After the eye had passed over the mouth of the Bay (17 September), the flow direction changed to seaward along the entire cross-section in the lower Bay and mainly two-layered circulation in the deep portion of the Bay. The salinity decreased by approximately 3–4 ppt. On the next day (18 September), a landward return flow occurred throughout the entire transect (Fig. 12(a)). Stratification in the deep channel was increased by 3–4 ppt due to a relatively strong saltier water inflow through the bottom layer. Within a week, the non-tidal flow across the cross-section C646 manufacturer appeared to

return to a two-layered circulation pattern, and the vertical salinity structure appeared to be adjusted by the restratification process (not shown). Ipatasertib nmr During Hurricane Isabel, prior to the passage of the strongest wind, the salinity difference between surface and bottom waters in the deep channel was approximately 6–7 ppt, which is 4–5 ppt greater than the

pre-Floyd condition. On 18 September, with the northeasterly wind on the continental shelf, we see that vertically homogeneous saltwater was pumping into the Bay from the ocean (Fig. 12(b)). The mid- and upper Bay portions also have strong components of landward bottom flow. On 19 September, when the hurricane passed by, a strong band of surface landward flow showed in the mid- and upper Bay portions and the previously stratified water became relatively well-mixed. On 20 September, the

very strong seaward flow rebounded, and the Meloxicam stratification in the vertical water column of the Bay started to increase by 2, 1.5, and 5 ppt in the upper, middle, and the lower Bay, respectively (Fig. 12(b)). Within about a week, the net flow appears to return to a two-layered circulation pattern with a 7–8 ppt salinity difference between surface and bottom waters in the channel (not shown). A comparison of the Bay’s response to the two hurricanes features a few highlights: (1) Prior to the storms, there was a significant difference between the observed stratification (ΔS) in the Bay (Table 5). At CB4.4, pre-Floyd stratification was nearly 4 ppt whereas pre-Isabel stratification was nearly 11.5 ppt. (2) In the lower Bay, it is clear that the saltwater intrusion occurred during both hurricanes. (3) Overall, the winds during both hurricanes generated vertical mixing that destratified the water column. Even during the peak of the hurricane events, however, the deep portion of the mid-Bay remained stratified. Following Lerczak et al. (2006), the total salt flux is expressed by: equation(7b) Fs=〈∬usdA〉Fs=∬usdAwhere the angle bracket denotes a 33-h low-pass filter, u is the axial velocity, s is salinity, and the cross-sectional integral within the angle bracket represents the instantaneous salt flux.