Continuously updated
(last update: 1/20/98)

Contents
  1. Introduction
  2. Naming constructs
  3. Current listing of PCMDI standard variable names
1. Introduction

What follows is an overview of the PCMDI strategy to establish "reasonable" variable names for climate model and observational data.  Use of these naming conventions is strictly adhered to at PCMDI, and will be utilized for projects managed by PCMDI such as AMIP, CMIP and PMIP. The need for adherence to these conventions is essential for efficient managment of AMIP, a project for which PCMDI anticipates receiving over 1Tb of model output from over 30 modeling groups by the year 2000.

Variable names are created with naming constructs. The complete listing of PCMDI standard variable names is fully consistent with the naming constructs, and both are updated regularly. For convenience, the table of PCMDI standard variable names also includes standard units and metadata titles used by PCMDI.

This schema has been made public in response to a request made by several modeling groups. Those who are appreciative of the potential advantages of developing standards for the community may wish to adopt the PCMDI standards for their own use. Institutions choosing to collaborate with this effort should contact PCMDI amip@pcmdi.llnl.gov. Requests will be taken to continuously add new fields to this list as the demand arises.

2. Naming constructs

Certain rules and guidelines have been established for the creation of PCMDI variable names. For example, 1) Keeping the variable names as short as possible is a high priority, 2) Only basic properties of the variable should be described, and thus any spatial or temporal averaging (e.g., zonal and monthly respectively) is identified by file names, not the variable names, and 3) The methodology must ensure that the listing of PCMDI standard variable names can easily be continuously updated. This third criteria is the most serious constraint given the diversity of categories which are expected to arise (e.g., from the various sub-models of the atmosphere, ocean, land surface, trace chemistry, etc.). At PCMDI it has thus been concluded that constructing variable names in the future will require flexibility to expand the listing in ways that cannot be anticipated. Thus, many of the guidelines developed are unique to each variable property (e.g., albedo, radiation, temperature, etc.). This enables much more versatility than attempting to create a comprehensive set of rigid rules that all variable names must adhere to. On the other hand, a concerted effort is made to ensure that there is as much consistency as possible throughout the various variable properties.  The variable property is identified by the variable name prefix. Current prefixes in use are listed in the following table:

Variable property prefixes currently in use: 
please click buttons to right of prefix
constructs -      listing - 
alb (albedo)
 
 orog (orography) 
 
 t (temperature)   
bl (boundary layer) 
 
 p (pressure) 
 
 tau (wind stress)   
cl (cloud)
 
 pr (precipitation) 
 
 tn (tendency)   
en (energy)
 
 r (radiation) 
 
 tr (trace)  
ev (evaporation) 
 
 sft (surface type) 
 
 u (eastward wind)  
hf (heat flux) 
 
 si (sea ice) 
 
 v (northward wind)  
hu (humidity) 
 
 sn (snow) 
 
 vor (vorticity)   
mp (mean product)
 
 so (salinity)
 
 w (vertical velocity)  
mr (moisture)
 
 stf (stream function) 
 
 zg (geopotential)  
Naming constructs are isolated in tables by variable property, with the currents status of:
 Albedo-alb
 At TOA
t
  
 surface
s
  
 Clear sky (method 2)  
csm2
 
 Boundary layer- bl
 Height
h
   
 
 Cloud - cl 
 emittance 
em
 
 ext coef (opt thick/depth) 
exc
  
 ice
i
  
 total
t
  
 liquid water
w
  
 highest top height
topht
  
 vertically integrated  
vi
 
 Energy - en
 Eddy kinetic
ek
   
 
 Evaporation - ev
 Surface
s
  
 Plus sublimation   
psbl
     
 
 Heat flux - hf
 Correction
 corr
  
 Latent
l
  
 Net
n
  
 Surface  
s
 
 Humidity - hu
 Relative
r
    
 Specific
s
    
 Surface (2m)  
s
  
 Zonal mean    
zm
 
 Mean Product - mp
 of eastward and northward wind
uva
 of northward wind and specific humidity 
vhusa
 of northward wind and temperature 
vta
 of vertical motion and specific humidity
whusa
 
