Data analysis with NCL
Overview
Teaching: 0 min
Exercises: 0 minQuestions
What are the NCL data processing tools?
How to interpolate CESM CAM (Community Atmosphere Model) hybrid coordinates to pressure coordinates?
Objectives
Learn about NCL tools
Learn how to use verth2p_ecmwf
NCL Tools
The following shell commands are included in the NCL software distribution:
ncl_filedump
It generates an ASCII representation of supported files
(netCDF, HDF, GRIB1, GRIB2, shapefile) on the standard
output. It is similar to the netCDF program called ncdump –h.
ncl_filedump f2000.T31T31.control.cam.h0.0008-12-22-00000.nc
Copyright (C) 1995-2015 - All Rights Reserved
University Corporation for Atmospheric Research
NCAR Command Language Version 6.3.0
The use of this software is governed by a License Agreement.
See http://www.ncl.ucar.edu/ for more details.
Variable: f
Type: file
filename: f2000.T31T31.control.cam.h0.0008-12-22-00000
path: f2000.T31T31.control.cam.h0.0008-12-22-00000.nc
file global attributes:
Conventions : CF-1.0
source : CAM
case : f2000.T31T31.control
title : UNSET
logname : hanbre
host : hexagon-5
Version : $Name$
revision_Id : $Id$
initial_file : /work/hanbre/inputdata/atm/cam/inic/gaus/cami_0000-01-01_48x96_L30_c100426.nc
topography_file : /work/hanbre/inputdata/atm/cam/topo/USGS-gtopo30_48x96_c050520.nc
dimensions:
ncl_scalar = 1
lat = 48
lon = 96
time = 11 // unlimited
nbnd = 2
chars = 8
lev = 30
ilev = 31
variables:
double lev ( lev )
long_name : hybrid level at midpoints (1000*(A+B))
units : level
positive : down
standard_name : atmosphere_hybrid_sigma_pressure_coordinate
formula_terms : a: hyam b: hybm p0: P0 ps: PS
double hyam ( lev )
long_name : hybrid A coefficient at layer midpoints
double hybm ( lev )
long_name : hybrid B coefficient at layer midpoints
double ilev ( ilev )
long_name : hybrid level at interfaces (1000*(A+B))
units : level
positive : down
standard_name : atmosphere_hybrid_sigma_pressure_coordinate
formula_terms : a: hyai b: hybi p0: P0 ps: PS
double hyai ( ilev )
long_name : hybrid A coefficient at layer interfaces
double hybi ( ilev )
long_name : hybrid B coefficient at layer interfaces
double P0 ( ncl_scalar )
long_name : reference pressure
units : Pa
double time ( time )
long_name : time
units : days since 0001-01-01 00:00:00
calendar : noleap
bounds : time_bnds
integer date ( time )
long_name : current date (YYYYMMDD)
integer datesec ( time )
long_name : current seconds of current date
double lat ( lat )
long_name : latitude
units : degrees_north
double lon ( lon )
long_name : longitude
units : degrees_east
double time_bnds ( time, nbnd )
long_name : time interval endpoints
character date_written ( time, chars )
character time_written ( time, chars )
integer ntrm ( ncl_scalar )
long_name : spectral truncation parameter M
integer ntrn ( ncl_scalar )
long_name : spectral truncation parameter N
integer ntrk ( ncl_scalar )
long_name : spectral truncation parameter K
integer ndbase ( ncl_scalar )
long_name : base day
integer nsbase ( ncl_scalar )
long_name : seconds of base day
integer nbdate ( ncl_scalar )
long_name : base date (YYYYMMDD)
integer nbsec ( ncl_scalar )
long_name : seconds of base date
integer mdt ( ncl_scalar )
long_name : timestep
units : s
integer nlon ( lat )
long_name : number of longitudes
integer wnummax ( lat )
