The following is a listing of the first file provided on the magnetic tape distributed by CDIAC. This file provides variable descriptions, formats, units, and other pertinent information about each file associated with this coastal hazards data base. Title of the Data Base A Coastal Hazards Data Base for the U.S. Gulf Coast Contributors Vivien M. Gornitz National Aeronautics and Space Administration Goddard Institute for Space Studies 2880 Broadway New York, NY 10025 Tammy W. White Oak Ridge National Laboratory Carbon Dioxide Information Analysis Center Oak Ridge, TN 37831-6335 Scope of the Data The 29 data variables within A Coastal Hazards Data Base for the U.S. Gulf Coast, and the corresponding coastal vulnerability indices that may be derived, may be used by coastal planning, research, and management agencies to identify shorelines at risk from coastal erosion and inundation. This data base should be used to identify areas where further study is necessary. In addition, these data may be used in combination with appropriate climatological data (e.g., Birdwell and Daniels, 1991) to identify coastal areas that are vulnerable to coastal erosion and inundation from sea level rise or storm surge. This data base is comprised of the following data sets: elevation, bedrock geology, geomorphology, sea level trends, horizontal shoreline movements (erosion/accretion), tidal ranges, and wave heights. For several of these data sets minimum, mean, and maximum data values are available. These data variables may be divided into two basic classes, one that measures erosion potential and one that is related to inundation risk. The erosion risk of each coastal grid cell or line segment may be determined based on geology, geomorphology, shoreline displacement, tidal ranges and wave heights, while the inundation risk may be estimated based on sea level trends and elevations. Seven of the 29 data variables in this data base are classified versions of other variables within this data base. The seven classified risk variables contain "risk values" of one to five for each coastal grid cell in the data base. These risk variables may be used to calculate a Coastal Vulnerability Index (CVI) that may be used to identify areas on the U.S. Gulf Coast that are vulnerable to sea level rise or coastal erosion. Data Formats For ease of use, this data base has been divided into five data groups or coverages. Each of these five data groups are provided in two different data formats. The first format is designed for use by the ARC/INFOTM Geographic Information System (GIS). This format stores the data as polygons (e.g., GCGRID and GCRISK), as arcs (e.g., GCLINE and GCOAST), or as points (e.g., GCPOINT). The second format contains comparable data that has been converted into flat ASCII data files for use by raster GISs or non-GIS data base systems. The first two data groups are registered to a 0.25 degree latitude by 0.25 degree longitude grid. The first, GCGRID (Files 4 and 5) provides the 22 original data variables, while the second data group, GCRISK (Files 8 and 9) provides the seven relative risk variables. The third data group is registered to a 1:2,000,000 digitized U.S. Gulf coastline, GCLINE (Files 12 and 13), and provides 29 data variables (i.e., the 22 original and the seven relative risk data variables). The fourth data group, GCPOINT (Files 16 and 17), was originally obtained as point data. This data group provides the source information used in the development of the tidal range and sea- level-trends data sets. Data variables included in this data group are station names/numbers, record lengths, and longitude/latitude locations of the actual data point. These data represent the physical location of the occurring data point, and will allow the precise location of each station used in calculating the gridded tidal range and sea-level-rise data variables within the 0.25 degree grid cells of data groups GCGRID and GCRISK. Finally, the last group contains an auxiliary file, a 1:2,000,000 digitized coastline of the U.S. Gulf Coast, GCOAST (files 20 and 21). These line segments are identical to those found in data group GCLINE, however no data values are provided. A description of the contents of each of the data groups and files included with this data base follows: (1) GCGRID: Gridded polygon data for the 22 original data variables. Data sets contained in this group include elevation, geology, geomorphology, sea level trend, shoreline displacement (erosion/accretion), tide range, and wave heights. (2) GCRISK: Gridded polygon data for the seven classified risk variables. The risk variables are classified versions of the following original variables: mean coastal elevation, geology, geomorphology, local subsidence trend, mean shoreline displacement, mean tidal range, and maximum