Monitoring

Merged Station-Satellite Rainfall for

a) Dekadal (i.e., ~10-daily) rainfall for the selected region over the last 3 years.

b) Dekadal rainfall differences (from 1983-2014 mean) for the selected region over the last 3 years.

c) Smoothed dekadal rainfall for the current year (thick black line) compared to previous years(blue-1 yr from present; magenta- 2 yrs from present; grey-3 yrs from present).

d) Cumulative dekadal rainfall (solid blue line) and the cumulative long-term average rainfall (solid black line) from user-chosen calendar day in the selected region. The grey plume indicates the range of the 5 th and 95 th cumulative rainfall percentiles.

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Monitoring

Rainfall

This Analysis tool allows users to view different presentations of the the most recent dekad. The default map on This page displays dekadal (approximately 10-day) rainfall amounts over river basins. The default map shows rainfall totals for the most recently available dekad, but totals for previous dekads can be displayed as well. By clicking a location on the map, the user can generate four time series graphs that provide analyses of recent rainfall averaged over a river basin, with respect to that of recent years and the long-term mean.

Rainfall Anomaly

The rainfall Anomaly map displays the difference between the most recent dekadal rainfall and the long-term average (from 1983 to 2014). Positive (negative) values indicate dekadal rainfall that are above (below) the long-term mean or climatology.

Cumulative Rainfall

The cumulative rainfall map displays the accumulated rainfall over a selected period.

Standard Precipitation Index (SPI)

The SPI map displays the standard rainfall index of the most recent dekadal rainfall (using1983-2014 as base period). The SPI (McKee 1993) is the number of standard deviations that observed cumulative rainfall deviates from the climatological average. To compute the index, a long-term time series of rainfall accumulations over dekads are used to estimate an appropriate probability density function. The analyses shown here are based on the Pearson Type III distribution (i.e., 3-parameter gamma) as suggested by Guttman (1999). The associated cumulative probability distribution is then estimated and subsequently transformed to a normal distribution. The result is the SPI, which can be interpreted as a probability using the standard normal distrubtion (i.e., users can expect the SPI be within one standard deviation about 68% of the time, two standard deviations about 95% of the time, etc.) The analyses shown here utilize the FORTRAN code made available by Guttman (1999). Places where the dekadal climatology is less than 2 mm are masked out.

 
                                 SPI Values
                                 Category
                              
                              
                                   
                                 = 2.00
                                 Extremely Wet
                              
                              
                                   
                                 1.50 to 1.99
                                 Severely Wet
                              
                              
                                   
                                 1.00 to 1.49
                                 Moderately Wet
                              
                              
                                   
                                 -0.99 to 0.99
                                 Near Normal
                              
                              
                                   
                                 -1.00 to -1.49
                                   Moderately Dry  
                              
                              
                                   
                                   -1.50 to -1.99  
                                 Severely Dry
                              
                              
                                   
                                 = -2.00
                                 Extremely Dry

Table adapted from McKee et al. (1993)

Dataset Documentation

Reconstructed rainfall over land areas on a 0.1 x 0.1 deg. lat/lon grid from Ethiopia Meteorology Institute. The rainfall times series were created by combining quality-controlled observations from over 600 stations with satellite rainfall estimates.

How to use this interactive map

Helpdesk

Contact zekariasmaru@gmail.com with any technical questions or problems with this Map Room.