Comparison of Vaisala Radiosondes RS41 and RS92 at the Southern Great Plains Site

 

Authors

Michael Jensen — Brookhaven National Laboratory
Donna Holdridge — Argonne National Laboratory
Hannu Petteri Survo — Vaisala Oyj
Raisa Helena Lehtinen — Vaisala Oyj
Shannon Baxter — SUNY Geneseo

Category

General Topics

Description

Figure 1. Vertical profiles of mean differences between RS92 and RS41 for 20 flights at the ARM Southern Great Plains (SGP) site in Lamont, OK, during June 3 – 7, 2014. Showing mean differences and standard deviations of differences (dashed lines) for temperature, relative humidity, pressure, and wind.
This poster presents the results from a measurement campaign arranged at the ARM Southern Great Plains (SGP) Central Facility in Lamont, OK, in June 2014, to compare Vaisala Radiosonde RS92 and the new Vaisala Radiosonde RS41. Twenty soundings with one RS41 and one RS92 hanging from a rig and attached to a weather balloon were launched during June 3 – 7. Vaisala Radiosondes RS41 and RS92 have noteworthy differences in sensor technologies. RS41 uses a new type of resistive platinum temperature sensor characterized with very high stability, while RS92 uses a capacitive wire sensor. The RS41 sensor is integrated into the sensor support structure which reduces measurement noise in the upper part of the atmosphere. Both sensor models use an effective coating to protect the sensor from evaporative cooling. For humidity measurement, RS41 incorporates a new design of the humidity sensor based on the capacitive Vaisala Humicap® polymer technology. As a new feature, the humidity sensor contains an on-chip temperature sensing element. The effect of solar radiation is eliminated by utilizing the temperature data of the chip as an integral part of the humidity calculation. Pressure measurement in the RS41-SG model used in this campaign is provided with GPS-based technique, while RS92-SGP measures with a pressure sensor. The new design of the radiosonde and the sounding system MW41 user interface make the ground preparations of RS41 significantly easier. Figure 1 shows the results for vertical profiles of each variable. The RS41 and RS92 radiosondes showed very similar results for all measured quantities. Mean temperature differences were within ±0.1 °C. There were a few cases with larger differences, typically related to challenging conditions such as the radiosondes emerging from a cloud, or large gradients in the profiles. Mean humidity profiles agreed to within ±2.1% RH. The largest differences were observed at altitudes of 8 to 12 km, with RS92 measuring 1.6 – 2.1% RH lower humidity levels. Mean pressure differences were within ±0.2 hPa in altitudes above 2 km. Near-ground mean difference between RS41 and RS92 was 0.4 hPa. Zonal and meridional wind components were within ±0.05 m/s, with standard deviation of differences within 0.26 m/s. The observed differences between RS41 and RS92 are within the measurement uncertainty for all variables, and similar to those reported from previous campaigns arranged by UK MET Office and Czech Hydrometeorological Institute.