The Papagayo Wind
SeaWiFS winter (2000-2001) Level 3 chlorophyll image,
showing the increased productivity corresponding to the Tehuano (south of
Mexico), Papagayo (west of Nicaragua), and Panama (south of Panama) wind jets.
In many places around the world, a particular type of wind has a name. In
California, Santa Ana winds blow hot out of the desert through Santa Ana
Pass, drying the brush and then fanning the flames of wildfires. In the
Adriatic Sea, they speak of the cold Bora from Hungary. The Rocky
Mountains of the United States experience Chinook winds, abrupt warming
breezes that follow a cold snap. The famous Mistral winds are cold, dry
winds from the north that blow over the Mediterranean Sea. And there are many
more.
In the Central American winter, they feel Tehuanos and
Papagayos: gale-force winds from the Gulf of Mexico and Caribbean Sea
that funnel through narrow breaks in the Cordillera, gusting to wind speeds
normally found only in major hurricanes. The Papagayo wind shrieks over the
lakes of Nicaragua, a jet of wind that pushes far out over the Gulf of Papagayo
on the Pacific coast.
New Central American topographic map derived from Shuttle
Radar Topography Mission (SRTM) data. The Papagayo wind blows across the low
elevations near Lake Nicaragua from the Caribbean Sea. Chivela Pass in
Mexico, which spawns the Tehuano winds over the Gulf of Tehuantepec, is
just north of this map. Map courtesy of NASA Jet Propulsion Laboratory
And when the Papagayo blows, the sea follows. The wind mixes the normally
warm surface waters with colder, nutrient-rich water that lies beneath the
shallow thermocline near the coast. Algal blooms propagate in the path of the
Papagayo, fueled by the banquet of nutrients. An entire food chain, ascending
to the majestic marlin and sailfish sought by sport fishermen, depends on the
episodic Tehuano and Papagayo events.
Sea surface temperature image showing the cold
upwelling areas associated with the Tehuano and Papagayo winds. Wind vectors
are from the ERS-1 scatterometer. Image courtesy of D. Ballestero and E.
Coen, Universidad Nacional, Costa Rica. Click on the image for full-
size version.
The meteorological mechanism that causes Tehuano and Papagayo winds is
relatively simple. In the winter, cold high-pressure weather systems move
southward from North America over the Gulf of Mexico. These high pressure
systems create strong pressure gradients between the atmosphere over the Gulf
of Mexico and the warmer, moister atmosphere over the Pacific Ocean. Just as a
river flows from high elevations to lower elevations, the air in the high
pressure system will flow "downhill" toward lower pressure, but the Cordillera
mountains block the flow of air, channeling it through Chivela Pass in Mexico,
the lake district of Nicaragua, and also Gaillard (Culebra) Cut in Panama
(which also holds the Panama Canal). Many times, a Tehuano wind is
followed by Papagayo and Panama winds a few days later as the high pressure
system moves south.
The arrival of these cold surges, and their associated anticyclonic
circulation, strengthens the trade winds at low latitudes, and this effect can
last for several days. The wind flow over Central America is actually composed
of the confluence of two air streams; one from the north, associated with
cold surges, and the other from the northeast, associated with trade winds
north of South America.
The wind jets cause a localized, narrow entrainment of cold deep water
containing dissolved nutrients that foster increased productivity. The sea
surface temperature can drop 10 degrees Centigrade in a single day when the
wind jets blow over the ocean surface.
The SeaWiFS Level 3 composite image for the winter of 2000-2001 shows
the effect of the episodic wind events as increased productivity on the Pacific
coast of Central America, most pronounced where the Tehuano and Papagayo winds
originate. The two high-resolution SeaWiFS images below show a particularly
intense Papagayo wind-induced event on January 7 and January 14, 2001.
SeaWiFS chlorophyll images for January 7 (top) and
January 14, 2001 (bottom), showing a narrow Papagayo wind-induced zone
of productivity extending westward from the Nicaraguan coast. The
HRPT station at the University of Puerto Rico-Mayaguez acquired the data for
these images.
January 2001 was a particularly active month in this region, as
demonstrated by the SeaWiFS Level 3 image at the top of the page. The month
ended with another major event, illustrated by the two images below (provided
by Enrique Coen of the Laboratorio de Oceanografia y Manejo Costero,
Universidad Nacional, Costa Rica). The upper image is for January 30, 2001,
and the lower image is a five-day composite for January 26-30, 2001. These
images serve to further illustrate how the episodic Tehuano, Papagayo, and
Panama winter winds are critical to the productivity of the Pacific ocean
waters west of Central America.
SeaWiFS chlorophyll images for January 30, 2001 (top) and
five-day composite for January 26-30, 2001 (bottom) showing high productivity
off the Central American Pacific coast corresponding to the Tehuano, Papagayo,
and Panama wind jets. Note that the color scales are slightly different for
each image.
One of the reasons scientists observe oceanic productivity and connect it
to its physical causes in the atmosphere and ocean is to determine if climate
change will affect the productivity of the ocean. In the case of the Papagayo
wind, a warming climate may reduce the frequency of cold air masses from
North America that reach the Gulf of Mexico and the Caribbean Sea. In turn,
this would lead to reduction in the frequency and intensity of the episodic
upwelling events driven by the Tehuano and Papagayo winds, with the net
effect of a reduction of oceanic productivity in this region.
Acknowledgements
This Science Focus! article benefited greatly from reviews by
Paul Fiedler, NOAA/NMFS Southwest Fisheries Science Center, La Jolla,
California, and Enrique Coen, Universidad Nacional, Costa Rica.
Links
References
The linked documents are PDF documents, which require Adobe Acrobat
Reader.
C.L. Brenes, J.E. Coen, D.B. Chelton, D.B. Enfield, S. Leon, and
D. Ballestero, 2003: Wind driven
upwelling in the Gulf of Nicoya, Costa Rica. International
Journal of Remote Sensing, 24(5), 1127-1133.
P.C. Fiedler, 2002:
The annual cycle and biological effects of the Costa Rica Dome.
Deep-Sea Research, 49, 321-338.
D.M. Schultz, W. E. Bracken, and L. F. Bosart, 1998: Planetary- and synoptic-scale signals associated with Central American cold surges.
Monthly Weather Review, 126, 5-27.
W.J. Steenburgh, D.M. Schultz, and B.A. Colle, 1998: The
structure and evolution of gap outflow over the Gulf of Tehuantepec,
Mexico. Monthly Weather Review, 126, 2673-1691.
A. Trasvia, E.D. Barton, J. Brown, H.S. Velez,
P.M. Kosro, and R.L. Smith, 1995: Offshore wind forcing in the Gulf of
Tehuantepec, Mexico: The asymmetric circulation. J. Geophys. Res.,
100, 20,649-20,663
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