Continental Stations Research Articles

Environmental DNA sheds new insight on molecular adaptation of foraminifera to temperature from laboratory-controlled culture experiment.

Foraminifera is the most important temperature proxy of the ocean on long time scales. However, the absence of temperature-controlled experiments at different water depths hinders the advancement of paleotemperature reconstruction with foraminifera from the continental shelf. For the first time, this study investigated the response of benthic foraminifera to temperature change using microcosm culture and metabarcoding. Foraminiferal communities from three continental stations at varying water depths (6.0, 9.2, and 26.0 m) were cultured under five temperature gradients (6, 12, 18, 24, and 30°C), with each treatment performed in triplicate. The foraminifera were fed with microalgae every 4 days, and the filtered seawater (through 0.22 μm pores), acting as a medium, was changed accordingly. The experiment lasted for 80 days, and 47 DNA samples were obtained and analyzed, including three insitu samples. The results showed that foraminifera adjusted its growth rate within the low-temperature range and adopted an r-strategy to cope with high-temperature stress. In addition, the foraminifera from deeper water stations exhibited a pronounced vulnerability to diminishing read counts. The read counts, operational taxonomic units (OTU) counts and Margalef index of foraminifera and the read counts of Rotaliida exhibited a remarkably positive correlation with temperature. The recommended relationships were described as read counts = 1314.75*T + 44754.51; OTU counts = 1.13*T + 44.26; Margalef index =1.13*T + 44.26. This study established the first quantitative relationship between temperature and foraminifera molecular parameters that holds significant implications for long-time paleotemperature calibration in climate change.

Non‐Tidal Ocean Loading Signals of the North and Baltic Sea From Terrestrial Gravimetry, GNSS, and High‐Resolution Modeling

AbstractNon‐tidal ocean loading (NTOL) signals are known to be a significant source of geophysically induced noise in gravimetric and geodetic observations also far‐away from the coast and especially during extreme events such as storm surges. Operationally available corrections suffer from a low temporal and spatial resolution and reveal too small amplitudes on continental stations. Dedicated high‐resolution sea‐level modeling of the North and Baltic Sea provides an improved prediction of NTOL signals. Superconducting gravimeter and Global Navigation Satellite Systems observations on the small offshore island of Heligoland in the North Sea are used for an evaluation of the model values revealing largely increased correlations of up to 0.9 and signal reductions of up to 50% during a storm surge period of one month in January and February 2022. Evaluations on additional continental superconducting gravimeter stations also show significant improvements through the recommended high‐resolution modeling for improved signal separation further away from the coast.

Seismometer Orientation Correction via Teleseismic Receiver Function Measurements in West Africa and Adjacent Islands

AbstractTo establish a robust method of determining and correcting the misorientation of seismometers with radial and tangential components of the teleseismic receiver function (RF), we assess the measurement of the amplitude of P-wave phase arrivals at zero seconds (PRFamp method) and the energy of the width of the time window around the P-wave phase arrival (PRFenergy method) using varying Gaussian factors, ranging from 0.5 to 5.0 with equivalent cutoff frequencies. To understand the efficacy and discrepancies in these methods, and their results across different geological terrains, we conduct an assessment of their performance on 26 permanent seismic stations located in West Africa and adjacent islands. We conduct several tests to examine the effect of varying Gaussian factors on the estimates of misorientation. These effects are more noticeable in results from stations for which RFs are indicative of 3D or complex structures and islandic stations. Statistical analyses reveal good correlation between the results obtained from both the methods, although results from PRFamp method proves to be more stable due to their proximity to the statistical mean and standard deviation results. In comparison with the PRFenergy results, there is a smaller error difference and uncertainty, a higher correlation coefficient, a relatively lower standard deviation, and better convergence around the mean misorientation obtained using PRFamp. From both the methods, estimates from continental stations reveal similar trends, results from coastal stations tend to be consistent, whereas some island stations show a reverse trend in sensor misorientation classification. We propose that the PRFamp yields more consistent results and is less sensitive to subsurface heterogeneities. Gaussian filtering with an alpha value (α) of 1.5 is recommended as a trade-off between oversimplification and complications due to subsurface structures. However, we suggest that multiple approaches be adopted to provide robust bases for the estimation and comparison of sensor orientation correction calculations.

