1. Radiosondes launched at NSA during the WVIOP04 VAISALA RS90 (operated by ETL and ARM) 4 times per day at the ARM duplex (00, 06, 12, 18 UTC) 1 time per day at the ARM “Great White” site (00 UTC) Humidity sensor: H-Humicap Meteolabor “SNOW WHITE” (operated by NASA) 5 during the night, 3 during the day Humidity sensors: VIZ Carbon Hygristor; Snow White Chilled Mirror Sondes VIZ-B2 (from National Weather Service) 2 times per day in Barrow (00, 12 UTC) Humidity sensor: VIZ Carbon Hygristor Dual launches: Vaisala RS90 and Snow White at the ARM duplex

2. Comparisons of relative humidity measurements

3. Comparisons of PWV from RAOBs