qa/qc of ocean currents

QA/QC of Ocean Currents

Bill Burnett NOAA/NWS National Data Buoy Center

Stennis Space Center, MS

27 February 2008

Currents Working Group• The first workshop (QARTOD I) was held at the NOAA National Data Buoy

Center (NDBC) office at the Stennis Space Center, MS in the winter of 2003. Over 80 participants attended with the primary task to develop minimum standards for calibration, QA/QC methods and metadata http://nautilus.baruch.sc.edu/twiki/pub/Main/WebHome/QARTOD_final_09.pdf

• QARTOD II was held February 28-March 2, 2005 in Norfolk, VA. This workshop focused on wave and current measurements and thier unique calibration, metadata and QA/QC needs. http://nautilus.baruch.sc.edu/twiki/pub/Main/WebHome/QartodIIFinal.doc

• QARTOD III was held at Scripps Institution of Oceanography, La Jolla, CA on November 2-4, 2005. It addressed QC for CTDs, in-situ currents, remote currents and waves. http://nautilus.baruch.sc.edu/twiki/bin/view/Main/Qartod3Presentations

• QARTOD IV was held at Woods Hole Oceanographic Institution on June 21-23, 2006. The meeting was held to approve Quality Control standards developed in QARTOD I – III, and begin focusing on Quality Assurance standards.

• Current Profiler – Bridle-mount– Cage-mount– Buoy-mount

• Additional Current Profilers– Attached to C-MAN or ATON stations– Bottom-mounted

• Single Point Current Meters

Currents Strategy

Current Technologies

External Hull Mounts37SM CTD Sensor

External ADCP Battery Canisters (2) with Retainer Bracket

NDBC MMS Page

Apply quality control to real-time ADCP data from deep-water oil platforms and rigs

Surface Current Plots

Onslow BayInside Buoy

East ofVirginia Beach

Surface Current Plots

Lake Huron

Celtic Sea and Transocean Marianas Inertial Currents

and Current

Endeavour and Na KikaNear-Inertial Currents

Matterhorn and BoomvangPassing Eddies

Thunderhorse Currents

Ocean Star and DD-1 Currents

Max Smith Currents

Na Kika Bottom MountedDelayed-Mode Data

Data Quality

• Purpose: – Remove gross errors

• Data rejected: – Virtually certain to degrade products

• Typical causes: – Transmission errors, power degradations,

broken cables

• Limitations: – Won’t detect minor errors, biases

Data Quality

• Limit check – Are the currents within standard data limits?• Time continuity check• Vertical velocity relational check

• The limit and time continuity checks are applied to each velocity measurement• The vertical-velocity-relational check deletes horizontal current measurements when the corresponding absolute value of the vertical velocity is too high to be physically reasonable.

Teledyne RD Instruments ADCP QUALITY CONTROL SHEETS

Pass Suspect Fail

Level 1 - Red (required)

Bit status (Built In Test) - diagnostics BIT result is zero BIT result is non-zero BIT result is NA

Echo amplitude/intensityvalue between 70

and 220 countsvalues between 60 and

70 counts

values greater than 220 counts; values less

than 60 counts

Pitch/Roll (absolute value) 0-15 deg 15-20 deg >20deg

Heading 0-360 deg

rate of change greater than 5 degrees for

ens to ens >359.9deg or negative

Pitch/Roll (delta)<1 deg diff from

one ens to next>1 deg diff from one

ens to next ens>5 deg diff from one ens

to the next


Pass Suspect Fail


Vertical Velocity

The difference is less than or equal to 20

cm/s for OO 38 (BB and NB), OS 38, 75 and 150

(BB and NB), WH Long Ranger 75

(BB and NB) and WH

QuarterMaster 150 (BB and NB), WH 300, 600 and 1200 kHz (BB and

NB)

The difference is greater than 20

cm/s and less than or equal to 40cm/s

for OO 38 (BB and NB), OS 38, 75 and 150 (BB and NB), WH

Long Ranger 75 (BB and NB) and

WH QuarterMaster

150 (BB and NB), WH 300, 600 and

1200 kHz (BB and NB)