КРИОБИОЛОГИЧЕСКИЕ ИССЛЕДОВАНИЯ В СЕЗОН РАЭ-67

During the seasonal logistics operations of RAE-67 at the “Akademik Treshnikov” in the areas of the continental stations “Progress”, “Mirny” and “Bangera Oasis”, field work was carried out to collect water-ice and plankton samples on the topic “Cryal”, the purpose of which is to assess the role of sea ice biota in the pelagic ecosystem of the Southern Ocean.

ПРОСТРАНСТВЕННО-ВРЕМЕННАЯ ДИНАМИКА АМПЛИТУДЫ СУТОЧНЫХ КОЛЕБАНИЙ ТЕМПЕРАТУРЫ АТМОСФЕРНОГО ВОЗДУХА НА ДАЛЬНЕМ ВОСТОКЕ РОССИИ

To identify the spatial, inter-annual and inter-seasonal dynamics of the daily amplitude of air temperature, the author uses the data from 99 weather stations in the Russian Far East for the period of 2000– 2019. It is shown that the maximum values of the daily amplitude are typical for the continental territories in the north, while the minimum ones – for the continental areas in the south, and for sea stations. For almost all weather stations, the amplitude is minimal in winter – in December and January. In general, a clear annual range and significant differences in values during the year were revealed for continental stations. The maximum at the continental northern stations is shown for April, while at the continental southern stations – in February. Marine areas are characterized by a smoothed seasonal course of the studied parameter, with a certain dimly marked maximum in February-March. A decrease in the day–to-day dynamics of air temperature amplitude over the period of 2000–2019 was revealed due to a faster increase in minimum temperatures as compared to maximum, which is typical for most of the weather stations. At the same time, an increase in the amplitude is shown at some stations, which is associated with a higher positive trend of maximum temperatures.

Hull fouling marine invasive species pose a very low, but plausible, risk of introduction to East Antarctica in climate change scenarios

AbstractAimsTo identify potential hull fouling marine invasive species that could survive in East Antarctica presently and in the future.LocationAustralia's Antarctic continental stations: Davis, Mawson and Casey, East Antarctica; and subantarctic islands: Macquarie Island and Heard and McDonald Islands.MethodsOur study uses a novel machine‐learning algorithm to predict which currently known hull fouling MIS could survive in shallow benthic ecosystems adjacent to Australian Antarctic research stations and subantarctic islands, where ship traffic is present. We used gradient boosted machine learning (XGBoost) with four important environmental variables (sea surface temperature, salinity, nitrate and pH) to develop models of suitable environments for each potentially invasive species. We then used these models to determine if any of Australia's three Antarctic research stations and two subantarctic islands could be environmentally suitable for MIS now and under two future climate scenarios.ResultsMost of the species were predicted to be unable to survive at any location between now and the end of this century; however, four species were identified as potential current threats and five as threats under future climate change. Asterias amurensis was identified as a potential threat to all locations.Main conclusionsThis study suggests that the risks are very low, but plausible, that known hull fouling species could survive in the shallow benthic habitats near Australia's East Antarctica locations and suggest a precautionary approach is needed by way of surveillance and monitoring in this region, particularly if propagule pressure increases. While some species could survive as adults in the region, their ability to reach these locations and undergo successful reproduction is considered unlikely based on current knowledge.

Retrieval of Metop-A/IASI N2O Profiles and Validation with NDACC FTIR Data

This paper reports atmospheric profiles of N2O retrieved from Metop/IASI with the Software for the Retrieval of IASI Data (SOFRID) for the 2008–2018 period and their validation with FTIR data from 12 stations of the Network for the Detection of Atmospheric Composition Changes (NDACC). SOFRID retrievals performed in the 2160–2218 cm−1 spectral window provide 3 independent pieces of information about the vertical profile of N2O. The FTIR versus SOFRID comparisons display a better agreement in the mid-troposphere (MT, 700–350 hPa) than in the lower (LT, Surface–700 hPa) and upper (UT, 350–110 hPa) troposphere with correlation coefficients (R) in the 0.49–0.83 range and comparable variabilities (3–5 ppbv). The agreement for oceanic and coastal stations (R > 0.77) is better than for continental ones (R < 0.72). The SOFRID MT N2O mixing ratios are significantly biased high (up to 16.8 ppbv) relative to FTIR at continental stations while the biases remain below 4.2 ppbv and mostly unsignificant when oceanic data are considered. The average MT decadal trends derived from SOFRID at the 8 NDACC stations with continuous observations during the 2008–2018 period (1.05 ± 0.1 ppbv·yr−1) is in good agreement with the corresponding FTIR trends (1.08 ± 0.1 ppbv·yr−1) and the NOAA-ESRL trends from surface in-situ measurements (0.95 ± 0.02 ppbv·yr−1). In the Northern Hemisphere where they are clearly detected, the N2O MT seasonal variations from SOFRID and FTIR are phased (summer minima) and have similar amplitudes. SOFRID also detects the UT summer maxima indicating independent MT and UT information. The global MT N2O oceanic distributions from SOFRID display low geographical variability and are mainly characterized by enhanced tropical mixing ratios relative to mid and high latitudes.

