1. Density Ratios and Heat Flux within the Beaufort Sea Utilizing WHOI Ice-Tethered Profiler DataBy
LCDR Greg Caro

2. Motivation

3. Motivation
Determine typical density ratios within the Beaufort Gyre in order to model vertical heat fluxes within the thermocline.
Is the warming of the Atlantic Water layer significant enough to effect the melting rate of the Arctic sea ice cover?

4. Motivation
Turner (1973) describes double-diffusive convection as a phenomenon that occurs when there are gradients of two or more properties with different molecular diffusivities.
This difference leads to net density distribution which decreases upwards with the presence of instability within the concentration.

5. Motivation Alpha is the thermal expansion coefficient
(1)
Alpha is the thermal expansion coefficient
Beta is the saline contraction coefficient
Double Diffusion can occur when density ratio is greater than 1.
Heat fluxes increase as density ratio approaches 1

6. Motivation Cp is the specific heat capacity K is thermal diffusivity
(2)
Marmorino and Caldwell, 1976
Cp is the specific heat capacity
K is thermal diffusivity
Pr is the prandtl number (kinimatic vicscosity/K)
dθ is the background temperature gradient

7. Profiler Description

8. Measuring Capability
Measures Conductivity, Temperature and Depth at Hz sample rate
Profile design speed of .25 m/s yielding a nominal vertical resolution of 25 cm
Iridium satellite communication
Designed to collect 1500 profiles in upper 750m
1.5 million meter range
3 year life or ice floe life

9. Data Description LEVEL 1 RAW DATA
The raw sensor and engineering data acquired by the ITP profilers are uploaded after the completion of each one-way traverse. The binary data are unpacked and reformatted into Matlab, one file per profile, called raw####.mat, where #### is the profile number.

10. Data Description LEVEL 2 REAL TIME DATA
At this level of processing, the location data are filtered and interpolated to the start times of each profile, while the scientific and engineering data are averaged in 2-db bins and salinity is derived from bin-averaged pressure, temperature and conductivity.
No sensor response corrections, calibrations or editing are applied at this stage (beyond the internal sensor calibrations applied in the CTD instruments)..

11. Data Description LEVEL 3 ARCHIVE DATA
This form of ITP data represent our best estimates of the ocean properties derived from the sensor observations.
These data have had sensor response corrections applied, regional conductivity adjustments made based on historical hydrographic data, and edits performed.
Level 3 data products are derived for each ITP system after its mission has ended.

12. ITP Track

13. ITP Track 2 1 3 5 2 2
Start *
End O

14. T-S Profiles Depth, dbar Depth, dbar Potential Temp, deg C Salinity
ITP 2
244 profiles
Depth, dbar
Depth, dbar
Potential Temp, deg C
Salinity

15. Thermohaline Staircase
ITP 2
244 profiles
Every 20th
Depth, dbar
Potential Temp, deg C

16. Thermohaline Staircase
ITP 2
244 profiles
Every 50th
Depth, dbar
Potential Temp, deg C

17. Thermohaline Staircase
ITP 2
244 profiles
Every 50th
Depth, dbar
Potential Temp, deg C

18. Calculation Methodology
Depth, dbar
Potential Temp, deg C
Identified Steps (|dT/dZ|=max)
Difference of T and S at midpoint of each step
Used Matlab seawater toolbox to calculate alpha and beta
(1)

19. Results ITP 1 Number of occurrences Density Ratio
Mean = /    
Median = 4.5766      

20. Results ITP 2 Number of occurrences Density Ratio
Mean = /
Median =            

21. Results ITP 3 Number of occurrences Density Ratio
Mean = /    
Median = 5.2203      

22. Results ITP 5 Number of occurrences Density Ratio
Mean = /    
Median =   4.4726    

23. Results Profiler Heat Flux, watts/m^2 ITP 1 0.2765 ITP 2 0.2827 ITP 3
(2)
Marmorino and Caldwell, 1976
Profiler
Heat Flux, watts/m^2
ITP 1
0.2765
ITP 2
0.2827
ITP 3
0.2384
ITP 5
0.2810

24. Questions