11.07.12: Origin of the water mass inside the eddy during BIOLINCS using the data-assimilating global HYCOM modelΒΆ
I performed the same analysis concerning where the origin of the water inside the eddy during BIOLINCS except that I use the horizontal velocity at 30 m from the data-assimilating HYCOM global model instead of the geostrophic flow from AVISO SSH.
As we compare the same animation obtained with AVISO SSH (see 11.07.12: Origin of the water mass inside the eddy during BIOLINCS using AVISO SSH), we see that a different conclusion is drawn. With the model, we would say that the water entrained into the eddy about only 50 days before BIOLINCS.
Fig. 2 shows an animation when we now use the surface geostrophic flow from the model to compute the trajectories. It is in relative agreement with Fig. 1. This suggests that the difference with the trajectories deduced from AVISO SSH may be due to the noise in the AVISO SSH and/or the small-scale features in the model not resolved by AVISO SSH. We could start by comparing a section of the surface geostrophic flow between the model and AVISO.
Figure 1: Past distribution of parcels located within the eddy during BIOLINCS. Trajectories have been calculated by using the horizontal velocity field at 30 m from the data-assimilating global HYCOm model. In the upper panel, the grey shading is the model SSHA. The red line indicates the past trajectory of eddy with the numbers indicating the number of days in the past it corresponds to. The red circle is the edge of the eddy defined by fitting a Gaussian to the SSHA map. The blue dots show the position of parcels. The movie is running into the past with the number of days into the past indicating in the title. In the lower panel is shows the time series of the percentage of parcels that are still inside the eddy defined by the red circle in the upper panel. The time series run from the past to the left to the time of the BIOLINCS observations (day=0) to the right. The moving vertical dashed line indicates the time of the snapshot of the upper panel.
Figure 2: Same as in Fig. 1 except that we use the surface geostrophic flow from the HYCOM model to compute the trajectories.
Fig. 1 is plotted with plot_SSH_AVISO_HYCOM_global_eddy_coherence_comp.m and Fig. 2 is plotted with plot_HYCOM_global_eddy_coherence_geo.m. All are in RESEARCH/PROJECTS/MARINE_BIOLOGY/SUBMESOSCALE_PROCESSES/BIOLINCS/SSH_HYCOM_analysis_2_anim on the main disk.