SIBER SPIS sept 2011.pdf - IMBER

More documents

Recommendations

Info

SIBER Science Plan and Implementation Strategy Scientific ba c k g r o u n d Some fundamental scientific issues of relevance to SIBER are outlined in this section to set the scene for the program. Oc e a n c u r r e n t s a n d b i o g e o c h e m i c a l v a r i a b i l i t y The physical dynamics of the IO arise largely as a result of the seasonal cooling and warming of the Eurasian land mass to the north, which, among other things, gives rise to the strong semiannually reversing monsoon winds (Fig. 2, upper panels). These drive intense upwelling and downwelling circulations and seasonally reversing surface currents (see review by Schott and McCreary, 2001) that cause substantial variations in marine biogeochemical and ecosystem response (Lévy et al., 2007; Naqvi et al., 2006b). In the case of the Somali Current in the western AS, the reversal is equivalent to a seasonally reversing Gulf Stream in the Atlantic. Unusual current patterns, such as the poleward flowing eastern boundary current of western Australia (Leeuwin Current), also generate atypical biological signatures such as warm core rings with enhanced productivity (Waite et al., 2007). How do coastal and pelagic species respond across the IO basin to such dramatic changes in the physical regime Does the semi-annual timescale associated with its current reversals promote greater distinctiveness between the biomes of the northern IO and the southern IO relative to other basins Do these current reversals contribute to the differences between the BoB and AS In general, we need to better characterize and understand the ecological and biogeochemical responses to the complex IO physical forcing (Fig. 2) and how these in turn will be impacted by climate change. Many questions remain about primary production variability and dynamics in the IO (Resplandy et al., 2009; Wiggert et al., 2009). Some of these questions relate to the equatorial waters where the zonal thermocline and nutricline shoal toward the west rather than the east as in the Pacific and Atlantic Oceans. The equatorial IO is also strongly influenced by oscillations and perturbations that do not occur in other oceans, such as the Wyrtki Jets, the Madden-Julian Oscillation, and the Indian Ocean Dipole (McPhaden et al., 2009; Schott and McCreary, 2001). The state of understanding in the IO is in marked contrast to the Atlantic and Pacific, where the biogeochemical and ecological dynamics of the boundary currents and equatorial circulations have been intensively investigated and described, along with the impacts of inter-annual influences such as the North Atlantic Oscillation (NAO) and the El Niño-Southern Oscillation (ENSO). Although the Indian Ocean Dipole (IOD) is similar to La Niña in the Pacific, we still have a poor understanding of how climate oscillations impact the biogeochemistry and ecology of the upper ocean in the IO. Are IO ecosystems uniquely suited to this particularly dynamic and fluctuating environment Furthermore, unlike the Atlantic and Pacific, large volumes of water (some 10 million m3/s) flow into the IO at low latitudes from the Pacific through the ITF (McCreary et al., 2007). This inflow must impact nutrient concentrations in the IO and it must transport tropical plankton and even juvenile fish, but the magnitude and extent of this connectivity and its impacts are unknown. 8
SIBER Science Plan and Implementation Strategy NE Monsoon SW Monsoon 20°N 0 20°S 40°E 80°E 120°E 40°E 80°E 120°E 20°N 0 20°S 40°S 40°E 80°E 120°E 40°E 80°E 120°E 20°N 0 20°S 40°E 80°E 120°E 40°E 80°E 120°E Chl a (mg/m 3 ) 0.00 0.15 0.30 0.45 0.60 0.75 1.00 1.50 3.50 Fi g u r e 2 Comparison of winds (top), surface ocean circulation (center), and satellite-derived chlorophyll concentration (bottom) between the January-February (left column) and July-August (right column) periods in the IO. The wind and circulation fields reproduced with permission from Schott and McCreary (2001), and the satellite chlorophyll concentrations with permission from Wiggert et al. (2006). 9
Page 2 and 3: Additional copies of this document
Page 4 and 5: SIBER Science Plan and Implementati
Page 66 and 67:
SIBER Science Plan and Implementati
Page 68 and 69:
Page 70 and 71:
Page 72 and 73:
Page 74 and 75:
Page 76 and 77:
Page 78 and 79:
Page 80 and 81:
Page 82 and 83:
Page 84 and 85:
Page 86 and 87:
Page 88 and 89:
Page 90 and 91:
Page 92 and 93:
Page 94 and 95:
Page 96 and 97:
Page 98 and 99:
Page 100 and 101:
Page 102 and 103:
Page 104 and 105:
Page 106 and 107:
Page 108 and 109:
Page 110 and 111:
Page 112 and 113:
Page 114 and 115:
Page 116 and 117:
Page 118 and 119:
show all

SIBER SPIS sept 2011.pdf - IMBER

Create successful ePaper yourself

Delete template?

Save as template?