3D Lagrangian subduction of water volumes for 2 Apr 1200Z to 6 Apr 1200Z 2019, Issued 2 Apr 2019

The following figures show the water volumes that are forecast to subduct in 3D (computed based on our MSEAS forward flowmap forecast) from the surface layers to deeper layers. They illustrate in 3D+time where these waters start, how they move, and where they end up.

The waters that are plotted in this subduction analysis are only the volumes of water that start within the upper ocean layers (0-to-10 m depths) anywhere in our modeling domain and reach 50m after 4 days. This is all that is plotted, at 3 times (blue is day 0, green is day 2 and red is day 4).

Below, the blue water volumes are the initial positions of these waters that start within 0-to-10 m depths and reach 50m after 4 days. These water volumes are advected using a flowmap-based and composition-based advection scheme, using our MSEAS forecast of the 3D ocean currents (u, v and w). The green water volumes represent the location of the parcels after two days while the red water volumes represent the final location after 4 days. The combined figures in the last row show the 3D water volumes, overlaid, at the 3 different times.

As also shown in the forecast below, the ridges of the forward Finite-Time Lyapunov Exponents (FTLEs) are the repelling FTLE structures: they tend to 'repel' water parcels. Two parcels that are close to each other at t=0 but on different sides of the forward FTLE ridge will advect further away from each other than other parcels. The ridges of the backward FTLEs are the attracting FTLE structures: they tend to 'attract' water parcels.

The figures below illustrate the MSEAS forecast of 3D subduction for the period 2 Apr 1200Z to 6 Apr 1200Z 2019. The 3D subduction still occurs along (sub)-mesoscale eddies and frontal structures in the middle of the Alboran sea (e.g. sinking in thin sheets along convergent/attracting fronts and edges of interacting eddies.). However, winds are forecast to pick up late on Apr 03 with close to gale force winds to the east-southeast by Apr 04. As a result, subduction is forecast to increase along the African coastline. Note there is a direct relation between this 3D subduction (from above 10m depth to deeper than 50m depth) and the 3D attracting Lagrangian Coherent Structures that we forecast (see the maps of the forecast 3D backward FTLE fields).


3D Lagrangian subduction in the Calypso Domain (MSEAS 1/200deg tidally-forced forecasts downscaled from WMOP)

Time & Depths Top View 3D View Side View
t0 and upper 10m top_view_init.png
iso_view_init.png
side_view_init.png
t0 + 48 hours top_view_interm.png
iso_view_interm.png
side_view_interm.png
t0 + 96 hours and water reaching 60m top_view_final.png
iso_view_final.png
side_view_final.png
Overlaid top_view_combined.png
iso_view_combined.png
side_view_combined.png


96-hr Forecast Backward 3D FTLE field at various depths for April 2 1200Z - April 6 1200Z - The ridges in this 3D field are the flow structures that most attract fluid parcels in 3D over the 4 days.

Depth 2 m 4 m 20 m 40 m 60 m
April 2
-
April 6
new_FTLE_backward_002m_96hr.png
new_FTLE_backward_004m_96hr.png
new_FTLE_backward_020m_96hr.png
new_FTLE_backward_040m_96hr.png
new_FTLE_backward_060m_96hr.png


96-hr Forecast Forward 3D FTLE field at various depths for April 2 1200Z - April 6 1200Z - The ridges in this 3D field are the flow structures that most repel fluid parcels in 3D over the 4 days.

Depth 2 m 4 m 20 m 40 m 60 m
April 2
-
April 6
new_FTLE_forward_002m_96hr.png
new_FTLE_forward_004m_96hr.png
new_FTLE_forward_020m_96hr.png
new_FTLE_forward_040m_96hr.png
new_FTLE_forward_060m_96hr.png



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