Water vapor measurements on the Tibetan Plateau are crucial for understanding regional weather. Radiosonde data showed drier conditions compared to ground-based GPS measurements. Different sensors had varying levels of dry bias. New sensors reduced this bias over time. The dry bias varied throughout the day and year, with higher biases in the afternoon and summer. Solar heating of sensors likely contributed to these variations. Calibration methods were developed to correct the dry bias in the radiosonde data.