Comparison of AWOS, RSOIS, and Mesonet Dew Point Observations

Accurate dew point temperature measurements are critical to their utilization in various thermodynamic equations. Automated Weather Observing System (AWOS), Radiosonde Surface Observing Instrumentation System (RSOIS), Oklahoma Mesonet, and National Weather Center Mesonet atmospheric data at Norman, Oklahoma, USA were analyzed to determine the sensitivity of dew point temperatures to other derived thermodynamic variables. An inter-comparison of Radiosonde Surface Observation Instrumentation System dew point temperature observations with the National Weather Center Mesonet tower located 100 yards to the north of RSOIS indicate significant differences in surface dew point values. These RSOIS errors manifest as spurious moist layers at the surface in the NWS upper air sounding observations. It is not known how widespread this issue is and the impact of these spurious moist layers are significant when using soundings to determine aviation parameters such as cloud base, and severe weather parameters such as CAPE and LCL height. Additionally, extensive side-by-side comparisons were conducted between well calibrated Oklahoma Mesonet and existing AWOS IIIP/T sites in Oklahoma. Preliminary data analysis indicates that AWOS IIIP/T surface dew point data are unreliable. AWOS IIIP/T dew point temperatures are observed to be off by 3-5°F during certain times of day and during certain weather conditions.