MODIS

About

MODIS data is collected by two satellites called Aqua (MOLA/MYD) and Terra (MOLT/MOD). Each satellite uses a 16 day period, and they are in antiphase, giving 8-day resolution. Some products are already combined into single datasets (MCD). A variety of fields are available. This document will describe the generic things about the dataset.

Getting Access

You need to sign up for a password, but after that, downloads are free. The download process is a bit tedious too, so scripting is the way. The source folders we've had reason to use are:

https://e4ftl01.cr.usgs.gov/MOLA/MYD11A2.006/	MODIS/Aqua Land Surface Temperature and Emissivity 8-Day L3 Global 1 km Grid SIN V006
https://e4ftl01.cr.usgs.gov/MOLT/MOD11A2.006/	MODIS/Terra Land Surface Temperature and Emissivity 8-Day L3 Global 1 km Grid SIN V006
https://e4ftl01.cr.usgs.gov/MOLA/MYD13A2.006/	MODIS/Aqua Vegetation Indices 16-Day L3 Global 1km Grid SIN V006
https://e4ftl01.cr.usgs.gov/MOLT/MOD13A2.006/	MODIS/Terra Vegetation Indices 16-Day L3 Global 1km Grid SIN V006
https://e4ftl01.cr.usgs.gov/MOTA/MCD12Q1.051/	MODIS Combined Land Cover Type Yearly L3 Global 500 m SIN Grid

File Format

The file format is the HDF format. More details to follow, as I discover what exactly it is and how to interpet it.

Example Code

C

Two versions of HDF seem to be common: HDF4 and HDF5. I'm not clear yet which MODIS uses when they call theirs "HDF-EOS". But anyway. There are some ready-built binary libraries for both HDF4 and HDF5 which look promising. Some linux builds, and also Windows builds in release mode, both 32-bit and 64-bit, built with Visual Studio 2013 and 2015. That's more helpful than most. So.... Here are windows instructions. If you do this for linux, tell me how and I'll add instructions.

• Download the Library above, 64-bit, and the Visual Studio you're using, extract it, and run the installer, which unzips the library to a place of your choice. I recommend a place without spaces in the directory names - it usually makes things simpler somewhere along the lines. For this example, suppose you install it in C:\Lib\HDF.
• Get your project open in Visual Studio, and get into Release x64 bit mode. Open a C file, so you get the right project preferences, and then...
• Open Project Preferences - check it's still configuring 64-bit Release mode.
• In C/C++, General, Additional Include Directories, insert C:\Lib\HDF\include; (for example)
• In Linker, Input, Additional Dependencies, insert libxdr.lib;libszip.lib;libjpeg.lib;libzlib.lib;libmfhdf.lib;libhdf.lib; - which is a bit eye-boggling.
• In Linker, General, Additional Library Directories, insert (for example) C:\Lib\HDF\lib;

Citation

For the datasets we used above:-

Z. Wan, S. H., G.Hulley. (2015). MYD11A2 MODIS/Aqua Land Surface Temperature/Emissivity 8-Day L3 Global 1km SIN Grid V006. NASA EOSDIS Land Processes DAAC. https://doi.org/10.5067/MODIS/MYD11A2.006

Z. Wan, S. H., G.Hulley. (2015). MOD11A2 MODIS/Terra Land Surface Temperature/Emissivity 8-Day L3 Global 1km SIN Grid V006. NASA EOSDIS Land Processes DAAC. https://doi.org/10.5067/MODIS/MOD11A2.006

K. Didan. (2015). MYD13A2 MODIS/Aqua Vegetation Indices 16-Day L3 Global 1km SIN Grid V006. NASA EOSDIS Land Processes DAAC. https://doi.org/10.5067/MODIS/MYD13A2.006

K. Didan. (2015). MOD13A2 MODIS/Terra Vegetation Indices 16-Day L3 Global 1km SIN Grid V006. NASA EOSDIS Land Processes DAAC. https://doi.org/10.5067/MODIS/MOD13A2.006

(No specific citation for the MCD dataset)