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How to process NC file in matlab

조회 수: 27 (최근 30일)
Muhammad Usman Saleem
Muhammad Usman Saleem 2021년 12월 11일
댓글: Walter Roberson 2022년 1월 6일
I've monthly soil monisture NC file. This file contains monthly soil monisture data since 1948. I want to extract soil data within my shapefile in text file (Shapefile has also attached). I google alot to proccess NetCDF file in matlab find not solution, The ncdisp of my nc file is given below:
Format:
netcdf4_classic
Global Attributes:
_NCProperties = 'version=1|netcdflibversion=4.4.1.1|hdf5libversion=1.10.1'
Conventions = 'CF-1.0'
title = 'CPC Soil Moisture'
institution = 'NOAA/ESRL PSD'
dataset_title = 'CPC Soil Moisture'
history = 'Wed Oct 18 15:13:37 2017: ncks -d time,,-2 soilw.mon.mean.x.nc soilw.mon.mean.xx.nc
Wed Oct 18 15:12:08 2017: ncks -d time,,-3 soilw.mon.mean.nc soilw.mon.mean.x.nc
CPC Soil Moisture
Obtained on Nov 2004 from CPC's website
and written to netCDF by Cathy Smith 12/2004.
he CPC Global monthly soil moisture dataset is a 1/2 degree resolution grid from 1948 to the present.
The file is written in COARDS and CF compliant netCDF at NOAA ESRL/PSD https://www.esrl.noaa.gov/psd/
Converted to chunked, deflated non-packed NetCDF4 Jul 2014'
NCO = '4.6.9'
References = 'https://www.psl.noaa.gov/data/gridded/data.cpcsoil.html'
Dimensions:
lat = 360
lon = 720
time = 886 (UNLIMITED)
Variables:
lat
Size: 360x1
Dimensions: lat
Datatype: single
Attributes:
long_name = 'Latitude'
units = 'degrees_north'
actual_range = [8.98e+01 -8.98e+01]
standard_name = 'latitude'
axis = 'Y'
coordinate_defines = 'point'
lon
Size: 720x1
Dimensions: lon
Datatype: single
Attributes:
long_name = 'Longitude'
units = 'degrees_east'
actual_range = [2.50e-01 3.60e+02]
standard_name = 'longitude'
axis = 'X'
coordinate_defines = 'point'
soilw
Size: 720x360x886
Dimensions: lon,lat,time
Datatype: single
Attributes:
long_name = 'Model-Calculated Monthly Mean Soil Moisture'
missing_value = -9.97e+36
units = 'mm'
valid_range = [0.00e+00 1.00e+03]
dataset = 'CPC Monthly Soil Moisture'
var_desc = 'Soil Moisture'
level_desc = 'Surface'
statistic = 'Monthly Mean'
parent_stat = 'Other'
standard_name = 'lwe_thickness_of_soil_moisture_content'
cell_methods = 'time: mean (monthly from values)'
actual_range = [0.00e+00 1.00e+30]
time
Size: 886x1
Dimensions: time
Datatype: double
Attributes:
long_name = 'Time'
units = 'days since 1800-01-01 00:00:0.0'
delta_t = '0000-01-00 00:00:00'
avg_period = '0000-01-00 00:00:00'
standard_name = 'time'
axis = 'T'
bounds = 'time_bnds'
coordinate_defines = 'start'
prev_avg_period = '0000-00-01 00:00:00'
actual_range = [5.41e+04 8.10e+04]
I've tied
file='data.nc';
ncdisp(file)
long = ncread(file,'lon');
latt = ncread(file,'lat');
time = ncread(file,'time');
I want output of Soilw in this format in text file
Date Soilw
01/01/2015 10
01/02/2015 20
01/03/2015 0.5
Please help me to convert monthly netcdf datainto text file using matlab please?
  댓글 수: 7
Walter Roberson
Walter Roberson 2021년 12월 12일
I do not seem to find you in my list of customers of my company who have signed 4-Hour Response Time Contracts with us ?
Muhammad Usman Saleem
Muhammad Usman Saleem 2021년 12월 13일
@Walter Roberson Hahaha, you can signed with your company 4 Hour Response Time Contract. Actually Time is importantance for me, I'm end user of the NC files and all time of the research spent in proccessing the raw dataset.. I would like to thank you very much for your timely response..

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채택된 답변

Walter Roberson
Walter Roberson 2021년 12월 12일
file = 'data.nc';
shapefile = 'lahore.shp';
long = ncread(file, 'lon');
latt = ncread(file, 'lat');
time = ncread(file, 'time');
soilw = ncread(file, 'soilw');
S = shaperead(shapefile);
%ncread sometimes returns the transpose of what we expect
if size(soilw, 1) ~= length(lat)
soilw = permute(soilw, [2 1 3]);
end
Ntime = length(time);
Date = datetime('1800-01-01 00:00:00') + days(time(:));
mask = inpolygon(lat, lon, S.Y, S.X); %caution, lat is Y not X !
Soilw = zeros(Ntime, 1);
for K = 1 : Ntime
sl = soilw(:,:,K);
Soilw(K) = mean( sl(mask) );
end
output = table(Date, Soilw);
  댓글 수: 17
Muhammad Usman Saleem
Muhammad Usman Saleem 2022년 1월 6일
@Walter Roberson dear sir, whether the above code elimainating missing values (-9.97e+36) from the mean of dataset?
Walter Roberson
Walter Roberson 2022년 1월 6일
file = 'soilw.mon.mean.v2.nc';
shapefile = 'Shapefile/lahore.shp';
long = ncread(file, 'lon');
latt = ncread(file, 'lat');
time = ncread(file, 'time');
soilw = ncread(file, 'soilw');
info = ncinfo(file, 'soilw');
soil_fill = info.FillValue;
[found, idx] = ismember('missing_value', {info.Attributes.Name});
if found
soil_fill(end+1) = info.Attributes(idx).Value;
end
mask = ismember(soilw, soil_fill);
soilw(mask) = nan;
Then near the bottom
for K = 1 : Ntime
sl = soilw(:,:,K);
Soilw(K) = mean( sl(ind), 'omitnan' );
end

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추가 답변 (1개)

KSSV
KSSV 2021년 12월 12일
  댓글 수: 1
Muhammad Usman Saleem
Muhammad Usman Saleem 2021년 12월 12일
Many thanks for your reply @KSSV. I've read your number of answers on NC file proccessing in Matlab but I not able to form code according to my requirement. I spent one week fully to solve my this problem under your replies on different questions but not able to solve that why I post here a question. I not expert in coding will you please write code dear? Thanks for this

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