ISPOL Ocean Turbulence Project Miles McPhee McPhee Research Co. Naches WA USA.

ISPOL Ocean Turbulence Project

Miles McPhee

McPhee Research Co.

Naches WA USA

Objectives

Characterize exchanges at or near the ice/ocean interface, representative of the entire ISPOL floe.

Pertinent variables include:

• Turbulent stress

• Turbulent heat flux

• Turbulent salt (salinity) flux

• The ocean velocity profile, including an estimate of geostrophic flow

• Eddy exchange factors for momentum and scalar variables: eddy viscosity/eddy diffusivity

SonTek ADVOcean (5 Mhz)

SBE 03 thermometerSBE 07 microstructureconductivity meter

SBE 04 conductivity meter

SonTek Instrument Cluster

-20 -10 0 10 20

-40

-30

-20

-10

0

10

20

30

40

333 337

341

345

349

353

357

361

365

km East

km N

ort

h

(28 Nov 04)

(30 Dec 04) 67 30'S

68 S

55 W 55 30'W Two methods used for fitting ship GPS

positions to a differentiable function to obtain velocity:

(1) Polynomial fit: all 5-min position vectors in a 1-h time window centered at even half-hour intervals were converted to complex numbers and least-squares fitted to complex second-order polynomial. The derivative provides a continuous velocity record.

(2) Complex demodulation: fits all of the data over a 1-day time window to a position function including mean velocity and clockwise and anticlockwise oscillating components at the inertial and diurnal frequencies. Done every 90 minutes

335 340 345 350 355 360-0.2

-0.1

0

0.1

0.2

1.7 cm/s

V (north) ice velocity, Phase A

m s

-1

335 340 345 350 355 360

-0.2

-0.1

0

0.1

-1.5 cm/s

U (east) ice velocity, Phase A

Day of 2004 (335=30 Nov)

m s

-1

Polynomial fit

complex demod fit

361 362 363 364 365 366 367 368

-0.1

0

0.1

0.2

7.5 cm/s

V (north) ice velocity, Phase B

m s

-1

361 362 363 364 365 366 367 368

-0.1

0

0.1

0.2

0.3

1.5 cm/s

U (east) ice velocity, Phase B

Day of 2004 (367=1 Jan 2005)

m s

-1

Polynomial fit

complex demod fit

335 340 345 350 355 360

-10

-5

0

5

10

cm s

-1

Day of 2004

Eastward tidal components

335 340 345 350 355 360

-10

-5

0

5

10

cm s

-1

Northward tidal components

<VK1

>: 4.2 cm/s; <VM2

>: 2.6 cm/s

M2

K1

These are tidal components in the ice motion– they correspond to the ocean tidal current only if the ice drifts passively with the tide.

340 345 350 355 360 3650

2

4

6

8

10

12

Day of 2004

m s

-1

Ship Wind/Ice Speed Comparison

1.5%

Wind Speed

Mean ice speed*50

345 346 347 348 349 350 351 352-0.1

0

0.1

0.2Northward absolute velocity

345 346 347 348 349 350 351 352-0.2

-0.1

0

0.1

0.2

Day of 2004

Eastward absolute velocity

U20

Uice

V20

Vice

356.5 357 357.5 358 358.5 359 359.5 360 360.5-0.2

-0.1

0

0.1Northward absolute velocity

356.5 357 357.5 358 358.5 359 359.5 360 360.5-0.2

-0.1

0

0.1

Day of 2004

Eastward absolute velocity

U20

Uice

V20

Vice

Site A Deployment 1:

1 mast with 2 turbulence clusters nominally 6 and 10 m depth (4 and 8 m below the ice/ocean interface) with upward/downward looking RDI ADPs

From 336.75 to 343.75


Same mast as Deployment 1, plus 2nd mast with 1 turbulence cluster at 4 m depth (2 m from interface) and 500 kHz Sontek ADP

From 345.00 to 353.375


1 mast with 3 turbulence clusters nominally 4, 8, and 12 m depth (2, 4, 10 m below the ice/ocean interface) with upward/downward looking RDI ADPs, plus the Sontek ADP deployed separately in the same hydrohole.

From 354.75 to 360.25

Site B Deployment:

1 mast with 2 turbulence clusters nominally 2 and 4 m depth (1 and 2 m below the ice/ocean interface) with the Sontek ADP on the bottom of the mast.