Recent Macaronesian kinematics from GNSS ground displacement analysis

Macaronesia is a complex oceanic region spanning three tectonic plates in the northeast Atlantic ocean. It is composed of four archipelagos, widely distributed and limited to the east by the Iberian Peninsula and north-western coast of Africa. This study aims to clarify recent Macaronesian kinematics from 19 GNSS stations located on the four archipelagos and the Iberian and African coastlines. The analysis is based on nearly 15 years of common data acquisition and aimed to detect new effects of intraplate tectonics or similar local/regional events consistent with calculated ground displacements. Evaluating the GNSS stations residual velocities relative to those expected from the NNR-MORVEL56 model, higher residuals were found at continental coastal stations (Africa) than at oceanic ones (Canaries and Madeira). From the computed strain rate map, the possible existence of a shear zone connecting the Gloria and Transmoroccan fault systems, already mentioned by other authors, was depicted. Cluster statistical analysis of the horizontal residual velocities helped to identify tectonic boundaries in Macaronesia and four groups of analogous intraplate residual velocities within this region. Three of four groups were identified in the Azores, highlighting the African-Nubian-Eurasian diffuse plate boundary in this region. Furthermore, in the Canary Islands, two distinct kinematic behaviours were detected, possibly due to the activity along a previously detected tectonic fault between Tenerife and Gran Canaria, where some stations have similar intraplate residuals to those at Madeira and Cape Verde stations, while others have similar intraplate residuals to those of continental stations. Finally, all stations on oceanic crust, except Cape Verde, present recent ground subsidence which may be attributed to isostatic adjustment.

Robust estimation of spatially varying common-mode components in GPS time-series

We present a new method to estimate common-mode components (CMC) in global positioning system (GPS) position time-series. The method (‘CMC Imaging’) is fully automated, relies entirely on robust statistics, and exploits the recent proliferation of GPS stations by allowing stations with relatively short time-series to be considered as filter stations as well. The spatial extent of the CMC is purposely defined as local as possible and constrained by the proximity of nearby GPS stations. Our approach also avoids the need for subjective assignment of filter stations; every station is considered and those stations that deviate significantly from the local CMC are flagged and excluded as filter stations. We study thousands of GPS position time-series in the intraplate area of western Europe, and we show that CMC Imaging method is superior to other approaches in terms of noise reduction: we obtain an RMS reduction of 50%, 44% and 39% in the residual time-series in vertical, east, and north components, respectively. We show the importance of using filter stations that are as local as possible, because of systematic lateral variations in inter-station correlations and indeed in CMC, particularly in the vertical component. Those spatial variations are largest for continental stations, particularly those around the Baltic Sea, and could be due to atmospheric and nontidal ocean loading. CMC filtering has a large influence on reducing the temporal trend variability and approximately doubles the trend accuracy (by comparing variability in short-term trends with the long-term estimate).

Possible Linkages between Microseisms in the Andaman-Nicobar Region and Swells in the South Indian Ocean

AbstractMicroseism source characterization and its genesis play a key role in linking microseism records to prevailing atmospheric and oceanic conditions. In the present study, we analyzed the spatial and temporal distribution of microseisms in the Andaman-Nicobar region using ocean-bottom seismometers and nearby continental stations data for the deployment period of January–April 2014. We attempted to establish a linkage between microseisms and ocean wave parameters derived from the ERA5 dataset. The short-period secondary microseisms (2–5 s) show a marked difference compared with long-period secondary microseisms (6–10 s) and are associated with local climatology and geomorphology. In contrast, long-period microseisms are related to distant sources in the South Indian Ocean. The primary microseisms (11–20 s) are weak in the Andaman region and do not correlate with any ocean wave parameters.

