[ncl-talk] Why the res of DstGridMask can not make the destination grid have missing values as defined?

[林祥]

Hi，Mary

   I found the problem might be in the inconsistence between “hsic" and “hlat”

        fi   = addfile("HadISST_ice.nc","r”)    
>   hsic = fi->sic                          ； it is global  
>   hlon = fi->longitude
>   hlat = fi->latitude({-90.:-50.})        ;  it is regional

   However, the same scripts with such error can not run in mac, while it  run well in my Linux and output figure & nc files although error existed in masking.
   
   

Thank


Lin


> 在 2016年12月20日，06:06，Mary Haley <haley at ucar.edu> 写道：
> 
> Lin,
> 
> I'm confused by the comment on this line:
> 
>     Opt at SrcGridMask      = where(.not.ismissing(thetao(0,:,:)),1,0)      ; thetao is the source grids, with data zero in land, no missing 
> 
> When you say "data zero in land, no missing", do you mean that the "thetao" variable is equal to 0 whenever it is over land, and that it contains no missing values?  If so, then using "ismissing" on a variable that doesn't contain missing values is never going to return True.
> 
> Instead, you want something like this:
> 
>     Opt at SrcGridMask      = where(thetao.ne.0,1,0)
> 
> This creates a mask array that is equal to 1 at locations where thetao is NOT equal to 0, and equal to 0 at locations where thetao is equal to 0. 
> 
> Just as an example, this line should produce the exact same mask array:
> 
>     Opt at SrcGridMask      = where(thetao.eq.0,0,1)
> 
> --Mary
> 
> 
> 
> 
> On Mon, Dec 19, 2016 at 11:53 AM, 林祥 <xianglin72 at icloud.com <mailto:xianglin72 at icloud.com>> wrote:
> Hi, all
> 
>        I have many CMIP5 sea ice concentration data and want to regrid them into the same grid coordinate as HadISST.
> 
>  Since the land area own missing_value (_FillValue) in HadiSST, I also want the regridded data show missing values in land .
> 
> I use the following  scripts:
>    
>    fi   = addfile("HadISST_ice.nc","r")
>   hsic = fi->sic
>   hlon = fi->longitude
>   hlat = fi->latitude({-90.:-50.})
>    …….
>     
>     Opt at SrcGridMask      = where(.not.ismissing(thetao(0,:,:)),1,0)      ; thetao is the source grids, with data zero in land, no missing 
>     Opt at DstGridMask      = where(.not.ismissing(hsic(0,:,:)),1,0)         ; hsic is the HadISST  SIC data, with missing values in land
>   
>     Opt at DstGridLat       = hlat
>   Opt at DstGridLon       = hlon 
> ……..
> 
>      thetao_regrid = ESMF_regrid(thetao,Opt)
> 
> However, I found the regridded data “thetao_regrid" show zero values, not missing values in land.
> 
> 
>        How to make the regridded data have missing values for the same grids as HadISST?
> 
> 
> Thank
> 
> 
> Lin  
> 
>  
> 
> 
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