View source for NetCDF multiple profiles

[[de:NetCDF Profile]]

=Introduction=

The location of different longitudinal as well as cross-sectional profiles is described. 

=Version ''Discrete Sampling Geometry'' '''trajectoryProfile'''=

Data for multiple locations along one or several profiles (trajectories) are stored in a netCDF file in accordance with the concept of a ''Discrete Sampling Geometry'' with '''featureType=trajectoryProfile'''. An example (output from NCDUMP) for geometry as well as data is shown in  [[File:P_synop_ncdump_2D.pdf]].

Short list and description of some relevant variables for profiles:
* '''Mesh0_node_x'''(nMesh0_trajectory,nMaxMesh0_trajectory_nodes): x-coordinate;
* '''Mesh0_node_y'''(nMesh0_trajectory,nMaxMesh0_trajectory_nodes): y-coordinate;
* '''Mesh0_node_lon'''(nMesh0_trajectory,nMaxMesh0_trajectory_nodes): geographic longitude;
* '''Mesh0_node_lat'''(nMesh0_trajectory,nMaxMesh0_trajectory_nodes): geographic latitude;
* '''Mesh0_trajectory_node_distance'''(nMesh0_trajectory,nMaxMesh0_trajectory_nodes): profile meter;
* '''Mesh0_trajectory_long_name'''(nMesh0_trajectory,nMesh0_strlen1): long name;
* '''Mesh0_trajectory_code_name'''(nMesh0_trajectory,nMesh0_strlen2): short name;
* '''Mesh0_trajectory_short_name'''(nMesh0_trajectory,nMesh0_strlen3): shorthand name;
* '''Mesh0_trajectory_id'''(nMesh0_trajectory): identification number, e. g. with ''cf_role'' matching respective ''featureType'';
* '''Mesh0_crs''': scalar container variable with informations (contents of attributes) about the coordinate transformation used (relationship between local and geographical coordinates).

Remarks:
# All two-dimensional coordinate variables may contain invalid data (''_FillValue''). This will always be the case if individual profiles (1 to ''nMesh0_trajectory'') consist out of different number of locations (1 to ''nMaxMesh0_trajectory_nodes''). 
# Variable '''Mesh0_trajectory_node_distance''' can be used as an auxiliary coordinate variable in geophysical variables. With this variable displaying data in dependence on profile meter is largely facilitated.

=Version [[DATACONVERT]]=

The basic concept follows the ideas described in [http://ugrid-conventions.github.io/ugrid-conventions/#1d-network-topology ''1D network topolgy''] 
which is part of the [http://ugrid-conventions.github.io/ugrid-conventions ''UGRID Conventions''].
But use of object ''<font color=darkorange>profile</font>'' is beyond what is covered by the ''UGRID conventions''.
All deviations from the ''UGRID conventions'' are highlighted in <font color=darkorange>''darkorange''</font> color.

==Dimensions==
    
# '''nMesh1_node''' : number of nodes
# '''nMesh1_edge''' : number of edges
# '''nMesh1_prof''' : number of profiles (longitudinal and cross-section)
# '''nMaxMesh1_prof_edges''' : maximum number of edges along a single profile
# '''nMaxMesh1_prof_nodes''' : maximum number of nodes along a single profile
# '''Two''' : constant ( = 2 ).

==Local coordinates==

===Nodes===
double Mesh1_node_x(nMesh1_node) ;
: Mesh1_node_x:long_name = "x-coordinate of nodes ;
: Mesh1_node_x:units = "m" ;
: Mesh1_node_x:name_id = 1650 ;
: Mesh1_node_x:standard_name = "projection_x_coordinate" ;
double Mesh1_node_y(nMesh1_node) ;
: Mesh1_node_y:long_name = "y-coordinate of nodes" ;
: Mesh1_node_y:units = "m" ;
: Mesh1_node_y:name_id = 1651 ;
: Mesh1_node_y:standard_name = "projection_y_coordinate" ;
Comment:
# "name_id" corresponds to the so-called PHYDEF-Code of variables which is used internally at BAW.

===Edges===
double Mesh1_edge_x(nMesh1_edge) ;
: Mesh1_edge_x:long_name = "x-coordinate of edges (center)" ;
: Mesh1_edge_x:units = "m" ;
: Mesh1_edge_x:name_id = 1650 ;
: Mesh1_edge_x:bounds = "Mesh1_edge_x_bnd" ;
: Mesh1_edge_x:standard_name = "projection_x_coordinate" ;
double Mesh1_edge_y(nMesh1_edge) ;
: Mesh1_edge_y:long_name = "y-coordinate of edges (center)" ;
: Mesh1_edge_y:units = "m" ;
: Mesh1_edge_y:name_id = 1651 ;
: Mesh1_edge_y:bounds = "Mesh1_edge_y_bnd" ;
: Mesh1_edge_y:standard_name = "projection_y_coordinate" ;
Comment:
# "name_id" corresponds to the so-called PHYDEF-Code of variables which is used internally at BAW.

