Observations of Autumnal Cooling in a Large Estuary: The Glider Data from Long Island Sound in 2014

This data file is a component of the data used in a paper to appear in the Journal of Geophysical Research in 2023 entitled "Observations of Autumnal Cooling in a Large Estuary" by Amin Ilia, Grant McCardell, Kay Howard-Strobel, and James O'Donnell.  The data file contains the measurements from a Slocum Glider (V1) from Webb Research used in the paper. The data is in a MATLAB binary (.mat) file as a structure variable with a field MetaData containing some notes, and data in 
    SampleTimeEST- the date and time of the sample (EST) in MATLAB's datenum() format
    Pressure_dBar - the pressure (or equivalently depth in m) that the sample was acquired 
    Temperature_C - the water temperature in Celcius
    PracticalSalinty - the practical salinty
    LatitudeDeg- the latitude of the sampling location (deg)
    LongitudeDeg - the longitude of the sampling location (deg east)

The paper's abstract is: 

Long Island Sound (LIS) is a large estuary on the eastern United States coast. Seasonal variations 
in solar insolation and wind create an annual water temperature cycle that impacts circulation 
and biological processes. The waters warm from March-February until August-October and then 
begins to cool. Ship surveys show that the vertical temperature structure becomes uniform during 
this season when the area experiences low air temperatures and high winds. However, there have 
been no observations that resolve the temporal evolution of the vertical structure of temperature 
during these cooling periods because conditions inhibit ship operations. We report glider 
measurements of the vertical structure of water temperatures and salinities from October 22 to 
November 4, 2014, in eastern LIS. We find that 20m of water can cool at approximately 0.5 
C/day intervals of cold air and strong winds. We use the data to estimate heat content tendencies 
and infer surface fluxes. We also estimate the surface heat fluxes using buoy-mounted 
instruments and the COARE 3.0/3.5 formulae and show they are consistent. Using the buoy 
fluxes and the products of an operation regional model, we show the agreement with the heat 
budget fluxes is best when the closest buoy and the model results are used. This suggests that 
resolving the temporally and spatially structure of the wind field is crucial to the accurate 
simulation of the temperature variability in LIS. These intervals of very rapid cooling can lead to 
significant density gradients between LIS and the shallow bays and marshes that surround it.