Why can't I calculate SPEI by using DMAP?

Apparently you have applied unregistered version. As we have mentioned in the related page of Drought Monitor and Prediction Tool (DMAP), you need to pass registration prosess and get a key from our website (Agrimetsoft), then the Drought Monitor and Prediction Tool would be ready to calculate different indices in an easy way via a user-friendly tool.

Knowing about SPEI and calculation phases in the Agrimetsoft tool(Drought Monitor and Prediction Tool) is so essential.The Standardized Precipitation Evapotranspiration Index (SPEI) is an extension of the widely used Standardized Precipitation Index (SPI). The SPEI is designed to take into account both precipitation and potential evapotranspiration (PET) in determining drought. Therefore, the input data for calculating SPEI are including precipitation and PET. SPEI (Standardized Precipitation Evapotranspiration Index) time-scales between 1 and 48 months are provided. In the Drought Monitor and Prediction Tool, the SPEI can calculate through ways:

First, the user should enter the precipitation, mean tempreture, and lat of the station, then Drought Monitor and Prediction Tool through Thornthwaite and Hamoon methods will calculate the ET amount. By the amount of ET calculated and precipitation then the value of SPEI would be computed though Drought Monitor and Prediction Tool.

Second, the user directly enter the amount of ET by every methods or sources that he/she wants. Then the user can apply ET as an input file into Drought Monitor and Prediction Tool, then the tool can calculate SPEI by the ET and entrance precipitation.

Name: Kalpana of Hamal