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

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

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

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 2900434 846 spikes meds 4900116 846 offset meds 51886 831 offset meds 51887 831 offset incois 2900783 846 offset coriolis 1900651 846 spike coriolis 5900198 842 ? coriolis 6900399 841 offset coriolis 69039 842 drift bodc 1900141 842 spike bodc 1900454 842 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

Representative anomalies Spike Float : 5900155 Visual control needed Bad salinity data at depth

Representative anomalies Offset Float : 1900581 r : 0.61 rms-diff : 2187.00 % mean-diff : 15 cm samples : 69 * statistics on DHA-Real  DMQC has extracted the offset  Salinity offset Vertically averaged correction applied= -0.243 psu

Representative anomalies Float : 5900963 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

Representative anomalies Chaotic Float : 1900259 r : -0.2 rms-diff : 815.00 % mean-diff : -10.3 cm samples : 95 Profile to profile high variability

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 …

Active floats – need urgent correction  Salinity offset Vertically averaged correction applied= -0.243 psu Two actions : - to put in the grey list - to extrapolate the correction to the RT PI’s decision ?!?

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

Global results – Updated every 3 to 4 months List of floats to be checked : DAC WMO INST-TYPE TYPE OF ANOM ------------------------------------------------------------------------------ kma 2900434 846 spikes meds 4900116 846 offset meds 51886 831 offset meds 51887 831 offset coriolis 5900198 842 ? coriolis 6900399 841 offset coriolis 69039 842 drift bodc 1900141 842 spike bodc 1900454 842 spikes …………. Are you happy with this ascii file ?!? Next update in November 2009 – correct your files !