1. Status on anomalies detected with altimetry
Stéphanie Guinehut
CLS, Space Oceanography Division

2. Reminder of the method The main idea is to compare co-located :
Altimeter Sea Level Anomalies (SLA)
and Dynamic Height Anomalies (DHA) from Argo T/S profiles
for each Argo float time series
Method :
DHA = DH – Mean-DH / SLA
2 times series co-located in time and space
SLA : AVISO combined maps
DHA : Argo Coriolis-GDAC data base
DH calculated from T/S profiles using a ref. level at 200, 400, 900, 1200 or 1900 dbar
only data with : POSITION_QC = ‘0’, ‘1’, ‘5’, ‘8’
JULD_QC = ‘0’, ‘1’, ‘5’, ‘8’
PRES/TEMP/PSAL_QC = ‘1’ (DATA_MODE=‘R’)
PRES_ADJ/TEMP_ADJ/PSAL_ADJ_QC = ‘1’ (DATA_MODE=‘A’/’D’)
Mean-DH : contemporaneous Argo mean dynamic height

3. Reminder of the method Grey list : not taken into account
 The method is useful to extract floats with data not consistent with the grey list
RT-Test 15 is supposed to do the work
GDAC user should not need to use the grey list file – only for GTS users

4. Global results – Updated every 3 to 4 months
ftp://ftp.ifremer.fr/ifremer/argo/etc/argo-ast9-item13-AltimeterComparison
List of floats to be checked :
DAC WMO INST-TYPE TYPE OF ANOM
kma spikes
meds offset
meds offset
meds offset
incois offset
coriolis spike
coriolis ?
coriolis offset
coriolis drift
bodc spike
bodc spikes
………….
The AIC monthly report
Dacs should check the suspicious floats they are managing together with their delayed mode operators and Pis and provide appropriate corrections if needed – provide feedback on the method

5. Representative anomalies
Spike
Float :
Visual control needed
Bad salinity data at depth

6. Representative anomalies
Offset
Float :
r : 0.61
rms-diff : %
mean-diff : 15 cm
samples : 69
* statistics on DHA-Real
 DMQC has extracted the offset
 Salinity offset
Vertically averaged correction applied= psu

7. Representative anomalies
Float :
Drift
SLA
DHA (real-time)
SP ~ –14 dbar
SLA-DHA ~ 6 cm
Figure : courtesy of Annie Wong
CYCLE NO ~ 119
 Careful analysis by the DM operator
 Evidence of a negative pressure drift

8. Representative anomalies
Chaotic
Float :
r : -0.2
rms-diff : %
mean-diff : cm
samples : 95
Profile to profile high variability

9. Status on the anomalies detected in August 2009
111 floats extracted – 101 RT and 10 DT
Feedbacks provided by a large number of groups : UW, PMEL, SOI, WHOI, Coriolis, JMA, INCOIS, KMA, MEDS = 48 floats
Good data – alti results not confirmed = 5
Floats to be further analyzed – to be kept in the list = 7
Alti results confirmed – corrected or to be corrected = 36
Large number of floats need still to be checked = 63 floats
(status file)
A need to classify them in different categories – in order to “prioritorize” the correction
- Spike = ~ isolated problem
- Drift/Offset/Chaotic
- Active floats – need urgent correction !!
- Dead floats – need to be corrected to clean up the data set, but less urgent …

10. Active floats – need urgent correction
 Salinity offset
Vertically averaged correction applied= psu
Two actions :
- to put in the grey list
- to extrapolate the correction to the RT
PI’s decision ?!?

11. Active floats – need urgent correction
 Drift
Further analyzes needed
- to be done by the PI ??
- to be done by the DAC ??

12. Global results – Updated every 3 to 4 months
List of floats to be checked :
DAC WMO INST-TYPE TYPE OF ANOM
kma spikes
meds offset
meds offset
meds offset
coriolis ?
coriolis offset
coriolis drift
bodc spike
bodc spikes
………….
Are you happy with this ascii file ?!?
Next update in November 2009 – correct your files !