8-ix-2005 SAMS and DAMTP 2004-05 1

SEA ICE AND POLAR OCEANOGRAPHY GROUP

Review 2004-05

8-ix-2005 SAMS and DAMTP 2004-05 2

Staff

• SAMSDunstaffnage Marine Laboratory

– Jeremy Wilkinson– Nick Hughes– Martin Doble

• DAMTPCentre for Mathematical SciencesUniversity of Cambridge

– Peter Wadhams– Joao Rodrigues– Arthur Kaletzky– Olivia Low

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2004-05

• Arctic submarine fieldwork

• Autosub Under Ice– JR106a East Greenland– JR97 Weddell Sea

• GreenICE

• IRIS– Baltic Sea ice fieldwork

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Arctic Submarine Fieldwork

• Royal Navy ICEX-04• Submarine HMS Tireless• April 2004• Sea ice thickness and oceanography• Investigated:

– Greenland Sea• CONVECTION chimney

– Fram Strait• Molloy Deep Eddy• Marginal Ice Zone

– Arctic Ocean• Morris Jessup Rise• Lincoln Sea and Ice Station SAMS (GreenICE)• North Pole

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Measuring Ice Thickness• Upward

echosounders– Forward– Fin– Stern

• Sidescan• Forward Look

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Preliminary Ice Thickness 85°N

Ice Draft 85°N Transit

y = -0.06x + 2.8511R2 = 0.5189

0

5

10

15

20

25

30

35

-70 -60 -50 -40 -30 -20 -10 0 10

Longitude

Dra

ft m

Ice Draft 10-point movavg 25-point movavg 5-degree average

Superb 87 Avg Superb 87 Max Linear (25-point movavg)

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Atlantic Water Depth 85°N

Atlantic Water Depth (0° Isotherm)

150

200

250

300

-70 -60 -50 -40 -30 -20 -10 0 10

Longitude

Dep

th

1989

1984

1979

Wader

ICEX-04

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Remote Sensing Validation

• Envisat ASAR– Scenes coincident

with submarine track

• Passive microwave cluster analysis– Alternative method

for obtaining polar synoptic sea ice thickness

8-ix-2005 SAMS and DAMTP 2004-05 9

Use of MODIS to validate ASAR interpretation

• Cloudy over area of interest at 82°N on 1 April 2004

• However possibility of cloud-free comparison on other days or areas– Similar ASAR

dataset from ice edge at 78°N

8-ix-2005 SAMS and DAMTP 2004-05 10

GreenICEGreenICE seeks to measure and understand the changes that have occurred in sea ice north of Greenland, in response to a reversal in the Arctic Oscillation (AO). This response will be related to past changes, as determined from sediment cores, placing them in the context of natural climate variability. Benefits will include a better understanding of Europe’s medium-term climate prospects and a better understanding of ice conditions in the Arctic Ocean, past, present and future.

• Co-ordinated by SAMS•Pilot experiments from RV Polarstern and Beaufort Sea ice camp (APLIS) 2003•Main ice camp experiment May 2004•Combined buoy monitoring with sediment coring (GEUS) and remote sensing

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Wave Measuring Buoys

Solar panel

Iridium antenna

GPS antennae4m apart to givereliable headingclose to magneticPole

8-ix-2005 SAMS and DAMTP 2004-05 12

Ice Station SAMS

• Ice camp– May 2004– 85°N 62°W– Full scientific programme

• Sediment cores• Ice thickness measurement

Location of GreenIce buoys

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Buoy Drift Data

Tracks of GreenICE buoys from launch (date shown) to 10 Nov 04.

Dots indicate buoy positions on the first of each month

Buoy 3 was startedwhen the campwas abandoned

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IRISIce Ridge Information System

• The overall strategy is to develop ice modelling and SAR interpretation so that ridging parameters are obtained, to include the parameters into systems of ice information delivery, to relate the parameters to the trafficability of ships, and finally develop methods to apply the enhanced ice information in routeing and decision making during marine operations.

