Assessing the Impact of Instrument Changes on Critical Atmospheric Measurements
Measurements of temperature and humidity profiles are critical to a range of atmospheric and climate studies. ARM scientists assess the impacts of instrument changes on these measurements.
Manufacturers are continuously upgrading and updating their instrumentation. Changes in sensitivity or performance characteristics of observational instruments can have big impacts on scientific studies that use data from two different instrument versions. Scientists at the Department of Energy’s (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility performed a careful study to assess the impacts of a new version of the radiosonde sensor, a critical instrument for measuring profiles of atmospheric temperature and humidity.
A comparison of 20 twin-radiosonde balloon flights shows that the new (RS41) and older (RS92) radiosonde sensors generally agree within the manufactured-defined uncertainties of the instruments. Exceptions were noted after traversing liquid cloud layers where instrument wetting and evaporative cooling impacts were mitigated in the RS41. For many science applications, a switch from the RS92 to RS41 will likely have little impact.
In June 2014, 20 twin-radiosonde balloon flights were performed at the ARM Southern Great Plains site to evaluate and quantify differences in atmospheric state variable measurements from the current-generation Vaisala RS92 and next-generation RS41 radiosondes. Complementary observations from the ARM site were used to put these measurements in context, including Ka-band ARM zenith radar (KAZR) observations for documenting cloud occurrence and microwave radiometer observations for integrated water vapor. Efforts were made to sample the diurnal cycle and a variety of cloud and weather conditions. The results show small biases and root mean square differences between the radiosonde measurements over all conditions and heights. A closer examination shows that when exiting liquid cloud layers the RS41 measurements show less impact related to instrument wetting and evaporative cooling.
Brookhaven National Laboratory
This research was supported by the Department of Energy (DOE), Office of Science, Office of Biological and Environmental Research as part of the Atmospheric Radiation Measurement Climate Research Facility, a DOE user facility.
Jensen, M. P., D. J. Holdridge, P. Survo, R. Lehtinen, S. Baxter, T. Toto, and K. L. Johnson. 2016. “Comparison of Vaisala Radiosondes RS41 and RS92 at the ARM Southern Great Plains Site,” Atmospheric Measurement Techniques 9, 3115-29. DOI:10.5194/amt-9-3115-2016.