Keywords: pdbi-amp-cal

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## No Nitrogen available : AUTO mode

Another alternative is to assume that you know the water vapor content, either from a previous measurement and assuming the weather is stable, or from theoretical curves as a function of pressure, temperature and relative humidity. With the knowledge of the atmospheric parameters, the model predicts and . In this mode, instead of above, you must supply the amount of precipitable water vapor in millimeter. is then given by (from Eq. 7)

| (11)

This is what happens in OBS when used in AUTO mode (specified by `OBSSET CAL AUTO`) and when you do a CAL command without the argument COLD.