long_name : cutoff Fourier wavenumber
double gw ( lat )
long_name : gauss weights
integer ndcur ( time )
long_name : current day (from base day)
integer nscur ( time )
long_name : current seconds of current day
double co2vmr ( time )
long_name : co2 volume mixing ratio
double ch4vmr ( time )
long_name : ch4 volume mixing ratio
double n2ovmr ( time )
long_name : n2o volume mixing ratio
double f11vmr ( time )
long_name : f11 volume mixing ratio
double f12vmr ( time )
long_name : f12 volume mixing ratio
double sol_tsi ( time )
long_name : total solar irradiance
units : W/m2
integer nsteph ( time )
long_name : current timestep
float AEROD_v ( time, lat, lon )
_FillValue : 1e+36
missing_value : 1e+36
units : 1
long_name : Total Aerosol Optical Depth in visible band
cell_methods : time: mean
float ANRAIN ( time, lev, lat, lon )
mdims : 1
units : m-3
long_name : Average rain number conc
cell_methods : time: mean
float ANSNOW ( time, lev, lat, lon )
mdims : 1
units : m-3
long_name : Average snow number conc
cell_methods : time: mean
float AODDUST1 ( time, lat, lon )
_FillValue : 1e+36
missing_value : 1e+36
units :
long_name : Aerosol optical depth 550 nm model 1 from dust
cell_methods : time: mean
float AODDUST3 ( time, lat, lon )
_FillValue : 1e+36
missing_value : 1e+36
units :
long_name : Aerosol optical depth 550 nm model 3 from dust
cell_methods : time: mean
float AODVIS ( time, lat, lon )
_FillValue : 1e+36
missing_value : 1e+36
units :
long_name : Aerosol optical depth 550 nm
cell_methods : time: mean
float AQRAIN ( time, lev, lat, lon )
mdims : 1
units : kg/kg
long_name : Average rain mixing ratio
cell_methods : time: mean
float AQSNOW ( time, lev, lat, lon )
mdims : 1
units : kg/kg
long_name : Average snow mixing ratio
cell_methods : time: mean
float AREI ( time, lev, lat, lon )
mdims : 1
units : Micron
long_name : Average ice effective radius
cell_methods : time: mean
float AREL ( time, lev, lat, lon )
mdims : 1
units : Micron
long_name : Average droplet effective radius
cell_methods : time: mean
float AWNC ( time, lev, lat, lon )
mdims : 1
units : m-3
long_name : Average cloud water number conc
cell_methods : time: mean
float AWNI ( time, lev, lat, lon )
mdims : 1
units : m-3
long_name : Average cloud ice number conc
cell_methods : time: mean
float BURDEN1 ( time, lat, lon )
_FillValue : 1e+36
missing_value : 1e+36
units : kg/m2
long_name : Aerosol burden mode 1
cell_methods : time: mean
float BURDEN2 ( time, lat, lon )
_FillValue : 1e+36
missing_value : 1e+36
units : kg/m2
long_name : Aerosol burden mode 2
cell_methods : time: mean
float BURDEN3 ( time, lat, lon )
_FillValue : 1e+36
missing_value : 1e+36
units : kg/m2
long_name : Aerosol burden mode 3
cell_methods : time: mean
float BURDENBC ( time, lat, lon )
_FillValue : 1e+36
missing_value : 1e+36
units : kg/m2
long_name : Black carbon aerosol burden
cell_methods : time: mean
float BURDENDUST ( time, lat, lon )
_FillValue : 1e+36
missing_value : 1e+36
units : kg/m2
long_name : Dust aerosol burden
cell_methods : time: mean
float BURDENPOM ( time, lat, lon )
_FillValue : 1e+36
missing_value : 1e+36
units : kg/m2
long_name : POM aerosol burden
cell_methods : time: mean
float BURDENSEASALT ( time, lat, lon )
_FillValue : 1e+36
missing_value : 1e+36
units : kg/m2
long_name : Seasalt aerosol burden
