C-ICE - Counteracting effect of future antarctic sea-ice loss on projected increases of summer Monsoon rainfall

Project Department: Uni Research Climate period: 01.05.16 - 31.03.19

About the project

South-Asian society and economy are heavily dependent on the seasonal rainfall during the Indian Summer Monsoon (ISM). This rainfall has large spatio-temporal variability, the main pattern of which is expressed in an alternation of “break” and “active” phases. Break phases imply dry conditions over India’s main agricultural areas. When sufficiently prolonged or repeated in the course of the season, they are associated with droughts. Food production is highly sensitive to both dry and wet rainfall extremes. Under anthropogenic climate change, model-derived projections generally predict an increase in seasonal-mean rainfall totals along with a reduction in the number of rainy days. However, the associated spatio-temporal patterns of change in mean rainfall are very uncertain.

The transition between break and active phases of the ISM corresponds with a large meridional excursion of the precipitation maximum,  reflecting a tendency for rainfall to occur over preferred geographical loci: one over the Gulf of Bengal and the Indo-Gangetic plains; and one over the Equatorial Indian Ocean. These map onto oscillations of the zonal-mean Inter-Tropical Convergence Zone, suggesting a link with the global circulation. As a result, the position and intensity of the ITCZ is sensitive to changes in extratropical heat sources. Antarctic sea-ice loss will result in an additional heat source in the SH of about 0.3 PW in austral winter.

Hence, we will investigate whether a substantial ISM rainfall response may be induced by large-scale interhemispheric heating anomalies. The focus will be on future Antarctic sea-ice loss, the associated heat-flux changes, and their impact on the global atmospheric circulation. Throughout the project, a strong emphasis will be placed on collaborative research and in particular on both formal and research training with the Indian partners.

cp: 2019-08-25 21:17:51