README -- describes contents of MODIS_LAI_201806/ directory
5 Jun 2018
Jenny Fisher
jennyf@uow.edu.au

Overview:
===============================================================================

This directory contains MODIS LAI data from the BNU product developed by Yuan
et al. (2011).

Reference:
----------
Yuan, H., Dai, Y., Xiao, Z., Ji, D., Shangguan, W., 2011. Reprocessing the 
MODIS Leaf Area Index Products for Land Surface and Climate Modelling. Remote
Sensing of Environment, 115(5), 1171-1187. doi:10.1016/j.rse.2011.01.001

URL:
----
http://globalchange.bnu.edu.cn/research/lai

Files:
===============================================================================

MODIS.LAI.vBNU.generic.01x01.YYYY.nc

 -- Weekly MODIS LAI data for a given year

    Source      : Yuan et al. (2011), http://globalchange.bnu.edu.cn/research/lai
    Resolution: : Generic 0.1 x 0.1 grid (3600 x 1800 boxes)
    Units       : m2/m2
    Timestamps  : Weekly based on day of year
    Compression : Level 1 (e.g. nccopy -d1)

    NOTE: The HEMCO philosophy is to use the data at the highest resolution
    possible; however, the native files are at an extremely high resolution
    of 30sec. We have regridded here to 0.1 degree to save space and match
    other high resolution emission inventories.

How the netCDF files wwere created:
===============================================================================

The above files were created as follows:

1) Download the original 30-second resolution netcdf files from
   http://globalchange.bnu.edu.cn/research/lai#download.

   This results in a set of very high resolution yearly files:
     global_30s_YYYY.nc

2) Regrid using cdo. Note this requires a large amount of memory, and on my
   system at least required submitting to an interactive queue specifying a 
   requirement for 30GB memory.

   The cdo command uses the included grid description file.

   cdo remapdis,globalgrid_gen_01x01 global_30s_YYYY.nc LAI.01x01.YYYY.nc

   Note YYYY in the above command should be replaced by the year in question.

   This results in a set of 0.1x0.1 resolution yearly files:
     LAI.01x01.YYYY.nc

3) Fix time, variable names, attributes, etc. The remapping command above
   messes up the time dimension, which must be extracted from the original
   file and added to the new file. Other attributes must also be fixed,
   compression added, etc. All steps are done using the included bash script:

   ./fix_LAIv2.bash YYYY

   Note YYYY in the above command should be replaced by the year in question.

   This results in a set of 0.1x0.1 resolution yearly HEMCO-ready files:
     MODIS.LAI.vBNU.generic.025x025.YYYY.nc

4) Repeat steps 1-3 for all years. The following intermediate files can be
   deleted:
     global_30s_YYYY.nc
     LAI.01x01.YYYY.nc