• Field work on ridge structures in Baltic 2004 and 2005

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Big Ridge

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Big Ridge – Ice Thickness

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Big Ridge - Freeboard

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Small Ridge

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Small Ridge – Ice Thickness

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Rubble Field

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Autosub Under Ice

• August 2004 RRS James Clark Ross sailed to the Belgica Bank

• Sensors: Multibean Sonar, ADCP and Seabird 911

Mission Length CumulativeNo. km Length km361 12.48 12.48362 14.60 27.08363 45.54 72.62364 42.63 115.25365 148.51 263.76366 70.42 334.18367 108.06 442.24368 16.47 458.71

8-ix-2005 SAMS and DAMTP 2004-05 23

North East Water Polynya

78 oN

79 oN

80 oN

81 oN

82 oN

Lat

itu

de

18oW 15oW 12oW 9oW 6oW 3

oW

Longitude

M361

M362M363-5

M366

M367-8

Nor

ske

Tro

ugh

Bel

gica

Ban

k

Ob Bank

Westwind Trough

NØIB

-500

-450

-400

-350

-300

-250

-200

-150

-100

-50

0

Longitude

Latit

ude

-4000

-4000

-3500

-3500

-3500

-3500

-30

00

-3000

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-3000

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-3000-30

00

-2500

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0-5

00

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-30

0-3

00

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-300-20

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00

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0 -4000

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0-5

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-500

18oW 15oW 12oW 9oW 6oW 3oW

78oN

79oN

80oN

81oN

82oN

1

234

567

89

1011

1213

1415

16171819

20

Bathymetry of the study area. CTD locations are shown for JCR106a (blue ‘*’, 1-19), and historical data 1993 (red ‘*’, courtesy G. Budeus) and 1979 (green , ‘*’, courtesy T. Wen).

MODIS visual image from 12 August. The bathymetry of the study area and Autosub II runs are shown.

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Currents Beneath The NØIB

Vertical section of northwards current velocity (bottom) and ice draft (top) from Mission 365 (east to west) beneath the NØIB. Previous and new estimate of bathymetry shown. A-D indicate multibeam plots in next slide.

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Under Ice Images From EM-2000

Ice draft from Autosub-II multibeam sensor. Examples of a) Along-track ridge system,

c) Lead through fast ice and

a) b)

c) d)

b)Transition from across-track ridge system to ‘level’ iced) Fast ice (after a summer melt season).

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Validating AUV Ice ThicknessStation 3: Line 3 - Ridge

-300

-250

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-50

0

50

100

0 10 20 30 40 50

Distance m

Th

ickn

ess

cm

Draft Freeboard Snow

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Validating AUV Ice Thickness

Collaborative programme with AWI. Run Autosub under the ice and ground truth using different techniques.

• Ground EM

• Airborne EM

• Wave measurements

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Probability Density FunctionBy combining the autosub measurements of currents (ADCP) with the ice draft (multi-beam) we can see that the northward flowing current, North East Greenland Coastal Current (NEGCC) has a different ice regime to the southward flowing East Greenland Current (EGC).

-5 -4 -3 -2 -1 0 10

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

Draft (m)

Pro

babi

lity

All draft data (0 to 68 km)Ice region 1 (0 to 30 km)Ice region 2 (30 to 68 km)

PDF of ice draft during:

Entire run in: 0 to 64 km

Through the EGC: 0 to 30 km

Through the NEGCC: 30 to 64 km

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Autosub: Conclusions

The combination of scientific instruments on board Autosub has allowed us to investigate both the sea ice and oceanographic properties of the North East Water Polynya (NEW). Major insights include:

• First mapping of the topography under the ice barrier (NØIB). This barrier is instrumental in the formation of the NEW!

• First continuous current and oceanographic measurements of the region.

• First measurements of the bathymetry of the region. This has shown significant errors in the existing charts.

Autosub’s unique abilities have led to the successful interaction between scientists and the Autosub team through the NERC funded Autosub Under Ice programme. This has produced important groundbreaking science.

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Venue For Next Meeting?

• Dunstaffnage Marine LaboratoryOban, Scotland

• Friday 15 September 2006

• Coincides with the Challenger Society meeting at SAMS that week