New research – summer rains in the mid-latitudes

The study has found that the influence of climate change and the depletion in stratospheric ozone are the major drivers over the Atlantic Oceans that shift the westerly winds further south. However, over the Pacific and Indian oceans, natural variations induced by sea surface temperature changes in the tropical Pacific also play an important role in the southward shift and can intensify these winds in the southwest Pacific Ocean.

A major component of this natural variation is the Interdecadal Pacific Oscillation (IPO). This is a shift in the state of sea surface temperatures, air pressure and wind direction over decadal timescales. The study found that the state of the IPO in the early-21st Century led to warming in the subtropics and mid-latitudes, which increased the generation of transient eddies at around 55°S, acting to strengthen and shift the winds south. Changes in the Southern Hemisphere westerly winds have profound impacts on Southern Hemisphere rainfall patterns, the Southern Ocean and Antarctica. Understanding the mechanisms that create these wind shifts has significant implications for prediction of Southern Hemisphere climate over the coming decades.

Paper: Yang, D., Arblaster, J. M., Meehl, G. A., England, M. H., Lim, E. P., Bates, S., & Rosenbloom, N. (2020). Role of tropical variability in driving decadal shifts in the Southern Hemisphere summertime eddy-driven jet. Journal of Climate, (2020). https://doi.org/10.1175/JCLI-D-19-0604.1

New research – choosing sorghum varieties based on seasonal forecast: does it pay?→

The value of targeted crop design depends on the diversity of traits among commercial hybrids and the availability of a skilful seasonal climate forecast to allow farmers to match hybrids and management to prevailing and expected seasonal conditions.

Agronomic management treatments included plant density, row configuration, level of irrigation and fertiliser inputs, and time of sowing. Six hybrids contrasting in maturity and tillering type were characterised relative to the industry standard MR-Buster in terms of yield potential, yield stability (bi), and an expected utility index that combines both indices. A medium-late maturity and high tillering hybrid (MR-Scorpio), had the highest utility rank and showed high bi values due to high tiller productivity. A variety of significant row spacing and configuration, and plant density effects on yield were observed, but these were inconsistent across sites and seasons. A long-term simulation experiment across contrasting environments was used to identify hybrid traits and managements capable of modifying yield stability.

 This is an open-access journal. Click on the image to be directed to the link!