Initial quality controlled subset release

Table of Contents

  1. Introduction
  2. Available data fields
  3. Perturbations
  4. References

Introduction

This document describes data from the climateprediction.net project which was the basis for the analysis published in the paper [Stainforth et al.]. The data comprises a grand ensemble of 2578 simulations of the HadAM3 GCM exploring 6 independent physical perturbations and perturbed initial conditions.

A brief description of the format of the data, and associated metadata, is given below. See [Stainforth et al.] for a detailed discussion of the experiment.

Further enquiries can be directed to Stephen Pascoe at the Rutherford Appleton Laboratory, UK.

Available data fields

The GCM experiment is composed of phases of 15 years:

  1. 1811-1825. Spin up.
  2. 1826-1840. Pre-industrial CO2
  3. 2051-2065. Double CO2

The data fields available for each model simulation are described in Table 1. These fields are distributed amongst 17 netCDF files depending on the experiment phase, UM ouput stream and field domain. Each filename is of the form:

<job_id>.<output_stream>.<domain>.x<phase>.nc

The filenaming convention is demonstrated in Table 2. Note that when constructing filenames the UM job id is composed of the 4 character experiment id followed by either aa, ba or ca according to the experiment phase. Also note from Table 2 that some climatology fields are seasonal means and some are monthly means. The heat convergence field (UM output stream pc) is also available in UM ancillary format with the file extension .anc.

Table 1: Fields available for each simulation
Field Description UM output stream Domain
field3201 HEAT FLUX THROUGH SEA ICE (GBM) W/M2 pa 8yac
hfbl SURFACE & B.LAYER HEAT FLUXES
tauxbl X-COMP OF SURF & BL WIND STRESS
tauybl Y-COMP OF SURF & BL WIND STRESS
field3223 SURF & BL TOTL MOISTURE FLUX KG/M2/S
field3224 WIND MIXING EN\'GY FLUX INTO SEA W/M2
gm_field40201 GLOBAL MEAN ANOMALOUS HEAT CONVERGENCE(SLAB) W/M2 pc gmts
gm_ps GLOBAL MEAN Surface pressure pd gmts
gm_clc GLOBAL MEAN Convective Cloud amount
gm_ts GLOBAL MEAN Ground Surface Temperature
gm_field31 GLOBAL MEAN SEA ICE FRACTION AFTER TIMESTEP
gm_field32 GLOBAL MEAN SEA ICE DEPTH (MEAN OVER ICE)
gm_netrsds GLOBAL MEAN NET DOWN SURFACE SW FLUX: SW TS ONLY
gm_rsdt GLOBAL MEAN SW radiation downward TOA
gm_rsutcs GLOBAL MEAN SW radiation upward TOA clear sky
gm_field1210 GLOBAL MEAN CLEAR-SKY (II) DOWN SURFACE SW FLUX
gm_field1211 GLOBAL MEAN CLEAR-SKY (II) UP SURFACE SW FLUX
gm_field1235 GLOBAL MEAN TOTAL DOWNWARD SURFACE SW FLUX
gm_rlnds GLOBAL MEAN Net downward surface LW radiation
gm_rlutcs GLOBAL MEAN LW radiation TOA clear sky
gm_rlds GLOBAL MEAN LW radiation downward surface
gm_field2208 GLOBAL MEAN CLEAR-SKY (II) DOWN SURFACE LW FLUX
gm_field3237 GLOBAL MEAN SPECIFIC HUMIDITY AT 1.5M
gm_field3245 GLOBAL MEAN RELATIVE HUMIDITY AT 1.5M
gm_field3314 GLOBAL MEAN SURFACE NET RADIATION
gm_field4203 GLOBAL MEAN LARGE SCALE RAINFALL RATE KG/M2/S
gm_field4204 GLOBAL MEAN LARGE SCALE SNOWFALL RATE KG/M2/S
gm_field5205 GLOBAL MEAN CONVECTIVE RAINFALL RATE KG/M2/S
gm_field5206 GLOBAL MEAN CONVECTIVE SNOWFALL RATE KG/M2/S
gm_field5214 GLOBAL MEAN TOTAL RAINFALL RATE: LS+CONV KG/M2/S
gm_field5215 GLOBAL MEAN TOTAL SNOWFALL RATE: LS+CONV KG/M2/S
gm_field12201 GLOBAL MEAN OMEGA ON MODEL LEVELS
gm_field13201mlyr GLOBAL MEAN QT SOURCE SINK IN QT POS KG/M2/S
gm_field14201 GLOBAL MEAN ATMOS ENERGY CORR\'N IN COLUMN W/M2
rsut SW radiation upward TOA pe 8yac
field2204 TOTAL CLOUD AMOUNT IN LW RADIATION
rlut LW radiation TOA (OLR)
field3228 SURFACE SH FLUX FROM SEA (GBM) W/M2
hfls Heat flux latent surface
tas Surface (1.5m) air temperature
pr Total precipitation rate
psl Mean sea-level pressure
gm_rsut GLOBAL MEAN SW radiation upward TOA pe gmts
gm_field2204 GLOBAL MEAN TOTAL CLOUD AMOUNT IN LW RADIATION
gm_rlut GLOBAL MEAN LW radiation TOA (OLR)
gm_field3228 GLOBAL MEAN SURFACE SH FLUX FROM SEA (GBM) W/M2
gm_hfls GLOBAL MEAN Heat flux latent surface
gm_tas GLOBAL MEAN Surface (1.5m) air temperature
gm_pr GLOBAL MEAN Total precipitation rate
gm_psl GLOBAL MEAN Mean sea-level pressure
gm_field210 GLOBAL MEAN FIELD 210 pf gmts
gm_field40023 GLOBAL MEAN SNOW AMOUNT AFTER SLAB KG/M2
gm_field40024 GLOBAL MEAN SURFACE TEMPERATURE AFTER SLAB K
gm_field40031 GLOBAL MEAN SEA ICE FRACTION AFTER SLAB K
gm_field40178 GLOBAL MEAN REF. SEA SURF TEMP (SLAB MODEL) K A
gm_field40203 GLOBAL MEAN SEAICE DEPTH(GRD BOX MN)AFTER SLAB M
gm_field40220 GLOBAL MEAN SLAB CARRYHEAT (W M-2) SLAB
gm_field40221 GLOBAL MEAN SLAB HEATING RATE (ICE) K/S
gm_field2max GLOBAL MEAN U COMPNT OF WIND AFTER TIMESTEP pg gmts
gm_field3max GLOBAL MEAN V COMPNT OF WIND AFTER TIMESTEP
gm_tasmin GLOBAL MEAN Daily minimum surface (1.5m) temperature
gm_tasmax GLOBAL MEAN Daily maximum surface (1.5m) temperature
gm_prmax GLOBAL MEAN Total precipitation rate
Table 2: Example of mapping experiment phase, UM output stream and domain onto netCDF filenames
UM output unit Domain Spacial domain Time domain Phase availability Example filename
label 1 2 3 for UM experiment id 01lz
pa 8yac global 2.5x3.75 grid monthly mean yes no no 01lzaa.pa.8yac.x1.nc (phase 1)
pc gmts global mean monthly mean yes no no 01lzaa.pc.gmts.x1.nc (phase 1)
pd gmts global mean seasonal climatology yes yes yes 01lzba.pd.gmts.x2.nc (phase 2)
pe 8yac global 2.5x3.75 grid seasonal climatology yes yes yes 01lzce.pe.8yac.x3.nc (phase 3)
gmts global mean seasonal climatology yes yes yes 01lzba.pe.gmts.x2.nc (phase 2)
pf gmts global mean seasonal climatology yes yes yes 01lzce.pf.gmts.x3.nc (phase 3)
pg gmts global mean monthly mean yes yes yes 01lzaa.pg.gmts.x1.nc (phase 1)

