Closed lizadams closed 3 years ago
I also plotted the LANDMASK variable from the WRF output used to generate the MCIP output. I believe this also shows that the exported shapefile is shifted to the south west. Used VERDI > Control > Show Lat/Lon Then put my cursor at the lower left corner of the grid cell to record the lat/lon values displayed by VERDI. I then compared that with the lower left corner of the grid cell lat/lon values displayed in QGIS. The exported shapefile is shifted to the west of where it should be according to the VERDI values of the llc.
It would be easier to compare the LWMASK and LANDMASK with the geographical features, if the grid resolution were finer. These files are 12km grid resolution, not fine enough for correlating the data with the islands.
In the following documentation they mention that the corner_lats and corner_lons global attributes in a WPS-generated GEOGRID file must be known: https://ral.ucar.edu/sites/default/files/public/WRFHydro_GIS_Preprocessor_v5.pdf
"Compatibility of the pre-processing tools with subsetted domainsMany programs such as NCO and NCL will allow a user to subset a 2D netCDF file. However, only files that are generated using the WPS geogrid.exe program may be used as input to the WRF-Hydro ArcGIS Pre-processing tools. This is because the georeferencing of GEOGRID files requires the corner latitude and longitude to be known. This is stored in the ‘corner_lats’ and ‘corner_lons’ global attributes in a WPS-generated GEOGRID file. If a user wishes to subset a WRF domain, they must also update the values in these attributes in order for the domain to be properly georeferenced."
The ncdump GRIDCRO2D_04OTC2_160930.nc file contains the LAT and LON values a the cell centers. LON:var_desc = "longitude at cell centers
The following links describes the GEOGRID file, and lat/lon values for the MASS, U, V, and unstaggered variables. https://www2.mmm.ucar.edu/wrf/users/docs/user_guide_V3/users_guide_chap3.htm#_WPS_Output_Fields
Retested with VERDI_2.0_linux64_20210427.tar.gz, the zoomed in tile plots in VERDI is shown as below: The corresponding exported shapefiles in QGIS is shown as below: We can see that the grid cell boundary between rows 59 and 60 for the LATU_GRIDDOT2D file is directly over Harker's Island, which is consistent with the location shown in the VERDI Tile Plot Display.
The projection information in the exported shapefiles is changed into: PROJCS["unknown", GEOGCS["GCS_unknown", DATUM["D_unknown", SPHEROID["unknown", 6370000.0, 0.0]], PRIMEM["Greenwich", 0.0], UNIT["degree", 0.017453292519943295], AXIS["Longitude", EAST], AXIS["Latitude", NORTH]], PROJECTION["Lambert_Conformal_Conic"], PARAMETER["central_meridian", -97.0], PARAMETER["latitude_of_origin", 40.0], PARAMETER["standard_parallel_1", 45.0], PARAMETER["false_easting", 0.0], PARAMETER["false_northing", 0.0], PARAMETER["scale_factor", 1.0], PARAMETER["standard_parallel_2", 33.0], UNIT["m", 1.0], AXIS["x", EAST], AXIS["y", NORTH]]
Retested with VERDI_2.1_linux64_20210906.tar.gz, confirmed that the upgraded openJDK has not caused any problem on this issue.
Describe the bug This bug is related to #223, but demonstrates it using different input datasets and Harker's Island in NC as geographic reference point.
To Reproduce Steps to reproduce the behavior:
Load datasets into verdi verdi.sh -f $cwd/GRIDCRO2D_160702.nc -f $cwd/GRIDDOT2D_160702.nc -s "DLUSE[1]" -g tile -s "LATU[2]" -g tile
Zoom into the region over Harker's island for both plots Click on Controls > Set Row and Column Ranges > Select Rows 59 .. 60, Select Columns 89 .. 89.
Use the Externalize this view into a Floating Window to place the plots side by side.
Use File > Export as Image/GIS > Select the File Format: Shapefile Specify the filenames: LATU_GRIDDOT2D_160702_zoomed_in_Rows59_60_Col_89_89_island_near_Hatterous DLUSE_GRIDCRO2D_160702_Zoomed_in_ROW59_60_COL_89_89
Load files into QGIS Layer > Add Vector Layer > Categorize the variable and zoom into layer
A zoomed out image in QGIS showing all of the outer banks, and the full extent of both exported grid cells.
Expected behavior The Grid Cell boundary between rows 59 and 60 for the LATU_GRIDDOT2D file should be directly over Harker's Island according to the VERDI Tile Plot Display. The exported shapefile shows this boundary shifted to the West and perhaps a bit South as well.
Using QGIS, examining the Properties > Information, the following information including the Extent for each of the files was obtained.