[gradsusr] 回复: NETCDF4 problem
weather.man
weather.man at aliyun.com
Sat Mar 10 07:26:58 EST 2018
you must write a ctl for this data.
------------------------------------------------------------------发件人:jorge.conrado <jorge.conrado at cptec.inpe.br>发送时间:2018年3月9日(星期五) 21:27收件人:gradsusr <gradsusr at gradsusr.org>主 题:[gradsusr] NETCDF4 problem
Hi,
I have some NDI data in netcdf4 format, here is the result of the
ncdfdump for my data:
ncdump -h ndvi3g_geo_v1_1981_0712.nc4
netcdf ndvi3g_geo_v1_1981_0712 {
dimensions:
lon = 4320 ;
lat = 2160 ;
time = 12 ;
variables:
double lon(lon) ;
double lat(lat) ;
double time(time) ;
short satellites(time) ;
short ndvi(time, lat, lon) ;
ndvi:units = "1" ;
ndvi:scale = "x 10000" ;
ndvi:missing_value = -5000. ;
ndvi:valid_range = -0.3, 1. ;
short percentile(time, lat, lon) ;
percentile:units = "%" ;
percentile:scale = "x 10" ;
percentile:flags = "flag 0: from data
flag 1: spline interpolation flag 2: possible snow/cloud cover" ;
percentile:valid_range = "flag*2000 + [0 1000]" ;
// global attributes:
:FileName = "ndvi3g_geo_v1_1981_0712.nc4" ;
:Institution = "NASA/GSFC GIMMS" ;
:Data = "NDVI3g version 1" ;
:Reference = "1. Pinzon, J.E.; Tucker, C.J.
A Non-Stationary 1981-2012 AVHRR NDVI3g Time
Series. Remote Sens. 2014, 6, 6929-6960.
2. Pinzon, J.E.; Tucker, C.J.
A Non-Stationary 1981-2015 AVHRR NDVI3g.v1 Time Series: an
update. Remote Sens. 2016, in preparation
" ;
:CommentsVersion1 = "version1 includes two major fixes
(a and b), and three minor (c-g): (a) Reprocessed Level 2 entire
SeaWIFS mission for the land products to reduce artifacts in the
data, particularly changes in calibration after 2006 that generates
drops in ndvi lower values. OB.DAAC / Ocean Biology
Processing group NASA/GSFC 616 (april 2016) (b) Recovered ndvi negative
values of snow-covered regions in winter Northern latitudes. In
Version0, we masked them with zero values, creating artifacts in
phenology parameters. (c) Arranged data in ncd
format, compiled it in two nc4 files a year. Each nc4 file
includes 6 months of ndvi data (jan-jun and jul-dec), with a total
of 12 (15-day) composites each semester. (d) Rescaled ndvi
values and splitted the flag values from them. (e) Added a new
variable, percentile, to represent the distribution of ndvi values
in the time series. Range 10*[0, 100] (f) Flag values
are (simpler): flag 0: ndvi
without apparent issues (good value) flag 1: ndvi
retrieved from spline interpolation flag 2: ndvi
retrieved from seasonal profile (possible snow/cloud) (g) Flag values
are embeded on the percentile variable: 2000*flag +
percentile. Thus, the actual percentile three ranges [0 1000],
[2000 3000] and [4000 5000] could provide direct
information of how interpolation is affecting the time series. " ;
:Temporalrange = "1981-07-01 -> 2015-12-31" ;
:Year = 1981. ;
:RangeSemester = "Jul 1 - Dec 31 (7:0.5:12.5)" ;
:SpatialResolution = "1/12 x 1/12 degrees" ;
:TemporalResolution = "1/24 a year" ;
:_fill_val = -32768. ;
:NorthernmostLatitude = "90" ;
:SouthernmostLatitude = "-90" ;
:WesternmostLongitude = "-180" ;
:EasternmostLongitude = "180" ;
}
Then I did: grads -p
sdfopen ndvi3g_geo_v1_1981_0712.nc4
and I had:
Scanning self-describing file: ndvi3g_geo_v1_1981_0712.nc4
gadsdf: SDF file has no discernable X coordinate.
Please, what can I do to solve this.
Thanks,
Conrado
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