GCOS Reference Upper-Air Network


Comparison of the GRUAN data products for Meisei RS-11G and Vaisala RS92-SGP radiosondes at Tateno (36.06° N, 140.13° E), Japan


Kobayashi, E., Hoshino, S., Iwabuchi, M., Sugidachi, T., Shimizu, K., and Fujiwara, M.



by Atmospheric Measurement Techniques (AMT) at 2019-06-04



A total of 87 dual flights of Meisei RS-11G radiosondes and Vaisala RS92-SGP radiosondes were carried out at the Aerological Observatory of the Japan Meteorological Agency (36.06°N, 140.13°E, 25.2m) from April 2015 to June 2017. Global Climate Observing System (GCOS) Reference Upper-Air Network (GRUAN) data products from both sets of radiosonde data for 52 flights were subsequently created using a documented processing program along with the provision of optimal estimates for measurement uncertainty. The authors then quantified differences in the performance of the radiosondes using GRUAN data products. The temperature measurements of RS-11G were 0.4K lower than those of RS92-SGP in the stratosphere during daytime observation. The relative humidity measurements of RS-11G were 2‰RH lower than those of RS92-SGP under 90–100‰RH conditions, while RS-11G gave 5‰RH higher values than RS92-SGP under ≤ 50‰RH conditions. The results from a dual flight of RS-11G and a cryogenic frostpoint hygrometer (CFH) also showed that RS-11G gave 1–10‰RH higher values than the CFH in the troposphere. The authors additionally investigated the RS-11G minus RS92-SGP difference of temperature and relative humidity based on combined uncertainties to clarify major influences behind the difference. It was found that temperature differences in the stratosphere during daytime observation were within the range of uncertainty (k=2), and that sensor orientation is the major source of uncertainty in RS92-SGP temperature measurement, while sensor albedo is the major source for RS-11G. The relative humidity difference in the troposphere was larger than the uncertainty (k=2) after the radiosondes had passed through the cloud layer, and temperature-humidity dependence correction was the major source of uncertainty in RS-11G relative humidity measurement. Uncertainties for all soundings were also statistically investigated. Most night-time temperature differences for pressures of >10hPa were in agreement, while relative humidity differences in the middle troposphere exhibited significant differences. Around half of all daytime temperature differences at pressures of ≤150hPa and relative humidity differences around the 500hPa level were not in agreement.





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