 Moisture - mr
 soil 
so
    
 field capacity  
fc
  
 frozen  
f
  
 runoff 
ro
    
 surface    
s
 
Orography - orog
     
 
 Pressure - p
 surface
s
  
 below ground
bg
  
 Mean sea-level
sl
  
 
 Precipitation - pr
 convective
c
  
 minus evaporation
me
  
 snowfall
sn
  
 
 Radiation - r
longwave
l
        
shortwave
s
        
downward  
d
      
upward  
u
      
surface    
s
    
top (of atmosphere)    
t
    
clear-sky      
cs
  
Cloud radiative forcing (method 2)      
crfm2
  
model top        
mt
 
 Surface type - sft
 glacier
gl
  
 land 
l
  
 
 Sea ice - si 
 concentration
c
  
 boundary conditions   
bc
 thickness 
t
  
 
 Salinity - so
 Atlantic ocean
atl
  
 global ocean 
go
  
 Indian ocean
ind
  
 Pacific ocean
pac
  
 surface
s
  
 zonal mean
zm
  
 
 Snow - sn
 cover (percent area)
c
  
 depth 
d
  
 water 
w
  
 
 Stream function - stf
 barotropic
baro
  
 Mean meridional circulation   mmc  
 Atlantic ocean  
atl
 global ocean   
go
 Indian ocean  
ind
 Pacific ocean  
pac
 
 Temperature - t
 atmosphere
a
        
 ocean
o
        
 surface  
s
      
 Atlantic ocean    
atl
    
 global ocean     
go
    
 Indian ocean    
ind
    
 Pacific ocean    
pac
    
 Maximum      
max
  
 Minimum      
min
  
 Brightness MSU ch 2        
msu2
 Brightness MSU ch 4        
msu4
 Brightness MSU ch 6 (2R)        
msu6
 
 Wind stress- tau
 Eastward
u
      
 Northward
v
      
 
 Tendency - tn
 moisture 
m
  
 temperature 
t
  
 due to diabatic processes  
d
 due to dry convective processes  
dc
 due to large scale precipitation  
lsp
 due to longwave radiation  
lw
 due to moist convective processes  
mc
 due to shortwave radiation  
sw
 
 Trace gases - tr
 ozone  o3  
     
     
 
 Eastward wind or current - u
 atmosphere
a
    
 ocean
o
    
 surface  
s
  
 Zonal mean  
z
  
 
 Northward wind or current - v 
 atmosphere
a
  
 ocean
o
  
 surface  
s 
 Zonal mean  
z
 
 Vorticity - vor
 Potential 
pot
  
 On theta sfc  
ts
 
 Vertical velocity or current - w
 atmosphere
a
  
 ocean
o
  
 In units of p tendency  
p
 
 Geopotential - zg
   
   
 
 

