We examined 21 Coastal Zone Color Scanner (CZCS) images of the southeastern Bering Sea to map the near-surface distribution of phytoplankton during 1979 and 1980 and compared this information with the mesoscale (100-1000 km) distribution of phytoplankton inferred from ship sampling. Pigment patches coherent over length scales of about 1000 km along isobaths were detected in the satellite data. The patches straddled boundaries of hydrographic domains that were previously defined from the ship observations. Smaller patches (order of 100 km diameter and less) were common. The imagery indicated that open-water phytoplankton blooms occur first in late April in coastal waters, peak in early May over the middle shelf, and decay rapidly afterwards, reaching concentration minima in June in both regions. These patterns show that earlier ship observations are valid for most of the eastern Bering shelf. Images from August and September 1979 revealed the occurrence of fall blooms, previously unrecorded in this area perhaps because of scarce ship observations after summer. Interannual variation in the distribution of biomass was evident, with April-May 1979 showing less pigment near the surface than April-May 1980. These changes were in part related to aliased sampling by the CZCS.

Also, the wind was downwelling favorable in late April 1979 but upwelling favorable during late April 1980. CZCS values underestimated the ship data by a factor of at least 2 during spring 1979. During spring of 1980 the CZCS and ship-based data were similar. The apparent errors remain unexplained, but it appears that in particular time aliasing of the evolution of the blooms by the CZCS leads to serious problems in comparisons with ship time series. It also seems that region-specific pigment algorithms are required for proper quantitative interpretation of remote sensing data from the Bering Sea. ¿ American Geophysical Union 1990