Database Structures for TAOS/L

Introduction

This document outlines the base structure of data bases used by TAOS/L and TAOS/R. The directory structure is discussed, followed by the two mandatory and one optional files which make up a TAOS/L data set.

Directory Structure

The file data.idx points to data sets available for TAOS runs. The format of this file is as follows:

NumberofDB
DBpath                                       Dbname
…

NumberofDB is the number of data bases available. Each data base definition is on one line. The format of each line is: "I2,X,35A,X,40A". DBPath is the path where the data base files reside. Dbname is the name which will appear in the taos  menu to allow selection of the data set.

The DB code MUST match the code in the area.dat file located in the directory path. DB codes are discussed in more detail in the following section.

Area Definition File

The file area.dat contains the study area geographic coordinates, vertical coordinate multiplier, and data base code. The format is as follows:

MinLon MaxLon MinLat MaxLat Rows Columns
VertMult
DBCode

All TAOS/L data bases are in the Lat/Long coordinate system. The vertical coordinate is in TAOS is assumed to be meters, however, the VertMult value in area.dat may be used for non-standard data sets. VertMult is the value the DEM must be multiplied by to get meters. For example, if the DEM is in feet, VertMult would be entered as 3.2808. For data sets in meters VertMult should be set to 1.0.

Note: sub-regional data sets are assumed to be set to MLLW for tide calculation purposes. All other data sets are assumed to be WGS-84. This primarily effects tide calculations.

The data base code is a two digit code (00-99) to insure a match between the data.idx definition and the area.dat file. Data base codes are presently grouped as follows:

* Within the Caribbean, the following specific codes are already in use:

** Codes between 90-99 should be used for user created data sets which will not be exported outside the user’s organization.

User’s note: any lines after the data base code are ignored. The user may wish to include a documentation file from the source GIS used to create the DEM. For example, the .doc file from Idrisi, or the .hdr file from an Arc/View export may be appended to the area.dat file.

DEM File

Topo.bin is the DEM file. It is a IEEE 32 bit (4 byte) floating point format file in native form corresponding to a REAL*4 (FORTRAN) or float (c) variable. Topo.bin has no header; all of the coordinate information is stored in area.dat. As noted earlier, the topo.bin vertical datum for sub-regional data sets is assumed to be registered to MLLW for tide calculation purposes.

LULC File

Lulc.bin is the optional land use/land cover file which specifies the frictional surfaces of the terrain. If it is absent, generic friction values are used for land and ocean bottom. Lulc.bin is a single byte format file corresponding to a CHARACTER*1 (FORTRAN) or unsigned char (C) variable. lulc.bin codes are from Anderson et al, 1976, commonly called the Level II USGS codes. These are the same codes used in the GIRAS format files available from the USGS EROS data center. Internally to TAOS, each LULC code has an associated hydrological and aerodynamic friction factor to allow the proper calculation of surface friction to the forces of air or water. General codes and types are below. For more details see the reference.

References

Anderson, Hardy, Roach, Whitmer, 1976: A land use and land cover classification scheme for use with remote sensor data. US Geol. Survey Prof. Paper 964.