Validating rain along the trajectory.

[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

[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.

[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,

[glenn.rolph]

No, there is no converter from ARL HYSPLIT formatted meteorology back to GRIB or NetCDF.

[midhun]

Ok. Is there any way to read .gbl file in matlab or in any other software?

[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.

[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?

[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.

[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.

[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])