The Mona Passage ( es, Canal de la Mona) is a

strait A strait is an oceanic landform connecting two seas or two other large areas of water. The surface water generally flows at the same elevation on both sides and through the strait in either direction. Most commonly, it is a narrow ocean chan ...

that separates the islands of

Hispaniola Hispaniola (, also ; es, La Española; Latin and french: Hispaniola; ht, Ispayola; tnq, Ayiti or Quisqueya) is an island in the Caribbean that is part of the Greater Antilles. Hispaniola is the most populous island in the West Indies, and th ...

and

Puerto Rico Puerto Rico (; abbreviated PR; tnq, Boriken, ''Borinquen''), officially the Commonwealth of Puerto Rico ( es, link=yes, Estado Libre Asociado de Puerto Rico, lit=Free Associated State of Puerto Rico), is a Caribbean island and unincorporated ...

. The Mona Passage connects the

Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...

to the

Caribbean Sea The Caribbean Sea ( es, Mar Caribe; french: Mer des Caraïbes; ht, Lanmè Karayib; jam, Kiaribiyan Sii; nl, Caraïbische Zee; pap, Laman Karibe) is a sea of the Atlantic Ocean in the tropics of the Western Hemisphere. It is bounded by Mexic ...

and is an important shipping route between the Atlantic and the

Panama Canal The Panama Canal ( es, Canal de Panamá, link=no) is an artificial waterway in Panama that connects the Atlantic Ocean with the Pacific Ocean and divides North and South America. The canal cuts across the Isthmus of Panama and is a condui ...

. The Mona Passage is 80 miles (130 kilometer). It is fraught with variable tidal currents created by large islands on either side of it, and by sand banks that extend out from both coasts.

Islands

There are three small islands in the Mona Passage: * Mona Island lies close to the middle of the Mona Passage. *Five kilometers northwest of Mona Island is the much smaller Monito Island. *Fifty kilometers northeast of Mona Island and much closer (21km) to the Puerto Rican mainland is

Desecheo Island Desecheo ( es, Isla Desecheo) () is a small uninhabited island of the archipelago of Puerto Rico located in the northeast of the Mona Passage; from Rincón on the west coast ( Punta Higüero) of the main island of Puerto Rico and northeast ...

Structure and seismicity

The Passage was the site of a devastating earthquake and resulting tsunami that hit western Puerto Rico in 1918.http://soundwaves.usgs.gov/2007/05/ Uri ten Brink, ''New Bathymetric Map of Mona Passage, Northeastern Caribbean, Aids in Earthquake- and Tsunami-Hazard Mitigation,'' USGS Sound Waves Newsletter, May 2007 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.

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 4000 m deep Mona Canyon which extends toward the north to the

strike slip fault In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectoni ...

zones which bound Puerto Rico and Hispaniola. The east face of the rift has a sharp relief of 3km and is controlled by the N - S trending Mona Rift Fault. The epicenter of the 1918 earthquake was located along the east or southeast edge of the Mona Rift.

Physical oceanography

The Mona Passage connects the

waters and

waters, above a

sill Sill may refer to: * Sill (dock), a weir at the low water mark retaining water within a dock * Sill (geology), a subhorizontal sheet intrusion of molten or solidified magma * Sill (geostatistics) * Sill (river), a river in Austria * Sill plate, ...

depth of 400 to 500 meters. The sill runs along a northwest to the southeast direction between Cabo Engaño (DR) in the west and the Cabo Rojo Shelf (PR) in 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 meters, with the upper water masses, the

Caribbean The Caribbean (, ) ( es, El Caribe; french: la Caraïbe; ht, Karayib; nl, De Caraïben) is a region of the Americas that consists of the Caribbean Sea, its islands (some surrounded by the Caribbean Sea and some bordering both 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. 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 ''M''₂) 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. Semidiurnal tidal currents impinging on a submarine ridge known as ''El Pichincho'' can force the generation of an

internal tide Internal tides are generated as the surface tides move stratified water up and down sloping topography, which produces a wave in the ocean interior. So internal tides are internal waves at a tidal frequency. The other major source of internal wa ...

with a wave height of 40 meters. Underwater glider observations reveal wave damping as the internal tide propagates south along the Mona Passage towards the open Caribbean Sea. Internal tides at ''El Pichincho'' can elevate the turbulent vertical diffusivity values (or Eddy diffusion), and with a reduction of the

Richardson number The Richardson number (Ri) is named after Lewis Fry Richardson (1881–1953). It is the dimensionless number that expresses the ratio of the buoyancy term to the flow shear term: : \mathrm = \frac = \frac \frac where g is gravity, \rho is den ...

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 Nitrate is a polyatomic ion with the chemical formula . Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are soluble in water. An example of an insolu ...

(NO₃⁻) into the

photic zone The photic zone, euphotic zone, epipelagic zone, or sunlight zone is the uppermost layer of a body of water that receives sunlight, allowing phytoplankton to perform photosynthesis. It undergoes a series of physical, chemical, and biological pro ...

and can sustain

new production In biological oceanography, new production is supported by nutrient inputs from outside the euphotic zone, especially upwelling of nutrients from deep water, but also from terrestrial and atmosphere sources (as opposite to regenerated production, w ...

locally. 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 The International Space Station (ISS) is the largest Modular design, modular space station currently in low Earth orbit. It is a multinational collaborative project involving five participating space agencies: NASA (United States), Roscosmos ( ...

(ISS) photography show the sea-surface manifestation of packets of internal

solitons In mathematics and physics, a soliton or solitary wave is a self-reinforcing wave packet that maintains its shape while it propagates at a constant velocity. Solitons are caused by a cancellation of nonlinear and dispersive effects in the mediu ...

(or nonlinear

internal waves Internal waves are gravity waves that oscillate within a fluid medium, rather than on its surface. To exist, the fluid must be stratified: the density must change (continuously or discontinuously) with depth/height due to changes, for example, in ...

) generated at ''Banco Engaño'', located at the northwest margin of the Mona Passage. The packets propagate either into the Caribbean Sea or the Atlantic Ocean depending on the direction of the currents that forced their generation. 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.

Boating

Cruising boaters entering the Caribbean from the north often do so via a stop at Samaná in the northeastern part of the

Dominican Republic The Dominican Republic ( ; es, República Dominicana, ) is a country located on the island of Hispaniola in the Greater Antilles archipelago of the Caribbean region. It occupies the eastern five-eighths of the island, which it shares with ...

, then continuing across the Mona Passage to Puerto Rico without stopping. Under sail it means an even longer distance because of having to "tack" a zig-zag course into the easterly

trade winds The trade winds or easterlies are the permanent east-to-west prevailing winds that flow in the Earth's equatorial region. The trade winds blow mainly from the northeast in the Northern Hemisphere and from the southeast in the Southern Hemisp ...

. At the stop of Saona Island on the southeast coast of the Dominican Republic, boaters can sit and wait for a lull in the trade winds when seas are down to start their eastward crossing. This is an advantage that is not possible when departing from Samaná. It is only about from Saona to the protected anchorage inside the barrier coral reef on the west coast of Mona Island. And from there it is another to the popular and spacious cruising anchorage at Boquerón in Puerto Rico.

References

External links