Spatial patterns and trends of extreme rainfall over the southern coastal belt of West Africa

The southern coastal belt of West Africa (SCWA) with its high population density and many major cities, combined to the low elevation and poor urban planning, is very vulnerable to floods resulting from extreme rainfall events. The aim of this paper is to analyze the characteristics of extreme rainfall in the SCWA during the 1981–2015 period, in terms of frequency, intensity, seasonality, and trends. Therefore, daily rainfall of 31 stations located in the southern part of Cote d’Ivoire, Ghana, Togo, and Benin and rainfall estimation products combining in situ observations and satellites rainfall estimation data have been used. For each station and pixel, the local 95th percentile (P95) computed on all rain days of at least 1 mm was used to define extreme rainfall events. Rainfall on the coastal belt is heavier than further inland, with P95 values reaching 82 and 52 mm/day for coastal and continental stations, respectively. Extreme rainfall along the coast occurs predominantly between May and July. Interannual variations of different indicators of extreme rainfall show a broad agreement between rain gauge data and rainfall estimates from CHIRPS (Climate Hazards Group InfraRed Precipitation with Station) data. In the southern part of Cote d’Ivoire and Togo/Benin, increase of number of extreme rainfall event (NP95) and stability number of days with rainfall less than P95 (NL95) are recorded, which induces an increase of total rainfall. But, in the southern part of Ghana, there is a stable total rainfall due to an increase in NP95 compensated by a decrease in NL95.

First observation of atmospheric electric field at Kashmir valley North Western Himalayas, Srinagar (India)

Preliminary results from the measurement of potential gradient (PG) for the period of March 2018–February 2019 at the University of Kashmir, Srinagar, (34° 03′ N, 74° 51’ E, 1585 m amsl) India is reported. The annual mean diurnal variation of PG represents typical double-maxima pattern with the primary maximum at 0900–1000 LT and the secondary maximum at 1900–2000 LT which is in accordance with the measurements at different continental stations. The primary maximum of PG and its extended duration is explained by the sunrise effect due to increasing surface temperature, the development of surface convection and hence the boundary layer probably favour the uplifting of the surface aerosols. The higher PG values measured at Kashmir valley were explained with the height of the measurement from the surface and the role of mountain-valley winds circulation. Monthly mean PG showed the higher value during December and minimum in June and the amplitude variations were attributed to the local PM concentrations. PG is found to be highly influenced by PM2.5 compared to PM10, due to the high suspension duration in the ambient air. Measurement of PM2.5 to Srinagar showed higher values in December followed by the November and January under the strong inversion layer formation in Kashmir valley with the westerly winds apart from an increase in the local tourist activity. The measured PG values and its observed variations are explained considering the role of aerosol concentration, atmospheric mixing and mountain-valley wind circulations. The present results are comparable with measurements of PG at different continental stations. The level of aerosols and site location shows variation in amplitude as well as temporal shift.

60-year trends of δ18O in global precipitation reveal large scale hydroclimatic variations

Abstract Sixty years of monthly data series of δ18O in precipitation revealed distinctive decadal long-term patterns and break points for the isotope composition of global precipitation. Our results showed that at the multi-decadal scale, δ18O in precipitation displayed changes due to large-scale hydroclimate processes, and particularly, from atmospheric oscillations. Break point and segmented regression trend analyses for δ18O and air temperature revealed influences of the North Atlantic Oscillation (NAO) on the long-term isotope variability for most continental stations in Northern Hemisphere. Long-term trends of δ18O and precipitation amount for Southern Hemisphere stations were mostly indicative of changes in regional hydroclimate processes driven by the larger scale Atlantic and Pacific atmospheric oscillations. For oceanic island stations, the δ18O variations could be described by sinusoidal trends with a ~ 20–40 years-time cycle and δ18O amplitude of ~1–2‰, suggesting these stations have a higher sensitivity to multi-decadal atmospheric circulation. Our findings reveal that coordinated long-term monitoring of stable isotopes in precipitation, coupled with basic meteorological parameters such as air temperature and precipitation amount, are essential to better understand the impact of larger scale hydroclimate variation on regional and local climate variability, and to help interpret long-term hydroclimatic changes of the past, present and future.

