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are predominantly due to the square of the buoyancy frequency N 2 , although the diapycnal diffusivity D dominates the spatial patterns in the equatorial region. Fig . 7. I ɛ (0) referenced at the sea surface (mW m −2 ). 5) Comparison of the maps of I Θ (0), I θ (0), I η (0), and I ɛ (0) From these maps it can be concluded that I Θ (0) is the smallest of the variables Θ, θ , and η . The mean values of I Θ (0), I θ (0), I η (0), and I ɛ (0) can be compared to the mean geothermal heat
are predominantly due to the square of the buoyancy frequency N 2 , although the diapycnal diffusivity D dominates the spatial patterns in the equatorial region. Fig . 7. I ɛ (0) referenced at the sea surface (mW m −2 ). 5) Comparison of the maps of I Θ (0), I θ (0), I η (0), and I ɛ (0) From these maps it can be concluded that I Θ (0) is the smallest of the variables Θ, θ , and η . The mean values of I Θ (0), I θ (0), I η (0), and I ɛ (0) can be compared to the mean geothermal heat
, … , with T indicating the forcing period (so-called Poincaré planes of section). These subsequent intersections define a map, called the Poincaré map, P . A strictly periodic signal (of period T ) thus yields the same intersection. Compiling each of these subsequent intersections on one and the same horizontal (phase) plane, a stroboscopic impression of the slow evolution of the nearly periodic behavior is obtained. An example of such a Poincaré plane is presented by the dots in Fig. 3b . Here
, … , with T indicating the forcing period (so-called Poincaré planes of section). These subsequent intersections define a map, called the Poincaré map, P . A strictly periodic signal (of period T ) thus yields the same intersection. Compiling each of these subsequent intersections on one and the same horizontal (phase) plane, a stroboscopic impression of the slow evolution of the nearly periodic behavior is obtained. An example of such a Poincaré plane is presented by the dots in Fig. 3b . Here
each upper-layerbox. The algebraic sum of the applied freshwater fluxesmust be zero for a steady model. The upwind scheme is used for the advection termsin the heat and salinity equations. Assuming the velocity pattern is that in Fig. 1, we can write down theheat and salinity balance for each box. We introducethe nondimensional variables T~ = ToT'i, & = SoS'~ (u+, u-) -- (u+', u-'), wi = -- w'~ H ooCv 00% F HpoCp
each upper-layerbox. The algebraic sum of the applied freshwater fluxesmust be zero for a steady model. The upwind scheme is used for the advection termsin the heat and salinity equations. Assuming the velocity pattern is that in Fig. 1, we can write down theheat and salinity balance for each box. We introducethe nondimensional variables T~ = ToT'i, & = SoS'~ (u+, u-) -- (u+', u-'), wi = -- w'~ H ooCv 00% F HpoCp
. Comparisons with the Mediterranean and Labrador Seas are favorable and alternative interpretations of some of the data are suggested. To the extent that many, and perhaps all, water mass sites neighbor continental boundaries, the interactions discussed here are of general significance to water mass dispersal. a. Background Deep convection has been frequently studied in the marginal seas of the North Atlantic. A comprehensive review appears in Marshall and Schott (1999) , who discuss observational
. Comparisons with the Mediterranean and Labrador Seas are favorable and alternative interpretations of some of the data are suggested. To the extent that many, and perhaps all, water mass sites neighbor continental boundaries, the interactions discussed here are of general significance to water mass dispersal. a. Background Deep convection has been frequently studied in the marginal seas of the North Atlantic. A comprehensive review appears in Marshall and Schott (1999) , who discuss observational
the free falling high-resolution profiler (HRP; Schmitt et al. 1987 ), as a means of assessing the diapycnal fluxes occurring in the thermocline at the North Atlantic Tracer Release Experiment (NATRE) site. A previous comparison of microstructure-derived diffusivities ( Toole et al. 1994 ) and tracer-derived diffusivities ( Ledwell et al. 1993 ) has indicated general agreement. This paper will strive to identify the turbulent and salt-finger contributions to the net diffusivities. Furthermore, we
the free falling high-resolution profiler (HRP; Schmitt et al. 1987 ), as a means of assessing the diapycnal fluxes occurring in the thermocline at the North Atlantic Tracer Release Experiment (NATRE) site. A previous comparison of microstructure-derived diffusivities ( Toole et al. 1994 ) and tracer-derived diffusivities ( Ledwell et al. 1993 ) has indicated general agreement. This paper will strive to identify the turbulent and salt-finger contributions to the net diffusivities. Furthermore, we