cell_methods : time: mean
float BURDENSO4 ( time, lat, lon )
_FillValue : 1e+36
missing_value : 1e+36
units : kg/m2
long_name : Sulfate aerosol burden
cell_methods : time: mean
float BURDENSOA ( time, lat, lon )
_FillValue : 1e+36
missing_value : 1e+36
units : kg/m2
long_name : SOA aerosol burden
cell_methods : time: mean
float CCN3 ( time, lev, lat, lon )
mdims : 1
units : #/cm3
long_name : CCN concentration at S=0.1%
cell_methods : time: mean
float CDNUMC ( time, lat, lon )
units : 1/m2
long_name : Vertically-integrated droplet concentration
cell_methods : time: mean
float CLDHGH ( time, lat, lon )
units : fraction
long_name : Vertically-integrated high cloud
cell_methods : time: mean
float CLDICE ( time, lev, lat, lon )
mdims : 1
units : kg/kg
long_name : Grid box averaged cloud ice amount
cell_methods : time: mean
float CLDLIQ ( time, lev, lat, lon )
mdims : 1
units : kg/kg
long_name : Grid box averaged cloud liquid amount
cell_methods : time: mean
float CLDLOW ( time, lat, lon )
units : fraction
long_name : Vertically-integrated low cloud
cell_methods : time: mean
float CLDMED ( time, lat, lon )
units : fraction
long_name : Vertically-integrated mid-level cloud
cell_methods : time: mean
float CLDTOT ( time, lat, lon )
units : fraction
long_name : Vertically-integrated total cloud
cell_methods : time: mean
float CLOUD ( time, lev, lat, lon )
mdims : 1
units : fraction
long_name : Cloud fraction
cell_methods : time: mean
float DCQ ( time, lev, lat, lon )
mdims : 1
units : kg/kg/s
long_name : Q tendency due to moist processes
cell_methods : time: mean
float DMS_SRF ( time, lat, lon )
units : kg/kg
long_name : DMS in bottom layer
cell_methods : time: mean
float DTCOND ( time, lev, lat, lon )
mdims : 1
units : K/s
long_name : T tendency - moist processes
cell_methods : time: mean
float DTH ( time, lev, lat, lon )
mdims : 1
units : K/s
long_name : T horizontal diffusive heating
cell_methods : time: mean
float DTV ( time, lev, lat, lon )
mdims : 1
units : K/s
long_name : T vertical diffusion
cell_methods : time: mean
float EMISCLD ( time, lev, lat, lon )
mdims : 1
units : 1
long_name : cloud emissivity
cell_methods : time: mean
float FICE ( time, lev, lat, lon )
mdims : 1
units : fraction
long_name : Fractional ice content within cloud
cell_methods : time: mean
float FLDS ( time, lat, lon )
Sampling_Sequence : rad_lwsw
units : W/m2
long_name : Downwelling longwave flux at surface
cell_methods : time: mean
float FLNS ( time, lat, lon )
Sampling_Sequence : rad_lwsw
units : W/m2
long_name : Net longwave flux at surface
cell_methods : time: mean
float FLNSC ( time, lat, lon )
Sampling_Sequence : rad_lwsw
units : W/m2
long_name : Clearsky net longwave flux at surface
cell_methods : time: mean
float FLNT ( time, lat, lon )
Sampling_Sequence : rad_lwsw
units : W/m2
long_name : Net longwave flux at top of model
cell_methods : time: mean
float FLNTC ( time, lat, lon )
Sampling_Sequence : rad_lwsw
units : W/m2
long_name : Clearsky net longwave flux at top of model
cell_methods : time: mean
float FLUT ( time, lat, lon )
Sampling_Sequence : rad_lwsw
units : W/m2
long_name : Upwelling longwave flux at top of model
cell_methods : time: mean
float FLUTC ( time, lat, lon )
Sampling_Sequence : rad_lwsw
units : W/m2
long_name : Clearsky upwelling longwave flux at top of model
