Re: Pseudogravity

Hi Mikhail,

Thanks for the pointers.

The software did not recognise my GMT grids directly, and had to convert to Surfer when loading: saving was fine to netCDF.

I tried the pseudo gravity on a RTP grid (which was still Lat-Long), and it seemed to work fine. The RTP grid was generated from the grdredpol GMT function as I needed the differential RTP.

I am assuming that a basic scripting function would be a 3 step process:

1. Reduce-to-pole (or equator if low magnetic latitide) GRDREDPOL
2. vertical integration GRDFFT
3. Applying a scaling function (a constant or differential value over a large area ?) - GRDMATH - 

Currently, with GMT5, we can do the RTP (via grdredpol), but not the RTE explicitly. Although I need to see what happens with a magnetic dataset that is low lat in grdredpol

Certainly, for a localised are Magpick works fine.

Cheers

Lester

Date: Tue, 4 Feb 2014 10:29:27 -0800
From: [email protected]
Subject: Re: [GMT-HELP] Pseudogravity
To: [email protected]


  
    
  
  
    Hi Lester,

      

      I am pretty sure it can be done with GMT, but some scripting
      programming could be required.

      If you want command-line solution to process bulk amount of data
      it is certainly way to go.

      

      The other  answer might be off the list, but there is "magpick"
      program available 

      from

      http://www.geometrics.com/geometrics-products/geometrics-magnetometers/download-magnetometer-software/

      

      direct download link:

      

      ftp://geom.geometrics.com/pub/mag/Software/magpick-latest.exe

      

      MagPick can load / save GMT grid NC files.  It also has all
      potential fields

      transformations implemented, such as reduction to the pole,
      analytic signal,

      pseudo gravity etc.

      There are some limitations however:

      

      1. Grids must be projected (not Lat/Lon grids)

      2. There should be no gaps in the grid.  This could be
      circumvented by making

      transformation and clipping grid after.

      

      There is also Linux version with the same functionality, not
      widely used.

      Let me know if you are interested in Linux.

      

      I hope it helps,

      

      Best Regards

      Mikhail Tchernychev

      

      

      

      On 2/4/2014 1:21 AM, Lester Anderson wrote:

    
    
      
      
      Hello,

         

        Is there a way to get the pseudogravity from magnetics using GMT
        yet? I have not spotted that option in any of the obvious
        functions.

         

        Cheers

         

        Lester

      
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