significant wave height. (3) GCLINE: 1:2,000,000 digitized line segment data for the U.S. Gulf Coast containing the 29 data variables (i.e., the 22 original data variables and the seven classified risk variables). Data contained within this group include elevation, geology, geomorphology, sea level trend, horizontal shoreline displacement, tide range and wave heights. The seven risk variables are classified versions of the following original data variables: mean coastal elevation, geology, geomorphology, local subsidence trend, mean shoreline displacement, mean tidal range, and the maximum significant wave height. (4) GCPOINT: Point data for the stations used in calculating the sea-level-trend and tide-range data sets. Data include station names/numbers, record length, latitude/longitude location, and mean and maximum data values (when available). (5) GCOAST: 1:2,000,000 digitized coastline of the U.S. Gulf Coast. The coastline was extracted from a digitized map of the United States compiled by the U.S. Geological Survey. To improve the portability of the information in the data files, FORTRAN 77 and SASTM input/output routines have been included with this data base for each of the flat ASCII data files. These input/output routines are intended to be used to read/write the data values contained in the flat ASCII data files [containing the gridded data base, the original point data (for the sea level trend and tide range variables), and the digitized U.S. Gulf coastline]. The data groups in this data base are available as compressed and uncompressed exported ARC/INFO coverages (Version 6.0.1). Both sets of export files contain identical data and must be read into ARC/INFO or ARCVIEW using the COVER OPTION of the IMPORT command. The compressed export coverages are located in the pub/ndp043b subdirectory and were generated using the FULL option of the ARC/INFO EXPORT command. These coverages contain ASCII compression characters that do not have equivalent EBCDIC characters on an IBM computer. The uncompressed ARC/INFO export coverages are IBM compatible and are located in the pub/ndp043b/asciiexp subdirectory. These files were generated using the NONE option of the ARC/INFO EXPORT command. Both the compressed and uncompressed sets of export files contain identical data and differ only in file format. These files are in a GEOGRAPHIC projection, which means that the coverages are projected in a spherical reference grid using latitude and longitude coordinates that are stored in decimal degrees (DD). The flat ASCII files contain an identical version of this data base. The gridding method used in this data base consists of 0.25 degree latitude by 0.25 degree longitude grid cells. These cells cover the area defined by the following coordinates: 100 degrees W, 24 degrees N; 100 degrees W, 32 degrees N; 80 degrees W, 32 degrees N; and 80 degrees W, 24 degrees N. The origin of the grid is at 100 degrees W, 24 degrees N, and grid identifiers increase from left to right, bottom to top. The data contained within each grid cell are an average for the entire grid cell. The grid cell identification number is located in the center of each cell and although it is not the physical location of each data value, it represents averages for all data points located within the cell. The flat ASCII versions of the files have been provided to allow use of these data by users who do not have access to ARC/INFOTM. The format and contents of each of the flat ASCII files are described in the following section (the ARC/INFOTM coverages have the same variables and general format as described herein for the ASCII files). Data Group GCGRID: This data group contains gridded data for the 22 original data variables. These data variables are from the seven data sets and are as follows: mean, maximum, and minimum elevation, and the number of 5' grid cells used in deriving the data values; geology; geomorphology; relative sea level trend, global-trend, corrected sea level trend, local subsidence trend, and the years of record of the gauge stations used in calculating these values; mean, maximum, and minimum shoreline displacement, and the number of 3', 7.5', or 15' grid cells used in deriving the data values; mean and maximum tidal range, mean tide level, and the number of tidal stations used in calculating these values; 20 year mean wave height, maximum significant wave height, and the 20 year mean wave height standard deviation. The names of the ARC/INFOTM coverage and flat ASCII files providing these data are GCGRID.E00 (File 4) and GCGRID.ASC (File 5), respectively. File 5 is formatted as follows: 10 READ(5,100,END=999) ID,ELAVG,ELMAX,ELMIN, 1 ELNUM,GL,GM,SLR,SLG,SLC,SLYR READ(5,110) ERAVG,ERMAX,ERMIN,ERNUM,TRAVG, 1 TRMAX,TRLVL,TRNUM,WHAVG,WHMAX,WHSD 100 FORMAT(I5,4F8.2,2I4,3F8.2,I4) 110 