Interannual variability of wintertime temperature on the inner continental shelf of the Middle Atlantic Bight

Abstract

The shallow depth of the inner continental shelf allows for rapid adjustment of the ocean to air-sea exchange of heat and momentum compared with offshore locations. Observations during 2001-2013 are used to evaluate the contributions of air-sea heat flux and oceanic advection to interannual variability of inner-shelf temperature in the Middle Atlantic Bight. Wintertime processes are important for interpreting regional interannual variability at nearshore locations since winter anomalies account for 69-77% of the variance of the annual anomalies and are correlated over broad along-shelf scales, from New England to North Carolina. At the Martha's Vineyard Coastal Observatory on the 12 m isobath, a heat budget is used to test the hypothesis that interannual differences in winter temperatures are due solely to air-sea heat flux. Bimonthly averages of air-sea heat flux are correlated with temporal changes in temperature, but overestimate the observed wintertime cooling. Velocity and satellite-derived temperature data show that interannual variability in wintertime surface cooling is partially compensated for by alongshore advection of warmer water from the west at this particular location. It is also shown that surface heat flux is a strong function of air-sea temperature difference. Because of this coupling between ocean and air temperatures in shallow water, along-shelf advection can significantly modify the surface heat flux at seasonal and interannual time scales. While along-shelf advection at relatively small ($100 km) scales can be an important component of the heat budget over the inner shelf, interannual temperature variability is still largely determined by adjustment to large-scale air-temperature anomalies.

Interannual variability of winter‐spring temperature in the Middle Atlantic Bight: Relative contributions of atmospheric and oceanic processes

“…[] discussed the SST over the shelf and slope of the entire Northwest Atlantic. Note the temperature discussed here is for the control volume of the MAB, not a specific location in the MAB, where ocean advection could be important in controlling the temperature variability [e.g., Connolly and Lentz , ; Forsyth et al ., ]. The implications of studying the temperature variability in the control volume instead of focusing on a certain location or a certain layer (e.g., upper mixed layer or bottom layer) is that impacts of climate variability to the ecosystem such as migration of fish stocks are affected by the thermal condition of the entire water column on the shelf, not SST or temperature at one specific location.…”

“…For spring, the seasonal mean temperature varies from 12 to 14.9°C from year to year. In comparison, winter mean SST has larger interannual variability, consistent with earlier studies [ Joyce , ; Connolly and Lentz , ]. Again, the model hindcast compares well with the observations.…”

“…How does the relative importance of ocean advection versus atmospheric forcing change from year to year? The analysis will focus on the winter (January‐February‐March, JFM) and spring (April‐May‐June, AMJ) period, when interannual anomalies are the largest [ Joyce , ; Connolly and Lentz , ]. This is also the seasonal time frame when the extreme warm anomaly in 2012 and the record‐low temperatures in early 2014 occurred.…”

Contrasting Heat Budget Dynamics During Two La Niña Marine Heat Wave Events Along Northwestern Australia

“…In addition to heat advection, local air-sea heat fluxes can also substantially influence ocean heat budgets over a range of temporal and spatial scales (Connolly & Lentz, 2014;Foltz & McPhaden, 2006;Lin et al, 1992;Schiller et al, 2009). For shallow and/or semienclosed water bodies (e.g., coral reefs and shallow enclosed seas), the impact of local surface heat fluxes can be more profound compared to the responses observed in deeper, open ocean waters (Evan et al, 2008;Finnigan et al, 2001;Zhang et al, 2013).…”

Some considerations about coastal ocean observing systems

“…A number of efforts in other science areas have addressed the errors in projecting imagery onto geographic coordinates (Kaufmann et al 2000;Khlopenkov and Trishchenko 2008), and currently available processing algorithms should help eliminate errors masking or georectifying (Yang and Di 2004). However, recent studies of small-scale variability in complex coastal zones have rejected as much as 20% of the publicly available SST data because of erroneous or questionable georectifying (Connolly and Lentz 2014). Thus, the issue is apparently not yet resolved routinely at the scales potentially important to smallscale coastal applications.…”