Our Environmental Analysis System (EASy©) is an advanced geographical information system designed for the storage, analysis, and presentation of diverse spatially and temporally referenced information. As documented on this website, EASy has already been successfully used in a wide range of oceanographic applications, and we are confident that it can be used for a much broader range of GIS applications. Unlike other GIS software, EASy has been specifically designed for oceanographic applications in which dynamic, 3 dimensional treatment of data is required. It provides a powerful yet easy to use tool the will allow environmental scientist, resource managers, and educators to better interpret and communicate their ideas about the processes of the natural world.

Software Description

EASy's power as an analytical and communication tool is based upon an elegant integration of the modules shown in Figure 1. Its modular architecture makes it simple to extend the functionality, and to link additional database libraries, data analysis tools and other services. The key modules of the system consist of Multi-Mode Executive that through the commands of the user controls the operation of the other 3 modules: the Graphics User Interface, the Sensor/Communication Interface, and the Model/Data Interface. The yellow symbols in the figure represent either databases, data streams, images/maps or computer code that can be easily linked to the 3 modules.

Figure 1. Modular architecture with an emphasis of flexibility and expandability underlies the EASy GIS software system.

Model/Data Interface Module
The Model/Data Interface Module enables the integration of diverse forms of information shown in the figure into a 4 dimensional system, consisting of the 3 dimensions of space (latitude, longitude, and depth or elevation) and time. This information includes scientific and engineering algorithms and models, statistical analyses, GIS products, satellite imagery, and oceanographic data obtained from ships, moorings, and other field sensors. Project files that have been developed using EASy are typically linked to Microsoft ACCESS relational databases. Since EASy links queries to the project database via standard SQL calls, this permits interfacing to alternative relational database software such as ORACLE without necessitating changes in the specific project file. By linking to such popular databases as ACCESS and ORACLE rather than custom GIS databases, EASy not only shortens the learning curve of the user, but also insures that their GIS database is well supported and economical to use, independent of EASy.

EASy project files that have integrated models and algorithms into the GIS have done so via dynamic link libraries. Such algorithms and models can be written in C++, C, or Fortran. Examples range from complex, application-specific simulation models to generic statistical functions and spatial interpolation methods used for data tranformation and analysis. There is much general and site specific environmental knowledge encoded in such standard programming languages which can be readily mobilized for import into the EASy's GIS. We have designed a standard application interface to expedite incorporating such code.

Graphical User Interface Module
The Graphical User Interface Module enables interactive selection and control of the data processing and model/algorithm computational sequence. It provides "click and drag" query tools for selecting and displaying diverse information from the multiple sources described above. Such information is automatically integrated and transformed via the tool set to produce a dynamic time series of maps and images of selected duration and time-step and within a 3 dimensional locale. We of course live in a 4 dimensional world so that almost all types of information are most comfortably retrieved and analyzed within this context. This is particularly true of oceanographic information where both horizontal and vertical features are closely tied through time varying processes. Time series information can be viewed in: "run mode" in which data and model outputs are processed and queried automatically in sequence, or "browse mode" in which database items and images can be queried out of sequence. A sequence of information can also be stored as a filmstrip and played back as a stream of model images or other data products at higher speed.

The Graphical User Interface Module enables viewing and information export in a variety of forms commonly used by environmental scientists and engineers. These include: variable contours in latitude-longitude views, false color images in latitude-longitude views, ocean variable versus time plots (specified interactively by selecting the latitude-longitude and depth of the source data), dynamic 2 dimensional contoured or false color transects taken though vertical depth planes (specified by "slicing" along a line in latitude-longitude space), dynamic xy plots at a given location showing ocean variable versus ocean variable, and vectors for viewing current and wind fields. These forms of visualization can be overlaid either directly in the case of contours, images and vectors, or as multiple windows on a computer screen.

