Day 7-MODIS Details

Vegetation Indices Products 16 and Monthly time scales & 250m-5600m resolution

The 500m 16-day Vegetation Indices product provides consistency for usage and centers blue at 469nm, red at 645nm, and NIR to 858nm which are used to defined daily vegetation indices. It tries to maintain sensitivity over dense areas (which we are interested in) and uses the EVI(Enhanced Vegetation Index) to correct for atmospheric contamination by smoke and sub-pixel thin clouds. The product is computed from a corrected product. The data is aimed for use in monitoring land cover changes as well as inputs for modeling climate change.

The lower resolution MOD13A2 is the same sort of thing but at 1000m instead. The 250m band since it lacks a 250m blue band it uses the 500m to correct for atmospheric effects. The image of this one looks less crisp than the 500m one. The 1000m monthly image uses a weighted average of the the data if it is cloud free.

Burned Area Monthly 500m

Uses daily surface reflectance values to look for rapid changes indicative of burning and maps the extent of recent fires only. It gives a quality "score" per pixel. It is based on 3 months of corrected daily reflectance data

Thermal Anomalies and fire at 1000m and 5 min, Daily, and 8 day time scales

It derives these areas from micrometer radiances based on its difference from background and is used to advance the monitoring of fires globally. The Daily one has three dimensions, the fire-mask, fire radiative power, and are given for an 8-day period. The 8 day product gives the average of these days which gives a fire-mask and the algorithm quality.

Leaf Area Index 8 day time scale 1000m resolution

It defines the number of equivalent layers of leaves per unit ground area and are used to calculated surface photosynthesis etc.

Land Cover Type Yearly Time scale and 1000m and 5600m

Taking a years worth of data it classifies the areas into 17 different classes defined by the International geosphere Biosphere Programme.

Opinion

The one 250m product seems too derived to work well but the multiple 500m look useful. However, these are much bigger than we really want to use. The 1000m are useful if we want to look at more 'general' trends that is not the focus. I think the combined burned, a vegetation index, and a leaf area index would be most useful. Preferably at 500m and looking at the daily to 16-day cycles rather than the monthly.