The Weighted Mean Vegetation Health Index (Weighted Mean VHI) allows the user to assess the severity of the drought from the start of the growing season, examining the vegetation health and the influence of temperature on plant conditions. It is an average of the dekadal VHI values over the crop growing season (from the start until the last dekad of analysis), weighted by crop coefficients (Kc), assigned to VHI values at the dekads corresponding to the Start of the Season (SOS), Maximum of the Season (MOS) and End of the Season (EOS). Crop coefficient is applied for the purpose of reflecting the crop’s water sensitivity at different phenology stages.
Weighted Mean VHI Annual Summary is processed at the end of crop season. It allows the user to assess the overall severity of drought for an entire growing season. To cover the crop seasons, two consecutive years data are needed to compute the Mean VHI Annual Summary. The output of the first year (1984) may not be fully consistent with the years onwards.
Two quick-look indicators in ASIS: Agricultural Stress Index (ASI) and Drought Intensity are both based Weighted Mean-VHI dataset.
More information please visit FAO GIEWS Earth Observation website: https://www.fao.org/giews/earthobservation/index.jsp?lang=en
Data creation: 2014-01-01
Supplemental Information:
No data value: -9999
Citation:
Recommended citation: © FAO - Agricultural Stress Index System (ASIS), http://www.fao.org/giews/earthobservation/, [Date accessed]
Contact points:
Resource Contact: Yanyun Li
Metadata Contact: Global Information and Early Warning System (GIEWS)
Resource constraints:
Data license policy: Creative Commons Attribution- NonCommercial-ShareAlike 3.0 IGO (CC BY-NC- SA 3.0 IGO)
Online resources:
Agricultural Stress Index maps (annual summary)