cell_methods : time: mean
float FREQI ( time, lev, lat, lon )
mdims : 1
units : fraction
long_name : Fractional occurrence of ice
cell_methods : time: mean
float FREQL ( time, lev, lat, lon )
mdims : 1
units : fraction
long_name : Fractional occurrence of liquid
cell_methods : time: mean
float FREQR ( time, lev, lat, lon )
mdims : 1
units : fraction
long_name : Fractional occurrence of rain
cell_methods : time: mean
float FREQS ( time, lev, lat, lon )
mdims : 1
units : fraction
long_name : Fractional occurrence of snow
cell_methods : time: mean
float FSDS ( time, lat, lon )
Sampling_Sequence : rad_lwsw
units : W/m2
long_name : Downwelling solar flux at surface
cell_methods : time: mean
float FSDSC ( time, lat, lon )
Sampling_Sequence : rad_lwsw
units : W/m2
long_name : Clearsky downwelling solar flux at surface
cell_methods : time: mean
float FSNS ( time, lat, lon )
Sampling_Sequence : rad_lwsw
units : W/m2
long_name : Net solar flux at surface
cell_methods : time: mean
float FSNSC ( time, lat, lon )
Sampling_Sequence : rad_lwsw
units : W/m2
long_name : Clearsky net solar flux at surface
cell_methods : time: mean
float FSNT ( time, lat, lon )
Sampling_Sequence : rad_lwsw
units : W/m2
long_name : Net solar flux at top of model
cell_methods : time: mean
float FSNTC ( time, lat, lon )
Sampling_Sequence : rad_lwsw
units : W/m2
long_name : Clearsky net solar flux at top of model
cell_methods : time: mean
float FSNTOA ( time, lat, lon )
Sampling_Sequence : rad_lwsw
units : W/m2
long_name : Net solar flux at top of atmosphere
cell_methods : time: mean
float FSNTOAC ( time, lat, lon )
Sampling_Sequence : rad_lwsw
units : W/m2
long_name : Clearsky net solar flux at top of atmosphere
cell_methods : time: mean
float FSUTOA ( time, lat, lon )
Sampling_Sequence : rad_lwsw
units : W/m2
long_name : Upwelling solar flux at top of atmosphere
cell_methods : time: mean
float H2O2_SRF ( time, lat, lon )
units : kg/kg
long_name : H2O2 in bottom layer
cell_methods : time: mean
float H2SO4_SRF ( time, lat, lon )
units : kg/kg
long_name : H2SO4 in bottom layer
cell_methods : time: mean
float ICEFRAC ( time, lat, lon )
units : fraction
long_name : Fraction of sfc area covered by sea-ice
cell_methods : time: mean
float ICIMR ( time, lev, lat, lon )
mdims : 1
units : kg/kg
long_name : Prognostic in-cloud ice mixing ratio
cell_methods : time: mean
float ICWMR ( time, lev, lat, lon )
mdims : 1
units : kg/kg
long_name : Prognostic in-cloud water mixing ratio
cell_methods : time: mean
float IWC ( time, lev, lat, lon )
mdims : 1
units : kg/m3
long_name : Grid box average ice water content
cell_methods : time: mean
float LANDFRAC ( time, lat, lon )
units : fraction
long_name : Fraction of sfc area covered by land
cell_methods : time: mean
float LHFLX ( time, lat, lon )
units : W/m2
long_name : Surface latent heat flux
cell_methods : time: mean
float LWCF ( time, lat, lon )
Sampling_Sequence : rad_lwsw
units : W/m2
long_name : Longwave cloud forcing
cell_methods : time: mean
float NUMICE ( time, lev, lat, lon )
mdims : 1
units : 1/kg
long_name : Grid box averaged cloud ice number
cell_methods : time: mean
float NUMLIQ ( time, lev, lat, lon )
mdims : 1
units : 1/kg
long_name : Grid box averaged cloud liquid number
cell_methods : time: mean
float OCNFRAC ( time, lat, lon )
units : fraction
