This map shows the historical probability (given in percentile) of seasonal average monthly rainfall falling within the upper (wet), middle (normal), or bottom (dry) one-third ("tercile") of the 1983 to present historical distribution in Zambia given the Terciles of IOD (Postive, Neutral, Negative) during that same season.
The IOD is defined as the difference between SST anomalies of a West box average (50E-70E, 10S-10N) and an East box average (90E-110E, 10S-0N). Anomalies are computed for and with respect to the period of rainfall data availability (1983-present). The IOD is categorized in 3 Tercile classes and the positive tercile indicates warmer SST conditions in the West compared to the East.
Clicking on the map will then display, for the selected point, yearly seasonal rainfall averages time series. The colors of the bars depict what IOD Tercile it was that year, and the horizontal lines show the historical terciles limits. This allows to quickly picture what years fell into what IOD Tercile and into what Rainfall Tercile category.
NB: This is not a forecast. It is based just on historical observations of rainfall and SST. However, it would be a good tool for exploring the effect of different IOD Terciles on seasonal rainfall.
Observations
Monthly Rainfall: Reconstructed rainfall over land areas on a 0.0375˚ x 0.0375˚ lat/lon grid from Zambia Meteorological Department. The rainfall time series (1981 to present) were created by combining quality-controlled station observations in ZMD’s archive with satellite rainfall estimates.
Sea Surface Temperature: Extended Reconstructed Sea Surface Temperatures (ERSST), at 2˚ spatial resolution, beginning January 1854 from NOAA NCDC.
Contact info@zmd.gov.zm with any questions about or problems with this Map Room.