3. Current listing of PCMDI standard variable names

PCMDI Standard Variable Name Listing
Name
Title 
Units
LATS
Param Tbl
 albp  Planetary albedo
%
---
 albs  Surface albedo
%
---
 blh  Planetary boundary layer height
m
A2
 cl  Cloud amount
%
A2
 clem  Cloud emittance (cloud emissivity/layer depth)
1/Pa
A2
 clexc  Extinction coef (cloud optical thickness/layer depth)
1/Pa
A2
 cli  Cloud ice
kg/kg
A2
 clivi   Vertically integrated cloud ice
kg/m2
A2
 clt  Total cloud amount
%
A2
 cltopht  Highest cloud top height
m
---
 clw  Cloud liquid water
kg/kg
A2
 clwvi   Vertically integrated cloud water (liquid and solid phase)
kg/m2
A2
 enek  Eddy kinetic energy
m2/s2
A2
 evspsbl   Surface evaporation plus sublimation rate
kg/(m2*s)
---
 hfcorr   Flux correction (or "adjustment") for heat flux 
W/m2
C2
 hfls  Heat flux latent surface
W/m2
A2
 hfns  Heat flux net surface
W/m2
---
 hfss  Heat flux sensible surface
W/m2
A2
 hur   Relative humidity
%
A2
 hus  Specific humidity
kg/kg
A2
 huss  Surface specific humidity (2m)
kg/kg
A2
 mpuva   Mean product of eastward and northward wind 
m2/s2
A2
 mpvhusa   Mean product of northward wind and specific humidity 
m/s
A2
 mpvta   Mean product of northward wind and temperature 
m*K/s
A2
 mpwhusa   Mean product of vertical motion and specific humidity 
Pa/s
A2
 mrsof   Total soil frozen water content 
kg/m2
A2
 mrro   Total runoff rate (including drainage) 
kg/(m2*s)
A2
 mrros   Surface runoff rate 
kg/(m2*s)
A2
 mrso   Total soil water content 
kg/m2
A2
 mrsofc   Soil moisture field capacity 
kg/m2
A2
 mrsofcs   Surface soil moisture field capacity 
%?
A2
 mrsos   Surface soil water content (upper 0.1m) 
kg/m2
A2
 orog   Model orography 
m
A2
 pr   Total precipitation rate 
kg/(m2*s)
A2
 prc   Convective precipiation rate 
kg/(m2*s)
---
 prme   Net surface freshwater flux (P - E + sea ice effects) 
kg/(m2*s)
---
 prsn   Snowfall rate (water equivalent)
kg/(m2*s)
A2
 prw   Precipitable water 
kg/m2
A2
 ps   Surface pressure 
Pa
A2
 psbg   Pressure surface below ground percentage 
%
A2
 psl   Mean sea-level pressure 
Pa
A2
 rlds   LW radiation downward surface 
W/m2
A2
 rldscs   LW radiation downward surface clear sky 
W/m2
A2
 rls   LW radiation net surface   
A2
 rlt   LW radiation TOA (OLR)   
A2
 rltcs   LW radiation TOA clear sky   
A2
 rlus   LW radiation upward surface   
A2
 rluscs   LW radiation upward surface clear sky   
A2
 rlutcs   LW radiation upward TOA clear sky   
A2
 rsds   SW radiation incident at the surface   
A2
 rsdscs   SW radiation downward clear sky surface   
A2
 rsdt   SW radiation downward TOA   
A2
 rss   SW radiation net surface   
A2
 rst   SW radiation net TOA   
A2
 rsus   SW radiaton upward (reflected) surface   
A2
 rsuscs   SW radiation upward surface clear sky   
A2
 rsut   SW radiation upward TOA   
A2
 rsutcs   SW radiation upward TOA clear sky   
A2
 rtmt   Net Radiation at Model Top   
A2
 sftglif   Sfc type % glacier 
%
A2
 sftl   Sfc type % land 
%
A2
 sic   Sea-ice concentration 
%
A2
 sicbcs   AMIP II BCS Psuedo Sea-ice concentration 
%
A2
 sit   Ice thickness 
m
---
 snc   Snow cover (percent area) 
%
A2
 snd   Snow depth 
m
A2
 snw   Snow depth (water equivalent) 
kg/m2
A2
 soatlzm   Zonal mean salinity: Atlantic basin 
per mil
C2
 sogozm   Zonal mean salinity: global ocean 
per mil
C2
 soindzm   Zonal mean salinity: Indian basin 
per mil
C2
 sopaczm   Zonal mean salinity: Pacific basin 
per mil
C2
 so   Ocean salinity 
per mil
---
 sos   Ocean surface salinity 
per mil
---
 stfbaro   Oceanic barotropic stream function  
---
 stfmmcatl   Mean meridional circulation streamfunction: Atlantic basin   
C2
 stfmmcgo   Mean meridional circulation streamfunction: global ocean   
C2
 stfmmcind   Mean meridional circulation streamfunction: Indian basin   
C2
 stfmmcpac   Mean meridional circulation streamfunction: Pacific basin   
C2
 ta   Air Temperature 
K
A2
 tas   Surface (2m) air temperature 
K
A2
 tasmax   Daily maximum surface (2m) temperature 
K
A2
 tasmin   Daily minimum surface (2m) temperature 
K
A2
 taamzmsd   Standard deviation of annual mean zonal mean air temperature   
---
 tadmzmsd   Standard deviation of decadal mean zonal mean air temperature   
---
 to   Ocean temperature 
K
---
 toatlzm   Ocean temperature: Atlantic basin 
K
---
 togozm   Ocean temperature: global ocean 
K
---
 toindzm   Ocean temperature: Indian basin 
K
---
 topaczm   Ocean temperature: Pacific basin 
K
---
 tos   Sea Surface Temperature 
K
---
 tosbcs   AMIP II BCS Psuedo Sea Surface Temperature 
K
---
 ts   Ground Surface Temperature 
K
---
 tro3   Ozone Concentration 
ppmv
---
 tauu   Eastward surface wind stress (positive for eastward wind) 
N/m2
---
 tauv   Northward surface wind stress (positive for northward wind) 
N/m2
---
 tnmd   Moisture tendency due to diabatic processes 
(Kg/Kg)/s
---
 tnttd   Total diabatic temperature tendency 
K/s
---
 tntdc   Temperature tendency due to dry convective processes 
K/s
---
 tntlsp   Temperature tendency due to large scale precipation 
K/s
---
 tntlw   Temperature tendency due to LW radiation 
K/s
---
 tntmc   Temperature tendency due to moist convective processes 
K/s
---
 tntsw   Temperature tendency due to SW radiation 
K/s
---
 ua   Eastward wind 
M/s
---
 uaz   Eastward wind zonal mean 
M/s
---
 uas   Surface (10m) eastward wind 
M/s
---
 va   Northward wind 
M/s
---
 vaz   Northward wind zonal mean 
M/s
---
 Vorpotts   Potential vorticity (350, 380, 405K) 
1/(Pa*s)
---
 wap   Vertical motion (omega) 
Pa/s
---
 zg   Geopotential height 
m
---
 

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Last updated June 27, 1997. For questions or comments contact gleckler@pcmdi.llnl.gov.
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