The Sonde-Adjust VAP produces data that corrects documented biases in radiosonde humidity measurements. Unique fields contained within this datastream include smoothed original relative humidity, dry bias corrected relative humidity, and final corrected relative humidity. The smoothed RH field refines the relative humidity from integers — the resolution of the instrument — to fractions of a percent. This profile is then used to calculate the dry bias corrected field. The final correction fixes a time-lag problem and uses the dry-bias field as input to the algorithm. In addition to dry bias, solar heating is another correction that is encompassed in the final corrected relative humidity field.
For more details, see Sonde Adjust Value-Added Product technical report.