaction- SOR: Social Response

SEARCH ImplementationSEARCH Implementation

Distributed Terrestrial ObservatoriesDistributed Terrestrial ObservatoriesRussia

Nor

AlaskaEureka

Alert

Greenland

Canada

Thule

Tiksi

Arcic Ocean

Distributed TerrestrialObservatories

Kolyma R

Lena R

Ob R

Mackenzie R

Yukon R

Yenisey R

x

x

x

x

x

x

x

x

x x

x

x

x

xx

x Extensive Site

Intermediate Site(e.g., ITEX, CEON)

Intensive Site

Barrow

Cherksiy

Svalbard

Resolute

Abisko

BonanzaToolik

Large-scale Atmospheric ObservatoriesLarge-scale Atmospheric Observatories

Norway

Greenland

Canada

Thule

Resolute

AbiskoKolyma R

Lena R

Ob R

Mackenzie R

Yukon R

Yenisey R

Cherksiy

Large-scale AtmosphericObservatoriesAlaska

Russia

Eureka

IABP Drifting BuoysAutomated Drifting Stations

DTO Intensive SiteDTO Intermediate Site

x DTO Extensive Site

x

x

x

x

x

x

x

x

x x

x

x

x

xxBonanza

Toolik

GCOS - GTOSGCOS - GTOSRemote Sensing, e.g. TOVSRemote Sensing, e.g. TOVS

AlertAlertBarrowBarrow

SvalbardSvalbard

Major Weather StationsMajor Weather Stations

TiksiTiksi

DTO Sites

DMO: Distributed Marine Observatories

Make large-scale atmospheric, oceanographic, sea ice and ecosystem observations in the marine environment.

SEARCH Implementation Strategy available at SEARCH Implementation Strategy available at http://psc.apl.washington.edu/search/index.htmlhttp://psc.apl.washington.edu/search/index.html

Distributed Marine ObservatoriesDistributed Marine Observatories

Norway

Eureka

Alert

Greenland

Canada

Thule

Barrow

Svalbard

Resolute

AbiskoKolyma R

Lena R

Ob R

Mackenzie R

Yukon R

Yenisey R

RussiaTiksi

Cherksiy

Distributed MarineObservatories

IABP Drifting Buoys

2

34

5

10

6

7

8

11

12

1

Ocean Pathway Moorings

9

13

15

14

16

Cross Shelf Exchange Moorings

17

20

19

18

Basin Moorings

21

22

23

24

25

Gateway Moorings

42

41

43

4445

46

Shelf Moorings & Surveys

26

27

28

29

30

31

32

33

35

34

3337

36

Clic Hydrographic SectionsOther Sections

ASOF Hydrographic Sections

38

39

40

Automated Drifting StationsUpward Looking Sonars

DMO Philosophy

Scales are pan-Arctic and decadal. Therefore the DMO emphasis is on:

And because startup is urgent: - Use of proven, existing technologies

- Basin-wide coverage- Long, relatively low res time-series

So, what role can a high-tech, high-bandwidth cabled observatory at

Barrow have in DMO?

Two DMO elements near Barrow:

• Ocean pathway moorings

• Cross shelf exchange moorings

Role for high-bandwidth, localized measurements particularly in

• Cross shelf exchange mooring function of DMO, and

• The Linkages and Global Coupling (LGC) activity area

Processes in the shelf and slope region are important to ventilation of the deep ocean, e.g.

These processes tend to be intermittent and spatially variable.

• Generation of eddies that move into the basin

• Cross shelf exchange driven by buoyancy flux in the Seasonal Ice Zone (SIZ) and winter shore leads and polynyas

AIDJEX Lead Experiment, 1974

Indication of cross-shelf exchange

Example of bottom boundary layer generated by Barrow shore lead (ALEX, 1974)

Consider buoyancy flux and cross shelf exchange.

WIND MOVES PACK ICE AWAY FROMSHOREFAST ICE

HALINE CONVECTIONSHELF BREAK FRONT

SHORE LEAD

SHOREFAST ICE

+

Consider buoyancy flux and cross shelf exchange.

These processes create density structure parallel to shore and cross shore pressure gradients, which drive alongshore currents.

WIND

WIND SWEEPS NEW ICE OFFSHORE

HALINE CONVECTIONSHELF BREAK

FRONT

COASTAL POLYNYA

+

So where does cross-shelf exchange occur?

In the surface and bottom boundary layers where flow moves down pressure gradient.

WIND

WIND SWEEPS NEW ICE OFFSHORE

HALINE CONVECTIONSHELF BREAK

FRONT

COASTAL POLYNYA

+

How would we use the BCO to measure shelf processes?

Shore Lead

Convective Plume

SalinityProfile

BottomBoundaryLayer

Monitoring Winter Shelf Convection With the BCO

Pack Ice Fast Ice

Fixed CTD, ABPR, ADCP, ULS Cable

Turbulent InstrumentCluster "Pods"

ROV Hangar

Instrumented ROVServicing Arrays

AUV HangarAUV NavXponders

AUV NavXponders

AUV

Iridium, Met SensorsHoming Beacon

Supercoolometer:Seamore ROV

SBE 39 T Probe

Heater

SBE-19+Temperature & Conductivity

Optical Backscatter

Water In

JAMSTEC UROV 7k Remotely Operated

Vehicle

Battery OperatedFiber Optic Link

KAIKO Hanger

UROV

QuickTime™ and aDV/DVCPRO - NTSC decompressor

are needed to see this picture.

TIC

SonTekADVOcean (5 MHz)

SBE 03 thermometer

SBE 07 micro-conductivity meter

SBE 04 conductivitymeter

SonTek Instrument Cluster

.

8

IceT-string

ROV-CTD

0.6 m

1 m

Van Mijen Fjord Instruments

Miles McPhee Turbulent Inst Cluster

Autonomous Flux Buoy

Tim Stanton Flux Buoy

The Autonomous Microconductivity-Temperature Vehicle (AMTV)

1.6 m

Weight = 36.2 kgSpeed = 1.0-1.6 m/s

Micro T and C SensorsAltimeter

Autonomous Micro-conductivity Temperature Vehicle (AMTV)

RecoveryBarb

HomingHydrophones

Tracking Hydrophone

Figure 1. The AMTV during testing at the SHEBA Ice Station, August, 1998.

QuickTime™ and aDV/DVCPRO - NTSC decompressor

are needed to see this picture.

AMTV

AMTV Results SHEBA Summer Lead Study, Day 219.9

Under Lead

S constant?

Cooler

Back Toward Ice

Warmer

FresherS constant &S’ small

Cooler &T’ small

Under Ice

From Hayes Dissertation, 2003

AMTV Turbulence on 219.9

S’ and T’ Vigorous Under Lead

Turbulence Significant Under Lead

S’ and T’ Reduced Under Ice

Turbulence EnhancedUnder Ice? Lower Frequency

From Hayes Dissertation, 2003

AMTV Turbulent Fluxes on 219.9, 1998 at SHEBA Summer Lead

Turbulent Stress, u*=()1/2, Increased Under Ice

From Hayes Dissertation, 2003

98 W m-2 144 W m-2

Substantial Turbulent Heat and Salt Flux in the Lead, Reduced Fluxes Under Ice

2.4x10-5 kg m-2 s-11.7x10-5 kg m-2 s-1 1.9x10-5

Conclusions:

The BCSO can play an important part in SEARCH.

Focus as an intensive observing point for shelf-basin processes critical for the large scale behaviour of the marine environment

The End