Network Equipment
Cooperative observers use a variety of equipment
types. The type used will depend on what services are needed at a particular
station. Most observers report at least 24-hour precipitation; some will also report
snowfall, high and low temperature. Fewer observers report evaporation measurements,
river stages, soil temperatures, or solar readings.
Precipitation Gages
(Rain gage at station Athens 2SW. Click to enlarge.)
This rain gage is what most observers use. It is called a "Standard Rain
Gage" (SRG), and consists of a funnel 8 inches in diameter, leading to a tube inside
the gage. The inside tube can hold up to 2 inches of rain; any excess will flow into
the main container to be measured after the inside tube is emptied. The rainfall is
measured using a specially calibrated dipstick. During the winter, the funnel and inside
tube are removed; snow falls into the main container, and then is melted to determine the
liquid equivalent of the snowfall.
 (Recording
rain gage at station Flora 5NW. Click to enlarge.)
Selected stations have a recording rain gage. Inside the gage is a bucket on a
scale. Every 15 minutes, a punch block inside punches a hole onto a paper tape,
indicating the level of the bucket's contents. Using this tape, hourly amounts of
precipitation can later be determined. Each month, the observer removes the tape,
and mails it in for processing. Upgrades to this gage are beginning, to replace the tape punch
feature with an electronic data logger.
Temperature Gages
 (Thermometer
shelter at the University of Illinois. Click to enlarge.)
Some stations use mercury and alcohol thermometers to register high and low temperatures.
The thermometers are kept inside a ventilated box called a Cotton Region Shelter
(CRS, so named because of the location where they were first used). The maximum
thermometer pushes the mercury to the highest temperature observed that day, where it stays until it is reset by
the observer. The minimum thermometer has a small pin inside, which marks the low
temperature.
 (Electronic
temperature shelter at station Loami 3SSW. Click to enlarge.)
Many temperature-reporting stations use electronic thermometers in place of the
mercury thermometers. This particular system is called a Maximum-Minimum Temperature
System (MMTS). The sensor is mounted outside, and cables are routed to a digital
display inside a nearby building. The digital readout logs the high and low
temperatures until reset by the observer. The next generation of MMTS
will log high and low temperatures
from midnight to midnight (some stations log high and low temperatures currently from 7 am
to 7 am, or 6 pm to 6 pm) and keep the last 30 days of observations in memory.
River Gages
 (Staff
gage at Havana. Click to enlarge.)
Some observers read river levels using a staff gage. These gages are basically large
rulers mounted or painted onto objects such as bridge supports, walls, etc. River
levels are read from this gage to the nearest tenth of a foot.
 (Wire weight gage.
Click to enlarge.)
At some locations, river levels are read using a wire weight gage. This type of gage
has cable wound around a drum; a brass or bronze weight is attached to the end of the
cable. A crank is used to lower the weight to the surface of the water; a counter
and disk on the crank handle indicates the river reading, usually to a hundredth of a
foot.
 (Data
Collection Platform at Allenville, IL. Click to enlarge.)
Many river levels are read using automated methods. Data Collection Platforms (DCP)
collect the river level readings, and relay them via satellite or telephone lines.
Inside the DCP houses, river levels may be determined using nitrogen gas, voltmeters, or
electrical tapes. Many of these DCP sites also have a staff or wire weight gage for
backup purposes, especially if river forecasts are issued.
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