Precipitation index: Threshold Temporal information Spatial information Pi (Ps) Total precipitation in Pi <1mm Record at station level As a dry spell evolves with time 24 hours. information on the it is important to use preferably a starting time, ending GIS to: description: Quantitative time and duration of wet 1. Calculate the area affected by spell. Keep the the wet spell information in a 2. Locate the coordinates of the database. impact stations and the center with the peak values of the index Magnitude Duration Extent Percent of total number of days with precipitation < 1 mm Computed at station The geographical area computed compared to the average length of the season. level which is a number based on multi-station data with Dry periods, such as during dry seasons in arid or semi-arid of consecutive days gridding when observing areas should not be accounted. satisfying the threshold. networks are dense. Another option is to use remote sensing characterizations: Note: the definition of the wet/dry season is defined by and model analysis. each country, where the start and end of the season should also be defined based on average conditions. Severity: Is based on duration. It should be categorized in three levels: minor, long, and verylong.
Quantitative description: Precipitation index: Pi Threshold (Ps) Temporal information Spatial information Total precipitation in 24 hours. Pi <1mm Record at station level information on the starting time, ending time and duration of wet spell. Keep the information in a database. As a dry spell evolves with time it is important to use preferably a GIS to: 1. Calculate the area affected by the wet spell 2. Locate the coordinates of the impact stations and the center with the peak values of the index characterizations: Magnitude Duration Extent Percent of total number of days with precipitation < 1 mm compared to the average length of the season. Dry periods, such as during dry seasons in arid or semi-arid areas should not be accounted. Note: the definition of the wet/dry season is defined by each country, where the start and end of the season should also be defined based on average conditions. Computed at station level which is a number of consecutive days satisfying the threshold. The geographical area computed based on multi-station data with gridding when observing networks are dense. Another option is to use remote sensing and model analysis. Severity: Is based on duration. It should be categorized in three levels: minor, long, and verylong.
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