long_name : Fraction of sfc area covered by ocean
cell_methods : time: mean
float OMEGA ( time, lev, lat, lon )
mdims : 1
units : Pa/s
long_name : Vertical velocity (pressure)
cell_methods : time: mean
float OMEGAT ( time, lev, lat, lon )
mdims : 1
units : K Pa/s
long_name : Vertical heat flux
cell_methods : time: mean
float ORO ( time, lat, lon )
units : frac
long_name : ORO
cell_methods : time: mean
float PBLH ( time, lat, lon )
units : m
long_name : PBL height
cell_methods : time: mean
float PHIS ( time, lat, lon )
units : m2/s2
long_name : Surface geopotential
float PRECC ( time, lat, lon )
units : m/s
long_name : Convective precipitation rate (liq + ice)
cell_methods : time: mean
float PRECL ( time, lat, lon )
units : m/s
long_name : Large-scale (stable) precipitation rate (liq + ice)
cell_methods : time: mean
float PRECSC ( time, lat, lon )
units : m/s
long_name : Convective snow rate (water equivalent)
cell_methods : time: mean
float PRECSL ( time, lat, lon )
units : m/s
long_name : Large-scale (stable) snow rate (water equivalent)
cell_methods : time: mean
float PS ( time, lat, lon )
units : Pa
long_name : Surface pressure
cell_methods : time: mean
float PSL ( time, lat, lon )
units : Pa
long_name : Sea level pressure
cell_methods : time: mean
float Q ( time, lev, lat, lon )
mdims : 1
units : kg/kg
long_name : Specific humidity
cell_methods : time: mean
float QFLX ( time, lat, lon )
units : kg/m2/s
long_name : Surface water flux
cell_methods : time: mean
float QREFHT ( time, lat, lon )
units : kg/kg
long_name : Reference height humidity
cell_methods : time: mean
float QRL ( time, lev, lat, lon )
mdims : 1
Sampling_Sequence : rad_lwsw
units : K/s
long_name : Longwave heating rate
cell_methods : time: mean
float QRS ( time, lev, lat, lon )
mdims : 1
Sampling_Sequence : rad_lwsw
units : K/s
long_name : Solar heating rate
cell_methods : time: mean
float RELHUM ( time, lev, lat, lon )
mdims : 1
units : percent
long_name : Relative humidity
cell_methods : time: mean
float SHFLX ( time, lat, lon )
units : W/m2
long_name : Surface sensible heat flux
cell_methods : time: mean
float SNOWHICE ( time, lat, lon )
units : m
long_name : Snow depth over ice
cell_methods : time: mean
float SNOWHLND ( time, lat, lon )
units : m
long_name : Water equivalent snow depth
cell_methods : time: mean
float SO2_SRF ( time, lat, lon )
units : kg/kg
long_name : SO2 in bottom layer
cell_methods : time: mean
float SOAG_SRF ( time, lat, lon )
units : kg/kg
long_name : SOAG in bottom layer
cell_methods : time: mean
float SOLIN ( time, lat, lon )
Sampling_Sequence : rad_lwsw
units : W/m2
long_name : Solar insolation
cell_methods : time: mean
float SWCF ( time, lat, lon )
Sampling_Sequence : rad_lwsw
units : W/m2
long_name : Shortwave cloud forcing
cell_methods : time: mean
float T ( time, lev, lat, lon )
mdims : 1
units : K
long_name : Temperature
cell_methods : time: mean
float TAUX ( time, lat, lon )
units : N/m2
long_name : Zonal surface stress
cell_methods : time: mean
float TAUY ( time, lat, lon )
units : N/m2
long_name : Meridional surface stress
cell_methods : time: mean
float TGCLDCWP ( time, lat, lon )
units : kg/m2
long_name : Total grid-box cloud water path (liquid and ice)
cell_methods : time: mean
float TGCLDIWP ( time, lat, lon )
units : kg/m2
long_name : Total grid-box cloud ice water path
