The construction and installation of a rainfall or snowfall measurement station is shown above. The collector can be a polyester or plastic pipe, with a tube connection in the bottom and room for the logger below the bottom. The maximum height of the collector is fixed by the measurement range of the Differential Logger which is 2 meters. The diameter and length of the collector have to be adjusted to the expected rain during the period of measuring. The snowfall station should have an anti freeze reservoir on top to melt the snow.
The reservoir logger room must be situated below the ground surface
to keep the logger room temperature as constant as possible to prevent
unreliable pressures due to temperature variations. Realize an air compensation
inlet in the logger reservoir room to compensate for the air pressure,
avoid water coming in through the air compensation inlet.
The differential logger will register the water pressure in the reservoir
and is automatically compensated for the air pressure so it will immediately
register the water level in the reservoir. If the measurements take
place during a period in which frost could occur anti freeze should be
used to protect the sensor for ice. Pressure sensors can NOT withstand
direct contact with ice.
In the Tirtaharapan Data Viewer software the raw data of the differential logger can be converted to milli meter rainfall. Compensations can be applied for evaporation and for the difference in density of the antifreeze and water.
In area's with little rainfall or when measuring for short periods you can amplify the measurements by using a funnel with a larger diameter then the pipe. If the square area of the funnel is twice as big as the square area of the pipe 1 milli meter of rainfall will give 2 milli meter difference in the pipe. In this way your measurements are more accurate, in the Tirtaharapan Data Viewer software you can divide the values again so that they represent the actual amount of rainfall again.