RS-11G GRUAN Data Product Version 1 (RS-11G-GDP.1)

This dataset comprises reference radiosoundings performed with the Meisei RS-11G. Reference in this case means that: all known biases are corrected for, best possible vertically resolved uncertainty estimates, well-documented correction algorithms, extensive meta data collection.

The GCOS (Global Climate Observing System) Reference Upper-Air Network (GRUAN) data processing for the Meisei RS-11G radiosonde was developed to meet the criteria for reference measurements. These criteria stipulate the collection of metadata, the use of well-documented correction algorithms, and estimates of the measurement uncertainty. An important and novel aspect of the GRUAN processing is that the uncertainty estimates are vertically resolved. The algorithms that are applied in version 1 of the GRUAN processing to correct for systematic errors in radiosonde measurements of pressure, temperature, humidity, and wind, as well as how the uncertainties related to these error sources are derived. The RS-11G was regularly launched at Tateno (TAT) between July 2013 and September 2017 and during January to February, 2018. It has also been regularly launched at Syowa (SYO) since March 20th, 2018.

An additional GRUAN requirement for performing reference measurements with the RS-11G is that the manufacturer-prescribed procedure with the indoor environment for the radiosonde's preparation and the supplementary procedure with the Standard Humidity Chamber (SHC) at 0 %RH and 100 %RH environment are followed. The reference measurements with SHC are applied for the recalibration of the humidity sensors. For the dominant error source, solar radiation, laboratory experiments were performed to investigate and model its effect on the RS-11G's temperature and humidity measurements.

GRUAN uncertainty estimates are 0.22 K for night-time temperature measurements and approximately 0.30 K at 25 km during daytime. The other uncertainty estimates are up to 8 %RH for humidity, 50 m for altitude, 0.1 hPa for pressure, 1 m/s for wind speed, and 1° for wind direction.

Intercomparison measurements with Vaisala RS92-GDP show that the temperature of RS-11G-GDP is 0.4 K lower than RS92-GDP in the stratosphere at daytime. For the relative humidity measurements, the difference of RS-11G-GDP from RS92-GDP is -2 %RH under 90 – 100 %RH conditions and 5 %RH under <= 50 %RH conditions. Intercomparison measurements with the cryogenic frostpoint hygrometer (CFH), RS-11G gave 1 – 10 %RH higher values than the CFH in the troposphere.