The Local Drain Direction (LDD) in a hydrological model is the essential component to connect the grid cells in order to express the flow direction from one cell to another, and forming a river network from the springs to the mouth. LDD represents flow directions from each grid-cell to its steepest down-slope neighbor. Geographical directions in the LDD file are coded with values from "1" to "9", with "5" representing pits (grid-cells with only inflow of water).
Download the LDD file for GloFAS here: ldd_glofas_v4_0.nc (5MB21MB) Code Block |
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language | bash |
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title | LDD NetCDF metadata |
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collapse | true |
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| dimensions:
latlon = 15007200 ;
lonlat = 36003000 ;
variables:
double lon(lon) ;
lon:standard_name = "longitude" ;
lon:long_name = "longitude coordinate" ;
lon:units = "degrees_east" ;
double lat(lat) ;
lat:standard_name = "latitude"projection_x_coordinate" ;
latlon:long_name = "latitude coordinatelongitude" ;
latlon:units = "degrees_northeast" ;
ubyte ldd(lat, lon) ;
ldd:_FillValuelon:axis = 0UB"X" ;
ldd:coordinates = "lon lat"double lat(lat) ;
lddlat:esristandard_pe_stringname = "GEOGCS[\"GCS_WGS_1984\",DATUM[\"D_WGS_1984\",SPHEROID[\"WGS_1984\",6378137,298.257223563]],PRIMEM[\"Greenwich\",0],UNIT[\"Degree\",0.0174532925199433]]"projection_y_coordinate" ;
lddlat:standardlong_name = "lddlatitude" ;
lddlat:units = "-degrees_north" ;
lddlat:long_nameaxis = "Local drain directionY" ;
// global attributes: char crs ;
:Conventionscrs:longitude_of_prime_meridian = "CF-1.7"0. ;
crs:Sourcesemi_major_Softwareaxis = "JRC.E1 lisfloodutilities nexus wefe - pcr2nc"6378137. ;
crs:inverse_flattening = 298.257223563 ;
crs:sourcegrid_mapping_name = "JRC Space, Security, Migration (L.A.)latitude_longitude" ;
crs:referencelong_name = "JRC Space, Security, MigrationCRS definition" ;
crs:history = "Fri Dec 2 16:49:41 2022: ncatted -a long_name,ldd,o,c,Local drain direction ldd_glofas.nc ldd_glofas_ln.nc\nCreated Tue Dec 3 14:11:34 2019" ;
:NCO = "netCDF Operators version 4.9.7 (Homepage = http://nco.sf.net, Code = http://github.com/nco/nco)" ;
} | Panel |
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| title | Pre-release: GloFAS version 4.0 - LDD |
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| Download the LDD file for v4.0 here: ldd_glofas_v4_0.nc (21MB) Code Block |
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language | bash |
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title | NetCDF metadata |
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collapse | true |
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| dimensions:
spatial_ref = "GEOGCS[\"WGS 84\",DATUM[\"WGS_1984\",SPHEROID[\"WGS 84\",6378137,298.257223563,AUTHORITY[\"EPSG\",\"7030\"]],AUTHORITY[\"EPSG\",\"6326\"]],PRIMEM[\"Greenwich\",0,AUTHORITY[\"EPSG\",\"8901\"]],UNIT[\"degree\",0.0174532925199433,AUTHORITY[\"EPSG\",\"9122\"]],AXIS[\"Latitude\",NORTH],AXIS[\"Longitude\",EAST],AUTHORITY[\"EPSG\",\"4326\"]]" ;
lon = 7200 ;
crs:GeoTransform = "-180 0.05 0 90 lat = 30000 -0.05 " ;
variables:
ubyte doubleldd(lat, lon (lon) ;
lonldd: standardlong_name = " projection_x_coordinateLocal drain direction" ;
lonldd: longgrid_ namemapping = " longitudecrs" ;
lonldd: units_FillValue = "degrees_east"255UB ;
lonldd: axismissing_value = "X"255UB ;
// global attributes:
:CDI = double lat(lat)"Climate Data Interface version 1.9.10 (https://mpimet.mpg.de/cdi)" ;
lat: standard_nameConventions = " projection_y_coordinateCF-1.9" ;
lat: long_namehistory_of_appended_files = " latitude" ;
lat:units = "degrees_north" ;
lat:axis = "Y"Fri Dec 10 11:49:28 2021: Appended file ldd_ORIG_03min.nc had following \"history\" attribute:\nWed Nov 18 13:59:27 2020: ncks -A -v lat,lon /hugetmp/NOT_Permanent/LDD/LDD_BOX/data/flwdir_202001_03min.nc /hugetmp/NOT_Permanent/LDD/LDD_BOX/res/CHECKED/ldd_Global_03min.nc\nWed Nov 18 13:59:27 2020: cdo -invertlat tmp_5.nc /hugetmp/NOT_Permanent/LDD/LDD_BOX/res/CHECKED/ldd_Global_03min.nc\nWed Nov 18 13:59:27 2020: GDAL CreateCopy( tmp_5.nc, ... )\n" ;
char crs ;
crs:longitude_of_prime_meridian = 0.:GDAL_PCRASTER_VALUESCALE = "VS_LDD" ;
