Mona Passage

Islands

There are three small islands in the Mona Passage:

• Mona Island lies close to the middle of the Mona Passage.
• 3 mi northwest of Mona Island is the much smaller Monito Island.
• 30 mi northeast of Mona Island and much closer (13 mi) to the Puerto Rican mainland is Desecheo Island.

Structure and seismicity

The Passage was the site of a devastating earthquake and tsunami that hit western Puerto Rico in 1918. It is the site of frequent small earthquakes. The passage is underlain by a seismically active rift zone that overprints an older, partly eroded tilted-block structure.

Physical oceanography

The Mona Passage connects the Atlantic Ocean waters and Caribbean Sea waters, above a sill depth of 400 to. The sill runs along a northwest to the southeast direction between Cabo Engaño in Hispaniola in the west and the Cabo Rojo Shelf in Puerto Rico to the east margin of the Mona Passage. The vertical profile of the low-frequency (periods longer than 2 days) mean meridional water transport is characterized by a two-layer structure. The upper layer lies above a depth of 300 m, with the upper water masses, the Caribbean Surface Water, Subtropical Underwater and Sargasso Sea Water entering the Caribbean Sea from the Atlantic Ocean. Below this layer, the Tropical Central Water exits toward the Atlantic Ocean. The mean value for the meridional (North-South) transport for a sampled year was –1.85 ± 0.25 sverdrup (Sv) into the Caribbean Sea.{{Cite book

The barotropic tide (surface tide) propagates from northeast to southwest along Mona Passage. The "principal lunar semi-diurnal" constituent, also known as the M2 (or M2), accounts for 52.35% of the total variance observed in the ocean currents, and the semidiurnal current ellipses, with a clockwise rotation, are roughly aligned in a north-south direction.{{Cite book

Semidiurnal tidal currents impinging on a submarine ridge known as El Pichincho can force the generation of an internal tide with a wave height of 40 m.{{Cite book

Internal tides at El Pichincho can elevate the turbulent vertical diffusivity values (or eddy diffusion), and with a reduction of the Richardson number at the base of the pycnocline. The development of Kelvin-Helmholtz instability during the breaking of the internal tide can explain the formation of high-diffusivity patches that generate a vertical flux of nitrate (NO3−) into the photic zone and can sustain new production locally.{{Cite book

Higher values of primary productivity were observed near the wave trough, than those observed during periods of maximum solar irradiance at noon.

Images from the Moderate-Resolution Imaging Spectroradiometer (MODIS) and International Space Station (ISS) photography show the sea-surface manifestation of packets of internal solitons (or nonlinear internal waves) generated at Banco Engaño, located at the northwest margin of the Mona Passage.

Surface tides, internal tides, internal solitons, inertial currents, and the low-frequency water mass transport between the Atlantic Ocean and the Caribbean Sea make the Mona Passage a very dynamic environment.

References

References

1. https://soundwaves.usgs.gov/2007/05/ {{Webarchive. link. (2017-04-05 Uri ten Brink, ''New Bathymetric Map of Mona Passage, Northeastern Caribbean, Aids in Earthquake- and Tsunami-Hazard Mitigation,'' USGS Sound Waves Newsletter, May 2007)
2. [[Desecheo Island]] sits on the Desecheo ridge, a narrow east-west ridge that extends west from the northwest corner of Puerto Rico. The ridge forms the southern boundary of the {{Convert. 4. km. 3. km. 978-0-8137-2385-3