December 2, 1999

Task Assessment at the Luquillo, Puerto Rico, LTER



Myself as PI, and Mike Willett the Project's Senior Technical Consultant, visited Puerto Rico from November 21st to the 23d, 1999. The purpose of the trip was several fold:

a. To determine exactly what will be required to accomplish the first priority named by Dr. Jess Zimmerman, the overall Luquillo Experimental Forest LTER PI for our NSF Wireless Project in support of Field Research for Biological Sciences. That priority is to link the three Weather Stations that operate in three separate places within the El Yunque Rain Forest on the eastern end of the island of Puerto Rico.

b. To determine the way the El Verde Research Station will be linked to the Internet from its currently isolated (only a cell phone) location in the Forest.

c. To assess the general electromagnetic environment within which the wireless links will have to operate - density and location of RF Transmitters. And operating experience by other operators of RF equipment on the island.

d. To better understand the scope and variety of scientific data-gathering experiments that are being done as part of the Long Term Ecological Research NSF Projects so we design the first links in ways that will support later experiments.

e. To explore the next priority - after the 3 Weather Stations are connected and operating reliably - for implementation in 2000.



One of the special reasons why the El Yunque Rain Forest is used for long-term ecological research is that it is at once a U.S. National Forest, under the control and protection of the US Government. It is the only rain forest with such status. Thus there is careful control over any intrusion by man - whether roads or facilities or permitted activities -inside its' perimeter. Together with its natural characteristics - of a forest which receives 5 meters - over 200 inches of rain a year, and ranging from near sea level to over 1000 meters in elevation - in an area of the Caribbean subject to severe weather extremes - it is an ideal laboratory for study of the natural environment, and rare species of both plant and animals.

The denseness of the forest, with high canopy, the humidity and destructive effect of tropical atmosphere, makes it difficult to set out experiments, keep them operating gathering useful data for years, and gathering the data from them. It is very labor intensive to conduct field studies in the rough, wet, jungle that is El Yunque. The typical experiment is set out where it is recurringly accessible by researchers. In the case of the weather stations, which measure Min/Max Temperatures, Relative Humidity, Precipitation, Wind Direction, and Speed, the systems are placed in varying locations in the forest, and at varying heights from the forest floor to above the canopy. Data loggers are attached to the sensors at each station, but in every case, only accumulate data in a memory bank, which is offloaded by a researcher or assistant, generally every two weeks.

It is self-evident that if these data loggers were in continuous communication back to the El Verde Field Research Center - and through it to the global internet - not only could the data be collected continuously, and perturbations indicating trouble - storms damaging the systems or their mountings permitting immediate repair visits - but also certain devices could be 'commanded' via the wireless link, to perform certain tasks at times not anticipated when the static data loggers were put out.

However the dense forest which can severely attenuate radio signals, with far less light reaching the forest floor than above the canopy - making solar panel power more difficult, as well as the weather extremes that can blow over antennas or otherwise yank the radio equipment around, plus the deterioration to sensitive electronic equipment by the humidity, heat, and moisture, all make it challenging to connect up the ultimate sensors no matter where they are and must be, reliably to the Research Center and the Internet, where distant researchers can access them. (Of the 60 research scientists working with the El Yunque Experimental Forest LTER, only a small number are year around in Puerto Rico).

You may click on this next link to bring up an enlarged view, fitting one browser screen, of the El Yunque forest. In green is highlighted the three Weather Stations which are the special research project of Dr. Doug Schaefer, whose offices at the Center for Tropical Studies are on the grounds of the Medical Center part of the University of Puerto Rico, in San Juan -20 miles from the forest. It also shows the area around the top of El Toro mountains where two subspecies (Eneidae, and Richmondi) of the Coquigenus Eleutherodactylus - exist, and are studied, and which the U.S. Forest Service biologists study in loose collaboration with the NSF LTER project and which they wish we could connect wirelessly. Then in white, the dominant peak 'Pico el Yunque' at 1050 feet is shown, where there is a large concentration of communications towers, and which will probably have to be used by the LTER project to reach, wirelessly at affordable recurring costs, San Juan. Which is a separate University and LTER project from this NSF project - but which project will have to depend on the links back to San Juan from El Verde Field Station, and the data collection points in the forest.

And RF interference with the low power radios we expect will be most useful where economics is also an issue.


The high bandwidth link from El Verde Research Station (and its associated 'Stream House' buildings about 1.5 miles north along Road 186) is NOT part of this NSF wireless project. It IS however part of the LTER NSF Funded LTER Project under Jess Zimmerman. But it's a critical requirement before any of the data from the field locations will be able to be accessed via the Internet at large - beyond El Verde. So the LTER is negotiating with Open Minds Company, to provide that links - both data and voice - back to the Ecological Institute's premises in San Juan. The url below is a proposed schematic wireless, and voice over IP solution by OMC.