Sensor/Communication Interface Module
EASy's Sensor and Communication Interface is used to import data and images from local networks, the Internet, or remote sensor sources. The importing of data can be done manually, via a prompt, or automatically at specified times. For example satellite imagery in specified format such as HDF can be automatically downloaded at a specified time from a specified ftp site and automatically geo-referenced and placed correctly in the time sequence of the EASy project file. In another example, telemetered data from field sensors (including GPS receivers) on board ship or buoys can be automatically downloaded into the database and processed in real time.

Multi-Mode Executive Module
The Executive Module sends commands and co-ordinates the activities of the 3 modules described above. In a stand-alone application EASy will be run on the user's PCs under the Windows operating system. However, the Executive Module can also be interfaced with supplemental code, which allows a client using an Internet browser to take command of EASy running on a server. This Netviewer version of EASy allows the administrator of the server to provide visitors the freedom to view, analyze, and download data and images interactively. By making the GIS available over the Internet, the Website greatly reduces the need to create large catalogues of pre-defined information that must cover the range of client's interests.

Sample EASy Projects

EASy has been successfully applied as geographic information system for a wide range of oceanographic applications. Sample outputs from some of the projects involving the coupling of biophysical datasets for the mapping and analysis of marine populations are presented below. These serve to illustrate the range of data integration and display capabilities listed above.

CalCOFI
EASy has been applied to integrate perhaps one of the world's most extensive series of multivariate oceanographic and fish distribution data. The California Cooperative Oceanographic Fisheries Investigation (CalCOFI) dataset comprises 60 years worth of spatial abundance data for eggs, larvae and adults of over 100 fish species. It also includes coincident oceanographic measurements of the water column, such as salinity and temperature, nutrient and chlorophyll concentrations. EASy with its Netviewer interface will soon be used by the Southwest Fisheries Center to interactively visualize and distribute portions of CalCOFI data via the Internet.

The image adjacent is a snapshot taken from the CalCOFI EASy project. It shows a false color image plot of surface chlorophyll concentrations. A large phytoplankton bloom off Point Conception is clearly shown as red in the image. This bloom is associated with coastal upwelling as seen in the temperature and chlorophyll contour plots in the upper left of the screen. These plots are produced in EASy by simply clicking and dragging the mouse along a transect and thereby vertically slicing the 3 dimensional data field. In this case the slice started at Point Conception and moved offshore into the Bight. EASY also produces vertical profiles of any oceanographic station where models are simulated or measurements are taken. Stations are represented by green dots in the figure above. Along with the oceanographic data, time series of the wetfish catch of anchovy, mackerel and sardine at three ports along the coast from 1980 to 1995 are displayed. From these plots one sees that anchovy and mackerel catches appear to be out of phase with those of sardine. By analyzing large scale oceanographic features with fisheries catch, managers gain an understanding of the effects of changes in these features on the dynamics of fish populations.

Red Eye Herring in the southern Benguela Current
Collaborative work with oceanographers at the University of Capetown resulted in the development of a GIS project in EASy for the fusing and mapping of physical oceanographic measurements and catch data for the small pelagics fishery off southern Africa. The data set consists of a time series of geo-referenced catch data for three commercially harvested species (anchovy, sardine and redeye), satellite images of sea surface temperature, and in-situ data on water temperature, salinity, chlorophyll concentration, wind and current vectors.

The figure adjacent further demonstrates EASy's data integration, display and analysis capabilities. False color imagery of sea surface temperature reveals the dynamic and heterogeneous nature of the physical environment. Depth structure is also important in this regard. The vertical contour plot (bottom right window) of water temperature measurements made over a range of depths along an inshore-offshore transect (blue line) show the importance of local upwelling processes. Interrogation of data collected at individual sampling stations (black dots) is also a feature of EASy, as illustrated by the vertical profile plots of chlorophyll and temperature (two middle, right graphs). Hydrographical and meteorological information are also included. Here, current data collected along the sampling transect are displayed as vector plots, the size and orientation of the arrows representing the speed and direction of currents respectively. Redeye fishery catch data available for the current time step in the viewing sequence are presented as contours for the inshore northern portion. Sequential viewing of data outputs in time is achieved via the simulation control panel (window top, right). This allows users to step or run through the data series and view dynamically updated plots of selected variables at time steps that are interactively defined.