We compared six years of carbon dioxide and methane measurements from two nearby laboratories at the high mountain station on Mount Cimone, Italy. Both recorded similar long-term and seasonal changes, but hourly readings often differed beyond limits recommended by WMO. Sampling location, data selection and moisture removal contributed to these differences; human presence may also have played a role. Standardization of sampling and procedures can make greenhouse gas measurements more consistent.

This study tests whether laboratory calibration of visibility sensors can be applied outdoors. Using controlled filter experiments and field measurements, it separates sensor-related effects from background atmospheric effects. The results show that calibration can improve agreement under clear conditions for suitable forward-scatter sensors, but success depends on stable sensor behavior and weak atmospheric interference.

This study retrieves RO observations from the FY‑3E satellite using 1‑s undifferenced LEO clock corrections. Results are compared against those from 30‑s undifferenced and single‑difference approaches. The 1‑s clock corrections outperform the other two schemes, yielding the greatest improvement in bending‑angle profiles within the 40–60 km altitude range. These findings support future operational processing and archive reprocessing of all Fengyun GNSS occultation datasets.