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Using geogrid.exe for Antarctica (Antartica), help with DEM data

R

RSAPIAIN_DMC

Member
Good morning from Chile.

I would like your assistance with this; using WPS4.1; I'm a computer specialist, and not an Earth-science minor/major, so I'm a bit in the dark regarding this.

We are trying ro create a set of nested domains for Antarctic continent (Antarctica/Antarctica); I'm also aware of the need to remove the 'search' from the GREENFRAC in GEOGRID.TBL, detailed here.

The little documentation that we have, states that we need to:

1.- Download the DEM / RAMP data from ftp://sidads.colorado.edu/pub/DATASETS/nsidc0082_radarsat_dem_v02
There is 1km, 400m, and 200km data, in different formats and projections: Polar-WGS and OSU.

2.- Create an index file that should look like: (the docs stated the -91.0, which I think is not correct)
type=continuous
signed=yes
projection=polar_wgs84
#projection=polar
dx=1000.
dy=1000.
known_x=2868.0
known_y=2458.0
known_lat=-90.0
known_lon=0.0
wordsize=2
truelat1=-71.0
truelat2=-90.0
#truelat2=-91.0 ## this was an example we had... I think this value is not correct
stdlon =0.0
tile_x=1434
tile_y=1229
tile_z=1
tile_bdr=100
units="metersMSL&quot"
description="Topography height"


3.- Modify the GEOGRID.TBL, changing the HGT_M section to this:

name = HGT_M
priority = 2
dest_type = continuous
smooth_option = smth-desmth_special; smooth_passes=1
fill_missing=0.
interp_option = ramp1km:average_gcell(4.0)+four_pt
interp_option = ramp400m:average_gcell(4.0)+four_pt
interp_option = ramp200m:average_gcell(4.0)+four_pt
interp_option = default:average_gcell(4.0)+four_pt
rel_path= ramp1km:ramp1km/
rel_path= ramp400m:ramp400m/
rel_path= ramp200m:ramp200m/
rel_path= default:ramp200m/

(currently for all other domains in Continental Chile it uses 'topo_gmted2010_30s')

What I don´t know, and request help/clarifications:
  1. The index file should be different for each value-set (1km, 400m, 200m)?
    • How do I calculate the correct values for each set?
  2. Is it the same for binary/arcinfo, or we only need the binary files for running WPS in Antarctica ?
  3. For the WPS, which should I use, the binary data?
  4. In the case of the geog_v4 data, the files/folders have an index file, and then some other data files with numbers on their name.
    • Do we have to convert the DEM .bin/.hdr files to that format, or just creating the index file should do the trick?
    • Is there a correct and hopefully automated way to create/define the index file and/or perform the conversion?

Thank you in advance for the help.
 

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RSAPIAIN_DMC said:
What I don´t know, and request help/clarifications:
  1. The index file should be different for each value-set (1km, 400m, 200m)?
    • How do I calculate the correct values for each set?
Click to expand...
You are right that you need different index files for different datasets
The items in the 'index' file are described here, which tells how to determine their values.
RSAPIAIN_DMC said:
  1. Is it the same for binary/arcinfo, or we only need the binary files for running WPS in Antarctica ?
Click to expand...
WPS/Geogrid only accepts binary files in a specific geogrid format. Please see details of the format here.
RSAPIAIN_DMC said:
  1. For the WPS, which should I use, the binary data?
Click to expand...
Please use data in Geogrid Binary Format.
RSAPIAIN_DMC said:
  1. In the case of the geog_v4 data, the files/folders have an index file, and then some other data files with numbers on their name.
    • Do we have to convert the DEM .bin/.hdr files to that format, or just creating the index file should do the trick?
Click to expand...
Please convert DEM .bin/.hdr files to binary files with geogrid format.
RSAPIAIN_DMC said:
    • Is there a correct and hopefully automated way to create/define the index file and/or perform the conversion?
Click to expand...
I am sorry hat we don't have such utilities. With a large variety of data, it is hard to create a utility that can handle all the data.
RSAPIAIN_DMC said:
Thank you in advance for the help.
Click to expand...
 
Hello.
Thank you for the answer.

Currently what it seems to be in the process of working is:

convert the ARCPDF downloaded data to GEOTIFF, and generate the hdr (ENVI header) translation with gdal_translate.

After that, I think there should be a way to given the ENVI header and the GEOTIFF, to the WPS binary format.
Will update when I get it done, thanks for the guidance.
 
Thank you for the update. Yes please post your approaches in the Forum so that other users will benefit from your work. Thanks in advance.
 
Hello.

Finally managed something:

1.- Using QGIS + GIS4WRF, import a GeoTIFF file as raster data in an empty project.

2.- In GIS4WRF there is a nice button called "Convert active layer to WPS binary"

After this, and modifying the HGT_M section in GEOGRID.TBL like this:
name = HGT_M
priority = 1
dest_type = continuous
smooth_option = smth-desmth_special; smooth_passes=1
fill_missing=0.
interp_option = rema1km:average_gcell(4.0)+four_pt+average_4pt
interp_option = rema500m:average_gcell(4.0)+four_pt+average_4pt
interp_option = rema100m:average_gcell(4.0)+four_pt+average_4pt
interp_option = gmted2010_30s:average_gcell(4.0)+four_pt+average_4pt
interp_option = gtopo_30s:average_gcell(4.0)+four_pt+average_4pt
interp_option = gtopo_2m:four_pt
interp_option = gtopo_5m:four_pt
interp_option = gtopo_10m:four_pt
interp_option = lowres:average_gcell(4.0)+four_pt
interp_option = default:average_gcell(4.0)+four_pt+average_4pt
rel_path = rema1km:rema1km/
rel_path = rema500m:rema500m/
rel_path = rema100m:rema100m/
rel_path = gmted2010_30s:topo_gmted2010_30s/
rel_path = gtopo_30s:topo_30s/
rel_path = gtopo_2m:topo_2m/
rel_path = gtopo_5m:topo_5m/
rel_path = gtopo_10m:topo_10m/
rel_path = lowres:rema1km/
rel_path = default:rema100m/

it works well. Also the converted datasets were copied in the directory where I have the geog_v4 files.

Dataset: used the REMAv2 dataset in 100m (they have 1km, 500m, 100m, and even more resolution.)

Do one import-convert cycle for each of the relevant resolutions you want.

The NSIDC dataset can be used as well, but you have to import the ARCINFO data files as raster (not the ones in the 'info' dir).

Kind regards, Roberto Sapiain.
 
Hi Roberto,

Thank you so much for the detailed description ! We have increasing number of users who tend to use high-resolution DEM data, --- the information you provide will be of great help for the broad community. Thanks again!
 
No problem at all :)

Used the REMAv2 dataset, because it comes with the GeoTIFF files with all the proper metadata, ready for QGIS usage and conversion.

I'm now having issues with the SEAICE component; it seems that the NSIDC data has to be converted to an intermediate format:

There is a remap_ice binary, that seems to come from a reformat_seaice_fractional.F file (should be called .f90 by what I found) and it uses a fortran module called 'kwm_plot_utilities'.

But I haven't found anything to how to compile it, nor the full source code (instructions? heh :censored:, i'm basically creating the documentation...).

If you have any pointers to how to get and successfully compile that program, that would be most helpful.

About the data for this program: from NASA Earthdata
Earthdata Login , the NISE_SSMISF18_${YESTERDAY}.HDFEOS is used.

Thank you again.
 
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