MRG Interactive Developments

General Patch Information

The patches provided on this page have been developed by MRG Interactive and tested for basic functionality. However, they do not represent features incorporated into the MC2 model, and should be applied only when specifically required. To apply a patch, follow the instructions particular to the patchfile. In general, you will have to extract a certain number of MC2 subprograms and common declaration files into you "experience" directory before applying the patch. To generated the patched files, simply type patch -p 0 -b -z .orig < patchfileName. Always double check that the patch has been properly applied using the diff utility.

Generating a Patch for the MC2

This patch was originally produced for version 4.9.7 of the MC2, although it has also been sucessfully applied to versions 4.9.6 and 4.9.8. The patch corrects errors in the argument list for the dynamic initialization that result in immediate segementaion (memory) faults in the stock version of the model. Note that the re-release of version 4.9.8 in the fall of 2004 contains the functionality of this patch (it should therefore not be applied to the updated version of the mc2). Local versions of the mc2dm.ftn and initdyn9.ftn subprograms are required in the local "experience" directory. To apply this patch:

Dynamic Initialization Stepping Patch

This patch was produced for version 4.9.8 of the MC2 in order to implement a forwards-backwards mass-based stepping during the dynamic initialization procedure. The stock version of the mc2 dynamic initialization uses the dynamical core of the model to integrate forwards in time for gndtini steps of grninit seconds. Thereafter, them model reverses its timestep and integrates backwards to the initial time, thus balancing the initial state. This patch changes the balancing procedure by doing a series of gndtini forwards-backwards steps at time zero. After each step, the mass field is redefined to its original value. Thus, the end result of this patch is to force the balancing of the winds to the analyzed mass field. Depending on the scale of the systems to be balanced, this balancing may take numerous steps since the geostrophic adjustment process for smaller-scale systems is generally dominated by the flow field. This patch is not beautifully implemented, and appears to have problems when initialization steps are too large or too numerous; however, it is included here it the hopes that it may be useful. To apply this patch:

RPN Standard File Cascade Patch

This patch was produced for version 4.9.8 of the MC2 in order to maintain potentially useful (but dangerous) functionality involving the production of self-nesting (cascade) grids in RPN Standard File (FST) format. Before proceeding with the application of the patch, the user must understand that the cascade output files produced by the MC2 should not be modified. That being said, it may - on rare occasions - be useful to be able to view and access these files using standard ARMNLIB utilities such as 'X-Reveur en Couleurs' (xrec). This patch implements an additional parameter (fst_casc) in the &mc2_cfgs namelist in the mc2_settings.nml file. By default, RPN Standarad files are not produced, even after patching - as described below, the user must insert the fst_casc=.true. in the &mc2_cfgs namelist to access the functionality of this patch. To apply this patch:

Relative Humidity Initialization Patch

This patch was produced for version 4.9.8 of the MC2 in order to allow for the reading of relative humidity data in the initial conditions. Although the CMC does not routinely store relative humidity (HR) data in their analysis files, grids produced by other centres often contain these fields as moisture specification. Adding this patch allows the user to read directly from HR data since the conversion to specific humidity is included explicitly in the initial setup of the MC2 using the conversion forumlated by Gill (1982). Additionally, this patch allows for missing humidity data at levels above the bottom layer of the analysis. This is particularly useful for NCEP analysis and reanalysis data that often only has moisture fields available to 100 and 300 hPa respectively. Any moisture field above the bottom layer is automatically initialized to zero if it is not found in the analysis. The functionality of this patch is enitrely transparent, and its application will not affect any other components of the MC2 mode. To apply this patch: