An Improved Aspirated Temperature System for Mobile Meteorological Observations, Especially in Severe Weather

It is unarguable that air temperature measurements being made in any meteorological field project are of the highest possible quality. It is also unarguable that regardless of the accuracy or sensitivity of a temperature sensor itself, there are a wide variety of field environment factors that can degrade the quality of the temperature measurement. Additionally, in severe weather conditions these factors change rapidly, requiring constant awareness as to their influence on instrumentation and measurements. Since the original Verification of the Origin of Rotation in Tornadoes Experiment (VORTEX) project in 1994, mobile weather platforms known as the Mobile Mesonet have used an aspirated temperature shield called a “J-tube” that address some of these factors encountered during severe weather. Since the implementation of the J-tube, its use outside of the original design limitations has raised questions about the quality of some of the data collected. This paper examines the task of developing and fielding a more robust, versatile, and higher quality aspirated temperature measuring system, called the “U-tube,” for mobile use in both severe and non-severe environments. The U-tube expands upon the J-tube's design, addressing issues such as sensitivity to ambient wind speed and direction, solar radiation, rain, and time constant effects (gradient dampening) due to upstream thermal masses. For 6 weeks during the 2010 season of VORTEX2, data were collected consisting of continuous comparisons between the U-tube, the J-tube, and a model 43408 RM Young Aspirated Radiation Shield on seven Mobile Mesonet vehicles in both severe and benign meteorological conditions. Analyses suggest that the U-tube has considerable advantages over the J-tube.