Probability of Seasonal Temperature Conditioned on IOD

This map explores the historical probability of seasonal average monthly temperature given the Terciles of IOD.

This map shows the historical probability (given in percentile) of seasonal average monthly temperature falling within the upper (hot), middle (normal), or bottom (cold) one-third ("tercile") of the 1961-2020 historical distribution in Lesotho 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 temperature data availability (1983-2020). 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 temperature 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 Temperature Tercile category.

While the IOD is often referred to as a distinct feature of climate variability, a similar pattern of sea surface temperature variations on the Indian Ocean often occurs as a response to ENSO in the Pacific Ocean. That is, the two phenomena are often related. As a result, one should expect similar impacts of El Niño (La Niña) phase and Positive (Negative) IOD to climate in Eastern and Southern Africa. Therefore, this Maproom doesn't exhibit an independent feature that comes on top of the information that is displayed by the ENSO Maprooms, but rather complementary information that can help intricate the delicate cases when ENSO and IOD could be out of sync at some critical seasons.

NB: This is not a forecast. It is based just on historical observations of temperature and SST. However, it would be a good tool for exploring the effect of different IOD Terciles on seasonal temperatures.

Dataset Documentation

Reconstructed temperature data over land areas on a 0.0375˚ x 0.0375˚ lat/lon grid (about 4 km of resolution). Minimum and maximum temperature time series (1961 to 2020) were generated by combining quality-controlled station observations with downscaled reanalysis product.

How to use this interactive map

Helpdesk

Contact help@iri.columbia.edu with any questions about or problems with this Map Room.