MAY ICES – MDM 2004, BRUSSELS Processing and Quality Checks of Shipboard ADCP Michèle FICHAUT, IFREMER/SISMER

lfremer MAY ICES – MDM 2004, BRUSSELS2 Ship and Equipment Three IFREMER Ships L’ATALANTE : NB 75 and NB 300 THALASSA : NB75 and BB 150 SUROÎT : BB 150 One Hydrographic Office Ship BEAUTEMPS-BEAUPRE : NB 38 and BB 150

lfremer MAY ICES – MDM 2004, BRUSSELS3 Data transmission Since 2001, standard configuration on the IFREMER vessels Raw data at SISMER at the end of the cruise Errors in the acquisition are detected when processing the data Since 2004, Beautemps-Beaupré transmits ADCP data each day in real time Data are processed at the end of the cruise But errors in the acquisition can be detected on the first file and corrected directly onboard

lfremer MAY ICES – MDM 2004, BRUSSELS4 Processing Software CASCADE developed in IFREMER by the Laboratory of Physical Oceanography (Matlab) 4 steps for the processing : Reformatting raw data into NetCDF Generation of processed files (attitude and time corrections, calculation of terrestrial coordinates, filtering, means) Ground speed calculation Quality checks of the data

lfremer MAY ICES – MDM 2004, BRUSSELS5 Quality checks of the data Flags are attributed to the numerical values automatically and visually (flag 9)

lfremer MAY ICES – MDM 2004, BRUSSELS6 Example of QC Cruise of the BEAUTEMPS- BEAUBRE in the Red Sea, Aden Gulf and Oman Sea Corresponding quality flags for the whole cruise Inconsistent values -> Flag 9

lfremer MAY ICES – MDM 2004, BRUSSELS7 Presentation of the data For one cruise, one or several sections are defined

lfremer MAY ICES – MDM 2004, BRUSSELS8 Images of the sections Section 1, in the Red Sea E/W horizontal current speed component N/S horizontal current speed component Current vertical speed

lfremer MAY ICES – MDM 2004, BRUSSELS9 Whole cruise’s vector plots 0 – 100 m 100 – 300 m

lfremer MAY ICES – MDM 2004, BRUSSELS10 Section’s vector plots Eddies in the superficial water (0-100m and m) Current aligned on the central valley in the deepest part ( m)

lfremer MAY ICES – MDM 2004, BRUSSELS11 Detected errors Errors detected at the beginning of data processing : ADCP time is wrong and cannot be related to the navigation Raw data files are too big to be processed by the software : typically the standard procedure is one raw data file per one day of cruise maximum (12 hours is the optimal size). Errors detected after data processing Strong correlation between current speed and ship velocity Unrealistic current vectors

lfremer MAY ICES – MDM 2004, BRUSSELS12 Example of wrong data (1) Detected with correlation between ship velocity and current speed

lfremer MAY ICES – MDM 2004, BRUSSELS13 Example of wrong data (2) Detected with section’s vector plots

lfremer MAY ICES – MDM 2004, BRUSSELS14 Data distribution Since 2001 : 49 IFREMER cruises (21 processed), 3 SHOM cruises (all processed)

lfremer MAY ICES – MDM 2004, BRUSSELS15 Data volume 52 cruises : Raw data : 49 Gigabytes ~= 1 gigabyte per cruise Data dissemination : between 1 to 100 Mb per cruise

lfremer MAY ICES – MDM 2004, BRUSSELS16 Provinding data One NetCDF file per cruise Date/time, Latitude, Longitude, Depth, N/S, E/W, Vertical current speed, Echo intensity One tar file with figures Section map, images and vector plots of the sections One report Information about data collection Information about the quality checks and the processing procedures Any problem encountered with the data

lfremer MAY ICES – MDM 2004, BRUSSELS17 Conclusive remarks and questions Not fully compliant with MDM guidelines for ADCP: Dissemination format is NetCDF in stead of ASCII There is no international exchange for ADCP data : Is it worth doing one? What about the WDCA ? What do other members do with ADCP shipboard data if they have some ?