Maureen H. Taylor

Spatial coherence of interannual variability in water properties on the U.S. northeast shelf

Interannual variability in the surface and bottom temperature and salinity on the U.S. northeast shelf is described by using hydrographic data from the Northeast Fisheries Science Center (NEFSC) MARMAP program. This 10 year data set provides the spatial resolution to describe spatial patterns in the variability of the shelf water properties. An empirical orthogonal function analysis is used to determine the primary modes of variability. All parameters investigated have significant first modes, which contain 40–50% of the variance in the winter and 25–35% in the summer period. All parameters, except the summer surface temperature, exhibit coherent variability across the entire shelf region from near Cape Hatteras to the central Gulf of Maine. The summer surface temperature appears to have two regions of coherent variability: in the central Middle Atlantic Bight and in the western Gulf of Maine. This regionalization is believed due to the effect of local sources of coastal runoff.

Fluorescence structure in the region of the tidal mixing front on the southern flank of Georges Bank

Abstract Transects of fluorescence measurements were made across the region of the tidal-mixing front on the southern flank of Georges Bank in 1992, 1993 and 1994. The fluorescence distribution exhibited three characteristic patterns: (i) a subsurface maximum associated with the pycnocline in stratified water columns; (ii) a spatially incoherent variability with a characteristic spectral slope, believed to be related to the local vertical mixing processes; and (iii) a higher level of fluorescence within the front on some transects. This latter pattern was observed when the tidal current amplitude had recently increased with the local fortnightly/monthly variability.

The role of local wintertime atmospheric heat flux in determining springtime temperature variability in the northern Middle Atlantic Bight during 1965–1973

Abstract This project examines the role of local atmospheric forcing during the transition from relatively cold wintertime to relatively warmer springtime temperatures in the northern Middle Atlantic Bight (MAB) region during 1965–1973. A one-dimensional water column model is run for eight consecutive winter seasons with local surface heat flux used as the only external forcing. Historical data from the Nantucket Light Ship, along with modeled radiation estimates for New York and Boston are used for the heat flux calculations. Two model simulations were made for each winter season, allowing for both a qualitative and quantitative comparison of model output with observed regional temperature variability and with observed temperature changes measured at Nantucket Lightship (NLS). Interannual variability (IAV) in local atmospheric heat flux during wintertime is shown to be a dominant factor in determining springtime temperature conditions during the study period. However, the residuals from a regression analysis suggest that advective processes may have contributed to the observed temperature variability, although it is believed that the advective influence is secondary to local surface heat flux in the northern MAB for this study period.