This paper describes GRUAN's strategy to a network-wide change in the operational radiosonde, from Vaisala RS92 to RS41. GRUAN's main goal is providing long-term data records that are free of inhomogeneities due to instrumental effects, which requires proper change management. The approach is to fully characterize the differences between both radiosonde types, using a.o. laboratory tests, twin soundings, ancillary data, and by drawing from the various fields of expertise available in GRUAN.

This paper developed a drilling trajectory measuring instrumentation (DTMI) based on the interference fiber optic gyro (FOG), which can work continuously, for 4 hours, in an environment where the ambient temperature does not exceed 270 °C and the pressure does not exceed 120 MPa in ultra-deep borehole. The DTMI has the characteristic of anti-electromagnetic interference, therefore，this DTMI has great potential in the promotion and development of geological drilling technology.

We report the results from the deployment of a newly developed in situ sensor for dissolved gases measurements. Its adaptation to high gas concentrations and dissolved gas pressures was proven. The campaign leads to a first continuous profile of methane on the first 150 m, and allowed to compare the data with previous measurements. The fast response of the instrument makes this technique a good candidate for regular monitoring of those type of lakes, for anticipating disastrous gas eruptions.

Soil moisture plays a key role in the hydrological cycle and the climate system. Although soil moisture can be observed by the means of satellites, ground observations are still crucial for evaluating and improving these satellite products. In this study, we investigate the performance of a consumer low-cost soil moisture sensor in the lab and in the field. We demonstrate that this sensor can be used for scientific applications, for example to create a dataset valuable for satellite validation.

Middle Frequency radars measure winds (between 55 & 100 km altitude). As part of their final year undergraduate project, the lead author used 2 radars in Antarctica to look at how the wind speed varied with the aim of identifying when the wind was too fast to be a real measurement. Instead we discovered that the variance depends strongly on factors in the analysis technique rather than due to natural features such as gravity waves, and that the sun and geomagnetic activity play a role.