FLUORESCENCE OF DISSOLVED ORGANIC-MATTER - A COMPARISON OF NORTH PACIFIC AND NORTH-ATLANTIC OCEANS DURING APRIL 1991

Profiles of airborne-laser-induced fluorescence emission from dissolve d organic matter in the upper ocean have been produced and compared fo r the Southern California Bight (SCB) and the Mid-Atlantic Bight (MAB) . Findings were as follows. (1) The fluorescent components of dissolve d organic matter (FDOM) are present in easily measurable quantities fr om near shore to well over 300 km offshore in the SCB and are likewise easily measurable in the coastal, shelf, slope, and Gulf Stream water s of the MAB. (2) The range of FDOM in the MAB is considerably greater than that in the SCB. (3) The lowest FDOM levels observed in the SCB were higher than those found in the Gulf Stream. (4) The onshore-to-of fshore spatial gradient of the FDOM was found to be considerably lower in the SCB than in the MAB, with the highest levels of FDOM being fou nd immediately adjacent to the coast in the MAB. This suggests that th e water adjacent to the SCB shoreline is not as strongly influenced by terrestrial and estuarine sources of FDOM as the MAB is. (5) The spat ial distribution of the FDOM within both the SCB and the MAB is freque ntly coherent with the spatial distribution of chlorophyll determined from the concurrent airborne-laser-induced phytoplankton pigment fluor escence measurements. However, distinct noncoherency is sometimes obse rved, especially at water mass boundaries.