From 362.625 to 367.50

337 338 339 340 341 342 343

4

6

8

10

12

x 10-3

Day of 2004

m s

-1

u*=1/2

345 346 347 348 349 350 351 352 353

2

4

6

8

10

x 10-3

Day of 2004

m s

-1

u*=1/2

4 m

6 m10 m

6 m

10 m

5.4

5.8

3.4

4.4

5.0

Site A-1

Site A-2

4/122

* )( wvwuu 15-minute realizations (covariance calculations) averaged for 3 hours.

355 355.5 356 356.5 357 357.5 358 358.5 359 359.5 360

2

4

6

8

10

x 10-3

Day of 2004

m s

-1

u*=1/2

363 363.5 364 364.5 365 365.5 366 366.5 367 367.5

4

6

8

10

12

14x 10

-3

Day of 2004

m s

-1

u*=1/2

2 m

4 m

4 m

8 m12 m

3.9

4.6

5.4

7.3

Site A-3

Site B

337 338 339 340 341 342 343

-20

-10

0

Day of 2004

W m

-2

Hf=c

p<w'T'>

337 338 339 340 341 342 343

0.04

0.06

0.08

Day of 2004

K

T=T-Tf(S)

6 m

6 m

10 m

-4.3

-3.9

0.041

Site A-1

Site A-2

345 346 347 348 349 350 351 352 353-40

-20

0

Day of 2004

W m

-2

Hf=c

p<w'T'>

345 346 347 348 349 350 351 352 353

0.04

0.06

0.08

0.1

Day of 2004

K

T=T-Tf(S)

6 m

10 m

4 m

6 m

10 m

+1.6

-4.2

-1.7

0.064

355 355.5 356 356.5 357 357.5 358 358.5 359 359.5 360

-60

-40

-20

0

Day of 2004

W m

-2

Hf=c

p<w'T'>

355 355.5 356 356.5 357 357.5 358 358.5 359 359.5 360

0.06

0.08

0.1

Day of 2004

K

T=T-Tf(S)

8 m

12 m

4 m

8 m

12 m

-1.8-2.1-3.2

0.0620.061

Site A-3

363 363.5 364 364.5 365 365.5 366 366.5 367 367.5

0

5

10

Day of 2004

W m

-2

Hf=c

p<w'T'>

363 363.5 364 364.5 365 365.5 366 366.5 367 367.5

0.05

0.055

0.06

0.065

Day of 2004

K

T=T-Tf(S)

