Wiggert1, Jerry D.,
Raleigh R. Hood2, K. Banse3, John C. Kindle4,
Julian P. McCreary5, Ragu G. Murtugudde1, Charles R.
McClain6
1ESSIC,
University of Maryland, College Park, MD 20742, Tel: 301-405-4971, Fax:
301-405-8468, E-mail: jwiggert@essic.umd.edu,
2University of Maryland Center for
Environmental Science, Cambridge, MD 21613, 3Dept. of Oceanography,
University of Washington, Seattle, WA 98195, 4Oceanography Division,
Naval Research Laboratory, Stennis Space Center, MS 39529, 5International
Pacific Research Center, University of Hawaii, Honolulu, HI 96822, 6NASA
Goddard Space Flight Center, Code 970.2, Greenbelt, MD 20771
Monsoon-driven
biogeochemical processes in the Arabian Sea
The comprehensive observational data sets of the Arabian Sea obtained during the 1990s by the various JGOFS survey expeditions and automated measurement platforms represent a significant addition to the in situ observational database for this region. In addition, the SeaWiFS ocean color measurements of the last five years have served to both reinforce and revise our CZCS-based view of the region's seasonal to interannual biogeochemical variability. Within the context of the JGOFS-SMP, both the in situ and remotely sensed data have provided a significant impetus to, and are an integral component of, ongoing research employing coupled physical-biogeochemical models that cover the full range of spatial domains (i.e., local to regional to basin scale). These modeling studies have already significantly advanced our understanding of the physical mechanisms behind the complex spatial and temporal biogeochemical variability that characterizes the Arabian Sea.
Although it is in a nominally tropical locale, the semiannual wind reversals associated with the Monsoon result in two distinct periods of elevated biological activity over much of the Arabian Sea. While in both cases monsoonal forcing drives the surface layer nutrient enrichment that supports the increased rates of primary productivity, different entrainment mechanisms are in force for the winter (convective mixing) and summer (vigorous coastal upwelling and Ekman pumping) monsoons. Here we revisit the pre-JGOFS paradigms related to these two monsoon periods, the seasonal cycle and interannual variability, and contrast them with the fresh insights garnered from the recent JGOFS-SMP modeling and data synthesis efforts.