Yafang Su

Interfacing Oceanographic Database by ArcView

Abstract

Monterey Bay Aquarium Research Institute (MBARI) has collected a large amount of oceanic data from various ocean observation platforms. The management of the oceanographic data collected from various platforms is a challenging issue. It is very difficult for scientists and engineers to use these data without a user friendly interface. In the paper, ArcView and Avenue are employed to interface the database and establish the application models. All the previous collected data can be incorporated for further analysis.

INTRODUCTION

GIS (Geographic Information System) is very efficient in the representation, management, processing and analysis of spatial information in the geo-sciences. Terrestrial GISs are widely established and have proved to be very effective and successful. Despite its popularity in land-based applications, GIS has been modestly applied in oceanographic studies. With the development of new technology, more and more spatially referenced oceanic information has been collected by various ocean observation platforms; On the other hand, GIS becomes increasingly powerful in the integrating different systems. Therefore, GIS has great potential in oceanographic applications.

MBARI has collected extensive data sets in Monterey Bay, including physical, chemical, biological, geological data by various sensors, and numerous video tapes by ROV(Remotely Operated Vehicle), ranging from ocean surface, midwater to seafloor. Most of the data is spatially referenced. Therefore, to establish a GIS system is necessary.

The development of GIS technology has made it available to non GIS background people from different disciplines. GIS interface is oriented to fill the gap between user's knowledge and the technical knowledge required to operate a software system. In the paper, A user friendly desktop GIS interface has been developed for scientific research, which allows non-GIS background oceanographers to query and analyze the data very easily. With the highly user-friendly ArcView GIS, we are now able to develop sophisticated analysis routines that are accessible to the oceanographic scientists. The developed ArcView GIS interface provides access to previously unavailable data as well as provides analysis options for existing data that was nearly shelved due to lack of use.

MBARI GIS DATABASE

MBARI enjoys a great advantage in acquiring oceanographic data from its multi-platform systems, and has regularly collected various datasets, such as ship cruise data, ROV diving data, profile data, drifter data, mooring data and NOAA/AVHRR data etc. The oceanographic data from different sources are stored in various formats. The ocean observation data of biological, physical, chemical instruments and video annotation from ship cruises and ROV dives are stored in MODB database supported by SYBASE(Gritton, etal., 1992). The "drifter" and daily "mooring" data are stored in ASCII format. The sea surface satellite data from NOAA/AVHRR sensor are stored in digital image format(see Fig. 1).

Fig. 1 MBARI GIS Database

The Sybase-based MODB oceanographic database represents an improvement in MBARI's oceanographic data management in late 80's. The MODB system contains all the ship expedition records, cruise data of biological, physical, chemical data, and part of the lab analysis data from sampling ocean water, video annotation data through the digitization of video tapes. However, MODB does not support spatial analysis and does not have a user friendly interface. There are many tables and the query of the data needs a chain of joins. For example, to query physical data by an expedition number needs four tables and three joins. It is very slow to query the data using SQL through DBI connection by ArcInfo and ArcView in this way. Therefore, the GIS database is redesigned(see Fig.1). The tables were generated according to the purpose and the year in order to accelerate the query speed. For best performance, the joins are minimized in the design of the tables. There are one Expedition table, one Expd_data_run table and seven types of biological, physical, chemical, video annotation, biological lab analysis, chemical lab analysis and lab_sample data.

Besides the data in MODB, MBARI employs biological and physical time series ocean measurement data with various instruments to determine the relation to climate and ocean variability( Chavez etal.). These "mooring" data and drifter data are stored in ASCII format. The spatial locations of the platforms can be determined by the GPS receiver.

MBARI receives AVHRR images of the Central California Coast, roughly from Point Reyes to Point Conception. Only those passes with clear views of one or both of the MBARI moorings positioned in Monterey Bay are processed, as we use the Sea Surface Temperature from those moorings in truthing the images.

MBARI also takes a lot of deep ocean videos by under water ROV. Some of the video frames have been captured through JPEG conversions of the raw RGB frame captures made real time aboard the ship using the Silicon Graphics system named Ariel.

Other available geographic data sets include bathymetry, contours, coastline, fault, Side-scan images (Sonar_beam) etc.

INTERFACING THE DATABASE

Although ArcView provides a set of default tools and general interface to perform basic analysis, more user-friendly interface is needed in oceanographic analysis and MBARI's specific purpose. An Avenue-based ArcView interface for scientists to access all the available data and apply in oceanographic research has been created(see Fig. 2).

Fig. 2 Pull-down Application Menus

Fig. 2 Pull-down Application Menus

Among the five sets of menu buttons in Fig. 2, the "MODB" menu with an Expedition View and "OASIS" menu with a Mooring View are developed as two extensions in the default GUI so that users can turn them on/off easily.

Query of the Data in "MODB" Database

There are nine menu buttons under "MODB" menu(see Fig. 2). Among them, the first two buttons are designed to query the expeditions and seven other buttons are designed to query the physical data. Five keywords(expedition number, expedition date, platform used for the expedition, ROV diving number, scientific purpose) are designed to query the expeditions from the Expedition table and Expd_data_run table. The users are also allow to query the expeditions spatially from Expedition Map of Monterey Bay. The query results can be highlighted symbolically on a map or a table immediately, and saved as a new table or a new map for the users to use in the future.

