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On-going Projects

Shelf-Ocean Interactions in the Northwest Atlantic

Collaborators:
Jiayan Yang (WHOI)

This project aims to advance the understanding of shelf-ocean interactions in both Northwest Pacific and Northwest Atlantic. Both regions are subject to the influence of major western boundary currents—Gulf Stream and Kuroshio, and are experiencing some of the most rapid changes including accelerated warming and sea level rise. Meanwhile, different dynamical processes might be controlling the regional circulation. We will develop a better understanding of the similarities and differences between the two systems.

Past Projects

Interannual Variability of Winter-Spring Temperature in the Middle Atlantic Bight: Linkages to Large-Scale Atmospheric and Oceanic Changes

Collaborators:
Glen Gawarkiewicz (WHOI), Young-Oh Kwon (WHOI)

Recent studies indicate that Arctic warming (often called Arctic Amplification) increases the north–south amplitude of the polar jet stream and reduces its wind speed, resulting in slower-moving weather systems in mid-latitude regions and a higher probability of extreme events, such as cold spells/heat waves and flooding/drought. An intriguing question is how changes in the large-scale atmospheric/oceanic circulation impact the coastal ocean off the northeastern U.S. A recent study by the PIs identified a direct link between the atmospheric jet stream variability and ocean temperature anomalies on the shelf in the Middle Atlantic Bight during the unusually warm winter of 2011-2012. The proposed research would extend this case study from one winter to a longer period with multiple extreme warm/cold winter-springs to address the following scientific questions. What is the response of the coastal ocean in the northeastern U.S. to such extreme year-to-year variability of the climate system? To what extent is the interannual variability of temperature in the MAB, especially the extreme warm/cold events, due to the large-scale atmospheric forcing, e.g., jet stream variability? What are the relative contributions from oceanic processes versus atmospheric processes?

SST anomaly in March 2012 referenced to the March average SST for 2000-2010. White contours indicate standard deviations. Locations of National Data Buoy Center buoys (diamonds) and the Oleander line (grey dashed line) are shown. Square boxes (~0.25°) demonstrate the location of World Ocean Atlas profiles, which are used to estimate the relationship between SST and depth-averaged temperature for nearby. The 50 m, 100 m, 200 m and 1000 m isobaths (from ETOPO-1) are also shown. The thin black line is the smoothed 200 m isobath that is used to define along- and cross-shelf directions.

SST anomaly in March 2012 referenced to the March average SST for 2000-2010. White contours indicate standard deviations.

SST anomaly in March 2012 referenced to the March average SST for 2000-2010. White contours indicate standard deviations. Locations of National Data Buoy Center buoys (diamonds) and the Oleander line (grey dashed line) are shown. Square boxes (~0.25°) demonstrate the location of World Ocean Atlas profiles, which are used to estimate the relationship between SST and depth-averaged temperature for nearby. The 50 m, 100 m, 200 m and 1000 m isobaths (from ETOPO-1) are also shown. The thin black line is the smoothed 200 m isobath that is used to define along- and cross-shelf directions.
SST (left column, panel a-d) during late 2011 and 2012 (red) compared to the 2000- 2010 mean (blue) and standard deviation (shaded). SST anomalies (right Column, panel e-h) with respect to 2000-2010 means at the same four buoys.

SST (left column, panel a-d) during late 2011 and 2012 (red) compared to the 2000- 2010 mean (blue) and standard deviation (shaded). SST anomalies (right Column, panel e-h) with respect to 2000-2010 means at four NDBC buoys.

SST (left column, panel a-d) during late 2011 and 2012 (red) compared to the 2000- 2010 mean (blue) and standard deviation (shaded). SST anomalies (right Column, panel e-h) with respect to 2000-2010 means at the same four buoys.
Winter (a) and spring (b) temperature budget terms for each year. The seasonal mean temperature, initial temperature, mean cumulative air-sea and ocean advective flux are shown in black, gray, blue, and red. Corresponding root-mean-square (rms) and correlation (r) values are also shown.

Winter (a) and spring (b) temperature budget terms for each year. The seasonal mean temperature, initial temperature, mean cumulative air-sea and ocean advective flux are shown in black, gray, blue, and red.

Winter (a) and spring (b) temperature budget terms for each year. The seasonal mean temperature, initial temperature, mean cumulative air-sea and ocean advective flux are shown in black, gray, blue, and red. Corresponding root-mean-square (rms) and correlation (r) values are also shown.

Physical and Biological Exchange Processes and Lagrangian Pathways in the Northwestern Atlantic

Collaborators:
Irina Rypina (WHOI), Larry Pratt (WHOI), Joel Llopiz (WHOI)

Water mass exchanges between shelf and slope waters and the deeper ocean offshore are important for understanding the distribution of temperature, salinity and other physical, chemical, and biological water properties in the ocean. Despite their importance and the extensive number of previous studies, these exchange processes are not well understood. This is due to their small temporal and spatial scales, and the resulting challenging nature of observing them in situ or capturing them in numerical models. The proposed comprehensive study will make use of state-of-the-art realistic ocean circulation models in combination with novel dynamical system tools to better understand and quantify these exchanges. Improved understanding based on the proposed work has important implications for the larval dispersal of economically important fishery species such as American eel.

A schematic of the mean transports (in Sv) in the MAB and GoM. The mean transports (blue arrows) and SDs (in parentheses) across transects are shown. The 200 m isobath (black line) is divided into seven segments from North Carolina to Nova Scotia. Transports across this isobath were used to assess water exchange between the coastal region and the Slope Sea.

Statistical Forecasting System for Oceanographic Conditions and Living Marine Resources in the Northeast U.S. Shelf Ecosystem

Collaborators:
Young-Oh Kwon (WHOI), Glen Gawarkiewicz (WHOI), Terry Joyce (WHOI), Janet Nye (Stony Brook), Paula Fratantoni (NMFS), Jon Hare (NMFS), Vincent Saba (NMFS), Tim Miller (NMFS)

This project seeks to develop a prediction system for the Northeast U.S. shelf over seasonal to interannual time scales. Statistical analysis will be combined with dynamical understanding to identify robust processes important for prediction.

Physical-Biological Processes of Gulf Stream Warm Core Rings

Collaborators:
Peter Gaube (APL-UW)

Warm core rings, generated between western boundary currents and the continental shelf exert significant impact on the physical and biological environments of the slope seas and coastal oceans, which are major contributors to the global primary production. However, compared to that of eddies in the open ocean, the role of Gulf Stream (GS) warm core rings (WCRs) in the biophysical processes of the shelf-slope system has received less attention, and contrasting results exist. In this project, we will elucidate the key biophysical mechanisms by investigating the biomass characteristics and the dominant physical mechanisms controlling the vertical nutrient delivery associated with GS WCRs. Better understanding of physical mechanism of eddies for the nutrient delivery and biomass in the ocean is fundamentally important for the biogeochemical cycling and ecosystem dynamics.

Sea Surface Temperature (SST) showing Gulf Stream meanders and WCRs on May-05-2006 (a) and in the last five years on Jun-02-2011 (b), Mar-23-2012 (c), May-31-2013 (d), Jun-08-2014 (e), and Jun-11-2015 (f). Open circles in black dashed lines denote the approximate locations of WCRs.