Summary of Abstract Submission

Abstract Submission No. IO50-09-0005PresentationKeynote


Sharon L. Smith*1, Y.V.B. Sarma2, Dora Pilz1

1 University of Miami, USA
2 King Abdullah University of Science and Technology, Saudi Arabia


The cycle of events that leads to the SW Monsoon in the Arabian Sea depends in part upon the thickness of snow and ice on the Tibetan Plateau. If the ice layer is thick, solar energy in the spring primarily melts the ice. If the ice layer is thin, solar energy also heats exposed land surfaces creating a stronger high pressure over the Tibetan Plateau, a greater contrast between that high pressure and the low pressure over the northern Indian Ocean, and a stronger Findlater Jet and SW Monsoon. It has been shown that the ice cover on the Tibetan Plateau is decreasing, leading to the suggestion that the SW Monsoon will become stronger in coming years and may also begin earlier in spring and extend longer into autumn. We have investigated the ocean┐s planktonic ecosystem during late April through early June, the transition between the Spring Intermonsoon and the SW Monsoon, in order to characterize its present state, and we have begun studies of the SW Monsoon die-off in September and October. Predicted changes associated with general planetary warming should occur primarily in these time periods (strength and timing of the SW Monsoon). We have identified the most abundant large-bodied copepods of the SW Monsoon onset (Subeucalanus pileatus, Subeucalanus subcrassus) and they are unchanged by the passage of cyclones (Gonu in 2007; Phet in 2010). However, they were diminished greatly during a massive harmful algal bloom (Cochlodinium polykrikoides) in 2009. During the SW Monsoon die-off, S. pileatus remains abundant, S. subcrassus is replaced by Subeucalanus subtenuis, and the ontogentically migrating Calanoides carinatus s.l. and Subeucalanus crassus appear, presumably as holdovers from the height of the SW Monsoon (July) that we are unable to sample. The life cycles of the ontogenetically migrating, large-bodied copepods are tuned to the upwelling of the SW Monsoon and therefore may be disrupted by changes in the timing of the SW Monsoon. Understanding the present condition of the ecosystem will allow evaluation of change in response to global warming.