Is topo srtm_3s global?

Questions and other topics related to UEMS 18.
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norulz
Posts: 123
Joined: Thu Mar 12, 2015 1:43 pm

Is topo srtm_3s global?

Post by norulz »

My domain in the east Mediterranean localizes OK with srtm_3s (after using topo 30s) but i notice no difference of hgt resolution in the geo_em.d0x.nc files for 3km and 1km domains.

Is the interpolator sequence reducing the topo HGT to the domain resolution? If so what is the benefit of higher resolution topo data?

Is there perhaps another reason for this?

David
yairsuari
Posts: 2
Joined: Fri Jan 28, 2022 1:31 pm

Re: Is topo srtm_3s global?

Post by yairsuari »

Hi David.
this is quite a long text, so I will write the specific questions at the begining
1. Is there a uems knowledge resource I am missing? i am quite sure not everything is on the user guide.
2. Why can't I make uems use the high resolution srtm data?

I thought of asking again in person after seeing your message, I thought it might be better figuring it here, maybe we can help other beginers like me.
first, regarding the question in your post head, no, SRTM is not global it spreads 60S-60N.

Regarding your text, after some journey, I was getting the same results, but I found out that my namelist.wps was changing (the small domain was changing back to 30s+default) every time I was running ems_domain --localize.

Since this is the first time I am trying to run using the SRTM topography, I will describe what I did, maybe I have a mistake.
1. downloaded srtm data (90 meter version) using the srtm grabber http://dwtkns.com/srtm/
2. downloaded and compiled convert_geotiff https://github.com/openwfm/convert_geotiff
3. converted the geotiff to binary files using convert_geotiff
4. put the created binary files in a new folder with the other static data ($EMS_FOLDER/data/geog/srtm3)
5. modified GEOGRID.TBL.ARW so that under HGT_M I now have two new lines (marked by -------):

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        priority = 1
        dest_type = continuous
        smooth_option = smth-desmth_special; smooth_passes=1
        fill_missing=0.
        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
 ----- interp_option =       3s:average_gcell(4.0)+four_pt+average_4pt
        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:topo_gmted2010_5m/
        rel_path =     default:topo_gmted2010_30s/
-------rel_path =     3s:srtm3/
6. changed the line (4th domain only) in namelist.wps from:

Code: Select all

 geog_data_res              = 'modis_30s+modis_lai+2m+default', 'modis_30s+modis_lai+30s+default', 'modis_15s+modis_lai+30s+default', '30s+default'
to:

Code: Select all

 geog_data_res              = 'modis_30s+modis_lai+2m+default', 'modis_30s+modis_lai+30s+default', 'modis_15s+modis_lai+30s+default', '3s'
as I told you, when I run ems_domain --localize, I am getting the default topography, and the line goes back to its original state.
Thanks for your help!!

ps.
I saw somewhare ems_domain --localize -topo s3 but this also did not work.
Last edited by yairsuari on Sat Jan 29, 2022 12:23 pm, edited 1 time in total.
norulz
Posts: 123
Joined: Thu Mar 12, 2015 1:43 pm

Re: Is topo srtm_3s global?

Post by norulz »

Hi Yair,

I think that one needs to be specific about the topo set and a generic '3s' is not enough.
This setting using 'strm_3s' worked for me.

Code: Select all

 geog_data_res              = 'srtm_3s+modis_30s+modis_lai+5m+default', 'srtm_3s+modis_15s+modis_lai+30s+default', 'srtm_3s+modis_15s+modis_lai+30s+default'
However, I don't think that using the 3s topo provided any benefits for domains > 1km. I may be wrong on this
yairsuari
Posts: 2
Joined: Fri Jan 28, 2022 1:31 pm

Re: Is topo srtm_3s global?

Post by yairsuari »

Hi David and thanks again for your much needed help!

Sorry, but this did not do the trick for me
Like you suggested, I changed namelist.wps & geogrid section to

Code: Select all

 geog_data_res              = 'srtm_3s+modis_30s+modis_lai+5m+default', 'srtm_3s+modis_15s+modis_lai+30s+default', 'srtm_3s+modis_15s+modis_lai+30s+default' 

and tried localizing the domain again
Only to get the same results. The localization process changed the geogrid line to:

Code: Select all

 geog_data_res              = 'modis_30s+modis_lai+5m+default', 'modis_15s+modis_lai+30s+default', 'modis_15s+modis_lai+30s+default', '30s+default'
to make sure, I also changed GEOGRID.TBL.ARW:

Code: Select all

interp_option =       3s:average_gcell(4.0)+four_pt+average_4pt
                     -----
to

Code: Select all

interp_option =       srtm_3s:average_gcell(4.0)+four_pt+average_4pt
                   ----------
Also, when I look at DomainGeogrid.log I can see the following lines relating to HGT_M:

Code: Select all

2022-01-29 16:31:22.783 --- INFORM: For HGT_M, couldn't find interpolator sequence for resolution modis_30s.
2022-01-29 16:31:22.784 --- INFORM: For HGT_M, couldn't find interpolator sequence for resolution modis_lai.
2022-01-29 16:31:22.784 --- INFORM: For HGT_M, couldn't find interpolator sequence for resolution 2m.
2022-01-29 16:31:22.784 --- INFORM: Using default interpolator sequence for HGT_M.
2022-01-29 16:31:22.784 --- INFORM: For HGT_M, couldn't find modis_30s data source.
2022-01-29 16:31:22.784 --- INFORM: For HGT_M, couldn't find modis_lai data source.
2022-01-29 16:31:22.784 --- INFORM: For HGT_M, couldn't find 2m data source.
2022-01-29 16:31:22.784 --- INFORM: Using default data source for HGT_M.
Somehow it seems like I missed something in importing the SRTM dataset

Thanks agin
Yair
lpajurek
Posts: 9
Joined: Tue Dec 01, 2015 8:30 am

Re: Is topo srtm_3s global?

Post by lpajurek »

If You use the newest verision of UEMS V22.2.1 there is already srtm data available in ems_domain:

--topo [TOPO DSET] Specify the topography elevation dataset to use (gmted2010|gtopo|srtm; default gmted2010)
norulz
Posts: 123
Joined: Thu Mar 12, 2015 1:43 pm

Re: Is topo srtm_3s global?

Post by norulz »

Thanks. I've also found it and have started testing with it.
I suggest taking a look at this post viewtopic.php?p=6425#p6425 as the data set's index file needs fixing.
I'm not sure if the index file has been fixed in the uems repository.
David
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