Open Minds (OMC) Proposed Links:




The El Verde Research Center is inside the forest. It is the base of operations for field experiments into the forest. It has minimum living accommodations for researchers, and buildings where the desktop computers available for work reside.



The current location of one of the weather stations managed by Dr. Doug Schaefer is on the building which houses the computers. Its' data loggerleads extend into the building. It is not an ideal place for it to be, far below the canopy. So it is being moved to the top of the 75 foot tower which sits at 350 feet of elevation, just south of the Research Station, and about 300 feet away.


Thus this will be one of the tower-weather station sites (we will call it arbitrarily weather station #1) to be linked to the Internet. But it is likely that the most efficient way to do this will be to lay cable from the Campbell CR10X data logger the short distance to the computer center. But the tower above the canopy will be used to mount the El Verde base radio and antennas, for communications with both the wireless link to the top of Pico el Yunque, where its' corresponding radio will be interfaced to whatever link is made to San Juan, 20 miles away, and the Ecological Studies Center. Whether this radio on Tower #1 will, or can, directly communicate with the radios on Towers 2 and 3 remains to be seen. Only the physical test from on the top of the towers will determine that. A previous helium 'balloon' test at Tower #1 at El Verde by Mike Willett shows that an antenna high enough above the 75 foot Tower #1 can be seen directly from a radio tower complex on the top of El Yunque.



The second Weather Station is in an area named after a stream, Bisley. This one is sampled by the collaborative National Forest Service researchers, under the supervision of Dr. Fred Scatena shown here at the Catelina NSF Field Office - one of the two places (the other being the Sabana Work Center) on the eastern half of El Yunque from which the National Forest Service works and administers the 'Caribbean National Forest' - El Yunque.

It is a jeep ride over roads closed to the public to get to the Bisley area, where, after a 1/2 mile climb through the forest to a ridge at the same 350 foot altitude level as Weather Station #1 at El Verde, one reaches Tower and Weather Station #2 - the Bisley Weather Station.

This tower is over 110 feet high, clearing the canopy, and with a good view blocked only by the terrain forms, in every direction, including the top of El Yunque, and the location of Weather Station #3 on Pico del Este, 700 feet higher in elevation. This station also tracks Min/Max Temperatures, Relative Humidity, Precipitation, Wind Direction and Speed. But it also, reflecting an interest by researcher Fred, contains devices for measurements with a quantum light sensor, which measures a wide range of light spectrum, including IR, as well as a PARE light sensor, which is primarily sensitive to the light spectrum most effective in the photosynthesis process of plants.

At the bottom of the tower is a second Weather Station, used for spare parts for the first, but also collects data at the forest floor to be compared with the collectors at the top of the Tower above the trees.

Close by is a third data collector station, which is on a stream, where stream data - a specialty of Dr Scatena - resides. This is discussed in Progress Report 7. We will be working with the technician stationed at Sabena under Fred Scatena's supervision when we install the wireless at Bisley and Pico del Este, so he learns how to handle the wireless, and further develop or troubleshoot it.

The Bisley sites, however, will pose a substantial challenge to supply sufficient recharge power to the battery systems serving both the weather stations. Solar power may not be enough.



The third weather station we have been asked to link up, is high on a ridge near the Naval Radar Facilities on Pico Del Este, reachable by a closed to public very rough (in stretches) road, generally requiring a 4 wheel drive vehicle. This high area gets large quantities of rain, and is often 'in the clouds.'

This weather station is low to the ground, only rising perhaps 10 feet from its base, but on a saddle of the ridge open to the north. It has all the elements of the other stations, with one interesting exception. It has a 'Cloud Drip' collector that is designed to capture and measure the water which collects and condenses on vegetation as the wind pushes the ever present low fog-like clouds over the 1000 foot ridge. At one time when a researcher reported more water coming down the mountain than could be accounted for by rainfall, it was concluded that the balance 'may come from cloud drip.' This station tests that thesis. The prevailing winds may make our use of wind generated recharge power feasible, and more useful than solar panels.


On the way down from Pico del Este, we spotted some of the wildlife that inhabit the forest. A large Iguana, which Dr. Scatena states is rarely seen this 'high' because of the colder climate on the higher ridges and hills.



Our site survey of the three Weather Station sites clearly show the problems we face. Since all three stations use similar Campbell Scientific sensors and data loggers (they will be concentrating on using the CR10Xseries), we should have little problem interfacing them to the data radios. But getting the date radios to link to each other and the El Verde Research Center reliably, and maintain rechargeable power at each site, will pose the biggest challenge.

In Progress Report #7 I will detail other work we will do in the future, after the three Weather Stations are satisfactorily linked to El Verde, the Tropical Studies Center in San Juan, and the Internet at large.

Dave Hughes

Principal Investigator


Note - there are two textual reports accompanying this Progress Report.

1. Report by Engineer Mike Willett who accompanied me and drew his own conclusions. It is a 'sub' report like the Progress Reports, but only accessible from here.

2. An informal narrative report on this trip by me.