Time–height variation of winds and turbulence during typical tropical pre-monsoon thunderstorm events observed from high-resolution Doppler wind lidar measurements

High spatiotemporal resolution measurements of horizontal and vertical winds made using a Doppler wind lidar during development and mature stages of few typical tropical thunderstorm events in 2014 over a continental Indian station are used to study the dynamical changes that take place in the lower atmospheric layers close to surface. Results show significant time–height variability in horizontal wind especially 2–3 h before rainfall on ground. The recorded vertical motions on the thunderstorm days showed that during its developing stage, alternating updrafts and downdrafts are prevalent through the entire vertical column of the lower atmosphere with the magnitude of fluctuations being higher compared to those on non-thunderstorm days. Turbulence intensity is high in magnitude during the evolution of intense convection. Alternating layers of convergence and divergence with horizontally time-stratified layers of strong positive and negative wind shear are observed which seem to contribute to strengthening and vertical growth of local convection. Thus, high-resolution time–height variations in horizontal and vertical winds in the lower atmosphere during the life cycle of a tropical thunderstorm provide a better understanding of the atmospheric dynamics associated with it and short-duration heavy precipitation it produces.

МОНИТОРИНГ ВОДНО-ЛЕДОВОЙ ЭКОЛОГИЧЕСКОЙ СИСТЕМЫ ПРИБРЕЖНОЙ ЗОНЫ АНТАРКТИКИ ПО МАТЕРИАЛАМ РАБОТ РАЭ-64

During the seasonal work of the Russian Antarctic expedition (RAE-64) in the Nella fjord at the continental station “Progress” (Prydz Bay, Eastern Antarctica), the monitoring of the water-ice ecological system has been carried out here annually since the International polar year (2007). The purpose of monitoring is to show the role of sea ice biota in the global biosphere processes of the Southern ocean.

Assessment of the total precipitable water from a sun photometer, microwave radiometer and radiosondes at a continental site in southeastern Europe

Abstract. In this study, we discuss the differences in the total precipitable water (TPW), retrieved from a Cimel sun photometer operating at a continental site in southeast Europe, between version 3 (V3) and version 2 (V2) of the AErosol RObotic NETwork (AERONET) algorithms. In addition, we evaluate the performance of the two algorithms comparing their product with the TPW obtained from a collocated microwave radiometer and nearby radiosondes during the period 2007–2017. The TPW from all three instruments was highly correlated, showing the same annual cycle, with lower values during winter and higher values during summer. The sun photometer and the microwave radiometer depict the same daily cycle, with some discrepancies during early morning and late afternoon due to the effect of solar zenith angle on the measurements of the photometer. The TPW from V3 of the AERONET algorithm has small differences compared with V2, mostly related to the use of the new laboratory-based temperature coefficients used in V3. The microwave radiometer measurements are in good agreement with those obtained by the radiosonde, especially during night-time when the differences between the two instruments are almost negligible. The comparison of the sun photometer data with high-quality independent measurements from radiosondes and the radiometer shows that the absolute differences between V3 and the other two datasets are slightly higher compared with V2. However, V3 has a lower dependence from the TPW and the internal sensor temperature, indicating a better performance of the retrieving algorithm. The calculated one-sigma uncertainty for V3 as estimated, from the comparison with the radiosondes, is about 10 %, which is in accordance with previous studies for the estimation of uncertainty for V2. This uncertainty is further reduced to about 6 % when AERONET V3 is compared with the collocated microwave radiometer. To our knowledge, this is the first in-depth analysis of the V3 TPW, and although the findings presented here are for a specific site, we believe that they are representative of other mid-latitude continental stations.

