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Status on anomalies detected with altimetry

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 S ea L evel A nomalies ( SLA ) and D ynamic H eight A nomalies ( DHA ) from Argo T/S profiles

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Status on anomalies detected with altimetry

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  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 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

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

  6. 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

  7. Representative anomalies • Drift Float : 5900963 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 SLA DHA (real-time)

  8. Representative anomalies • Chaotic Float : 1900259 r : -0.2 rms-diff : 815.00 % mean-diff : -10.3 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 needto 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 • Float 1900581 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 ?!?

  11. Active floats – need urgent correction • Float 3900488  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 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 !

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