cell_methods : time: mean
float TGCLDLWP ( time, lat, lon )
units : kg/m2
long_name : Total grid-box cloud liquid water path
cell_methods : time: mean
float TMQ ( time, lat, lon )
units : kg/m2
long_name : Total (vertically integrated) precipitable water
cell_methods : time: mean
float TREFHT ( time, lat, lon )
units : K
long_name : Reference height temperature
cell_methods : time: mean
float TS ( time, lat, lon )
units : K
long_name : Surface temperature (radiative)
cell_methods : time: mean
float TSMN ( time, lat, lon )
units : K
long_name : Minimum surface temperature over output period
cell_methods : time: minimum
float TSMX ( time, lat, lon )
units : K
long_name : Maximum surface temperature over output period
cell_methods : time: maximum
float U ( time, lev, lat, lon )
mdims : 1
units : m/s
long_name : Zonal wind
cell_methods : time: mean
float U10 ( time, lat, lon )
units : m/s
long_name : 10m wind speed
cell_methods : time: mean
float UU ( time, lev, lat, lon )
mdims : 1
units : m2/s2
long_name : Zonal velocity squared
cell_methods : time: mean
float V ( time, lev, lat, lon )
mdims : 1
units : m/s
long_name : Meridional wind
cell_methods : time: mean
float VD01 ( time, lev, lat, lon )
mdims : 1
units : kg/kg/s
long_name : Vertical diffusion of Q
cell_methods : time: mean
float VQ ( time, lev, lat, lon )
mdims : 1
units : m/skg/kg
long_name : Meridional water transport
cell_methods : time: mean
float VT ( time, lev, lat, lon )
mdims : 1
units : K m/s
long_name : Meridional heat transport
cell_methods : time: mean
float VU ( time, lev, lat, lon )
mdims : 1
units : m2/s2
long_name : Meridional flux of zonal momentum
cell_methods : time: mean
float VV ( time, lev, lat, lon )
mdims : 1
units : m2/s2
long_name : Meridional velocity squared
cell_methods : time: mean
float WGUSTD ( time, lat, lon )
units : m/s
long_name : wind gusts from turbulence
cell_methods : time: mean
float WSUB ( time, lev, lat, lon )
mdims : 1
units : m/s
long_name : Diagnostic sub-grid vertical velocity
cell_methods : time: mean
float Z3 ( time, lev, lat, lon )
mdims : 1
units : m
long_name : Geopotential Height (above sea level)
cell_methods : time: mean
float bc_a1_SRF ( time, lat, lon )
units : kg/kg
long_name : bc_a1 in bottom layer
cell_methods : time: mean
float dst_a1SF ( time, lat, lon )
units : kg/m2/s
long_name : dst_a1 dust surface emission
cell_methods : time: mean
float dst_a1_SRF ( time, lat, lon )
units : kg/kg
long_name : dst_a1 in bottom layer
cell_methods : time: mean
float dst_a3SF ( time, lat, lon )
units : kg/m2/s
long_name : dst_a3 dust surface emission
cell_methods : time: mean
float dst_a3_SRF ( time, lat, lon )
units : kg/kg
long_name : dst_a3 in bottom layer
cell_methods : time: mean
float ncl_a1_SRF ( time, lat, lon )
units : kg/kg
long_name : ncl_a1 in bottom layer
cell_methods : time: mean
float ncl_a2_SRF ( time, lat, lon )
units : kg/kg
long_name : ncl_a2 in bottom layer
cell_methods : time: mean
float ncl_a3_SRF ( time, lat, lon )
units : kg/kg
long_name : ncl_a3 in bottom layer
cell_methods : time: mean
float num_a1_SRF ( time, lat, lon )
units : 1/kg
long_name : num_a1 in bottom layer
cell_methods : time: mean
float num_a2_SRF ( time, lat, lon )
units : 1/kg
long_name : num_a2 in bottom layer
cell_methods : time: mean
