CRU : Projects : SO&P : Data : Model Data : HadCM3 : HadCM3 Data

SO&P: HadCM3 Depth of lying snow

all : 1750-1999 all forcings

Important notes regarding the HadCM3 data:

Do not redistribute data to others outside the SO&P project.

Hadley Centre will require co-authorship and need to know from the start what analyses you are using the HadCM3 data for. Please contact Simon Tett (see SO&P participants table) and keep him informed.

To ensure collaboration between SO&P partners, please refer to the list of ongoing/planned model-data comparisons. Please contact others who have listed an interest in the same area, to initiate collaboration. To add your planned areas of model-data work to the list, email Tim Osborn.

A small climate drift, unrelated to the external forcings, is present in the HadCM3 simulations. It's significance depends on the region and variable being considered. Simon Tett describes how this should be dealt with, by reference to the HadCM3 control simulation, in this report (not yet available). The HadCM3 control simulation data is not yet available.

Please inform Tim Osborn of any errors that you find in the data.

For important notes regarding the all simulation: click here.

For important notes regarding the snowd variable: click here.

Obtaining fields of model data

Fields of model data, covering the entire globe, are available in netCDF format only (please email Tim Osborn if you cannot use netCDF files). For monthly and seasonal-mean data, there is usually one file for each decade (though not always and the filenames or headers will make it clear when this is not the case). For annual data there are usually separate files for each year.

The netCDF header contains all the information about coordinates and units that you need.

You have two options for downloading the files:

Use wget with the command listed below (click here to obtain the wget software, to understand its options and for an explanation of its advantages):

wget --mirror --no-parent --no-directories --accept=nc --http-user=soaphad --http-passwd=xe2005 http://www.cru.uea.ac.uk/cru/projects/soap/pw/data/model/hadcm3/soaparchive/all/nc/snow/

Click here to see a listing of all files, and right-click each one that you want to download/save.

Note that the data files use the HadCM3 variable name instead of the variable name used on the SO&P website. Instead of snowd, the files are named snow.

Note also that the units used in the data files may be different to those given in the time series plots/data, because I converted some variables to more common units. Refer to the netCDF file headers for the units used (and any notes below regarding errors in this information).

Select alternative simulation for this variable:
control : nat : all

Select alternative variable from this simulation:
slp__ : sst__ : airtm : rlhum : swrad : precp : snowd : soilm : soilt : win10 : z850_ : z500_ : u500_ : v500_ : iceco : iceth : lwrad : sealv

Important notes regarding the 'all' simulation:

The vegetation cover was incorrectly set to present-day, rather than pre-industrial, during the 'nat' simulation. The 'all' simulation should start smoothly from the 'nat' simulation in 1750, but because of the sudden change from present-day to 1750 vegetation there is a step-change between the two simulations. Simon Tett will be calculating some correction fields for each variable, which can be applied to the 'nat' simulation data to remove the vegetation error effects.
The stratospheric ozone depletion used as a forcing in the 'all' simulation was too strong by a factor of around 2. This may affect some variables (e.g. Antarctic atmospheric circulation) in the final 3 decades of the simulation. Simon Tett is considering a re-run of these final decades.

Important notes regarding the snowd variable:

Some grid boxes (around Greenland and Antarctica) snow continually accumulates during the entire simulations, reaching very large values. I think this is because the model does not represent calving of glaciers. These grid boxes should probably just be ignored, and certainly should be removed from global-mean snow cover for instance. (They have not been removed from the area-average series included on the SO&P website, which is why those series show a continual upward trend in mean snow cover.)
The headers in the full fields of data indicate that values are stored in m, but it looks like they are actually in mm!
Be careful when using the full fields of data, because snow can (of course) occur on sea ice, and thus there are snow depth values over the (time-varying) region of the oceans that has sea ice.

Last updated: August 2004, Tim Osborn