Perturbations

The grand ensemble includes perturbations of 7 physical parameters and one initial condition parameter. These parameters are listed in Table 3 and are also included as attributes within each netcdf file. The physical parameters CW_LAND and CW_SEA are always varied together and therefore there are 6 independent physical perturbations.

The actual parameter values for each simulation are stored as attributes in the netCDF file and are summarised in Table 4.

The perturbations applied to each simulation are tabulated in the file perturbations.dat which accompanies the dataset. This is a text file which can be easily imported into a spreadsheet or parsed by scripts. The format is two header lines, prefixed with the '#' character, followed by tab delimeted column data:

Column 1
lists the simulation directory.
Column 2
Perturbation id. This is a base 3 integer uniquely identifying the physical perturbations applied.
Columns 3-9
describe the 7 physical parameters as being unperturbed (stnd), perturbed low (low) or perturbed high (high).
Column 10
lists the initial condition ensemble parameter DTHETA.

The perturbation id repeats the information in columns 3-9 in a form that makes identifying duplicates easier. Each digit in the perturbation id corresponds to the value of a physical parameter using the encoding 0=low, 1=stnd and 2=high. The file has been sorted by perturbation id such that initial condition ensemble members occur together.

Table 3: Perturbed parameters. (* parameters perturbed together)
Perturbation label Description Sample size
CW_SEA * Threshold for precipitable water 3
CW_LAND * 3
ENTCOEF Entrainment coefficient 3
RHCRIT Critical relative humidity 3
CT Accretion constant 3
EACF Empirically adjusted cloud fraction 2
VF1 Ice speed fall 3
DTHETA Initial condition ensemble generator 10
Table 4: Parameter values
Parameter Perturbation Value
VF1 low 0.5
stnd 1.0
high 2.0
CT low 5.0e-5
stnd 1.0e-4
high 4.0e-4
RHCRIT low 0.95, 0.90, 0.85, 0.60, 0.60, 0.60, 0.60, 0.60, 0.60, 0.60, 0.60, 0.60, 0.60, 0.60, 0.60, 0.60, 0.60, 0.60, 0.60
stnd 0.95, 0.90, 0.85, 0.70, 0.70, 0.70, 0.70, 0.70, 0.70, 0.70, 0.70, 0.70, 0.70, 0.70, 0.70, 0.70, 0.70, 0.70, 0.70
high 0.95, 0.90, 0.90, 0.90, 0.90, 0.90, 0.90, 0.90, 0.90, 0.90, 0.90, 0.90, 0.90, 0.90, 0.90, 0.90, 0.90, 0.90, 0.90
CW_LAND low 1.0e-5
stnd 2.0e-4
high 2.0e-3
CW_SEA low 2.0e-5
stnd 5.0e-5
high 5.0e-4
ENTCOEF low 0.6
stnd 3.0
high 9.0
EACF stnd 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5
high 0.7, 0.7, 0.7, 0.7, 0.7, 0.666, 0.633, 0.6, 0.6, 0.6, 0.6, 0.6, 0.6, 0.6, 0.6, 0.6, 0.6, 0.6, 0.6

References

Stainforth 2004
Stainforth D.A. et al. Uncertainty in predictions of the climate response to rising levels of greenhouse gases, Nature, January 27.