I need the Evapotranspiration data for my study (The study area is located in Australia). Somebody told me maybe I can use MOD 16 MODIS actual ET estimates. I could not find this data on earth explorer. Instead I have found the following link http://www.ntsg.umt.edu/ which provide MOD 16 MODIS data. There are several folders in data folder which contain *.hdf files. Does anyone knows which folder I have to choose and how I can open the *.hdf files?(I tried to open one of *.hdf files in Arcmap. 3 bands are blank and one band is completely grey) .
The first document that you should read is MOD16_global_evapotranspiration_description.pdf where is pointed out that the MOD16 global evapotranspiration (ET)/ latent heat flux (LE)/ potential ET (PET)/ potential LE (PLE) datasets are regular 1-km2 land surface ET datasets for the 109.03 Million km2 global vegetated land areas at 8-day, monthly and annual intervals.
The users should multiply 0.1 to get the real ET/PET values in mm/8day or mm/month, or mm/yr, and 1.0e4 to get LE/PLE in J/m2/day.
For the 8-day and monthly ET/LE/PET/PLE, annual LE/PLE, the valid value range is -32767- 32700.
Fill value, out of the earth 32767 Water body 32766 Barren or sparsely vegetated 32765 Permanent snow and ice 32764 Permanent wetland 32763 Urban or Built-up 32762 Unclassified 32761
For the annual ET/PET, the valid value range is 0- 65500.
Fill value, out of the earth 65535 Water body 65534 Barren or sparsely vegetated 65533 Permanent snow and ice 65532 Permanent wetland 65531 Urban or Built-up 65530 Unclassified 65529
The above information is very important for map algebra.
Next, you have to choose the tile(s) of your study areas. Australia has representation in (horizontal tile number, vertical tile number): (h29,v10), (h30,v10), (h31,v10 )... to ... (h31,v12).
Assuming that you are interested in the annual product (year 2000) for tile (h30,v11):
you have to download MOD16A3.A2000366.h30v11.105.2013122030105.hdf.
This product has 5 data subsets (ET_QC, PLE, PET, LE, ET). ArcMap should load these subsets without problems. The projection is sinusoidal.
On the other hand, the reason of your 3 blank and one grey datasets is probably due to inclusion of high values corresponding to Barren or sparsely vegetated, etc compared to ET, etc values. They need to be excluded with map algebra.
For example, considering (in QGIS) only ET data values without excluding "Barren or sparsely vegetated" (65533 value):
Considering only ET data values and excluding "Barren or sparsely vegetated" (65533 value) with map algebra in the raster calculator (the style used was a pseudocolor band renderer):