netcdf files in a predefined domain

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IMC
IMC 2021-3-11
评论： IMC 2021-3-16
Hello,
I am trying to read multiple netcdf4 files in a predefined area (lat and lon). I want values OUTSIDE my predefined area to be equal to '-99' but below code changes all the values to -99.
NOTE: in the below code lat_edge and lon_edge are lat and lon values from first satellite and sub_lat and sub_lon are lat and lon values from second satellite. I'm doing collocation first.
lat_edge=double([min(lat(:)) max(lat(:))]);
lon_edge=double([min(lon(:)) max(lon(:))]);
index_out_edge=find(sub_lat(:)<=lat_edge(1) | sub_lat(:)>=lat_edge(2) | sub_lon(:)<=lon_edge(1) | sub_lon(:)>=lon_edge(2));
CLTT_temp = ncread(files{i},'CLTT');
CLTT_temp_FINAL=CLTT_temp(min(row):max(row),min(col):max(col)); %min and max row col are lat lon indices from second satellite.
CLTT_temp_FINAL(index_out_edge)=-99;
kindly tell me what I'm missing in my code.
thank you.
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Walter Roberson
Walter Roberson 2021-3-15
It looks like the distribution of your values might be biased. I suggest investigating with something like
lat_edge = double([min(lat(:)) max(lat(:))]);
lon_edge = double([min(lon(:)) max(lon(:))]);
fill(lon_edge([1 2 2 1]), lat_edge([1 1 2 2]), [.5 .5 .5]);
hold on
scatter(sub_lon, sub_lat, [], 'r')
hold off
xlim auto
ylim auto
The red marks that show up in the mid-gray background are the ones that should be located by index_out_edge. My suspicion is that you will find all your marks are outside the rectangle.

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回答（1 个）

KSSV
KSSV 2021-3-11
Something like this should work:
index_out_edge = ~(((sub_lat(:)<=lat_edge(1) | sub_lat(:)>=lat_edge(2)) && (sub_lon(:)<=lon_edge(1) | sub_lon(:)>=lon_edge(2))));

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