Comparative analysis of chlorophyll variability in the north Pacific
The climate regime of the North Pacific is known to have changed during the past 30 years. The changes are manifest in the spatial pattern of atmospheric pressure systems over the North Pacific and have affected the winds and the tracks of storms across the North Pacific. The new climate pattern has brought different conditions in the various ecosystems in the North Pacific. Added to this variability is the influence of the strong La Niña of 1998-1999 and moderate El Niño of 2002. What will be the consequences of such change in the marine ecosystems? PICES (North Pacific Marine Science Organization) has been making efforts in conjunction with the Census of Marine Life to document the ecosystem changes from physics and lower trophic level up to top predator level among the ten ecosystems in the North Pacific. The ten ecosystems are located north to 30˚ N and include the followings: 1) Yellow Sea-East China Sea, 2) JES, 3) Kuroshio/Oyashio region, 4) Okhotsk Sea, 5) West Subarctic Pacific region, 6) Bering Sea, 7) Gulf of Alaska, 8) California Current region, 9) Baja California, and 10) Transitional Zone. This endeavor, called NPESR (North Pacific Ecosystem Status Report), is an on-going project. As a part of NPESR efforts, inter-annual variation of chlorophyll in the ten ecosystems in the North Pacific is being analyzed using Level-3 8-day time series of SeaWiFS in 1998-2003. In all the ten ecosystems, seasonal cycles were evident although the amplitude of the cycles was quite variable. Here, year-to-year variability in the seasonal cycles in the ten ecosystems is analyzed.