The "U-Tube": An Improved Aspirated Temperature System for Mobile Meteorological Observations, Especially in Severe Weather.

Obtaining quality air temperature measurements in complex mesoscale environments, such as thunderstorms or frontal zones, is problematic and is particularly challenging from a moving platform. For some time, mobile weather platforms known as mobile mesonets (MMs) have used custom aspirated temperature shields. The original design was known as the "J-tube," which addresses some but not all of the unique problems associated with mobile temperature measurements. For VORTEX2 2009, a second, well-documented shield, the R.M. Young (RMY) 43408, was included but was also found to have certain shortcomings in some severe weather environments. Between the end of VORTEX2 2009 and the start of VORTEX2 2010, a third and new shield called the "U-tube" was designed, tested, and installed. Reported here are the results of efforts to better characterize the J-Tube, RMY 43408, and U-tube. Several tests designed to isolate key aspects of a radiation shield's performance, such as performance in rain, high solar radiation, varying wind conditions, and general response time, were completed. A period of intercomparison among the three shields during the 2010 season of VORTEX2 is also used to highlight each shield being used in "real world" conditions. Results indicate that the U-tube has several significant advantages over the J-tube and 43408 in terms of aspiration rate, sampling efficiency, performance during rain, variable winds, and high solar radiation periods, as well as response time. Given these results, the U-tube should be utilized for mobile observations going forward. Significance Statement: Observations of the atmosphere are a critical component of research, particularly that involving severe weather. Errors, biases, and incorrect readings of these observations can cause problems during analysis or lead to incomplete or even incorrect conclusions. Radiation shields used for temperature observations are used to protect sensors but can have a significant effect on the observations themselves. Older radiation shields such as the "J-tube" are shown here to have some potential problem areas when using them to house temperature sensors. A new shield, the "U-tube," has been created to mitigate these effects and to provide a functional radiation shield capable of performing in a wide range of conditions, from severe weather (thunderstorms, hurricanes, etc.) to more calm weather. [ABSTRACT FROM AUTHOR]