A Comparison of Six Expendable Bathythermograph Data Acquisition Systems Derrick Snowden Molly...
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Transcript of A Comparison of Six Expendable Bathythermograph Data Acquisition Systems Derrick Snowden Molly...
A Comparison of Six Expendable Bathythermograph Data Acquisition
Systems
Derrick SnowdenMolly BaringerGustavo Goni
Instruments ListSystem Name
Launcher Type
Recorder Type
Controller Software (PC)
aomlauto AOML Autolauncher
MK-12 AOML (DOS 386 PC)
devilhand Sippican LM-3A
Devil Devil Software(Win XP PC)
seasauto AOML Autolauncher
MK-21 SEAS2000 (WinXP PC)
seashand Sippican LM-3A
MK-21 SEAS2000(Win XP PC)
sioauto SIOAutolauncher
MK-21 SEAS2000(Win XP PC)
siok98 SIO Autolauncher
MK-12
366 total profiles
XBT Errors
XBT differs from the CTD due to :
A: inaccurate depth measurements
B: inaccurate temperature measurements
A B0
800
Depth
(m
)
0.25
0
MSE
Bias
Variance
0
800
Depth
(m
)
0.25
0
Fall Rate Error: Initial Conditions
Hallock and Teague 1992
Fall Rate Equation
a: Change of mass of the probe due to spooling wire.
b: Probe geometry and initial terminal velocity
c: Describes startup transients i.e. initial conditions
Currently used FRE (WMO 1770:52) for Deep Blue probes contains no constant term ( c ).
e.g. Hallock and Teague (1992)
Determining Depth Offset
Focus on the temperature gradient: derivative of temperature with respect to depth
Minimize temperature error effect
Hanawa et al (1995)
Depth Offset Prior to Correction
Depth Correction Algorithm
• Assemble the depth offsets (dZ)
• Recalculate XBT depths Znew = Zxbt+dZ
• Back calculate time (t)
• Fit new fall rate equation to (t)
z = at^2 + bt + c
Depth Offset: Post-Correction
Summary of Fall Rate Coefficients
A B C
Wmocode 52 -0.00225 6.691 0
this study -0.00191 6.487 0
this study -0.00299 6.639 -4.5117
other studies (1)
-0.00131 –
-0.00329
6.440 –
6.798
0 - 0
1: Taken from Hanawa et al 1995
1. aomlauto
2. devilhand
3. seasauto
4. seashand
5. sioauto
6. siok98