float num_a3_SRF ( time, lat, lon )
units : 1/kg
long_name : num_a3 in bottom layer
cell_methods : time: mean
float pom_a1_SRF ( time, lat, lon )
units : kg/kg
long_name : pom_a1 in bottom layer
cell_methods : time: mean
float so4_a1_SRF ( time, lat, lon )
units : kg/kg
long_name : so4_a1 in bottom layer
cell_methods : time: mean
float so4_a2_SRF ( time, lat, lon )
units : kg/kg
long_name : so4_a2 in bottom layer
cell_methods : time: mean
float so4_a3_SRF ( time, lat, lon )
units : kg/kg
long_name : so4_a3 in bottom layer
cell_methods : time: mean
float soa_a1_SRF ( time, lat, lon )
units : kg/kg
long_name : soa_a1 in bottom layer
cell_methods : time: mean
float soa_a2_SRF ( time, lat, lon )
units : kg/kg
long_name : soa_a2 in bottom layer
cell_methods : time: mean
ncl_convert2nc
It converts GRIB1, GRIB2, shapefile, HDF, or HDF-EOS files to NetCDF files
ng4ex
ng4exis a script for generating hundreds of available C, Fortran,
and NCL object-oriented examples.
WRAPIT
It wraps Fortran 77 or 90 code so you can call it directly from NCL
Data processing with NCL
Prior to visualization, it is quite often necessary to apply additional processing steps to the original data.
For processing NetCDF data, we recommend you to use separate tools such as CDO or NCO. These tools are designed to efficiently perform specific tasks and are usually be more efficient than NCL.
However, for specific tasks such as vertical interpolation and regridding, we recommend to use NCL.
Interpolation from CAM hybrid coordinates to pressure coordinates
It is very often handy to interpolate from CAM hybrid coordinates to pressure coordinates, especially when you need to compare with other models or observations.
NCL provides a built-in function called vinth2p_ecmwf.
f = addfile("f2000.T31T31.control.cam.h0.0008-12-22-00000.nc","r")
T = f->T ; get temperature
P0mb = 0.01*f->P0 ; get reference pressure
hyam = f->hyam ; get a coefficiants
hybm = f->hybm ; get b coefficiants
PS = f->PS ; get pressure
PHIS = f->PHIS ; get surface geopotential
; vector containing the new pressure levels
pnew = (/ 850.0,700.0,500.0,300.0,200.0 /)
nlev = dimsizes(hyam)
tbot = T(nlev-1,:,:)
T_p =vinth2p_ecmwf(T,hyam,hybm,pnew, \
PS,1,P0mb,1, \
True,1,tbot,PHIS)
- The first
1in the call tovinth2p_ecmwfcorresponds to the type of interpolation:- 1 LINEAR,
- 2 LOG,
- 3 LOG LOG
-
The second 1 is a parameter that is not used yet (for future improvement of this function) and should always be set to 1).
-
The parameter set to True means we allow extrapolation. If set to False = no extrapolation when the pressure level is outside of the range of psfc.
-
The last
1in the call is used to specify which variable you are willing to interpolate. This is due to the fact thatvint2p_ecmwfapplies different algorithm for temperature (=1), geopotential height (=-1) or other variables (=0). - tbot is an array with the same sizes as psfc equal to temperature at the lowest (i.e, closest to the surface) level. While this is used only if varflg=-1 (ie, geopotential height), it must still be provided for all cases.
For more information see here
NCL regridding
NCL regridding tools required to install ESMF regridding tools but since NCL 6.4.0, they are now fully integrated to NCL, simplifying their usage and installation.
Key Points
NCL data processing environment