To determine the role of synoptic forcing on the development and breakdown of stratification and dissolved oxygen (DO) variability via its influence on vertical versus advective processes. |
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| The strength of the vertical stratification (e.g., pycnocline) in the Long Island Sound is an important factor determining the evolution of the amount of dissovled oxygen (DO) in the bottom waters of the Sound, and in turn on the development of hypoxia. Over the course of the winter, the surface waters of the Sound cool considerably due to air-sea exchange processes (see Objective 2) and due to the greater frequency of strong wind events (i.e. storms) that keep the water colum vertically well mixed. Beginning in late spring, with the seasonal increase in solar radiation and the less frequent and weaker storm activity (e.g., left photo above) the surface waters begin to heat up and the column begins to stratify. This stratiifcation continues to strengthen over the course of the summer, leaving the bottom waters isolated from their primary source of oxygen Beginning in the fall, surface wind and cooling from clouds associated with stronger and more frequent weather disturbances begin to erode the stratification away until the column again becomes well mixed in the vertical (see Objective 5) and the bottom water DO becomes replenished. At present, there are still uncertainties regarding the manner that weather events (i.e. synoptic forcing), such as those depicted above, contirbute to both the development and breakdown of vertical stratification. This includes the weather's effects on local air-sea exchange processes as well as on the variations in circulation in the Sound and its horizontal exchange with the Ocean via the Race. The ferry-based marine and atmospheric observations as well as the observations from the Joint Project's profiling instruments will provide valuable information to help the address and reduce the above uncertainties. |
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