|About the Buoy Technology|
This instrument measures wind speed, wind gust, and wind direction. Standard CBIBS instrument is an R. M. Young 5103. Wind speed is measured by the propeller, and direction is measured by the orientation of the instrument, which is aligned by the vane opposite the propeller. Orientation is measured in degrees relative to the buoy, so the buoy's own magnetic orientation is measured using a fluxgate compass.
The antenna enables the buoy to transmit data to the shoreside computer via broadband data communications.
GPS Receiver/Satellite Transmitter
The buoy's position is reported via a GPSantenna/receiver system. The GPS is part of an INMARSAT-D transponder system mounted on the buoy. If the cellular communications should fail, or the buoy were to go adrift and out of cellular range, the INMARSAT satellite communications system could be activated to get continuous basic information on buoy position and health.
The solar panels provide power for the buoy's sensor and transmission capabilities. There are four solar panels on each buoy; each panel can generate 20 watts of power to keep the buoy's batteries charged.
Computer and Communications
Inside the upper section of the buoy, in waterproof housings, are the electronic components. A power regulator maintains the batteries charging by the solar panels; a computer(AXYS Watchman 500) collects data from the sensors and formats messages for transmission; and a CDMA modem active on the Verizon Wireless network transmits data over the internet to the main CBIBS computer. Also within this enclosure are the buoy's barometric pressure sensor and an electronic fluxgate compass to determine buoy orientation.
Cables to Acoustic Current Profiler
Cables connecting instruments mounted in the buoy's 10-inch diameter through-hull instrument wells are protected by heavy rubber hose.
Water Quality Monitor
The "WQM," which includes multiple integrated sensors, measures pressure (depth), water temperature, and conductivity (from which salinity is calculated); dissolved oxygen concentration; and turbidity and chlorophyll-a concentration using optical sensors. The standard CBIBS instrument is a WETLabs WQM mounted in the buoy well approximately 0.5 meters below the surface.
Acoustic Current Profiler
The profiler provides current speed and current direction at one-meter levels from the surface to the bottom. The current as reported on the CBIBS website and database is an average of the upper 5 meters. The CBIBS standard instrument is a NORTEK AquaDopp. It measures currents by analyzing acoustic(1 mHz frequency) reflections from the moving water below the instrument over a five-minute period once per hour.
Wave Measurement System
The buoy uses an AXYS TriAXYS directional wave sensor to measure waves. The sensor has precision accelerometers, angular rate sensors, and a compass, sampled four times per second. The waves that affect the buoy are estimated by analyzing buoy motion for a 20-minute period every hour. The buoy reports numerous parameters including mean wave height, significant wave height, and maximum wave height, as well as several measures of wave direction and wave period.
Inside the hull is a sealed steel battery case, housing four 100 A-h 12 volt batteries that run the buoy systems.
AXYS Technologies Watchkeeper Buoy
The is the yellow buoy itself. Each AXYS Watchkeeper buoy is 14 feet tall - roughly 10 feet above the waterline. They are based on a modified Tideland Signal P138 buoy hull. The 138 means that when the buoy is floating on its design waterline, located at the wide (1.75 m diameter) part of the hull, it takes 138 lbs to displace it one more inch. Buoys weigh around 1,300 pounds and made out of 1/2" thick rotomolded polyethylen - a durable plastic. The lower section of the buoy hull is filled with cement, the rest of the hull with closed cell foam and a sealed battery case.
Each CBIBS buoy is moored to the Bay bottom by way of a two-point chain bridle and 1" mooring chain connected to a 2,500 lb. steel anchor. The anchor is actually three repurposed railroad wheels. The chain length is approximately 2.5 times the water depth at the buoy's location.
Wind speed describes how fast the air is moving past a certain point at a certain time. CBIBS tracks this as a running mean over the previous 10 minutes. CBIBS measures wind speed in nautical miles per hour, or knots; it is also available in miles per hour (mph) and meters per second (m/s). Wind speed affects sea state (calm or wavy) as well as the mixing of water in the Bay.Go back to Previous Page
Temperature is how hot or cold something is as measured on a definite scale. CBIBS buoys measure air temperature in degrees Celsius and also convert this measurement into degrees Fahrenheit. Technically, heat is an indicator of the kinetic energy, or energy of motion, of the gasses that make up the air. As gas molecules move more quickly, air temperature increases. CBIBS buoys report air temperature as a 10-minute average.Go back to Previous Page
Barometric pressure--also referred to as air pressure--is the weight of the overlying air pressing down on the Earth. Barometric pressure is usually reported in inches mercury--inches Hg. Low barometric pressure means air is rising, while high pressure means the overlying air is sinking. Barometric pressure affects water chemistry and weather. Generally, high pressure (± 31 inches Hg) supports sunny, clear weather. Low pressure (~ 28 inches Hg) promotes rainy and cloudy weather conditions. Big changes in barometric pressure indicate big changes in weather. Barometric pressure can also affect the amount of a gas that can dissolve in water. When barometric pressure is high, more oxygen can be dissolved into the waters of the Bay; when the pressure is low, less oxygen can be dissolved into water. CBIBS buoys report barometric pressure as a 10-minute average.Go back to Previous Page
Chlorophyll is the main chemical responsible for photosynthesis in plants, the process by which sunlight is converted into food energy. To track chlorophyll levels, the CBIBS buoys measure the amount of algae in the water in micrograms per liter (ug/l). This is reported as an hourly average. Algal blooms can be very damaging to Bay habitats because they can drive dissolved oxygen concentrations to very low levels. Excess algae, usually caused by an excess of nutrients which stimulate their growth, can also make the water cloudy, or increase turbidity, blocking the light needed by underwater grasses to survive. These damaging algae blooms, which can also produce toxins in some cases, are collectively known as harmful algal blooms. There are no hard and fast rules as to what constitutes a harmful concentration of chlorophyll, but as a general guide, above 50 ug/l represents a significant algal bloom, and above 100 ug/l represents a severe bloom. Some research suggests that harmful effects can occur at chlorophyll concentrations as low as 15 ug/l.
