Spatially Average Over
Observations for

a)
b)
c)
d)

a) Dekadal (i.e., ~10-daily) precipitation estimates for the selected region from Dec 1999 to the present.

b) Same as (a) (solid black line) with the addition of the recent short-term average precipitation for the same region (grey dotted line). The blue (red) bars are indicative of estimates that are above (below) the short-term average. Note that the short-term average precipitation data has been smoothed.

c) Same as (a) for the current year (thick black line), as indicated by the axis labels. Precipitation estimates from previous years are also shown (blue-1 yr from present; magenta- 2 yrs from present; grey-3 yrs from present).

d) Cumulative dekadal satellite-derived precipitation estimates (solid black line) and the cumulative recent short-term average precipitation (grey dotted line) for the most recent 12-month period in the selected region. The blue (red) bars are indicative of estimates that are above (below) the short-term average.

NOTE: The recent short-term average (from 2000 to the latest complete year) of precipitation should not be interpreted as a climatological normal, which is typically based on a long-term (e.g., 30-year) time series. The length of this short-term average will increase over time as more data becomes available. (An additional year of data will be included in the average during January of each year.) Despite the limitations that the short-term average imposes, it may provide insight into changes in malaria risk in areas where precipitation anomalies are the principal cause of malaria epidemics by providing a recent historical reference.

Malaria Early Warning System

MEWS is a rainfall-monitoring product based on dekadal precipitation estimates from the Climate Prediction Center. The interface allows users to view recent rainfall estimates with a seasonal and recent historical perspective. Time series analyses of rainfall data are generated based on user-selected parameters.

Rainfall is largely responsible for creating the conditions which allow sufficient surface water for mosquito breeding sites and is, therefore, recognized as one of the major factors influencing malaria transmission in warm semi-arid and desert- fringe areas. Explosive epidemics often occur in these regions after excessive rains and, where these follow periods of drought and poor food security, can be especially severe.

Consequently, rainfall monitoring forms one of the essential elements for the development of integrated Malaria Early Warning Systems (MEWS) for sub-Saharan Africa, as outlined by the World Health Organization.

The map on this page displays dekadal (approximately 10-day) estimated precipitation amounts over Africa. The default map shows precipitation totals for the most recently available dekad, but totals for previous dekads can be displayed as well. By clicking on a location on the map the user can generate four time series graphs that provide analyses of recent rainfall averaged over an administrative district or box of a selected size, with respect to that of recent seasons and the short-term multiple-year average. These analyses of recent precipitation placed in historical context are intended to provide useful epidemic early warning information for epidemic-prone regions.

References

Grover-Kopec E., Kawano M., Klaver R. W., Blumenthal B., Ceccato P., Connor S. J. An online operational rainfall-monitoring resource for epidemic malaria early warning systems in Africa. Malaria Journal, 2005, 4:6.

Dataset Documentation

Precipitation Estimates

Data
Dekadal precipitation estimates over land areas on a 0.1° x 0.1° lat/lon grid
Data Source
Climate Prediction Center/Famine Early Warning System (CPC/FEWS RFE2.0)*

Epidemiological Mask

Mask
illustrating areas where malaria is considered to be epidemic. Areas where malaria transmission is considered absent or endemic are therefore excluded. This mask is based purely on climatic constraints to malaria transmission, and does not yet account for areas in the northern and southern margins of the continent where control has eliminated malaria risk.
Reference
WHO: Final report on the 3rd meeting of the RBM Technical Resource Network on Epidemic Prevention and Control. Geneva: World Health Organization; 2002.

*More dekadal and daily data from FEWS is available from the Africa Data Dissemination Service.

Dataset

Access the dataset used to create this map.

Helpdesks

Contact help@iri.columbia.edu with any technical questions or problems with this Map Room, for example, the forecasts not displaying or updating properly.