Atmospheric Measurement Techniques 

Occultation techniques for observing the Earth’s atmosphere and climate comprise solar, lunar, stellar, navigation, and satellite-crosslink occultation methods, exploiting the electromagnetic spectrum from optical to radio signals via refraction, absorption, scattering, and reflection. Retrieved atmospheric variables range from bending angle, refractivity, pressure, geopotential height, temperature, and water vapor to greenhouse gases and particulate species such as aerosols and cloud liquid water. Information on ionosphere and space weather is also provided.

Occultation methods share the unique properties of self-calibration; high accuracy and vertical resolution; global coverage; and, if using radio signals, all-weather capability. Global navigation satellite system (GNSS) radio occultation has become particularly successful over the recent decades and provides accurate refraction-based measurements using data from all GNSS systems.

Occultation data are of high utility in numerical weather prediction, atmospheric physics, and climate science. Their application has further broadened in recent years, and new satellite missions and observation methods are on the way.

The OPAC-IROWG 2022 workshop brought together members from the different sub-communities and users of occultation data. The present Atmospheric Measurement Techniques special issue is dedicated to the results of this conference and recent achievements.

An overlapping need exists between the climate research and the radiation protection communities to improve the metrology for atmospheric radon concentration and radon flux measurements. The EMPIR project 19ENV01 traceRadon works toward these goals for the benefit of both large scientific communities by providing the necessary infrastructure for measuring these aforementioned variables. In addition, it will generate data at four selected European sites for validation of radon flux models and inventories and will create the first standard protocol for applying the radon tracer method (RTM). The proposed special issue aims to collect the direct and indirect outcomes of the traceRadon project. It will include papers presenting results of the laboratory and field campaigns carried out within the project. In addition, papers directly related to the project goals will be welcome too.

The Tropospheric Ozone Assessment Report (TOAR-II) is an official activity of the International Global Atmospheric Chemistry Project (IGAC) (https://igacproject.org/activities/TOAR/TOAR-II). The goal of TOAR-II is to build on the success of TOAR-I (2014–2019) and produce an updated assessment of tropospheric ozone’s global distribution and trends from the surface to the tropopause. This effort will include an analysis of the impacts of ozone on human health, crop and ecosystem productivity, and climate. Original tropospheric ozone research conducted by the TOAR-II community may be submitted to one of six Copernicus journals (ACP/AMT/BG/GMD/ESSD/ASCMO), and the accepted papers will be linked through the TOAR-II Community Special Issue.

The proposed special issue has the goal of collecting original publications addressing profiles of the atmospheric boundary layer from a variety of perspectives. Aligned with the objectives of the EU COST action PROBE (http://probe-cost.eu), topics include both observational aspects (latest technological sensor developments, quality control and retrieval methods, calibration, implementation of harmonised monitoring networks, measurement campaigns, instrument synergy, combination with satellite data) and the exploitation of the profile observations (process understanding, model development and assessment, data assimilation) for a wide range of applications (including meteorology and climate, air quality, renewable energy, radio propagation).

The Tibetan Plateau is referred to as the third pole of the world and is representative of background region of the Earth’s atmosphere. Atmospheric photochemistry, in conjunction with the unique circulation pattern of Asian Monsoon outflow and prevailing westerly wind, leads to, as of yet, unidentified implications for climate change, the oxidative capacity of the atmosphere, local air quality, and health effects on local residents and visitors.

For a better scientific understanding of the background atmospheric chemistry and its impacts on climate change, air quality, and human health, multiple international campaigns, referred to as the @Tibet field campaigns, have been conducted since 2019 under the umbrella of the second Tibetan Plateau Scientific Expedition and Research Program (STEP). As supported by the major research plan of the National Natural Science Foundation of China (NSFC) entitled fundamental researches on the formation and response mechanism of air pollution complex, the research conducted in the Tibetan Plateau and eastern China was underpinned by a number of instrument developments required to meet the specific demands of exploring air pollution and fundamental atmospheric photochemistry. This AMT–ACP joint special issue is therefore designed to intensively discuss data from @Tibet field campaigns and instrument development progress.