Conductivity is the measurement of a substance's ability to conduct electricity. This is reported in S/m as an hourly average. Water conducts more electricity as chemicals such as salt are added to it. Like salinity, the conductivity of water influences the water's chemistry and helps determine which living resources are adapted to exist there.Go back to Previous Page
Current direction is the direction on a compass toward which water is moving. For example, a current direction reading of 90° indicates that the current is running toward the east. This is reported as an hourly average. Current direction is affected by tides, wind, and the shape of the water body.Go back to Previous Page
Current is a movement of water; current speed is the speed of this movement. CBIBS buoys measure current speed in nautical miles per hour, also known as knots. This is reported as an hourly average.Go back to Previous Page
The amount of oxygen dissolved in Bay waters is probably the single most important measure of habitat quality; without oxygen, living resources die. Dissolved oxygen (DO) is measured in milligrams per liter (mg/l). This is reported as an hourly average. When DO concentrations drop below 5 mg/l, the Bay's more sensitive organisms, such as fish, become stressed, especially if exposed to these conditions for prolonged periods. DO is affected by several factors. Temperature affects the concentration, because warmer water cannot dissolve as much oxygen as colder water. Salinity also affects the amount of dissolved oxygen; freshwater can hold more dissolved oxygen than can salt water. Photosynthesis by plants adds dissolved oxygen to the water. Because photosynthesis occurs during the day, dissolved oxygen is usually higher during the day and lower at night.
Relative humidity is the ratio, of the amount of moisture present in the air to the total amount of moisture that the air can hold at the same temperature. For example, if the relative humidity is 50%, then the air is only half saturated with moisture. This is reported as a 10-minute average. Without humidity, there would be no clouds and no precipitation. Warmer air can hold more moisture than colder air. Additionally, water vapor holds heat in the air--this is why humid air feels warmer.Go back to Previous Page
Salinity is the concentration of salt in the water. CBIBS measures salinity in practical salinity units--PSUs. (Salinity is also available in parts per thousand--ppt.) Salinity levels are a function of the mixing of ocean waters, which contain approximately 32 ppt (parts per thousand) salinity with freshwater from the Bay's tributaries (< 1 ppt salinity). This is reported as an hourly average. Salinity is an important factor in determining where the Bay's plants and animals live and in some cases when the animals reproduce or migrate. In any given location, salinity can vary greatly depending upon river flow, being low during high flows and high during droughts. Most of the Bay's living resources are adapted to these large swings in salinity, but extreme floods or droughts can lead to stressful conditions.Go back to Previous Page
Turbidity describes how clear the water is. This is measured using a transmissometer, which records turbidity values in nephelometric turbidity units (NTUs). This is reported as an hourly average. Turbidity values over 15 NTUs are detrimental to Bay grass growth because the cloudy water blocks sunlight from reaching the grass. Increased turbidity can also lead to decreased fish health by increasing susceptibility to infectious diseases through increased stress and reducing the ability of fish gills to extract dissolved oxygen from the water. Areas of high turbidity can also cause the silting over--burying alive--of benthic organisms.
The mean wave height is the average height of the waves--from crest to trough--that pass by the buoy. Measurements are based on data observed between 30 and 50 minutes past each hour as a representative sample of wave action. Mean wave height is the average wave height observed during this 20-minute time period.Go back to Previous Page
Significant wave height is the average height--from crest to trough--of the highest one-third of waves recorded in a given monitoring period at a buoy. Wave measurements are reported by CBIBS buoys every hour. Measurements are based on data observed between 30 and 50 minutes past each hour as a representative sample of wave action. Significant wave height is therefore the average height of the highest one-third of waves recorded during this 20-minute period.Go back to Previous Page
Significant wave period is the time that passes between two successive wave crests that move past a buoy. Wave measurements are reported by CBIBS buoys every hour. Measurements are based on data observed between 30 and 50 minutes past each hour as a representative sample of wave action. Significant wave period is the average wave period during this 20-minute time.Go back to Previous Page
Wind direction describes the direction on a compass from which the wind comes. For example, a wind direction reading of 90° indicates that the wind is coming from the east. This is an average over the previous 10 minutes.Go back to Previous Page
Wind gust describes the fastest wind speed recorded. At CBIBS buoys, this is the highest five-second running mean recorded during the previous 10-minute period. CBIBS measures wind gust in nautical miles per hour, or knots; wind gust is also available in miles per hour (mph) and meters per second (m/s).Go back to Previous Page