XBTCTD Comparisons

1
XBT/CTD Comparisons

• LCDR. Chin-lung Fang
• OC 3570
• Operational Oceanography

2
Contents

• Introduction
• Data Quality Control
• Processing and Discussion
• Temp comparison
• Depth comparison
• Conclusions

3
Introduction

• Insruments
• Sea Bird CTD
• T-7 Sippican XBTs
• T-4 Sippican XBTs
• Locations
• 31 XBTs
• 35 CTDs
• Co-located

4
Introduction

• Insruments
• Sea Bird CTD
• T-7 Sippican XBTs
• T-4 Sippican XBTs
• Locations
• 31 XBTs
• 35 CTDs
• Co-located

5
Data Quality Control

• Visual inspection
• Using MATLAB
• Final evaluation
• 28 pairs of data remain

Bad data profile
Normal data profile
6
Data Quality Control
Zn
Tn
Tn1
Tn-1

• Visual inspection
• Using MATLAB
• Final evaluation
• 28 pairs of data remain

Zn-1
Pn-1
Zn
Pn
Zn1
Pn1
If Tn - ( Tn1 Tn-1 ) /2 gt 2 Std.
(0.2C) Then Pn Possible bad data
point Total 83 points were found
7
Data Quality Control

• Visual inspection
• Using MATLAB
• Final evaluation
• 28 pairs of data remain

Possible bad data point
8
Processing and Discussion
Zn

• Temp comparison
• Converting P(db) to D(m)
• Linear interpolation
• Findings
• Composite results
• Separate results
• ?T effects
• Comparing previous studies
• Depth comparison

Z(1-C1)P-C2P² Where
C1(5.925.25sin²F)10?³ F is latitude
C2 2.2110?6
by Saunders (1981)
9
Processing and Discussion

• Temp comparison
• Converting P(db) to D(m)
• Linear interpolation
• Findings
• Composite results
• Separate results
• ?T effects
• Comparing previous studies
• Depth comparison

10
Processing and Discussion

• Temp comparison
• Converting P(db) to D(m)
• Linear interpolation
• Findings
• Composite results
• Separate results
• ?T effects
• Comparing previous studies
• Depth comparison

11
Processing and Discussion

• Temp comparison
• Converting P(db) to D(m)
• Linear interpolation
• Findings
• Composite results
• Separate results
• ?T effects
• Comparing previous studies
• Depth comparison

12
Processing and Discussion

• Temp comparison
• Converting P(db) to D(m)
• Linear interpolation
• Findings
• Composite results
• Separate results
• ?T effects
• Comparing previous studies
• Depth comparison

T-7 ? -0.1074 ? 0.1546
T-4 ? -0.0252 ? 0.2224
13
Processing and Discussion

• Temp comparison
• Converting P(db) to D(m)
• Linear interpolation
• Findings
• Composite results
• Separate results
• ?T effects
• Comparing previous studies
• Depth comparison

?T ? ? T. diff.?
?T ? ? T. diff. ?
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Processing and Discussion

• Temp comparison
• Converting P(db) to D(m)
• Linear interpolation
• Findings
• Composite results
• Separate results
• ?T effects
• Comparing previous studies
• Depth comparison

15
Processing and Discussion

• Temp comparison
• Depth comparison
• Linear interpolation
• Findings
• Results
• Relating to ?T and T diff.
• .

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Processing and Discussion

• Temp comparison
• Depth comparison
• Linear interpolation
• Findings
• Results
• Relating to ?T and T diff.
• .

T-7 ? 7.3911 ? 11.1775
T-4 ? 0.2867 ? 12.9654
17
Processing and Discussion
?T
T-7 Depth diff.
T-7 Temp diff.

• Temp comparison
• Depth comparison
• Linear interpolation
• Findings
• Results
• Relating to ?T and T diff.
• .

Simple Formularized-Relation among there 3 terms
Effects of ?T
Effects on Temp diff.
Effects of Depth diff.


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Processing and Discussion
?T
T-4 Depth diff.
T-4 Temp diff.

• Temp comparison
• Depth comparison
• Linear interpolation
• Findings
• Results
• Relating to ?T and T diff.
• .

Simple Formularized-Relation among there 3 terms
Effects of ?T
Effects on Temp diff.
Effects of Depth diff.


19
Conclusions

• This is similar to results obtained from previous
  OC3570 cruises
• XBT Temp. were systematically higher than those
  recorded by the CTD
• 0.0252 C for T-4 XBT
• 0.1074 C for T-7 XBT
• Std. for T-4 is 1.5 times larger than the std.
  for T-7
• XBT depth errors exist
• 0.2867 m for T-4 XBT
• 7.3911 m for T-7 XBT
• Stronger ?T ? larger Temp. diff.
• e.g. The greatest bias was in the upper levels

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Questions ?
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Thanks for your attention !!