INTERNATIONAL SYMPOSIUM ON INFORMATION TECHNOLOGY IN OCEANOGRAPHY (ITO-98)

GOA, INDIA 12-16 OCTOBER 1998

An Interactive Graphical System for XBT Data Quality Control and Visualisation

Pankaiakshan Thadathil, Poornima Jayanthi*, Silvia Bhobe*,
Jaydeep Pattanaik, J.S- Sarupria and Aravind K, Ghosh
Data and Information Division
National In,-;titute of OccanooTaphy
* MCA Third Year Students, Goa University

A PC based system has been developed for quality control and visualisation of XBT data archived at IODC ( Indian OceanoQraphic Data Centre). The archive includes XBT data from TOGA and other cruises of RV. Gaveshani and ORV. Sagar Kanya, The system, coded in Visual C ++, is user interactive and run on windows-95 platform. Quality control module of the system incorporates various qualitv norms/checks and has two levels; inventory and data level. Inventory level cheeks are applied for land-sea position, speed of the vessel, invalid dateltime, duplicates, and station soundinr, Station sounding cheek is performed based on the ETOPO bathometry file, having 5' X 5' spatial resolution. These inventory level cheeks are applicable to station data for other parameters as well.

Data quality module involves tests for surface transient, temperature inversions, fall rate and depth reversal. This level also involves visual inspection of the profile for features caused by vare stretch, wire break, bovang and nub in the mixed layer. Provision is given to compare individual XBT profiles with neiqhboring stations and also with 1 X 1 degree monthly, climatologies of Levitus. Quality flajs are assigned for each inventory and depth fields. Since data exchange national and international ), under the IODE system stipulates standard quality flags, the TGOOS ( Integrated Global Ocean Obsenation System ) recommended flags are applied in the system. Stations having data with erroneous or doubtful flags are sent to error bin, which can be accessed by privfieged users for possible correction and subsequent modifications, The data visualisation module has options for data queries, selection, and graphical presentations, like vertical and horizontal distribution of temperature.

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"to continously improve our understanding of the seas
around us and to translate this knowledge to benefit all"