The difference is greater than 40 cm/s for OO 38 (BB and NB), OS 38, 75 and 150 (BB and

NB), WH Long Ranger 75 (BB and NB) and WH

QuarterMaster 150 (BB and NB), WH 300, 600 and 1200

kHz (BB and NB)


Pass Suspect Fail


Correlation Magnitude Thresholds

At least 3 of the 4 correlation

magnitude values for each bin are greater than or equal to 115

for WH Long Ranger 75 kHz (BB

and NB), WH QuarterMaster 150 (BB and NB), WH 300, 600 and 1200 kHz (BB and NB): At least 3 of the 4

correlation magnitude values for

the bin are greater than or equal to 130 for OO 38 BB, OS 38, 75 and 150 BB or greater than or

equal to 170 for OO 38 NB, OS 38, 75

and 150 NB

At least 3 of the 4 correlation magnitude values for each bin are less than

115 and greater than or equal to 64 for WH

Long Ranger 75 kHz (BB and NB), WH QuarterMaster 150

(BB and NB), WH 300, 600 and 1200 kHz (BB and NB): At least 3 of

the 4 correlation magnitude values for the

bin are less than 130 and greater than or equal

to 100 for OO 38 BB, OS 38, 75 and 150 BB

or less than 170 and greater than or equal to 110 for OO 38 NB, OS

38, 75 and 150 NB

At least 3 of the 4 correlation magnitude values for each

bin are less than 64 for WH Long Ranger 75 kHz (BB

and NB), WH QuarterMaster 150 (BB and NB), WH 300, 600 and 1200 kHz (BB and NB): At least 3 of the 4 correlation magnitude

values for the bin are less than 100 for OO 38 BB,

OS 38, 75 and 150 BB or less than 110 for OO 38 NB, OS 38, 75 and 150

NB


Pass Suspect Fail


Error velocity - four beam disagreement indicator

Error velocity in each bin is less than or equal

to 15 cm/s

Error velocity in each bin is greater than 15 cms/s

and less than or equal to 30 cm/s or equals -32678

Error velocity for each bin exceeds 30 cm/s

Level 2 – Yellow (recommended)

Battery voltage (V1 & V2) two batteries 36 - 48 volts 30 - 36 volts < 30 volts

Water temperature Change in 0.25 degree C in 6

minutes >50degC or <-5degC

Pressure negative or >range of sensor

Timestamp stuck time or future time

Speed of sound (derived) >1600m/s or <1400m/s

Signal to noise level >70% >30% or <70% <30%

Surface (or bottom) reflection/ detection

No rise in echo intensity values on any beam

greater than 30 counts

Rise greater than 30 counts in echo intensity on only

one beam Rise greater than 30 counts on

two or more beams


Pass Suspect Fail

Percent solutions - number of beams used

The above values for each bin are

flagged as good

The above values for each bin flagged as

suspect or failed for less fewer than 50%

of the bins

The above values for each bin are flagged as

suspect or failed for greater than or equal to

50% of the bins

Percent good pings (PGP)

Workhorse Long Range 75 kHz:

Total percent good pings is

greater than 10%. Ocean

Observer 38 kHz: Total

percent good pings is greater

than 25%

Workhorse Long Range 75 kHz: Total

percent good pings is greater than or equal to 5% and less than

10%. Ocean Observer 38 kHz: Total percent

good pings is greater than or equal to 22% and less than 25%.

Workhorse Long Range 75 kHz: Total percent good pings is less than 5%. Ocean Observer 38 kHz: Total percent good

pings is less than 22%

Real-Time Quality Descriptor Flags

• Categories … agree with QARTOD I recommendations:– -9 = missing value– 0 = quality not evaluated– 1= bad– 2=questionable/suspect– 3=good

Questions?

See the data sheets at:

http://ioosdmac.fedworx.org

Contact Info:Bill BurnettDMAC Branch ChiefNational Data Buoy CenterStennis Space Center, MS [email protected]

qa/qc of ocean currents

Documents

quality control standards

realtime adcp data

situ currents

remote currents

gross errors data

quality assurance standards

standard data limits

velocity measurement