Aerosol connections between three distant continental stations

The present study is based on hourly aerosol particle and ancillary data taken at three stations in Northeastern Germany 150–200 km apart in the years 2009 through 2015 in order to investigate systematic process related differences that might show up when connecting their data with forward and backward air mass trajectories. The analysis of changes in the atmospheric aerosol during air mass transport between the stations focused on two low-pollution-to-high-pollution pathways of similar distance around 200 km. Despite rather different initial size distributions the increases in total concentration of particle number, volume, and black carbon agreed within 15%. Systematic variations were found in the different concentration increases as a function of time of day at which an interstation air mass transport took place that could be explained with related source and transport processes.With Radar-based precipitation data at the stations and along connecting trajectories sub-cloud particle scavenging was investigated. At each station sub-cloud particle scavenging coefficients were determined as a function of particle size between 10 and 700 nm diameter, and as a function of precipitation sums. Median particle scavenging coefficients taken over the central part of the size range of the study strongly increased between 0.2 and 1 mm of precipitation and then planed out towards higher precipitation values. With the particle scavenging coefficients determined at the individual stations and precipitation data along connecting trajectories the sub-cloud particle scavenging analysis was extended to wet scavenging along the transport paths yielding median sub-cloud scavenging ratios over the range 0.2–25 mm of precipitation sums with a non-linear shape similar to that of the median particle scavenging coefficients at the individual stations. Whereas in light precipitation more than 80% of the initial particles in the considered range survived 150–200 km of transport, more than 50% was scavenged by more than 15 mm of precipitation during aerosol transport.

Aerosol connections between three distant continental stations

Aerosol connections between three distant continental stations

Regional Pn Body‐Wave Magnitude Scale mb(Pn) for Earthquakes Along the Northern Mid‐Atlantic Ridge

AbstractWe obtained a robust regional body wave magnitude scale mb(Pn) for earthquakes along the Northern mid‐Atlantic Ridge by using Pn wave recorded at continental stations. The new magnitude scale is mb(Pn) = log10 A [nm] − 1.86 log10 (100/Δ) [km] + C + 1.62, where A is the zero‐to‐peak amplitude of Pn wave on the simulated vertical Wood‐Anderson seismogram in nanometers, Δ is the epicentral distance in kilometers, 1.86 represents amplitude attenuation, C is the station correction, and 1.62 anchors the mb(Pn) to the moment magnitude (Mw), plus amplitude loss in the two crustal legs. By using moment magnitude as reference, we obtained the event magnitude adjustments (EMAs), which represent the difference between the known long‐period Mw and the short‐period mb(Pn). EMAs correlate with the source property, where ridge events show strong long‐period waves but poor high‐frequency signals that lead to mb(Pn) < Mw and positive EMA of +0.08 ± 0.26 magnitude units (m.u.), whereas transform fault earthquakes show relatively strong high‐frequency waves that lead to mb(Pn) > Mw and negative adjustment of −0.20 ± 0.24 m.u. Almost all normal faulting events are along spreading ridges, whereas strike‐slip events are along the fracture zones and transform faults; hence, we developed source‐specific magnitude adjustments (SSMAs), which range from +0.27 m.u. for earthquakes along the ridges, to −0.26 m.u. for earthquakes along the transform faults. Using SSMA, we obtained a regional Pn magnitude that is consistent with Mw and mb(P). The regression relationship is Mw = 0.91 mb(Pn)[SSMA] + 0.46 with a standard deviation of ±0.15 m.u.

A European-wide <sup>222</sup>radon and <sup>222</sup>radon progeny comparison study

Abstract. Although atmospheric 222radon (222Rn) activity concentration measurements are currently performed worldwide, they are being made by many different laboratories and with fundamentally different measurement principles, so compatibility issues can limit their utility for regional-to-global applications. Consequently, we conducted a European-wide 222Rn ∕ 222Rn progeny comparison study in order to evaluate the different measurement systems in use, determine potential systematic biases between them, and estimate correction factors that could be applied to harmonize data for their use as a tracer in atmospheric applications. Two compact portable Heidelberg radon monitors (HRM) were moved around to run for at least 1 month at each of the nine European measurement stations included in this comparison. Linear regressions between parallel data sets were calculated, yielding correction factors relative to the HRM ranging from 0.68 to 1.45. A calibration bias between ANSTO (Australian Nuclear Science and Technology Organisation) two-filter radon monitors and the HRM of ANSTO ∕ HRM = 1.11 ± 0.05 was found. Moreover, for the continental stations using one-filter systems that derive atmospheric 222Rn activity concentrations from measured atmospheric progeny activity concentrations, preliminary 214Po ∕ 222Rn disequilibrium values were also estimated. Mean station-specific disequilibrium values between 0.8 at mountain sites (e.g. Schauinsland) and 0.9 at non-mountain sites for sampling heights around 20 to 30 m above ground level were determined. The respective corrections for calibration biases and disequilibrium derived in this study need to be applied to obtain a compatible European atmospheric 222Rn data set for use in quantitative applications, such as regional model intercomparison and validation or trace gas flux estimates with the radon tracer method.