CP1-Kinematics figures - essie-uf

Comments

Transcription

CP1-Kinematics figures - essie-uf
Observed circulation patterns in a back reef lagoon: Figures
Figure 1: Typical shallow reef circulation
This figure demonstrates the typically accepted and expected circulation in shallow reef
lagoon systems. Inflow into the system is caused by waves breaking over the reef,
creating set up that drives outflow through the reef breaks.
Observed circulation patterns in a back reef lagoon: Figures
Figure 2: Transects, Wind, & Wave Data Locations
The experiment was conducted in Puerto Morelos, Mexico; located on the northeast of
the Yucatan Peninsula in Quintana Roo (left). The transect locations are shown on the
bathymetric map (right), along with the wind and wave data locations. The numbered
arrows indicate the legs of the transect. Boca Chica data were collected from July 21-22,
2011 in 39 repetitions. Boca Grande data were collected from July 23-34, 2011 in 32
repetitions. Wave data were observed over the reef using a moored Aquadopp. Wind data
were observed at an onshore facility maintained by UNAM.
Observed circulation patterns in a back reef lagoon: Figures
Figure 3: Wind vectors and significant wave height
Prevailing winds are shown blowing from the origin in 3a, mainly southwestward during
the Boca Chica experiment and mainly northwestward during the Boca Grande
experiment. 3b shows the water surface elevation, eta, taken from the wave data captured
using an Aquadopp moored on the reef at the ‘wave’ location in Figure 2. The green
dashed line indicates the start of the experiment and the red solid line indicates the end of
the experiment. Boca Chica occurred July 21-22, 2011, and Boca Grande occurred July
23-24, 2011. 3c shows the significant wave heights that occurred during the experiments.
Observed circulation patterns in a back reef lagoon: Figures
Observed circulation patterns in a back reef lagoon: Figures
Figure 4: Depth averaged spatial and temporal comparison of inlet flows
Row 1 (Boca Chica) and Row 2 (Boca Grande) depict contours of U (East-West) and V (NorthSouth) components of flow with respect to distance across the inlet (x-axis) and to time (y-axis).
A figure of water surface elevation is shown in the center of each row. Eta (black line)
represents the tidal elevation, Hs (blue line) represents the significant wave height, and the sum
(red line) represents the total water surface elevation. Inlet bathymetry is referenced below the
contours. Note: contour values of East and North are positive and West and South are negative.
Observed circulation patterns in a back reef lagoon: Figures
Figure 5: Depth Averaged Residual and Tidal flows at the Inlets
The U component of flow (solid lines) and V component of flow (dashed lines) are
compared for the two inlet systems. 5a represents the dominance of U versus V residual
flows (cm/s) at Boca Chica Inlet. The properties of the tidal constituents (K1, M2, & M4)
are shown in the tidal amplitude (5b) and tidal phase (5c). It is clear that the U (EastWest) component of flow is modulated by the M2 constituent, and Boca Chica flow is
predominantly convergent outflow at the inlet. Figure 5d demonstrates the dominance of
V over U in the residual flows for Boca Grande Inlet. BG tidal amplitude (5e) and tidal
phase (5f) show that the K1 and M4 constituents dominate the inlet flows, which is
somewhat unexpected given the region has a form factor of 0.34, indicating diurnal
dominance.
Observed circulation patterns in a back reef lagoon: Figures
Observed circulation patterns in a back reef lagoon: Figures
Figure 6: Residual Flows for Boca Chica & Boca Grande Lagoon-Inlet Systems
The Boca Chica residual flows at the surface (6a) are compared to the depth averaged
flows (6b). Boca Chica exhibits typical characteristics of inlet flow in shallow reef
systems. Setup driven outflow at the inlet allows cross-lagoon flows to dominate
alongshore flows and causes flow convergence at the inlet.
The Boca Grande transects also compares surface residual flows (6c) to the depth
averaged flows (6d). Boca Grande flow behavior is atypical. In this system, alongshore
flow competes with cross-inlet flow to create recirculation patterns. The location of these
patterns varies with depth due to the increased influence of the alongshore component of
flow with respect to depth. Contrary to accepted circulation patterns for shallow reef
systems, inflow occurs at the north end of the inlet.
Observed circulation patterns in a back reef lagoon: Figures
Observed circulation patterns in a back reef lagoon: Figures
Figure 7: Residual flows at the inlets
This figure represents the residual flow patterns at the inlets. The colored contours
represent East (positive) and West (negative) flow as the U component. The V
component (North-South) flows are represented by the black vectors with a reference
scale at the bottom right of the figure. The Boca Chica inlet (7a) exhibits the typically
expected converging outflow at the inlet. At Boca Grande (7b), inflow occurs at the north
end of the inlet (right) and at depth in the center of the inlet. Note: bathymetry was
plotted at 80% true depth to eliminate side-lobe effects caused by interaction with the
bottom.
Observed circulation patterns in a back reef lagoon: Figures
Observed circulation patterns in a back reef lagoon: Figures
Figure 8: BG Horizontal Divergence and Vertical Component of Relative Vorticity
This figure depicts the horizontal divergence (left column) and the vertical component of
relative vorticity (right column) over the course of a semidiurnal tidal cycle. The values
were calculated approximately every 3 hours to capture the transition from high tide to ebb
to low tide to flood. At high tide, we see the highest divergence and lowest vorticity at the
inlet. In contrast, at flood we see the lowest divergence values and highest vorticity at the
inlet, which explains the susceptibility for gyre formation at the inlets during flood. There
is also a shift from N-S gradients of contours in the lagoon to E-W gradients at the inlet,
indicating competing alongshore and cross-lagoon flows.
Observed circulation patterns in a back reef lagoon: Figures
Observed circulation patterns in a back reef lagoon: Figures
Figure 9: BC Horizontal Divergence and Vertical Component of Relative Vorticity
9A depicts the horizontal divergence of flow over the course of a semidiurnal tidal cycle.
9B depicts the corresponding vertical component of relative vorticity. The values were
calculated approximately every 3 hours to capture the transition from high tide to ebb to
low tide to flood. However, all stages of the tidal cycle are shown because Boca Chica
behaved according to the diurnal constituent rather than the expected semidiurnal
constituent, due to the water surface elevation (see Figure 3).
At the start of the first semidiurnal cycle, we see converging flow and high vorticity, which
is again seen at the end of the second semidiurnal cycle. At the end of the first semidiurnal
cycle and beginning of the second semidiurnal cycle (mimicking the peak of a diurnal
cycle), we see divergence across the lagoon, corresponding with the lowest values of
vorticity.
Observed circulation patterns in a back reef lagoon: Figures

Similar documents