.. index::
   pair: MODIS; MOD29E1D_to_obs
   pair: MOD29E1D_to_obs; MODIS
   sea ice temperature

PROGRAM ``MOD29E1D_to_obs``
===========================

``MOD29E1D_to_obs`` reads a daily netCDF file of MODIS sea ice temperature
observations and writes a DART obs_seq file.

   "The MODIS/Terra Sea Ice Extent and IST Daily L3 Global 4km EASE-Grid Day 
   (MOD29E1D) data set consists of sea ice extent and ice surface temperature (IST), 
   generated by remapping 1 km resolution data from MOD29P1D to a 4 km resolution
   Equal Area Scalable Earth (EASE) grid, for both the Northern and Southern 
   Hemispheres. The gridded input observation nearest the center of the output 
   grid cell is assigned to that grid cell. As such, approximately every fourth 
   input grid cell is mapped to the output grid. No QA data is provided."

MOD29E1D data files are provided by the `National Snow and Ice Data Center <https://nsidc.org/>`__
in HDF format and can be accessed through the following link: 
https://nsidc.org/data/mod29e1d/versions/61.

The HDF files must be preprocessed to netCDF files before this converter can be used. 
An example conversion script titled MOD29E1D_hdf_to_netcdf.py has been 
provided in MODIS/shell_scripts.

.. warning ::

   ``MOD29E1D_to_obs`` only converts IST for the Northern Hemisphere (lat > 40.0)

Please make sure you cite the data in accordance with the National Snow and Ice Data Center
`citation agreement <https://nsidc.org/data/mod29e1d/versions/61>`__:

Hall, D. K. and G. Riggs. 2021. MODIS/Terra Sea Ice Extent and IST Daily L3 Global 
4km EASE-Grid Day, Version 61. [Indicate subset used]. Boulder, Colorado USA. NASA 
National Snow and Ice Data Center Distributed Active Archive Center. 
https://doi.org/10.5067/MODIS/MOD29E1D.061. [Date Accessed].