Prepare the maps required by TRIP2
In this version of TRIP2, we provide the 1.0 degree and 0.5 degree global flow direction map.
You can build a flow direction map with different resolution and for different regions by yourself. Some "rules" for the flow direction map that you should follow are listed below:
- Each grid point is allocated a number which indicates the outflow direction from the grid point. Grid point can have eight outflow directions; North (1), North East (2), East (3), South East (4), South (5), South West (6), West (7), and North West (8).
- Missing value is -9999.
- "9" implies that no outlet from that grid point. It could be a river mouth or an inland depression.
- Example with the 1.0 degree global flow direction map
[thanh@shui 1.0_deg_global]$ ncdump -h 1.0_deg_flwdir.nc
netcdf 1.0_deg_flwdir {
dimensions:
lon = 360 ;
at = 180 ;
variables:
float lon(lon) ;
lon:units = "degrees_east" ;
lon:valid_min = -180.f ;
lon:valid_max = 180.f ;
lon:long_name = "Longitude" ;
float lat(lat) ;
lat:units = "degrees_north" ;
lat:valid_min = -90.f ;
lat:valid_max = 90.f ;
lat:long_name = "Latitude" ;
int flwdir(lat, lon) ;
flwdir:missing_value = -9999 ;
}
Note: In the flow direction map, the longitude values were saved from "small to big". The latitude values were saved from "big to small".
