Precipitation
Precipitation measurements are made with an RM Young 50202 precipitation gauge. Precipitation is collected in a funnel whose cross sectional area is 100 cm2. After capture, it is drained from the funnel to a 20 cm2 cross-section measuring tube. A capacitive transducer located in the center of the tube senses water column height, while an integrated electronic circuit converts the capacitance value to a calibrated voltage proportional to collected precipitation. When the water column becomes full, additional precipitation starts the siphon process which empties the siphon in approximatively 30 seconds. Thus, the water level in the tube returns to 0 mm and the output voltage goes to 0 V. Then the cycle is repeated, and so on. The evaporation rate is assumed to be negligible between two siphoning events. The water column height, and thus precipitation amount collected at any given time, ranges between 0 to 50mm precipitation, with a detected accuracy of 1mm. A self-contained thermostatically controlled heater allows the gauge to operate at temperatures as low as -20°C. Therefore, when snow is encountered, it is melted so that an equivalent amount of rainfall is measured. The precipitation gauge is installed on the roof of the main bridge, on a small mast.
The rain gauge is secured to a mast on top of the main bridge.	The rain gauge is shown in the center of the picture.