There are seven menu buttons to query the Physical, Chemical, Biological measurement tables, Video-annotation table, Biological lab analysis, Chemical lab analysis and Lab_sample tables respectively. Three optional keywords are designed to query the physical data in each topic: expedition number, date range and depth range. Only one keyword is necessary to query a data subsets. Any two fields of measurements such as latitude, longitude, depth can be used to produce a two dimensional map. The query results can be displayed both in a table and a 2D map.

Query of "Oasis" Data

There are seven menu buttons under "Oasis" menu(see Fig.2). Headinfo button contains the head information of each sensor's measurement. It also explains the field definitions in the tables. M1 and M2 are the names of the two mooring locations in Monterey Bay. M1_Series and M2_Series buttons are designed for the query of time series physical and biological mooring data or do the daily summary of the selected measurements of M1 and M2. M1xym and M2xym buttons are employed to query various measurements of M1, M2 by date with a spatial location (latitude, longitude) which is estimated through relating the time to GPS time. M1meas and M2meas are employed to query the measurement tables of M1 and M2 by date. Drifter is used to query the drifter data according to the drifter time.

Geographic Data

The geographic data can be added to the active View under "Addthemes" menu. There are five menu buttons which include Coastline, Contourline, Fault, CTD site and Countymap. Coastline button has two options: Monterey Bay or San Francisco-Monterey Bay. Contourline button has four options: 20 meter or 100 meter contours of Monterey Bay, 50 meter or 100 meter contours of San Francisco-Monterey Bay. Fault button is to add the geological fault line to the active View. CTD Site button has options for the nine cruises of CTD sampling in Monterey Bay. Countymap button has three options of adding parcel map to the active view: Monterey county, Santa Cruz county and the two counties together.

Images

There are five menu buttons under "AddImages" menu. The image or grid data include bathymetry, NOAA/AVHRR satellite images, video JPEG images and TM images can be selected and added to the active View as image themes by the menu buttons. The Bathymetry button has four options which can add bathymetry or shaded relief of different resolution of Monterey Bay and San Francisco-Monterey Bay to the active View. The Videoframes button can add the video frames captured real time from ROV video camera by the date and image numbers of the day to the active view. NOAA_Sat is designed to add the NOAA/AVHRR images to the view by date and time. Sonar_Beam is used to add Side-scan sonar image to the active view. TM image is to add TM image to the active view.

Analysis and Conversion Tools:

There are seven menu buttons under "Analysis" menu. Among them, four are analysis tools for oceanographic studies, which include Interpolation, Contour, Buffer and Merge; three are data conversion tools, which include Point2line, Shp2gen and Shppoint2gen.

Many important datasets are nonuniformly sampled in oceanography; however, nonuniformly sampled data cannot be analyzed efficiently in GIS. Therefore, the sampled data needs to be uniformly interpolated in two dimensions. More than 10 interpolation methods provided by ArcInfo have been studied to interpolate oceanic measurement data. The accuracies of the different interpolation are compared and the most appropriate methods are selected for cruise data and CTD data interpolation respectively. The appropriate parameters for interpolation as default values are given in the message box for reference.

Contour button is designed to contour the grid data such as bathymetry, temperature, salinity etc. Both Interpolation and Contour buttons are realized by RPC connection to functions in ArcInfo because we do not have the Spatial Analysts at present.

Buffer button is designed to determine the buffer zone of sampling site point or ship track lines, coastlines etc.

Merge button is used to merge two or more themes into one shape file. Two or more expeditions can be merged as one theme for further analysis.

The positions of ship cruise, mooring and drifter are recorded by GPS receivers as points in each platform according to a certain time interval. Point2line button is developed to generate line from a point shape file. It is applied to produce a track line from ship navigation, mooring and drifter platform. Shp2gen button is used to generate a delimited ASCII file from the shape file(point, line and polygon). Shppoint2gen button is used to generate a delimited ASCII file from the point shape file because most of MBARI's data is point data from GPS receiver. The delimited ASCII file can be used to do more sophisticated analysis in ArcInfo.

Fig.3 An example of query the CTD cruise data

CONCLUSIONS

The GIS interface developed on the ArcView is very easy for the non-GIS background oceanographic scientists to use in their application by clicking the buttons. This interface can help scientists to fully use the data in the database, to design a new expedition track line, deployed markers, sample sites, store real time data into database and various sophisticated analysis and visualization.

REFERENCES

Chavez, F. P., Herlin, R., and Thurmond G., OASIS-Aquisition System for mooring/drifters, Sea Technology, 35, 51-59, 1994.

Gritton, B. R. and Baxter, C. H., Video Database Systems in the Marine Sciences. Marine Technology Society Journal, 26(4), 1992.

Sawicki, John R., Building an ArcView Application Framework, Esri User's Conference Proceedings, 1996.

Yafang Su
Post_doc Fellow, Monterey Bay Aquarium Research Institute
P.O. Box 628
Moss Landing, CA 95039-0628
Tel: 408-775-1782
Fax: 408-775-1620
Email: syf@mbari.org