FORMAT(3F8.2,I4,3F8.2,I4,3F8.2) The variables in data group GCGRID (File 5) are shown in Table 8 and are listed as they appear in the file. Table 8. Variable formats for GCGRID.ASC (File 5). Column Variable name Start End Variable type Variable description ID 1 5 Integer System variable - grid cell identifier. ELAVG 6 13 Real Data variable - mean elevation of all positive 5' by 5' grid cells within a given 0.25 degree grid cell; values in meters. ELMAX 14 21 Real Data variable - maximum elevation of all positive 5' by 5' grid cells within a given 0.25 degree grid cell; values in meters. ELMIN 22 29 Real Data variable - minimum elevation of all positive 5' by 5' grid cells within a given 0.25 degree grid cell; values in meters. ELNUM 30 33 Integer Data variable - number of 5' by 5' grid cells used in calculating ELAVG, ELMIN, and ELMAX for a given 0.25 degree grid cell. GL 34 37 Integer Data variable - ordinal value indicative of the type and resistance of the rocks within a given 0.25 degree grid cell to erosion. GM 38 41 Integer Data variable - ordinal value indicative of the type and susceptibility of the landforms within a given 0.25 degree grid cell to inundation and erosion. SLR 42 49 Real Data variable - relative sea-level trend within a given 0.25 degree grid cell; values in mm/year. SLG 50 57 Real Data variable - long-term geologic trend derived from 14C data for each 0.25 degree grid cell; values in mm/year. SLC 58 65 Real Data variable - corrected sea-level trend. Tide-gauge data (i.e., SLR) corrected for geologic trends (i.e., SLG) for each 0.25 degree grid cell. SLS 66 73 Real Data variable - the local subsidence trend. Tide-gauge data (i.e., SLR) corrected for the regional eustatic rate of sea level rise (i.e., 1.25 mm/year). SLYR 74 77 Integer Data variable - years of record used in estimating the sea level trend for each 0.25 degree grid cell. --------------- SECOND LINE READS AS FOLLOWS ----------------- ERAVG 1 8 Real Data variable - mean long-term erosion trend for a given 0.25 degree grid cell; values in meters. ERMAX 9 16 Real Data variable - maximum long-term erosion trend for a given 0.25 degree grid cell; values in meters. ERMIN 17 24 Real Data variable - minimum long-term erosion trend for a given 0.25 degree grid cell; values in meters. ERNUM 25 28 Integer Data variable - number of 3', 7.5', or 15' grid cells used in calculating ERAVG, ERMIN, and ERMAX for a given 0.25 degree grid cell. TRAVG 29 36 Real Data variable - average of the mean tide range for all the gauge stations that occur within a given 0.25 degree grid cell (mean tide range is the difference in height between mean high water and mean low water in 1988); values in meters. TRMAX 37 44 Real Data variable - maximum tide range measured for all gauge stations that occurred within a given 0.25 degree grid cell in 1988 (this value may be the "spring" or "diurnal" tide range, depending on geographic location); values in meters. TRLVL 45 52 Real Data variable - the average of the mean tide levels of all the gauge stations that occur within a given 0.25 degree grid cell (mean tide level is a plane midway between mean low water and mean high water in 1988). Values were reckoned from chart datums (i.e., the Gulf Coast Mean Low Water Datum). TRNUM 53 56 Integer Data variable - number of tide gauge stations used in calculating TRAVG, TRMAX, and TRLVL for a given 0.25 degree grid cell. WHAVG 57 64 Real Data variable - 20- year mean wave height experienced within each 0.25 degree grid cell; values in meters. WHMAX 65 72 Real Data variable - maximum significant wave height for each 0.25 degree grid cell; values in meters. WHSD 73 80 Real Data variable - standard deviation of the 20-year mean wave height experienced within each 0.25 degree grid cell; values in meters. Within GCGRID missing data values are identified as follows: 9999.99 - A grid cell with real data values that is missing data for a given data variable. 9999 - A grid cell with integer data values that is missing data for a given data variable. A value of 0.0 is a valid value for all variables. For the elevation variables 0.0 m indicates that land occurs within the given grid cell, but the mean elevation of this land is < 1.0 m. If the data variables in a given data set, such as elevation, contain data and the "number" variable is set to zero (i.e., ELNUM, ERNUM, TRNUM, or SLYR), then the data variables for the given 0.25 degree grid cell have been estimated. Data Group GCRISK: This data group contains gridded data for the seven classified risk variables. These risk variables are classified versions of the following original variables: mean coastal elevation, geology, geomorphology, local subsidence trend, mean shoreline displacement, mean tidal range, and maximum significant wave height. The names of the ARC/INFOTM coverage