Temperature compensation

Temperature corrections for the speed of sound must be applied to the readings by using temperature measurements from a reliable and accurate temperature sensor, such as the TempVue 10. The data logger program can use the following equation to apply temperature compensation to the SnowVue 10 output:

The SnowVUE_Sample.CRB example program (available at www.campbellsci.com/downloads/snowvue10-example-programs ) uses the following expression to apply the temperature compensation to the distance measurement :

'Distance corrected for speed of sound due to air temperature

TCDT=DT*SQR((AirTC+273.15)/273.15)

Where,

TCDT is the temperature corrected distance value.

DT is the variable containing the distance measurement.

AirTC is the variable containing the temperature measurement used to temperature compensate the distance measurement.

The SnowVue 10 can also internally apply temperature compensation by using the aXWT+CC.C! extended command (SDI-12 commands). To do this, the CRBasic program needs to convert the temperature measurement to a formatted string by using the Sprintf() instruction and then set the reference temperature measurement in the sensor by using the aXWT+CC.C! command. The SnowVUE_Sprintf_Example.CRB example program (available at www.campbellsci.com/downloads/snowvue10-example-programs ) uses this method to apply the temperature compensation.

CAUTION:

The SnowVue 10 calculates distance readings using the speed of sound at 0 °C (331.4 m/s). If the temperature compensation formula is not applied, the distance values will not be accurate for temperatures other than 0 °C.