2 m

4 m

2 m

4 m

2.6

4.6

0.0550.055

Site B

337 338 339 340 341 342 343

-2

0

2

4

x 10-6

Day of 2004

psu

m s

-1<w'S'> from std C

6 m

7.6x10-7

Site A-1

Site A-2

345 346 347 348 349 350 351 352 353

-2

0

2

4

6

x 10-6

Day of 2004

psu

m s

-1

<w'S'> from std C

345 346 347 348 349 350 351 352 353

-2

-1

0

1

x 10-6

Day of 2004

psu

m s

-1

<w'S'> from C

4 m

6 m

10 m

0.2x10-7

10.7x10-7

0.8x10-7

Site A-3

355 355.5 356 356.5 357 357.5 358 358.5 359 359.5 360-5

0

5

10

x 10-6

Day of 2004

psu

m s

-1

<w'S'> from std C

355 355.5 356 356.5 357 357.5 358 358.5 359 359.5 360

0

1

2

3

4

x 10-6

Day of 2004

psu

m s

-1

<w'S'> from C

4 m

8 m

12 m

6.9x10-7

8.8x10-7

4.8x10-7

Site B

363 363.5 364 364.5 365 365.5 366 366.5 367 367.5

-3

-2

-1

0

1x 10

-6

Day of 2004

psu

m s

-1

<w'S'> from std C

2 m

4 m-12.8x10-7

-9.6x10-7

0.15 m s-1

337 338 339 340 341 342 343 344

336 337 338 339 340 341 342 343 344 345-40

-20

0

20

Day of 2004

W m

-2

Hf=c

p<w'T'>

336 337 338 339 340 341 342 343 344 3450

5

10

15

mm

s-1

u*=1/2

4 m

4 m

8 m

10

cm s

-1

VTIC1

500 m

10 cm s-1

Vice

VTIC1

PS

3-h average centered at 336.75

10

cm s

-1

VTIC1

10 cm s-1

500 m

PS

VTIC1

Vice


Relative current, TIC 1

0.15 m s-1

337 338 339 340 341 342 343 344

336 337 338 339 340 341 342 343 344 345-40

-20

0

20

Day of 2004

W m

-2

Hf=c

p<w'T'>

336 337 338 339 340 341 342 343 344 3450

5

10

15

mm

s-1

u*=1/2

4 m

4 m

8 m


10

cm s

-1

VTIC1

3-h average centered at 339.75PS

VTIC1

Vice

10 cm s-1

500 m

0.15 m s-1

337 338 339 340 341 342 343 344

336 337 338 339 340 341 342 343 344 345-40

-20

0

20

Day of 2004

W m

-2

Hf=c

p<w'T'>

336 337 338 339 340 341 342 343 344 3450

5

10

15

mm

s-1

u*=1/2

4 m

4 m

8 m


10

cm s

-1

VTIC1


PS

VTIC1

Vice

10 cm s-1

500 m

0.10 m s-1

345 346 347 348 349 350 351 352 353

344 345 346 347 348 349 350 351 352 353 354

-40

-20

0

20

Day of 2004

W m

-2

Hf=c

p<w'T'>

344 345 346 347 348 349 350 351 352 353 3540

5

10

15

mm

s-1

u*=1/2

1 m

4 m8 m

1 m

4 m

8 m

10

cm s

-1

VTIC2

500 m

10 cm s-1

Vice

VTIC2

PS



354 355 356 357 358 359 360 361

-60

-40

-20

0

Day of 2004

W m

-2

Hf=c

p<w'T'>

354 355 356 357 358 359 360 3610

5

10

15

mm

s-1

u*=1/2

2 m

6 m10 m

2 m

6 m

10 m

0.10 m s-1

355 356 357 358 359 360

10

cm s

-1

VTIC1


Vice

VTIC1

PS

500 m

10 cm s-1


354 355 356 357 358 359 360 361

-60

-40

-20

0

Day of 2004

W m

-2

Hf=c

p<w'T'>

354 355 356 357 358 359 360 3610

5

10

15

mm

s-1

u*=1/2

2 m

6 m10 m

2 m

6 m

10 m

0.10 m s-1

355 356 357 358 359 360

10

cm s

-1

VTIC1

10 cm s-1

500 m

PS

VTIC1

Vice



0.10 m s-1

362 363 364 365 366 367

361 362 363 364 365 366 367 368-10

0

10

20

Day of 2004

W m

-2

Hf=c

p<w'T'>

361 362 363 364 365 366 367 3680

5

10

15

mm

s-1

u*=1/2

1 m

3 m

1 m

3 m

10

cm s

-1

VTIC1


Vice

VTIC1

PS

400 m

10 cm s-1


Day 363.50

Cluster u* U/u*

1 0.0085 4.5 2 0.0135 4.1

0.10 m s-1

362 363 364 365 366 367

361 362 363 364 365 366 367 368-10

0

10

20

Day of 2004

W m

-2

Hf=c

p<w'T'>

361 362 363 364 365 366 367 3680

5

10

15

mm

s-1

u*=1/2

1 m

3 m

1 m

3 m

10

cm s

-1

VTIC1

10 cm s-1

400 m

PS

VTIC1

Vice



Day 365.25

Cluster u* U/u*

1 0.0048 17.9 2 0.0059 16.6

2 4-9

-8

-7

-6

-5

-4

-3

-2

-1

z0=0.3 cm

z0=4.0 cm

Distance from ice, m

log

(z0),

z0 i

n m

Site A, 345.750 to 360.250

1 3-9

-8

-7

-6

-5

-4

-3

-2

-1

z0=0.1 cm

z0=12.4 cm


log

(z0),

z0 i

n m

Site B, 362.625 to 367.500Green circles: law of the wall, median value of log (z0) shown with error bars indicating 95% confidence interval for the median based on quartile limits.

Red squares: mixing length method, which includes as a measured parameter the length scale inversely proportional to the wavenumber at the peak of

the area-preserving w spectrum.

30 m10 m

North

Current measured relativeto ice, 3-h average centeredat day 365.25

V/V30

1+0i

V10

/V30

= 0.77-0.17i

=12.3

(10-30)

=14.6

Data, 345.000 to 367.750

Treat velocity vectors as complex numbers: V=u+iv

0 0.05 0.1 0.15 0.2-0.02

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

m s-1

m s

-1

GPS Ice Velocity, 3h average @ day 362.875

Vice

0 0.05 0.1 0.15 0.2-0.02

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18Day 362.875

m s-1

m s

-1

V20

(relative)

