In order to develop a reliable product, a suitably long time series of satellite images needs to be compared with the actual harvest yields on the fields. One prerequisite for this is that the crop that has been planted is recognisable, which is only possible with a relatively high spatial resolution, in conjunction with the appropriate computing capacity.
Another important factor with index calculation is the point in the vegetation period when the satellite images were taken. There is little information in the EVI from the fields shortly after sowing. However, between four and eight weeks before the harvest, the plants are at the peak of their vegetation phase. At this stage, they provide a very good indicator of the forthcoming crop yield.
Argentina is the perfect market for satellite-based index insurance because soy is grown over large areas there. The situation is quite different in Mexico or India, for example, where different crops are planted in relatively small areas. In this case, any insurance relying on a vegetation index quickly reaches its limits due to the lack of informative data. A further drawback is that crop losses from hail, pests, inundation and storm surge that occur after the vegetation index has been determined are not considered with this cover. S4 therefore developed an additional flood trigger for the harvest period. This is also based on satellite data, and reflects the proportion of flooded land in a county. This means that the bulk of potential agriculture losses are now covered.