/or different experiments have been foundto be rather inconsistent. In many cases, these reportedspectra disagree in terms of both the spectral level andthe spectral slope, two of the most important propertiescharacterizing the spectral function (see, for example,the comparisons and discussions in Lawner and Moore1984). Such discrepancies may be attributed to the factc 1996 American Meteorological SocietyJuLY 1996 HWANG ET AL
/or different experiments have been foundto be rather inconsistent. In many cases, these reportedspectra disagree in terms of both the spectral level andthe spectral slope, two of the most important propertiescharacterizing the spectral function (see, for example,the comparisons and discussions in Lawner and Moore1984). Such discrepancies may be attributed to the factc 1996 American Meteorological SocietyJuLY 1996 HWANG ET AL
.e., e >> 1; see appendix A). The leading order behavior of (14) and (15) maybe obtained by neglecting terms proportional to/~, inwhich case the lowest layer conserves potential vorticitywhen it is covered by layers I and 2. It is thereforerequired on the eastern boundary that all motion betrapped in the upper two layers. Equation (14) withP3 = 0 thus simplifies toh2 = -hi + [2Hi2 + 2H~H2 + H22 -- hi2] 1/2. (16)Using (16) in the upper-layer equations eventuallyyields an algebraic equation
.e., e >> 1; see appendix A). The leading order behavior of (14) and (15) maybe obtained by neglecting terms proportional to/~, inwhich case the lowest layer conserves potential vorticitywhen it is covered by layers I and 2. It is thereforerequired on the eastern boundary that all motion betrapped in the upper two layers. Equation (14) withP3 = 0 thus simplifies toh2 = -hi + [2Hi2 + 2H~H2 + H22 -- hi2] 1/2. (16)Using (16) in the upper-layer equations eventuallyyields an algebraic equation
might be a key to long-range weatherforecasting and short-term climate predictions. Thefirst attempt at modeling the evolution of the SSTanomalies was made by Namias (1959, 1965) whotried to reproduce observed cases of monthly or seasonal SST anomaly changes in the North Pacific. Heconsidered the advection of the mean temperaturegradient by anomalous surface currents which wereestimated from monthly maps of surface geostrophicwind. In later investigations the effect of heat fluxforcing and mixed
might be a key to long-range weatherforecasting and short-term climate predictions. Thefirst attempt at modeling the evolution of the SSTanomalies was made by Namias (1959, 1965) whotried to reproduce observed cases of monthly or seasonal SST anomaly changes in the North Pacific. Heconsidered the advection of the mean temperaturegradient by anomalous surface currents which wereestimated from monthly maps of surface geostrophicwind. In later investigations the effect of heat fluxforcing and mixed
(∼6 W m −2 ). Because the mixed layer depth changes are small in winter ( δd / d 0 ∼ 12.5/160 ≪ 1) and the wind is steady, the simple heat balance is expected to hold, where the prime denotes an anomaly and Q ann is the annual mean surface heat flux which varies with latitude as d 0 . For d 0 = 160 m, (25) recovers an annual heat flux anomaly of 5.8 W m −2 in quadrature with the SST anomaly, in agreement with Fig. 7 . The lower-layer PV is mapped for April of each year of the decadal
(∼6 W m −2 ). Because the mixed layer depth changes are small in winter ( δd / d 0 ∼ 12.5/160 ≪ 1) and the wind is steady, the simple heat balance is expected to hold, where the prime denotes an anomaly and Q ann is the annual mean surface heat flux which varies with latitude as d 0 . For d 0 = 160 m, (25) recovers an annual heat flux anomaly of 5.8 W m −2 in quadrature with the SST anomaly, in agreement with Fig. 7 . The lower-layer PV is mapped for April of each year of the decadal
water profiling mode 1 for “dynamic sea state” was selected. During the whole period at anchor, the ADCP operated in bottom tracking mode to remove ship movement around the anchor from the measured current profile data. A closer comparison between gyro heading and direction of the absolute current confirmed that this correction by means of the bottom-tracked ship motion worked perfectly. With a standard beam angle of 20° and a distance of 35 m between the transducer head at 3 m and the bottom at 38
water profiling mode 1 for “dynamic sea state” was selected. During the whole period at anchor, the ADCP operated in bottom tracking mode to remove ship movement around the anchor from the measured current profile data. A closer comparison between gyro heading and direction of the absolute current confirmed that this correction by means of the bottom-tracked ship motion worked perfectly. With a standard beam angle of 20° and a distance of 35 m between the transducer head at 3 m and the bottom at 38