Global Navigation Satellite System radio occultation data help monitor climate and weather prediction but are affected by residual ionospheric errors (RIEs). A new excess-phase-gradient method detects and corrects RIEs, showing both positive and negative values, varying by latitude, time, and solar activity. Tests show that RIE impacts polar stratosphere temperatures in models, with differences up to 3–4 K. This highlights the need for RIE correction to improve the accuracy of data assimilation.

This article introduces an experimental system for rapidly acquiring trace gas profiles using multi-channel spectroscopy, significantly enhancing the time resolution of spectral collection. The fast synchronous multi-axis differential optical absorption spectroscopy (FS MAX-DOAS) successfully obtains gas profiles. This work can also be integrated with mobile platforms for navigational observation research, which is crucial for making mobile MAX-DOAS profile measurements.

Significant improvements have been made to the instruments used to measure OH reactivity, which is equivalent to the sum of air pollutant concentrations. Accurate and precise measurements with a high time resolution have been achieved, allowing use on aircraft, as demonstrated during flights in the USA.