Precipitation Measuring Instruments
Non-Recording Gauges
Volume of collector must equal volume of measuring tube. So: where: R = radius of collector, D = depth of water through collector, r = radius of measuring tube, d = depth of water in measuring tube.
British Standard Rain Gauge
Canadian Standard Rain Gauge
PPT Slide
Recording Instruments
Advantages:
Tipping Bucket Gauge
Momentary current drives pen arm to record 0.01 inch of precipitation each time bucket flips.
Rate-of-Rainfall Recorders
Optical Rain Gauge
Rain Gauge with Alter Shield
Another type Alter Shield
Turf Wall Rain Gauge
Measurement of Snow
Snowcover: Areal extent of snow covered ground expressed as a percent of the total area of a given region.
Snow Sampling Tube: 8 or 3 inch diameter tube.
Snow Stick: A pre-placed measuring stick.
Acoustic Snow Depth Gauge
Snow Pillows
.
Billions of sand-sized meteorites enter the atmosphere daily. As each particle heats and burns in the region 50-75 miles above the surface, its disintegration creates a trail of ionized gases. These diffuse rapidly disappearing within a second. The process is long enough for SNOTEL communications. The process involves: (1) Master station sending request, (2) Site responds by transmitting data, (3) master station acknowledges receipt and site stops transmitting.
Representativeness
Accuracy of point-source measurements
Instrument Error
Non-uniformity of gauges and procedures
Recommendations
ASOS Precipitation Accumulation Sensor
Precipitation Identification Sensor
Two modulation frequencies are used.
Freezing Rain Sensor
Reporting Precipitation by ASOS with freezing rain
Obstruction to Vision
Email: alcorn@ariel.met.tamu.edu
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