數據獲取
NCEP數據air.2m.mon.mean.nc，下載地址
讀取
使用matlab命令讀取NCEP數據。
常用的讀取NC頭文件的命令是 nc_dump 和 nc_dump 。
執行nc_dump命令：
nc_dump('E:\數據\空間數據\NECP\air.2m.mon.mean.nc ')
得到如下結果：
NetCDF-3 Classic E:\數據\空間數據\NECP\air.2m.mon.mean.nc {
dimensions:
lon = 192 ;
lat = 94 ;
level = 1 ;
nbnds = 2 ;
time = UNLIMITED ; (420 currently)
variables:
// Preference 'PRESERVE_FVD': false,
// dimensions consistent with ncBrowse, not with native MATLAB netcdf package.
single level(level), shape = [1]
level:units = "m" ;
level:actual_range = 2.000000 2.000000 f;
level:long_name = "Level" ;
level:positive = "up" ;
level:axis = "Z" ;
level:coordinate_defines = "point" ;
single lat(lat), shape = [94]
lat:units = "degrees_north" ;
lat:actual_range = 88.542000 -88.542000 f;
lat:long_name = "Latitude" ;
lat:standard_name = "latitude" ;
lat:axis = "Y" ;
lat:coordinate_defines = "point" ;
single lon(lon), shape = [192]
lon:units = "degrees_east" ;
lon:long_name = "Longitude" ;
lon:actual_range = 0.000000 358.125000 f;
lon:standard_name = "longitude" ;
lon:axis = "X" ;
lon:coordinate_defines = "point" ;
double time(time), shape = [420]
time:units = "hours since 1800-1-1 00:00:00" ;
time:long_name = "Time" ;
time:actual_range = 1.56907e+06 1.87514e+06 ;
time:delta_t = "0000-01-00 00:00:00" ;
time:avg_period = "0000-01-00 00:00:00" ;
time:prev_avg_period = "0000-00-01 00:00:00" ;
time:standard_name = "time" ;
time:axis = "T" ;
time:coordinate_defines = "start" ;
time:bounds = "time_bnds" ;
double time_bnds(time,nbnds), shape = [420 2]
time_bnds:long_name = "Time Boundaries" ;
int16 air(time,level,lat,lon), shape = [420 1 94 192]
air:long_name = "Monthly Mean of Forecast of Air temperature at 2 m" ;
air:valid_range = -32765 -1765 s;
air:unpacked_valid_range = 120.000000 430.000000 f;
air:actual_range = 197.623840 313.472626 f;
air:units = "degK" ;
air:add_offset = 447.649994 f;
air:scale_factor = 0.010000 f;
air:missing_value = 32766 s;
air:_FillValue = -32767 s;
air:precision = 2 s;
air:least_significant_digit = 1 s;
air:GRIB_id = 11 s;
air:GRIB_name = "TMP" ;
air:var_desc = "Air temperature" ;
air:dataset = "NCEP/DOE AMIP-II Reanalysis (Reanalysis-2) Monthly Averages" ;
air:level_desc = "2 m" ;
air:statistic = "Mean" ;
air:parent_stat = "Individual Obs" ;
air:standard_name = "air_temperature" ;
air:cell_methods = "time: mean (interval: 6 hours to daily) time: mean (interval: 1 day to monthly)" ;
//global attributes:
:Conventions = "CF-1.0" ;
:title = "Monthly NCEP/DOE Reanalysis 2" ;
:history = "created 2002/03 by Hoop (netCDF2.3)" ;
:comments = "Data is from
NCEP/DOE AMIP-II Reanalysis (Reanalysis-2)
(4x/day). Data interpolated from model (sigma) surfaces to gaussian grid." ;
:platform = "Model" ;
:source = "NCEP/DOE AMIP-II Reanalysis (Reanalysis-2) Model" ;
:institution = "National Centers for Environmental Prediction" ;
:references = "http://wesley.wwb.noaa.gov/reanalysis2/
http://www.esrl.noaa.gov/psd/data/gridded/data.ncep.reanalysis2.html" ;
執行ncdisp命令：
ncdisp('E:\數據\空間數據\NECP\air.2m.mon.mean.nc ')
Time_bndsData = ncread('E:\數據\空間數據\NECP\air.2m.mon.mean.nc','time_bnds'); %讀入變量time_bnds
得到以下結果：
Source:
E:\數據\空間數據\NECP\air.2m.mon.mean.nc
Format:
classic
Global Attributes:
Conventions = 'CF-1.0'
title = 'Monthly NCEP/DOE Reanalysis 2'
history = 'created 2002/03 by Hoop (netCDF2.3)'
comments = 'Data is from
NCEP/DOE AMIP-II Reanalysis (Reanalysis-2)
(4x/day). Data interpolated from model (sigma) surfaces to gaussian grid.'
