EVI Meeting Notes (Martin + Victoria)

[vyelnats]

EVI - Notes:

Background:

Values between -1 -> 1, like NDVI, and 0.2-0.8 -> healthy vegetation

• [ ] background information and citations

Data:

Satellite: Sentinel 2 Level 2A Bands: NIR = B8A, B04, B02

Calculation:

3-band EVI

EVI = G*(B8A-B04)/(B8A + C1/B04 - C2/B02 +1) where: G = 2.5, C1 = 6, C2 = 7.5 and L = 1

Note: B8A chosen over B08 for the following reason:

• B08 NIR centre wavelength = 842 nm

• B8A NIR centre wavelength = 865 nm

• MODIS (original EVI) NIR sensor centre wavelength = 858 nm

• [ ] needs citation

Strategy

1 year vegetation index time series computing the monthly mean.....

• [ ] flush out details here

Steps

1. Extract script from raster dataset
2. Calculate buffer program
3. EVI calculation script
4. Data cleaning/handling/viz

Ideas

• plot per land use type?

[vyelnats]

Meeting Mon 07.02.2022

What bands do we want to use for the calculation? As far as we know, no empirical study has tried to adjust these parameters for the specific spectral response of the Sentinel-2 MSI bands, but they're "usable" like this.

Todo:

• [x] @vyelnats -> create repo for RS documentation
• [x] @vyelnats -> write in Senseco community about proposed band and constants
• [x] Martin -> review proposed calculation

[vyelnats]

Open Questions:

• [ ] transfer over assumptions and tasks from my notes in the Miro OKR board

Data prep

• Masking strategy
• Buffer size
• Feeding in precipitation and temperature data?
• How to sample spatially?
• How to sample temporally?
• Long scale series analysis?

Data analysis and viz

• How to represent this to the farmer?
• How do we represent this for the white paper
• How do we determine what is healthy or not?