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Validating rain along the trajectory.
Posted: April 30th, 2016, 11:33 am
by midhun
Hi,
I am interested in rain rate along the hysplit trajectory. I want to validate the rainfall data from NCEP/GDAS using trmm or gpcp. But i am unable to process the rainfall data in the hysplit input. Is there anyway to convert hysplit input data (.gbl file) to normal grib or netcdf data?
Regards,
Midhun
Re: Validating rain along the trajectory.
Posted: May 3rd, 2016, 8:02 am
by glenn.rolph
You can output the precipitation rate (mm/hr) along your trajectory by setting the TM_RAIN=1 in the SETUP.CFG or by choosing option (6) in the Advanced/Configuration Setup/Trajectory GUI menu and then checking the box for precipitation. Both of these methods will write the precipitation rate into the trajectory output file as a new column of data for each endpoint.
Re: Validating rain along the trajectory.
Posted: May 3rd, 2016, 10:02 pm
by midhun
Dear rolph,
Thank you for your reply.
I am able to simulate the rainratel along the trajectory. But this rainrate data is from model forecast (NCEP or GDAS). Hence I want to validate NCEP/GDAS rainrate with trmm or GPCP data. But the data input we use as hysplit input is in .gbl format. I want to know how to convert this data (.gbl files) to normal netcdf or grib format for doing the comparison.
Thanks,
Re: Validating rain along the trajectory.
Posted: May 4th, 2016, 9:32 am
by glenn.rolph
No, there is no converter from ARL HYSPLIT formatted meteorology back to GRIB or NetCDF.
Re: Validating rain along the trajectory.
Posted: May 4th, 2016, 1:09 pm
by midhun
Ok. Is there any way to read .gbl file in matlab or in any other software?
Re: Validating rain along the trajectory.
Posted: May 4th, 2016, 2:10 pm
by ariel.stein
At the bottom of this web page:
http://www.ready.noaa.gov/archives.php
you will find a description of the way the meteorological dataset are packed.
Re: Validating rain along the trajectory.
Posted: May 4th, 2016, 3:28 pm
by midhun
Thank you.
I found difficulty in unpacking the data using the given FORTRAN code. So I plan to download the original GDAS data from NCEP server. As I understand, precipitation rate (PRATEsfc) is not a variable in the GDAS analysis, so HYSPLIT taken it from the forecast fields (
https://www.ready.noaa.gov/gdas1.php).
But, which forecast hour is used in HYSPLIT?
For example, see
http://nomads.ncdc.noaa.gov/data/gfsanl ... /20130601/
There I can see two forecast output (3hr and 6hr) for each given time. (ie,
http://nomads.ncdc.noaa.gov/data/gfsanl ... 00_003.grb and
http://nomads.ncdc.noaa.gov/data/gfsanl ... 00_006.grb and corresponding to the time 2013-06-01 00:00). Which file is used to make the packed HYSPLIT(gbl) data?
Re: Validating rain along the trajectory.
Posted: May 4th, 2016, 8:47 pm
by yaqiang
MeteoInfo/MeteoInfoLab can read ARL data format and there is a sample script for getting meteorological data along trajectory (
http://www.meteothinker.com/examples/me ... _data.html). Using MeteoInfoLab you can also do model verification by specific script. Also it's possible to convert ARL data format to netCDF.
Re: Validating rain along the trajectory.
Posted: May 5th, 2016, 3:12 pm
by barbara.stunder
For precip, at hours 00, 06, 12, and 18z, the GDAS has the 6-four forecast from the previous cycle.
At hours 03, 09, 15, and 21z, the GDAS has the 3-hour forecast from the current cycle.
Re: Validating rain along the trajectory.
Posted: May 5th, 2016, 6:05 pm
by midhun
Dear Yaqiang,
Thank you!
Great! It worked!
Please see my script below. I have defined the lat/lon/time according to the description given at
http://ready.arl.noaa.gov/gdas1.php. Is there any way to get the lat/lon/time values directly from the input file?
Code: Select all
infn = '/home/midhun/Downloads/gdas1.jun13.w1'
outfn = '/home/midhun/Downloads/pr_gdas1.jun13.w1.nc'
inf= addfile(infn)
rain=inf['TPP6'][:,:,:,:]
#New netCDF file
ncfile = addfile(outfn, 'c')
#Add dimensions
x=ncfile.adddim('lon',360)
y=ncfile.adddim('lat',181)
t=ncfile.adddim('time',56)
ncfile.addgroupattr('history', 'source: ftp://arlftp.arlhq.noaa.gov/pub/archives/gdas1/gdas1.jun13.w1')
#create variables
lat = ncfile.addvar('lat', 'float', [y]) #Latitude
lat.addattr('long_name', 'Latitude')
lat.addattr('units', 'degrees_north')
lat.addattr('axis', 'Y')
lon = ncfile.addvar('lon', 'float', [x]) #Longitude
lon.addattr('long_name', 'Longitude')
lon.addattr('units', 'degrees_east')
lon.addattr('axis', 'X')
time = ncfile.addvar('time', 'int', [t])
time.addattr('long_name', 'time')
time.addattr('units', 'hours since 1900-01-01 00:00:0.0')
time.addattr('axis', 'T')
pr = ncfile.addvar('PR', 'float', [t,y,x]) #
pr.addattr('long_name', 'Accumulated precipitation (6 h accumulation)')
pr.addattr('units','m')
xx=arange(0,360,1)
yy=arange(-90,91,1)
tt=arange(0,168,3)
#write variables
ncfile.create()
ncfile.write(lat,yy,origin=[0])
ncfile.write(lon,xx,origin=[0])
ncfile.write(time,tt,origin=[0])
ncfile.write(pr,rain,origin=[0,0,0])