CANIGO

Canary Islands Azores Gibraltar Observations
MAS3-CT96-0060

The main goal of the CANIGO project is to understand the functioning of the marine system in the Canary-Azores-Gibraltar region of the Northeast Atlantic Ocean and its links with the Alboran Sea through comprehensive interdisciplinary basin scale studies.

The CANIGO project is divided into four subprojects:

  1. Circulation and Dynamics of Transports through the Eastern Boundary Current System
  2. The Contribution of the Pelagic System to the Carbon Flow
  3. Particle Flux and Paleoceanography in the Eastern Boundary Current System
  4. Fluxes and Outflow from the Mediterranean

Further details can be found on the CANIGO page at the Irish Marine datacentre.

As part of Subproject 1, the School of Mathematics at the University of East Anglia are responsible for constructing primitive equation numerical models of the CANIGO region. Four models are required under the original proposal.

The region west of Cape Ghir is the location of a semi-permanent cool filament and falls between the domains of the Gulf of Cadiz and Canary Islands models. To model this feature these two models have been combined into a larger model at the same resolution.

All models are based on the MOMA 1.3 (Webb 1995) rigid lid code. This is a primitive equation z-coordinate model based on the MOM code but adapted for efficient running on array processors.

A significant part of the model development was the inclusion of open boundaries to the north, west and south of the model domains and at the Strait of Gibraltar. These boundary conditions are based on those employed in the FRAM model.

The regional models are initialised to temperature and salinity from the OCCAM global model and zero velocity. Surface forcing is by ECMWF (1983) winds and relaxation to Levitus and Boyer (1994) temperature and Levitus et al. (1994) salinity. The streamfunction which is required at the open boundaries is calculated from the OCCAM barotropic velocities. The vertical discretization is to 36 levels which range in thickness from 20m at the surface to 255m at depth. The vertical viscosity Km = 1.0 cm²/s and vertical diffusion Kh = 0.5 cm²/s. The models differ in their domain, horizontal resolution, horizontal viscosity Am and horizontal diffusion Ah. These parameters are summarised in the table below.

Parameters of the regional models
Domain ResolutionAm Ah
Eastern North Atlantic 25°N - 42°N
35°W - 5.5°W		 1/6°1000000 cm²/s 1000000 cm²/s
Gulf of Cadiz and Canary Islands 25°N - 38°N
20°W - 5.75°W		 1/12°800000 cm²/s 800000 cm²/s
Cape St Vincent 34.5°N - 38°N
12.67°W - 5.83°W		 1/24°700000 cm²/s 500000 cm²/s

Development of the Eastern North Atlantic model is now complete. The model is spun up from rest for a period of three years and results output during year 4.

An analysis of the model results shows that it performs well and provides realistic descriptions of the Azores Current and Azores Front, the spreading of Mediterranean Water, the flow through the Canary Islands, coastal upwelling off Northwest Africa and Iberia and the variability around Madeira.

Examples of the model results are shown below for 9 Sept in year 4.

Zonal sections along 29°N.

Velocity field at a depth of 30.6 m.

A horizontal section of salinity at 1149.7 m.

Larger images can be obtained by clicking the appropriate frame. Higher resolution images in postscript format can be found here:

Work is continuing on improving the representation of the Mediterranean Outflow in the Gulf of Cadiz - Canary Islands and Cape St Vincent models.

i.stevens@uea.ac.uk

Last update: 14 Jan 1999