I am attempting to download the MODIS Chlorophyll data but the formats are giving me difficulties.  I have extracted the provided .bz2 files, but I am not sure how to read the resulting files --> e.g. "A20090012009365.L3m_YR_CHLO_4"
Ideally I would like to get a .HDF file, but I can't seem to extract the downloads properly.

Any help is greatly appreciated.

Thanks,
Gregg

Gregg,

While the file does not have the .hdf extension, it is indeed an HDF4 file.
For details on the format specs, see:

http://oceancolor.gsfc.nasa.gov/DOCS/ocformats.html

Sean

Thanks, Sean. but...

When I download the SMI/HDF file for Chlorophyll and add the ".hdf" extension it is readible in ArcGIS.

However, when I perform the same steps on Sea Surface SMI/HDF files they will not read.  Any idea why?

No, I cannot explain why ArcGIS has trouble with the SST files.

All the SMI files have the same l3m_data SDS.
The SST has an additional SDS (l3m_qual - for the SST quality level flag).
This is the only difference (aside from the obvious e.g. scaling factors)

Sean

Hi sean,

I read your reply and I have also a similar kind of problem in reading HDF files. I am a windows user and installed HDf View 2.6 to read HDF4 files downloaded from MODISA Mapped products.
In HDF View, I can see two files l3m_data and l3m_qual where l3m_data carries all scientific values of SST or Chlo etc. I have exported these hdf l3m_data to TXT file and then to excel for reading them.
In data table it shows 65535 as fill data and remaining are 5 or 4 digit values.
I understand fill value is a value for land area this is OK but I am confused  how to read other values as scientific references.
Can anybody help me how to refer these values as exact parameter values?

whether I should go for binned or any other products rather than mapped products to read exact parameter values.
Kindly sugggest is there a need to go for scripting in C for further processing of these values.

Thanks in advance

Mahesh

Mahesh,

Look here.
http://oceancolor.gsfc.nasa.gov/forum/oceancolor/topic_show.pl?pid=16896#pid16896

Norman