Re: density

Hi Igor,
In the future please respond to the ncl-talk email list with follow up
questions, as that way the community can assist you.

I was unable to run your test script because you didn't include the
exact data file names. However I think I know what the problem is. In my
original reply to you I stated the following:
3) The longitudes of arr run from 0:360, again matching your ascii data.
If a different ascii file contains longitudes that run from -180:180,
you will have to modify the script to account for this.

Your new data file contains longitudes that do run from -180:180, so as
I stated you will need to modify your program to take this into account.
The best way to do this is to use the where function:
http://www.ncl.ucar.edu/Document/Functions/Built-in/where.shtml

I would apply the where function to your lon array to add 360 to all
those values that are less than 0. If you have not used the where
function before I would recommend testing it out a bit to see how it
works. It is very easy to use, and is one of the more useful general
functions in NCL.
Good luck,
Adam

On 7/30/13 4:50 PM, igor akkerman wrote:
> I tried modifying the code to plot storm density for the Arctic but I
> failed to read in a different model data. It is on rotated grid for a
> limited domain (Arctic Ocean): 110 lons (-180,180), 100 lats
> (55N-90N). So, when I was debugging the code it crashed with the error
> message:
>
> "fatal:NclOneDValGetClosestIndex: finish coordinate index out of
> range, can't continue
> fatal:Could not obtain coordinate indexes, unable to perform subscript
> fatal:["Execute.c":8128]:Execute: Error occurred at or near line 39 in
> file density.ncl"
>
> Could you please take a quick look and suggest the ways to fix it? I
> uploaded the data that I was trying to read in and the ncl code your
> ftp server.
>
> files that I was reading in:
> -test_01_* (1 column - lats, 2 column - lons, 3d column - slp)
> -density.ncl - ncl code to plot the density.
>
> Thank you for your help,
> Igor
>
>
>
> ---------- Forwarded message ----------
> From: *Adam Phillips* <asphilli@ucar.edu <mailto:asphilli@ucar.edu>>
> Date: Fri, Jul 12, 2013 at 8:36 AM
> Subject: Re: density
> To: igor akkerman <igorakkerman89@gmail.com
> <mailto:igorakkerman89@gmail.com>>
> Cc: ncl-talk@ucar.edu <mailto:ncl-talk@ucar.edu>
>
>
> Hi Igor,
> I think the best thing to do would be to set up an array that
> contains the same coordinates that are present in your ascii file,
> and then use coordinate subscripting and a do loop to count the
> number of times the storm goes over a particular grid box. That
> way you end up with an array that can be easily plotted. I have
> attached a script that does this, along with a resulting plot.
>
> A few things to note:
> 1) Test out what I have created, including print and
> printVarSummary statements and such, to make sure the script is
> doing what you think it is doing and what it is supposed to be doing.
>
> 2) I set up the master array as follows:
> arr = new((/73,144/),integer,-999)
> arr!0 = "lat"
> arr&lat = fspan(-90,90,73)
> arr&lat@units = "degrees_north"
> arr!1 = "lon"
> arr&lon = fspan(0,357.5,144)
> arr&lon@units = "degrees_east"
>
> Your ascii file has storm locations on a 2.5 x 2.5 grid, so I set
> up the arr array to match. You don't necessarily need to match
> things up as I did. For instance you can set arr to be on a 1
> degree grid, and the coordinate subscripting will place the storm
> location at the nearest coordinates. This is a judgement call that
> you will have to make.
>
> 3) The longitudes of arr run from 0:360, again matching your ascii
> data. If a different ascii file contains longitudes that run from
> -180:180, you will have to modify the script to account for this.
>
> If you have any further questions please respond to the ncl-talk
> email list.
> Good luck,
> Adam
>
>
> On 07/10/2013 04:21 PM, igor akkerman wrote:
>> Hi all,
>>
>> I need to calculate the density of storms based on the data from
>> the ascii file.
>> One line in the ascii file means one storm with its latitude and
>> longitude. In order to get the storm density, I think the first
>> step is to save lon and lat of the first storm, then go to the
>> next storm, etc. The next step would be taking a particular grid
>> point and sum all the storms that passed through it. Looping
>> though all the grid points I think I will get the
>> density [number of storms] units. I got myself confused with
>> setting the counters to get the density. Could you please help me
>> with this?
>>
>> The ascii file:
>>
>> lon lat SLP
>> 3.75 19 267.50 47.50 998.40
>> 4.00 19 262.50 45.00 996.50
>> 4.25 19 262.50 45.00 994.80
>> 4.50 19 260.00 45.00 994.20
>> 4.75 19 257.50 42.50 993.90
>> 5.00 19 257.50 42.50 994.30
>> 5.25 19 255.00 42.50 993.60
>> 5.50 19 252.50 42.50 995.40
>> 5.75 19 247.50 42.50 996.00
>> 6.00 19 245.00 42.50 997.50
>> 6.25 19 240.00 45.00 1000.00
>> 6.50 19 235.00 45.00 999.90
>> 6.75 19 235.00 45.00 1000.20
>> 7.00 19 235.00 45.00 1001.50
>> 7.25 19 235.00 45.00 1004.30
>> 7.50 19 237.50 45.00 1006.30
>> 3.75 20 157.50 50.00 998.00
>> 4.00 20 152.50 47.50 1002.90
>> 4.25 20 155.00 47.50 1003.70
>> 4.50 20 155.00 47.50 1006.30
>> 4.75 20 155.00 47.50 1007.70
>> 3.75 21 147.50 62.50 994.60
>> 4.00 21 145.00 60.00 996.50
>>
>> stn_data = readAsciiTable("out_"+i+".txt",5,"float",0)
>> stn_data@_FillValue = -999.0
>> storm_number = stn_data(:,1)
>> lon = stn_data(:,2)
>> lat = stn_data(:,3)
>> slp = stn_data(:,4)
>>
>> n=0
>> lat1=lat(n)
>> lon1=lon(n)
>> storm(n)=n
>> n=n+1
>>
>> m=0
>> if (lat1(m)=lat2.and.lon1(m)=lon2) then
>> ...
>>
>>
>>
>> _______________________________________________
>> ncl-talk mailing list
>> List instructions, subscriber options, unsubscribe:
>> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
>
> --
> ______________________________________________________________
> Adam Phillipsasphilli@ucar.edu <mailto:asphilli@ucar.edu>
> NCAR/Climate and Global Dynamics Division(303) 497-1726 <tel:%28303%29%20497-1726>
> P.O. Box 3000
> Boulder, CO 80307-3000http://www.cgd.ucar.edu/cas/asphilli
>
>
> _______________________________________________
> ncl-talk mailing list
> List instructions, subscriber options, unsubscribe:
> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
>
>
>

_______________________________________________
ncl-talk mailing list
List instructions, subscriber options, unsubscribe:
http://mailman.ucar.edu/mailman/listinfo/ncl-talk
Received on Tue Jul 30 17:43:54 2013