[ncl-talk] Shapefile masking: masks not written out for regions west of greenwich meridian for fixed-offset grid

[Tabish Ansari]

Hi

I'm trying to write out masks for 3 distinct regions: Asia (AS), North
America (NA) and Europe (EU) for two grids: a high resolution grid with
greenwich meridian in the middle and a low resolution grid with greenwich
meridian at the left edge. The shapefile mask data function seems to work
fine and gives a "success" message in the end, however, while the output
file contains correct masks for all the 3 regions for the high-resolution
grid, the masks are incomplete for the low-resolution grid - anything west
of Greenwich meridian is missing. Can this be due to the low-res grid not
being centered at 0deg? The script is copied below:


======================================================================================
load "./shapefile_utils.ncl"

begin

sname =
"/work/users/tan/mask/ref-countries-2020-01m.shp/CNTR_RG_01M_2020_4326.shp/CNTR_RG_01M_2020_4326.shp"

correctedlist_AS = (/"Aksai Chin","Arunachal
Pradesh","Afghanistan","Bangladesh","Bhutan","Brunei","Cambodia","China","China/India","Jammu
Kashmir","Hong
Kong","India","Indonesia","Japan","Kazakhstan","Kyrgyzstan","Laos","Macao","Malaysia","Maldives","Mongolia","Myanmar/Burma","Nepal","North
Korea","Pakistan","Papua New Guinea","Philippines","Singapore","South
Korea","Sri Lanka","Taiwan_Province of
China","Tajikistan","Thailand","Timor-Leste","Turkmenistan","Uzbekistan","VietNam"/)

correctedlist_NA = (/"Canada","Saint Pierre and Miquelon","United States"/)

correctedlist_EU =
(/"Albania","Armenia","Austria","Azerbaijan","Belarus","Belgium","Bosnia
and
Herzegovina","Bulgaria","Croatia","Cyprus","Czechia","Denmark","Estonia","Faroes","Finland","France","Georgia","Germany","Gibraltar","Greece","Greenland","Hungary","Iceland","Ireland","Italy","Latvia","Lithuania","Luxembourg","North
Macedonia","Malta","Moldova","Norway","Poland","Portugal","Romania","Russian
Federation","Serbia","Slovakia","Slovenia","Spain","Sweden","Switzerland","Türkiye","Ukraine","United
Kingdom"/)

areas_of_interest = correctedlist_AS


data_lowres  =
addfile("/data/nosync/emissions/HTAPv3-Emissions-tan_regridMC/edgar_HTAPv3_2006_NMVOC.nc","r")
data_highres =
addfile("/data/nosync/emissions/HTAPv3-Fluxes-tan/edgar_HTAPv3_2006_NMVOC.nc","r")

;system("rm VOCregionmask2.nc")
VOCregionmask = addfile("VOCregionmask.nc","w")

;---Read any 3d variable and lat/lon coordinates off wrfchemi file.
  emislow    = data_lowres->HTAPv3_1_International_Shipping(0,:,:)
  emishigh   = data_highres->HTAPv3_1_International_Shipping(0,:,:)

;---Set all temperature values to 0 except for those over areas of interest
which will be equal to 1.
  opt             = True
  opt at debug       = True
  opt at shape_var   = "NAME_ENGL"
  opt at shape_names = areas_of_interest
  opt at return_mask = True               ; THIS RETURNS A MATRIX OF 0 AND 1
INSTEAD OF MASKED DATA

  print("masking lowres data...")
  emislowresmask  = shapefile_mask_data(emislow,sname,opt)

  print("masking highres temperature data...")
  emishighresmask   = shapefile_mask_data(emishigh,sname,opt)

  VOCregionmask->AS_lowres  = (/emislowresmask/)
  VOCregionmask->AS_highres = (/emishighresmask/)


print("Success!!!")

end


========================================================================

Thanks a lot.

with best regards,

Tabish
-------------------------------
Dr Tabish Ansari
Research Associate
Air Quality Modelling Group
IASS-Potsdam
Germany
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