platform = 'Model'
source = 'NCEP/DOE AMIP-II Reanalysis (Reanalysis-2) Model'
institution = 'National Centers for Environmental Prediction'
references = 'http://wesley.wwb.noaa.gov/reanalysis2/
http://www.esrl.noaa.gov/psd/data/gridded/data.ncep.reanalysis2.html'
Dimensions:
lon = 192
lat = 94
level = 1
nbnds = 2
time = 420 (UNLIMITED)
Variables:
level
Size: 1x1
Dimensions: level
Datatype: single
Attributes:
units = 'm'
actual_range = [2.00e+00 2.00e+00]
long_name = 'Level'
positive = 'up'
axis = 'Z'
coordinate_defines = 'point'
lat
Size: 94x1
Dimensions: lat
Datatype: single
Attributes:
units = 'degrees_north'
actual_range = [8.85e+01 -8.85e+01]
long_name = 'Latitude'
standard_name = 'latitude'
axis = 'Y'
coordinate_defines = 'point'
lon
Size: 192x1
Dimensions: lon
Datatype: single
Attributes:
units = 'degrees_east'
long_name = 'Longitude'
actual_range = [0.00e+00 3.58e+02]
standard_name = 'longitude'
axis = 'X'
coordinate_defines = 'point'
time
Size: 420x1
Dimensions: time
Datatype: double
Attributes:
units = 'hours since 1800-1-1 00:00:00'
long_name = 'Time'
actual_range = [1.57e+06 1.88e+06]
delta_t = '0000-01-00 00:00:00'
avg_period = '0000-01-00 00:00:00'
prev_avg_period = '0000-00-01 00:00:00'
standard_name = 'time'
axis = 'T'
coordinate_defines = 'start'
bounds = 'time_bnds'
time_bnds
Size: 2x420
Dimensions: nbnds,time
Datatype: double
Attributes:
long_name = 'Time Boundaries'
air
Size: 192x94x1x420
Dimensions: lon,lat,level,time
Datatype: int16
Attributes:
long_name = 'Monthly Mean of Forecast of Air temperature at 2 m'
valid_range = [-3.28e+04 -1.77e+03]
unpacked_valid_range = [1.20e+02 4.30e+02]
actual_range = [1.98e+02 3.13e+02]
units = 'degK'
add_offset = 448
scale_factor = 0.01
missing_value = 3.28e+04
_FillValue = -3.28e+04
precision = 2
least_significant_digit = 1
GRIB_id = 11
GRIB_name = 'TMP'
var_desc = 'Air temperature'
dataset = 'NCEP/DOE AMIP-II Reanalysis (Reanalysis-2) Monthly Averages'
level_desc = '2 m'
statistic = 'Mean'
parent_stat = 'Individual Obs'
standard_name = 'air_temperature'
cell_methods = 'time: mean (interval: 6 hours to daily) time: mean (interval: 1 day to monthly)'
另外，還可以用nc_varget來讀取數據，如：
lon=nc_varget('E:\數據\空間數據\NECP\air.2m.mon.mean.nc','lon');%查看經度的範圍
lat=nc_varget('E:\數據\空間數據\NECP\air.2m.mon.mean.nc','lat'); %查看緯度的範圍
data=nc_varget('E:\數據\空間數據\NECP\air.2m.mon.mean.nc','air',[0 0 0 0],[420 1 94 192]);%取值範圍從[0 0 0 0]到[time level lat 1on]
由以上命令可以得知，此NCEP數據爲192*94*420的高維數組，經度範圍是[0,358.1250]，緯度範圍是[88.5420,-88.5420]，時間範圍在數據裏沒給出，但從網站的數據說明中可以知道是1979年1月到2013年12月。（2016年1月13日查詢到，此數據已經更新到了2015年7月）。
相關鏈接：
Matlab處理氣象數據——目錄