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ACKNOWLEDGEMENTS:
-----------------

Please include the following acknowledgement (or similar) in any papers
that use this data:

"Lateral boundary data from the HadAM3 model were provided by the Hadley
Centre, and funded by the UK Department for Environment, Food and Rural
Affairs under contract PECD 7/12/37."


MODEL AND EXPERIMENT DESCRIPTION, AND CITATIONS:
------------------------------------------------

The atmospheric GCM used to provide the 6-hourly is known as HadAM3,
and is described by Pope et al. (2000) and references therein. This
data is made available to provide lateral boundary conditions for
regional climate models. Data from the last 6 years of an ensemble of
four integrations is provided. These are known as 'C20C simulations',
and each ensemble member simulates the period 1 February 1870 to 1
January 2006. All were forced by the HadISST1.1 global reconstruction
of observed SST and sea-ice extents (Rayner et al. 2003), which were
processed to preserve their monthly means during the model integration
(Taylor et al. 2000). They were also forced by time-varying
concentrations of well-mixed greenhouse gases including CO2, CH4, N2O,
CFCs, HCFCs, tropospheric ozone and stratospheric ozone (the latter
from 1975), changes in land use, anthropogenic sulphate aerosols,
volcanic aerosols, and solar irradiance variations. The ensemble
members differ only in their initial atmospheric conditions, which
were taken from an earlier HadAM3 simulation.

Further details of the forcing data are available on request.

Pope, V.D., Gallani, M., Rowntree, P.R. and Stratton, R.A.  2000  The 
impact of new physical parametrizations in the Hadley Centre climate 
model - HadAM3. Clim. Dyn., 16, 123-146

Rayner, N.A., Parker, D.E., Horton, E.B., Folland, C.K., Alexander, 
L.V., Rowell, D.P., Kent, E.C., and Kaplan, A., 2003: Global analyses 
of sea surface temperature, sea ice, and night marine air temperature 
since the late nineteenth century. J. Geophys. Res., 108(D14), 4407, 
doi: 10.1029/2002JD002670

Taylor, K.E., Williamson, D., and Zwiers, F., 2000: The sea surface 
temperature and sea-ice concentration boundary conditions for AMIP II 
simulations. PCMDI Report No. 60, Lawrence Livermore National 
Laboratory, Livermore, CA, 25 pp


DATA:
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All data are converted into netcdf CF1.0 convention and gzipped on
the DLTs. Please use the Linux/Unix command "unzip filename.gz".

Variables:

u, v, T, H, RH, Specific humidity, MSLP, T1.5m, SpecHum1.5m, u10m, v10m
with the first 6 at the following pressure levels:
1000,925,850,700,600,500,400,300,250,200,150,100,70,50,30,20,10hPa

Spatial coverage:

HadAM3 has a regular grid of 3.75deg longitude x 2.5deg latitude, ie.
73 x 96 points. The latitude and longitude ranges of the grid points
are 90.0N - 90.0S, 0.0E - 356.25E

Temporal coverage:  

6-hourly data in one month chunk files. Each file contains 120 time
points, since the model uses a 360 day calendar (each month has 30
days).

File naming convention:

{RUNID}a.pg{YR}{MON}.nc

where

{RUNID} is a five letters name used to identify the ensemble member
simulation.  The {RUNID} for the member1 is afoif, member 2 is afoig,
member 3 is afoih and  member 4 is afoii. Between each ensemble member
the only difference is the initial condition.

'a.pg' defines the type of data contained in the file (here lateral
boundary conditions for regional climate models)

{YR} represents the year coded using two characters: j9=1999, k0=2000,
k1=2001, k2=2002, k3=2003, k4=2004, k5=2005

{MON} are the first three letter of a given month, ie. jan, feb, mar,
apr, may, jun .. etc.


FINALLY:
--------

Please address any queries to wilfran.moufouma-okia@metoffice.gov.uk
or dave.rowell@metoffice.gov.uk