Trends in physical properties at the southern New England shelf break

Author Posting. © American Geophysical Union, 2020. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 125(2), (2020): e2019JC015784, doi:10.1029/2019JC015784.We analyze 11 years (2003–2013) of repeat temperature and salinity sections from across the New England shelf break south of Cape Cod during early summer (June–July). The mean sections resolved the shelf break front which supports the Shelf Break Jet, a vital component of the regional circulation. Individual sections showed a great deal of variability associated with meanders in the shelf break front consistent with previous studies in the region. Over the 11 year record, the shelf region (inshore of the 100 m isobath) warmed by 0.26 °C yr -1, with the majority of this warming occurring shallower than 20 m (0.58 °C yr -1). The full‐depth trend agrees well with previous studies of shelf warming to the north and the south of our study region. The temperature and salinity of the offshore edge of the Cold Pool Water on the shelf did not change significantly during this period. The surface warming on the shelf resulted in a decrease in near‐surface density of 0.12 kg m -3 yr -1 and an increase in stratification between 10 and 15 m of 6.7 X 10(-5) S -2 yr -1 . Offshore of the shelf break, the Slope Water also warmed and became more saline by 0.21 °C yr -1 and 0.04 yr -1 respectively, resulting in a maximal reduction in density of 0.01 kg m -3 yr -1. In the Shelf Break Front, there is some evidence of freshening and a reduction in density, which may have resulted from an offshore shift in the Cold Pool but the statistical significance is small.We wish to thank the Sea Education Association and the Woods Hole Oceanographic Institution for maintaining this collaboration. We also extend our warmest thanks to the numerous chief scientists, crew members, and student participants who collected the data and made this work possible. This work was supported by NSF Grants OCE‐1657853 and OCE‐1851261. G. G. was also supported by a Senior Scientist Chair from the Woods Hole Oceanographic Institution. The Jake Peirson Summer Cruises were supported using funds provided by a WHOI‐MIT Joint Program alumnus and by the WHOI Academic Programs Office. M. I. was supported by The Woods Hole Partnership Education Program, the Sea Education Association, and the Woods Hole Oceanographic Institution for her summer research work. We thank Jacob Forsyth for discussions on the seasonal variability of warming over the New Jersey shelf and warming rates for different time frames. Data used in this paper are available from the WHOI‐MBL Library (https://darchive.mblwhoilibrary.org/handle/1912/25158, doi:10.26025/dz4w‐kk13)