crs: semi_major_axisNCO = 6378137. ;
crs:inverse_flattening = 298.257223563"netCDF Operators version 4.9.7 (Homepage = http://nco.sf.net, Code = http://github.com/nco/nco)" ;
crs: grid_mapping_nameGDAL = " latitude_longitudeGDAL 3.2.1, released 2020/12/29" ;
crs: long_nameGDAL_AREA_OR_POINT = " CRS definitionArea" ;
crs: spatial_refhistory = "Fri Dec 02 15:24:49 2022: cdo chname,Band1,ldd ldd_ln.nc ldd_glofas_v4_0.nc\nWed Nov 23 10:14:40 2022: ncks -O -d lat,-59.975,89.975 /ec/vol/cems_floods/glofas/static_maps/4.0/ldd_repaired.nc out/ldd_repaired.nc\nFri Dec 10 11:49:28 2021: ncks -A -v lat,lon ldd_ORIG_03min.nc ldd_repaired.nc\nFri Dec 10 11:49:27 2021: cdo -invertlat tmp_repaired.nc ldd_repaired.nc\nFri Dec 10 11:49:26 2021: GDAL CreateCopy( tmp_repaired.nc, ... )" ;
:CDO = "Climate Data Operators version 1.9.10 (https://mpimet.mpg.de/cdo)" ;
}
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title | GloFAS version 1.0 to 3.4 - LDD |
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| Download the LDD file for forecasts produced before 2023-07-26 (versions 1.0 to 3.4) here: ldd_glofas.nc (5MB)
Code Block |
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language | bash |
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title | NetCDF metadata |
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collapse | true |
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| dimensions:GEOGCS[\"WGS 84\",DATUM[\"WGS_1984\",SPHEROID[\"WGS 84\",6378137,298.257223563,AUTHORITY[\"EPSG\",\"7030\"]],AUTHORITY[\"EPSG\",\"6326\"]],PRIMEM[\"Greenwich\",0,AUTHORITY[\"EPSG\",\"8901\"]],UNIT[\"degree\",0.0174532925199433,AUTHORITY[\"EPSG\",\"9122\"]],AXIS[\"Latitude\",NORTH],AXIS[\"Longitude\",EAST],AUTHORITY[\"EPSG\",\"4326\"]]" ;
lat = 1500 ;
crs:GeoTransform = "-180 0.05 0 90 0 -0.05 " ;
lon = 3600 ;
variables:
double lon(lon) ;
ubyte ldd(lat, lon):standard_name = "longitude" ;
lddlon:long_name = "Locallongitude drain directioncoordinate" ;
lddlon:grid_mappingunits = "crs"degrees_east" ;
double lat(lat) ;
lddlat:standard_FillValuename = 255UB"latitude" ;
lddlat:missinglong_valuename = 255UB"latitude coordinate" ;
// global attributes:
lat:CDIunits = "Climate Data Interface version 1.9.10 (https://mpimet.mpg.de/cdi)"degrees_north" ;
ubyte ldd(lat, lon) ;
ldd:Conventions_FillValue = "CF-1.9"0UB ;
:history_of_appended_filesldd:coordinates = "Fri Dec 10 11:49:28 2021: Appended file ldd_ORIG_03min.nc had following \"history\" attribute:\nWed Nov 18 13:59:27 2020: ncks -A -v lat,lon /hugetmp/NOT_Permanent/LDD/LDD_BOX/data/flwdir_202001_03min.nc /hugetmp/NOT_Permanent/LDD/LDD_BOX/res/CHECKED/ldd_Global_03min.nc\nWed Nov 18 13:59:27 2020: cdo -invertlat tmp_5.nc /hugetmp/NOT_Permanent/LDD/LDD_BOX/res/CHECKED/ldd_Global_03min.nc\nWed Nov 18 13:59:27 2020: GDAL CreateCopy( tmp_5.nc, ... )\nlon lat" ;
ldd:esri_pe_string = "GEOGCS[\"GCS_WGS_1984\",DATUM[\"D_WGS_1984\",SPHEROID[\"WGS_1984\",6378137,298.257223563]],PRIMEM[\"Greenwich\",0],UNIT[\"Degree\",0.0174532925199433]]" ;
ldd:standard_name = "ldd" ;
ldd:GDAL_PCRASTER_VALUESCALEunits = "VS_LDD-" ;
ldd:NCOlong_name = "netCDF Operators version 4.9.7 (Homepage = http://nco.sf.net, Code = http://github.com/nco/nco)Local drain direction" ;
// global attributes:
:Conventions = "CF-1.7" ;
:GDALSource_Software = "GDAL 3.2.1, released 2020/12/29JRC.E1 lisfloodutilities nexus wefe - pcr2nc" ;
:GDAL_AREA_OR_POINTsource = "AreaJRC Space, Security, Migration (L.A.)" ;
:historyreference = "FriJRC Dec 02 15:24:49 2022: cdo chname,Band1,ldd ldd_ln.nc ldd_glofas_v4_0.nc\nWed Nov 23 10:14:40 2022: ncks -O -d lat,-59.975,89.975 /ec/vol/cems_floods/glofas/static_maps/4.0/ldd_repaired.nc out/ldd_repaired.nc\nFri Dec 10 11:49:28 2021: ncks -A -v lat,lon ldd_ORIG_03min.nc ldd_repaired.nc\nFri Dec 10 11:49:27 2021: cdo -invertlat tmp_repaired.nc ldd_repaired.nc\nFri Dec 10 11:49:26 2021: GDAL CreateCopy( tmp_repaired.nc, ... )Space, Security, Migration" ;
:history = "Fri Dec 2 16:49:41 2022: ncatted -a long_name,ldd,o,c,Local drain direction ldd_glofas.nc ldd_glofas_ln.nc\nCreated Tue Dec 3 14:11:34 2019" ;
:CDONCO = "Climate DatanetCDF Operators version 14.9.107 (httpsHomepage = http://mpimet.mpg.de/cdonco.sf.net, Code = http://github.com/nco/nco)" ;
} |
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