Hi, John:
This is my own way to handle dimensional scale in WRF-HDF5 module since at
that time there was no implementation of dimensional scale at HDF5.
So it may not be a good example to follow with the current HDF5 dimensional
scale implementation.
Anyway, here is what I invented:
I used a compound datatype to store three piece information of HDF5 file:
1) name of the dimension 2) the length of the dimension(in the example,
length of time is 1 means only one timestep is generated) and also 3)
whether the current dimension is unlimited or not, if it is unlimited
dimension, the flag is set to 1, otherwise it is -1.
I can use these information to retrieve the dimensional information of the
HDF5 file.
The H5_Dimrank is used to retrieve information from each variable.
There are two confusion parts of the dumped file:
1) H5_Dimrank always starts with 1, the index of dumper output always
starts from 0.
2) I believe that except the first dimension is time(I hard-coded that); to
retrieve the rest dimensional rank, you have to reverse the dimension order.
For example, for dim rank 1(time),5,3, the actual dimension it is supposed
to point to is 1(time),3,5 in the table. I know that's odd. I am using
HDF5 fortran wrapper to do all WRF work, I am not sure whether that
explains something. It is possible that the dimension information I stored
is in fortran order but h5dump just display in C order. It is also possible
this is bug that has not been discovered. I just read my code and the part
that handles the dimensional scale is not straightforward, I cannot figure
out whether this is a bug or not with the limited time. Anyway, I will
leave the fix of this in the future WRF release if they still want PHDF5
module. Now, if you can use the previous approach, it should make sense to
you. I do remember I converted WRF-NetCDF output and then converted NetCDF
to HDF5 to make the comparison with WRF-HDF5 output. The data stored in the
two files are the same.
Hope this helps.
Kent
Kent
Thanks,
Kent
At 02:58 PM 3/30/2005, John Caron wrote:
I am trying to figure out how the WRF HDF5 files are put together, by
looking at a sample file i was given.
I guess that the attribute H5_DimRank associates the dimensions in a data
variable with the dimensions in the dim_table under the DIM_GROUP group.
but i cant figure out the specifics of this file, eg:
float P(1, 4, 20, 10); // 4 800
:H5_DimRank = 1, 5, 3, 4; // int
:MemoryOrder = "XYZ";
:FieldType = 104; // int
:description = "pressure";
:units = "pascals";
:stagger = " ";
float LU_INDEX(1, 20, 10); // 4 200
:MemoryOrder = "XY ";
:FieldType = 104; // int
:description = "LAND USE CATEGORY";
:units = " ";
:stagger = " ";
:H5_DimRank = 1, 5, 3; // int
can anyone explain?
the h5dim_table dump:
{
dim_name
"Time
"
dim_length =1
dim_unlimited =1
} DIM_GROUP/h5dim_table(0)
{
dim_name
"west_east_stag
"
dim_length =11
dim_unlimited =-1
} DIM_GROUP/h5dim_table(1)
{
dim_name
"south_north
"
dim_length =20
dim_unlimited =-1
} DIM_GROUP/h5dim_table(2)
{
dim_name
"bottom_top
"
dim_length =4
dim_unlimited =-1
} DIM_GROUP/h5dim_table(3)
{
dim_name
"west_east
"
dim_length =10
dim_unlimited =-1
} DIM_GROUP/h5dim_table(4)
{
dim_name
"south_north_stag
"
dim_length =21
dim_unlimited =-1
} DIM_GROUP/h5dim_table(5)
{
dim_name
"bottom_top_stag
"
dim_length =5
dim_unlimited =-1
} DIM_GROUP/h5dim_table(6)
{
dim_name
"soil_layers_stag
"
dim_length =5
dim_unlimited =-1
} DIM_GROUP/h5dim_table(7)
{
dim_name
"ext_scalar
"
dim_length =1
dim_unlimited =-1
} DIM_GROUP/h5dim_table(8)