and flat ASCII files are GCRISK.E00 (File 8) and GCRISK.ASC (File 9), respectively. A summary of the format used in File 9 follows: 10 READ(5,100,END=999) ID, 1 ELR,GLR,GMR,LSR,ERR,TRR,WHR 100 FORMAT(I5,7I4) The variables in data group GCRISK, listed in Table 9, are shown as they appear in File 13. Table 9. Variable formats for GCRISK.ASC (File 9). Column Variable name Start End Variable type Variable description ID 1 5 Integer System variable - grid cell identifier. ELR 6 9 Integer Data variable - classified version of the mean elevation variable (i.e., ELAVG). GLR 10 13 Integer Data variable - classified version of the geology variable (i.e., GL). GMR 14 17 Integer Data variable - classified version of the geomorphology variable (i.e., GM). LSR 18 21 Integer Data variable - classified version of the local subsidence trend variable (i.e., SLS). ERR 22 25 Integer Data variable - classified version of the mean erosion/accretion variable (i.e., ERAVG). TRR 26 29 Integer Data variable - classified version of the mean tide range variable (i.e., TRAVG). WHR 30 33 Integer Data variable - classified version of the maximum significant wave - height variable (i.e., WHMAX). A value of zero is used to identify missing data values within the grid cell for the risk variables. If several "no data" values occur within the same grid cell, then any calculated coastal vulnerability index that uses these relative risk factors may not accurately represent the risk of the given coastal area to sea level rise or coastal erosion (unless some type of corrective action is taken). Grid cells that are not in the coastal zone, or are totally ocean bound, have values of zero for all seven derived risk variables. Data Group GCLINE: This data group contains 1:2,000,000 digitized line segment for the 29 data variables contained within this data base (i.e., the 22 original and the seven relative risk data variables). These data variables are from the seven data sets and are as follows: mean, maximum, and minimum elevation, the number of 5' grid cells used in deriving the data values, and the elevation risk (i.e., the classified version of the mean elevation variable); geology and the geology risk (i.e., the classified version of the geology variable; geomorphology and geomorphology risk (i.e., the classified version of the geomorphology variable); relative sea level trend, global- trend, corrected sea level trend, local subsidence trend, the years of record of the gauge stations used in calculating these values, and the local subsidence trend risk (i.e., the classified version of the local subsidence trend variable); mean, maximum, and minimum shoreline displacement, the number of 3', 7.5', or 15' grid cells used in deriving the data values, and erosion risk (i.e., the classified version of the mean erosion/accretion variable); mean and maximum tidal range, mean tide level, the number of tidal stations used in calculating these values, and the tidal-range risk (i.e., the classified version of the mean tidal range); 20 year mean wave height, maximum significant wave height, the 20 year mean wave height standard deviation, and the wave-height risk (i.e., classified version of the maximum significant wave-height variable). The names of the ARC/INFOTM coverage and flat ASCII file that provide these data variables are GCLINE.E00 (File 12) and GCLINE.ASC (File 13), respectively. File 13 is formatted as follows: 10 read(5,100,end=999) id,elavg,elmax,elmin,elnum, 1 elr,gl,glr,gm,gmr,slr,slg,slc,sls, 1 slyr,lsr read(5,110) eravg,ermax,ermin,ernum,err,travg, 1 trmax,trlvl,trnum,trr,whavg,whmax, 1 whsd,whr 100 format(i5,3f8.2,6i4,4f8.2,2i4) 110 format(3f8.2,2i4,3f8.2,2i4,3f8.2,i4) The variables in data group GCLINE (File 13) are shown in Table 10 and are listed as they appear in the file. Table 10. Variable formats for GCLINE.ASC (File 13). Column Variable name Start End Variable type Variable description ID 1 5 Integer System variable - grid cell identifier. ELAVG 6 13 Real Data variable - mean elevation of all positive 5' by 5' grid cells within a given 0.25 degree grid cell; values in meters. ELMAX 14 21 Real Data variable - maximum elevation of all positive 5' by 5' grid cells within a given 0.25 degree grid cell; values in meters. ELMIN 22 29 Real Data variable - minimum elevation of all positive 5' by 5' grid cells within a given 0.25 degree grid cell; values in meters. ELNUM 30 33 Integer Data variable - number of 5' by 5' grid cells used in calculating ELAVG, ELMIN, and ELMAX for a given 0.25 degree grid cell. ELR 34 37 Integer Data variable - classified version of the mean elevation variable (i.e., ELAVG). GL 38 41 Integer Data variable - ordinal value indicative of the type and resistance of the rocks within a given 0.25 degree grid cell to erosion. GLR 42 45 Integer Data variable - classified