===(optional) Bounds for edges===
double Mesh1_edge_x_bnd(nMesh1_edge,Two) ; \\ no metadata required

double Mesh1_edge_y_bnd(nMesh1_edge,Two) ; \\ no metadata required

==Geographic coordinates==

===Nodes===
double Mesh1_node_lon(nMesh1_node) ;
: Mesh1_node_lon:long_name = "geographic longitude of nodes" ;
: Mesh1_node_lon:units = "degrees_east" ;
: Mesh1_node_lon:name_id = 1653 ;
: Mesh1_node_lon:standard_name = "longitude" ;
double Mesh1_node_lat(nMesh1_node) ;
: Mesh1_node_lat:long_name = "geographic latitude of nodes" ;
: Mesh1_node_lat:units = "degrees_north" ;
: Mesh1_node_lat:name_id = 1652 ;
: Mesh1_node_lat:standard_name = "latitude" ;
Comment:
# "name_id" corresponds to the so-called PHYDEF-Code of variables which is used internally at BAW.

===Edges===
double Mesh1_edge_lon(nMesh1_edge) ;
: Mesh1_edge_lon:long_name = "geographic longitude of edges (center)" ;
: Mesh1_edge_lon:units = "degrees_east" ;
: Mesh1_edge_lon:name_id = 1653 ;
: Mesh1_edge_lon:bounds = "Mesh1_edge_lon_bnd" ;
: Mesh1_edge_lon:standard_name = "longitude" ;
double Mesh1_edge_lat(nMesh1_edge) ;
: Mesh1_edge_lat:long_name = "geographic latitude of edges (center)" ;
: Mesh1_edge_lat:units = "degrees_north" ;
: Mesh1_edge_lat:name_id = 1652 ;
: Mesh1_edge_lat:bounds = "Mesh1_edge_lat_bnd" ;
: Mesh1_edge_lat:standard_name = "latitude" ;
Comment:
# "name_id" corresponds to the so-called PHYDEF-Code of variables which is used internally at BAW.

===(optional) Bounds for edges===
double Mesh1_edge_lon_bnd(nMesh1_edge,Two) ; \\ no metadata required

double Mesh1_edge_lat_bnd(nMesh1_edge,Two) ; \\ no metadata required

==Connectivities==

===Edge-node connectivity===
int Mesh1_edge_nodes(nMesh1_edge, two) ;
: Mesh1_edge_nodes:long_name = "edge-node connectivity of edges, start and end point" ;
: Mesh1_edge_nodes:cf_role = "edge_node_connectivity" ;
: Mesh1_edge_nodes:start_index = 0 ;

===Names of profiles===
char Mesh1_prof_long_name(nMesh1_prof, nMesh1_strlen1) ; 
: Mesh1_prof_long_name:long_name = "name of profile" ; 
Comment:
# Can be used as ''label coordinate variable'' to access individual profiles.

===Profile-edge connectivity===
int Mesh1_prof_edges(nMesh1_prof, nMaxMesh1_prof_edges) ;
: Mesh1_prof_edges:long_name = "profile-edge connectivity, sorted from start to end of profile" ;
: Mesh1_prof_edges:cf_role = "<font color=darkorange>prof_edge_connectivity</font>" ;
: Mesh1_prof_edges:_FillValue = -999 ;
: Mesh1_prof_edges:start_index = 0 ;
Comment: 
# Can be used to describe several profiles.
# Individual edges may belong to more than one profile.

===Profile-node connectivity===
int Mesh1_prof_nodes(nMesh1_prof, nMaxMesh1_prof_nodes) ;
: Mesh1_prof_nodes:long_name = "profile-node connectivity, sorted from start to end of profile" ;
: Mesh1_prof_nodes:cf_role = "<font color=darkorange>prof_node_connectivity</font>" ;
: Mesh1_prof_nodes:_FillValue = -999 ;
: Mesh1_prof_nodes:start_index = 0 ;
Comment: 
# Can be used to describe several profiles.

==Topology==

int Mesh1 ;
: Mesh1:long_name = "several 1D profiles, no sub-grid" ;
: Mesh1:topology_dimension = 1 ;
: Mesh1:cf_role = "mesh_topology" ;
: Mesh1:node_coordinates = "Mesh1_node_x Mesh1_node_y Mesh1_node_lon Mesh1_node_lat" ;
: Mesh1:edge_coordinates = "Mesh1_edge_x Mesh1_edge_y Mesh1_edge_lon Mesh1_edge_lat" ;
: Mesh1:<font color=darkorange>prof_coordinates</font> = "Mesh1_prof_long_name" ;
: Mesh1:<font color=darkorange>prof_node_connectivity</font> = "Mesh1_prof_nodes" ;
: Mesh1:<font color=darkorange>prof_edge_connectivity</font> = "Mesh1_prof_edges" ;
: Mesh1:edge_node_connectivity = "Mesh1_edge_nodes" ;

==Coordinate transformation==

See [[NetCDF grid mapping variable]].

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