Helmholtz-Zentrum Geesthacht, Institute of Coastal Research, Max-Planck-Str.1, Geesthacht, 21502, Germany
Abstract. Arabian Sea upwelling in the past has been generally studied based on the sediment records. We apply two earth system models and analyse the simulated water vertical velocity to investigate the variations of the coastal upwelling in the western Arabian Sea over the last millennium. In addition, the same models, with slightly different configurations, are also employed to study the changes in upwelling in the 21st century under the strongest and the weakest greenhouse gas emission scenarios. With a negative long-term trend caused by the orbital forcing of the models, the upwelling over the last millennium is found to be closely correlated with the sea surface temperature, the Indian summer Monsoon and sediment records. The future upwelling under the Representative Concentration Pathway (RCP) 8.5 scenario reveals a negative trend, in contrast with the positive trend displayed by the upwelling favourable along-shore winds. Therefore, it is likely that other factors, like water stratification in the upper ocean layers caused by the stronger surface warming overrides the effect from the upwelling favourable wind. No significant trend is found for the upwelling under the RCP2.6 scenario, which is likely due to a compensation between the opposing effects of the increase in upwelling favourable winds and the stratification of the water column.
How to cite. Yi, X. and Zorita, E.: Arabian Sea upwelling over the last millennium and in the 21st century as simulated by Earth System Models, Clim. Past Discuss. [preprint], https://doi.org/10.5194/cp-2016-124, 2016.
Received: 23 Nov 2016 – Discussion started: 07 Dec 2016
In this paper we study the upwelling in the Arabian Sea simulated in two Earth System Models for the last millennium and for the 21st century. Revealing a negative long-term trend due to the model orbital forcing, the upwelling over the last millennium is strongly correlated with the SST, the Indian summer Monsoon and the G.bulloides abundance observed in the sediment records. In the future scenarios the warming of the sea water tends to stabilize the surface layer and hinder the upwelling.
In this paper we study the upwelling in the Arabian Sea simulated in two Earth System Models for...