version of the geology variable (i.e., GL). GM 46 49 Integer Data variable - ordinal value indicative of the type and susceptibility of the landforms within a given 0.25 degree grid cell to inundation and erosion. GMR 50 53 Integer Data variable - classified version of the geomorphology variable (i.e., GM). SLR 54 61 Real Data variable - relative sea level trend within a given 0.25 degree grid cell; values in mm/year. SLG 62 69 Real Data variable - long-term geologic trend derived from 14C data for each 0.25 degree grid cell; values in mm/year. SLC 70 77 Real Data variable - corrected sea level trend. Tide-gauge data (i.e., SLR) corrected for geologic trends (i.e., SLG) for each 0.25 degree grid cell. ----------------------------- SECOND LINE READS AS FOLLOWS ----------------- SLS 1 8 Real Data variable - the local subsidence trend. Tide-gauge data (i.e., SLR) corrected for the regional eustatic rate of sea level rise (i.e., 1.25 mm/year). SLYR 9 12 Integer Data variable - years of record used in estimating the sea level trend for each 0.25 degree grid cell. LSR 13 16 Integer Data variable - classified version of the local subsidence trend variable (i.e., SLS). ERAVG 17 24 Real Data variable - mean long- term erosion trend for given 0.25 degree grid cell; values in meters. ERMAX 25 32 Real Data variable - maximum long-term erosion trend for a given 0.25 degree grid cell; values in meters. ERMIN 33 40 Real Data variable - minimum long-term erosion trend for a given 0.25 degree grid cell; values in meters. ERNUM 41 44 Integer Data variable - number of 3', 7.5', or 15' grid cells used in calculating ERAVG, ERMIN, and ERMAX for a given 0.25 degree grid cell. ERR 45 48 Integer Data variable - classified version of the mean erosion/accretion variable (i.e., ERAVG). TRAVG 49 55 Real Data variable - average of the mean tide range for all the gauge stations that occur within a given 0.25 degree grid cell (mean tide range is the difference in height between mean high water and mean low water in 1988); values in meters. TRMAX 56 64 Real Data variable - maximum tide range measured for all gauge stations that occurred within a given 0.25 degree grid cell in 1988 (this value may be the "spring" or "diurnal" tide range, depending on geographic location); values in meters. TRLVL 65 72 Real Data variable - the average of the mean tide levels of all the gauge stations that occur within a given 0.25 degree grid cell (mean tide level is a plane midway between mean low water and mean high water in 1988). Values were reckoned from chart datums (i.e., the Gulf Coast Mean Low Water Datum). TRNUM 73 76 Integer Data variable - number of tide gauge stations used in calculating TRAVG, TRMAX, and TRLVL for a given 0.25 degree grid cell. TRR 77 80 Integer Data variable - classified version of the mean tide range variable (i.e., TRAVG). ----------------------------- THIRD LINE READS AS FOLLOWS ----------------- WHAVG 1 8 Real Data variable - 20-year mean wave height experienced within each 0.25 degree grid cell; values in meters. WHMAX 9 16 Real Data variable - maximum significant wave height for each 0.25 degree grid cell; values in meters. WHSD 17 24 Real Data variable - standard deviation of the 20-year mean wave height experienced within each 0.25 degree grid cell; values in meters. WHR 25 28 Integer Data variable - classified version of the maximum significant wave-height variable (i.e., WHMAX). Within GCLINE missing data values are indicated as follows: 9999.99 - A line segment with real data values that is missing data for a given data variable. 9999 - A line segment with integer data values that is missing data for a given data variable. 0 - A line segment with missing data values for the risk variables. A value of 0.0 is a valid value for all variables. For the elevation variables 0.0 m indicates that land occurs within the given grid cell, but the maximum elevation of this land is < 1.0 m. If the data variables in a given data set, such as elevation, contain data and the "number" variable is set to zero (i.e., ELNUM, ERNUM, TRNUM, or SLYR), then the data variables for the given 0.25 degree grid cell have been estimated. Data Group GCPOINT: This data group contains the point data for the stations used in calculating the relative sea level trend, long-term geologic-trend, corrected sea level trend, local subsidence trend, mean tide range, maximum tide range, and mean tide level variables contained within data group GCGRID. Data include station names, station number, record length, latitude/longitude location, and data variable values. The names of the ARC/INFOTM coverage and flat ASCII file are GCPOINT.E00 (File 16 and GCPOINT.ASC (File 17), respectively. A summary of the format used for File 17 follows: 10 READ(5,100,END=999) ID,SLLONG,SLLAT,SLR,SLG, 1 SLC,SLS,SLYR,SLNAME