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C. E. Knowles

Abstract

Spectral parameters calculated from wind-wave measurements in a finite-depth restricted-fetch estuary are compared with similar deep-water parameters. The equilibrium range of these finite-depth spectral data seems to be fitted more satisfactorily by the −3 slope predicted for constant depth by Kitaigorodskii et al. (1975) and measured for shoaling waves by Thornton (1977). Non-dimensional effective-fetch x˜e appears to be the parameter of choice for use in displaying other scaled spectral data (like wave energy ε and peak frequency ν) because it reconciles differences in ε and ν data for short (5–7 km) and long (20–42 km) fetches without having to alter the ε and ν data, but the results also suggest that using fetch as a scaling parameter may not be satisfactory. Finite-depth effects were clearly shown in the ε-x˜e data (the slope of the power-law relation was significantly larger than for deep-water relations) and in the ν-x˜e data [the slope was between the relations of Phillips (1977), Ross (1978) and Liu and Ross (1980), but well above these power-law lines]. There was remarkable agreement between this study's finite-depth ε-ν equilibrium data and the relations of Ross (1978) and Liu and Ross (1980) when kph was 0(1) or greater, with the largest departure when kph≤0.7 (where kp is the wavenumber associated with the spectral peak). In addition to the expected restriction to wave growth by bottom dissipation, refraction and shoaling, there is evidence in the data supporting the calculations of Hasselmann and Hasselmann (1980) that show that resonant wave-wave interaction cross-spectral transfer rates for finite-depth waves increase rapidly above the deep-water rates when kph<O(1), which may help explain the departure from the deep-water power-law relations discussed above.

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C. E. Knowles

Abstract

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C. E. Knowles

Abstract

To convert the specific conductance C(S,t,p) measured by an in situ CTD sensor to salinity in a manner consistent with the international standard expression proposed by Cox et al., it is necessary to have established a means of estimating the specific conductance of seawater having a salinity of 35‰, [i.e., C(35,t,0)]. Third-order polynomial expressions formulated from samples having salinities near 35‰ are discussed. From the results of this study, it is recommended that an international expression for C(35,t,0) be established and that the conductivity ratio Rt calculated from this standard expression be used to obtain salinity using the UNESCO tables or the equation of Cox et al.

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C. E. Knowles and J. J. Singer

Abstract

During the period 20 June-2 July 1973, hydrographic data were collected at Oregon Inlet, N. C. An examination of the water temperature time-history record at three stations in and near the inlet show 1) that in two periods with predominately southerly winds, the temperature fluctuated in the range from 13.7° to 27.5°C with an apparent tidal periodicity; 2) that for nearly 48 h between these two periods and with northeasterly winds, a nearly constant temperature of 22.0° to 22.5°C was maintained in spite of normal tidal fluctuations; and 3) this constant temperature period is bracketed by two 24 h transitional periods that are initiated almost coincidently with wind directional changes. It appears that the sequence and relationship of these wind and water temperature data may be explained by and provide additional evidence and documentation of wind-induced upwelling along the northeastern North Carolina coast previously reported by Wells and Gray (1960), Carter, Pritchard and Carpenter (1966) and Boicourt (1973). Indeed, an important conclusion that can be drawn from this sequence and relationship of data is that temperature, salinity and current velocity records in and near a barrier island inlet can furnish much information about the exchange and mixing processes on the adjacent continental shelf, especially when there are large differences in temperature and salinity between the sound and shelf waters.

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W. E. Knowles Middleton
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