-1.85 -1.84 -1.83 -1.82

-35

-30

-25

-20

-15

-10

-5

C

m

Temperature, Day 362.875

34.32 34.33 34.34 34.35 34.36-40

-35

-30

-25

-20

-15

-10

-5

0

psu

Salinity

0 0.01 0.02 0.03-40

-35

-30

-25

-20

-15

-10

-5

0

m2s-1

Eddy viscosity/diffusivity

Km

Kh

-0.05 0 0.05 0.1 0.15-40

-35

-30

-25

-20

-15

-10

-5

0

m s-1

Model velocity (relative to Vgeo

)

u (east)

v (north)

1 2 3 4

x 10-3

-32

-30

-28

-26

m2s-1


Km

Kh

-0.05 0 0.05 0.1 0.15-40

-30

-20

-10

0

m s-1


)

u (east)

v (north)

0 0.01 0.02 0.03-40

-35

-30

-25

-20

-15

-10

-5

0

m2s-1


Km

Kh

-0.05 0 0.05 0.1 0.15-40

-35

-30

-25

-20

-15

-10

-5

0

m s-1


)

u (east)

v (north)

0 0.05 0.1 0.15 0.2-0.02

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

m s-1

m s

-1

z0= 50.0 mm, u

*0=13.23 mm s-1

Model velocity, T/S structure @ day 362.875

Ekman spiral

0 0.05 0.1 0.15 0.2-0.02

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18Model velocity, based on T/S structure @ day 362.875

m s-1

m s

-1

z0= 50.0 mm, u

*0=13.23 mm s-1

V20

(abs)

Vgeo

(10-30)

=6.1

Model with z0 = 1 mm

(10-30)

=14.6

Data, 361.875 to 367.750

(10-30)

=15.0

Model with z0 = 50 mm

(10-30)

=17.5

Model with z0 = 120 mmFor each 3-h segment of data, run the steady

model forced to agree with the current at 20 m, using the interpolated T/S structure in the upper ocean, adjusted to agree with upper cluster values. For each sample, calculate the nondimensional profile (with respect to the 30 m level) and compare the model average with measured.

2 4-9

-8

-7

-6

-5

-4

-3

-2

-1

z0=0.3 cm

z0=4.0 cm


log

(z0),

z0 i

n m

Site A, 345.750 to 360.250

1 3-9

-8

-7

-6

-5

-4

-3

-2

-1

z0=0.1 cm

z0=12.4 cm


log

(z0),

z0 i

n m

Site B, 362.625 to 367.500Green circles: law of the wall, median value of log (z0) shown with error bars indicating 95% confidence interval for the median based on quartile limits.

Red squares: mixing length method, which includes as a measured parameter the length scale inversely proportional to the wavenumber at the peak of

the area-preserving w spectrum.

335 340 345 350 355 360 365 3700

0.005

0.01

0.015

0.02

8.1 mm/sm s

-1

Day of 2004

Model u*0

= 01/2

335 340 345 350 355 360 365 3700

10

20

30

40

16.0 W m-2

W m

-2

Day of 2004

Model Hf=c

p<w'T'>

0

335 340 345 350 355 360 365 3700

1

2

3

4x 10

-6

1.6e-006

psu

-m s

-1

Day of 2004

Model <w'S'>0

335 340 345 350 355 360 365 3700

1

2

x 10-8

1.2e-008W k

g-1

Day of 2004

Model <w'S'>0

335 340 345 350 355 360 365 3700

0.005

0.01

0.015

58 cm2 s-1m2 s

-1

Day of 2004

Model Km

@ 2 m from ice

335 340 345 350 355 360 365 3700

0.02

0.04

115 cm2 s-1

m2 s

-1

Day of 2004

Model maximum Km

335 340 345 350 355 360 365 370

-0.2

-0.1

0

0.1

0.2

1.1 cm s-1

m s

-1

Day of 2004

Model vg (North pos)

335 340 345 350 355 360 365 370

-0.2

-0.1

0

0.1

0.2

-1.0 cm s-1

m s

-1

Day of 2004

Model ug (East pos)

Summary

The ocean turbulence data were characterized by much temporal variability and undersurface heterogeneity. For the purpose of estimating exchange properties for the entire floe, a relatively simple, steady state upper ocean model was applied to each 3-h average, for a range of roughness values. The modeled angular shear between 10 and 30 m was compared with observations, and from this, z0 = 0.05 m emerged as a representative value.

The model then provides interface values for the friction velocity, heat flux, salt flux. It additionally estimates eddy viscosity/diffusivity, and velocity through the boundary layer, along with estimates of the undisturbed geostrophic velocity.

ISPOL Ocean Turbulence Project Miles McPhee McPhee Research Co. Naches WA USA.

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Transcript of ISPOL Ocean Turbulence Project Miles McPhee McPhee Research Co. Naches WA USA.