READ(5,110) TRLONG,TRLAT,TRAVG,TRMAX,TRLVL, 1 TRID,TRNAME 100 FORMAT(I5,6F8.2,I4,A38) 110 FORMAT(5F8.2,I5,A45) The variables listed in Table 11 are listed as they appear in data group GCPOINT (File 17). Table 11. Variable formats for GCPOINT.ASC (File 17). Column Variable name Start End Variable type Variable description ID 1 5 Integer System variable - Point identification number. SLLONG 6 13 Real Data variable - longitude of the tide- gauge station used in determining the sea level trends. SLLAT 14 21 Real Data variable - latitude of the tide- gauge station used in determining the sea level trends. SLR 22 29 Real Data variable - relative sea level trend measured for each tide-gauge station; values are expressed in mm/year. SLG 30 37 Real Data variable - long-term geologic trend derived from C14 data; values are expressed in mm/year. SLC 38 45 Real Data variable - corrected sea level trend. Tide-gauge data (i.e., SLR) corrected for long-term geologic-trends (i.e., SLG); values are expressed in mm/year. SLS 46 53 Real Data variable - local subsidence trend. Relative sea level trend corrected for the regional eustatic rate of sea level rise (i.e., 1.25 mm/year). SLYR 54 57 Integer Data variable - years of record of the tide gauge station used in determining the sea level trends. SLNAME 58 81 Char Data variable - name of the tide gauge used for determining the sea level trends. ----------------- SECOND LINE READS AS FOLLOWS -------------------- TRLONG 1 8 Real Data variable - longitude of a tide-gauge station used for determining the tide range ariables. TRLAT 9 16 Real Data variable - latitude of a tide-gauge station used for determining the tide range variables. TRAVG 17 24 Real Data variable - difference between mean high water and mean low water for 1988; values in meters. TRMAX 25 32 Real Data variable - maximum tide range, maximum measured range for the gauge station in 1988 (this value may be the "spring" or "diurnal" tide range, depending on geographic location); values in meters. TRLVL 33 40 Real Data variable - mean tide level, a plane midway between mean low water and mean high water in 1988. Values are reckoned from chart datums (i.e., the Gulf Coast Mean Low Water Datum). TRID 41 44 Integer Data variable - station number (used in the 1988 Tide Tables) of a tide-gauge station. TRNAME 45 81 Char Data variable - name of a tide-gauge station (from the 1992 Tide Tables). Within this data file, GCPOINT, missing data values are indicated with one of the following values: 0.0 or 0 - A tide range or sea-level station that has not been assigned data for the variable in question. In this data group the sea level variables and tide range variables are mutually exclusive (i.e., if tide-range data are present, then the sea-level data are missing or vice versa). Data Group GCOAST: Auxiliary data group GCOAST (Files 20 and 21) contains a 1:2,000,000 digitized coastline of the U.S. Gulf Coast. Data in this coverage were extracted from a digitized map of the United States (originally compiled by the U.S. Geological Survey). This coastline may be overlaid onto any of the three data groups previously discussed to provide locational information when plotting any or all of the data variables. Unlike the other data groups within this data base, this coverage contains line segments (or arcs) that describe the Gulf Coast. The coastline provided has no attribute values associated with the line segments. However, such overlay commands as UNION, INTERSECT, and IDENTITY in ARC/INFOTM (or other GISs) may be used to transfer the gridded data values to the coastal segments, thus simplifying the interpretation of any derived indices. The name of the ARC/INFOTM coverage where the coastline resides is GCOAST.E00 (File 20), and the flat ASCII data file with this same information is in GCOAST.ASC (File 21). Since this file is line based, the data values in GCOAST.ASC contain the line segment name, and a listing of the points that describe each line, for all 934 line segments that define the Gulf Coast. The flat ASCII version of this file contains a listing of the line segments (or arcs) that describe the coast. An example of the format for this file is shown in Table 12. Table 12. Sample of the vector format used for GCOAST.ASC (File 21). Name, Number of points - Data points Data interpretation " 1", -14 -Vector 1 uses 14 points to describe the line -88.0000,30.7848 -Start at -88.00 W. Longitude, 30.78 N. Latitude -87.9967,30.7839 -87.9915,30.7806 -87.9883,30.7806 -87.9856,30.7806 -87.9825,30.7755 -87.9821,30.7705 -87.9821,30.7677 -87.9827,30.7645 -87.9843,30.7627 -87.9876,30.7605 -87.9898,30.7573 -87.9946,30.7551 -88.0000,30.7529 " 2", -35 -Vector 2 uses 35 points to describe the line -87.9361,30.7515 -Start at 87.94 W Longitude, 30.75 N Latitude -87.9355,30.7556 ... -Continued