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This report presents a review of data assimilation methods applicable to air quality. In the introduction, we first describe a brief history of data assimilation method development in the context of numerical weather prediction (NWP), and then we highlight key differences when applying data assimilation methods to air quality prediction from NWP applications. Based on these differences, we outline a set of key requirements for data assimilation when applied to air quality. Following this, we review the available data assimilation algorithms and attempt to identify suitable data assimilation methods that could be applied with air quality models. This review and its findings form the basis of the developments to be carried out in the Urban Data Assimilation Systems project.
NILU
2021
2021
Ren luft for alle. ExtraStiftelsen project 2019/HE1-263918.
In 2019, in the framework of Oslo being European Green Capital, NILU invited students from elementary schools to
measure air pollution in their neighbourhood, using simple and affordable measuring methods based on paper and
Vaseline. The students prepared the measuring devices and selected the places where they wanted to monitor. After one
week, they retrieved the devices and used a scale to compare the amount of dust fastened to the Vaseline. All of the data
gathered by the students was uploaded by the teachers to a website (https://luftaforalle.nilu.no/), where a map showed all the results from the participating schools. The school campaign has helped researchers to get data on particulate matter from many places where data was not available, and has increased awareness among the children about the sustainability challenges cities are facing.
NILU
2021
An update on low-cost sensors for the measurement of atmospheric composition
The report reflects on the state of the art in terms of accuracy, reliability and reproducibility of different sensors used for the measurements of reactive and greenhouse gases, and aerosols, along with the key analytical principles and what has been learned so far about low-cost sensors from both laboratory studies and real-world tests (up to August 2020). In some cases, scientific literature that had been accepted, but not yet published in a final form, was included in this review. Some national and international government documents were also included in this synthesis. The report includes eight distinct sections, including an Introduction to the Report, Main Principles and Components, Evaluation Activities, Sensor Performance, Communicating LCS to Society, and Expert Consensus and Advice. Communicating LCS to Society is a new section to the original 2018 report and includes a consensus viewpoint on strategies for communicating LCS data and technologies more broadly to the lay public. This report also includes a set of specific expert consensus recommendations for LCS users across different user groups.
WMO
2021
Monitoring of long-range transported air pollutants in Norway. Annual Report 2020.
This report presents results from the monitoring of atmospheric composition and deposition of air pollution in 2020, and focuses on main components in air and precipitation, particulate and gaseous phase of inorganic constituents, particulate carbonaceous matter, ground level ozone and particulate matter. The level of pollution in 2020 was generally low and this can partly be explained by special weather conditions in the first months with mostly clean, marine air from the west. The extensive restrictions on human activity in connection with the pandemic in Europe, have probably also contributed to lower levels of air pollution at the Norwegian background stations. In 2020, it was an unusual wide-spread episode during October causing high concentrations of most pollutants at all the sites.
NILU
2021
Grenseområdene Norge-Russland. Luft- og nedbørkvalitet 2020.
Smelteverkene i nordvest-Russland slapp ut store mengder svoveldioksid (SO2) og tungmetaller. Utslippene påvirket luft- og nedbørkvalitet i grenseområdene. Miljøovervåkingen viser at grenseverdier for SO2 er overholdt i kalenderåret 2020, samt for vinter 2019/20. Smelteverket i Nikel stengte ned 23. desember 2020 og dette er ventet å gi stor nedgang i
forurensningen i grenseområdene. Målsettingsverdier for Ni, As og Cd er overholdt.
NILU
2021
PAH measurements at Lista. January 2020 – December 2020.
On behalf of Aluminiumindustriens Miljøsekretariat (AMS) and Alcoa Lista, NILU – Norwegian institute for air research has
conducted a sampling campaign in the surroundings of the Alcoa Lista aluminium smelter in order to update the knowledge on PAH-concentrations around the smelter today. Samples were taken in the period January – December 2020 and
analysed for particle bound PAHs. As a consequence of reduced emissions compared to earlier measurements, the ambient
concentrations of benzo(a)pyrene (BaP) were reduced. BaP had an annual average concentration below the target value at
both sampling sites. At Huseby, the lower assessment threshold was exceeded. PAH-levels in the area were similar to those observed in Norwegian cities.
NILU
2021
Biomonitoring studies are helpful tools and can increase our knowledge on time trends in human blood concentrations of PFASs: how they relate to emission trends and the potential prenatal exposure for future generations. In this study, serum was sampled in cross-sections of men and women who were 30 years old in each of the years 1986, 1994, 2001, and 2007 in Northern Norway and analyzed for 23 PFASs. Differences in serum concentrations across sampling years were investigated graphically and with significance testing and compared with those observed in our previous longitudinal study using repeated individual measurements in older men in the same years. The results demonstrate overall increasing blood burdens of PFASs in men and women in reproductively active ages during 1986–2001 and decreases until 2007. However, longer chained PFASs were still increasing in 2007 indicating divergent time trends between the different PFASs, underlining the importance of continued biomonitoring. Comparisons between 30-year-old men and older men within the same population demonstrated variation in time trends in the exact same years, underlining that biomonitoring studies must regard historic exposures and birth cohort effects.
2021
2021
An optimized low volume sampler was developed to determine both gas- and particle bound concentrations of short and medium-chain chlorinated paraffins (S/MCCPs). Background contamination was limited by the sampler design, providing method quantification limits (MQLs) at least two orders of magnitude lower than other studies within the gas (MQL: 500 pg (ΣSCCPs), 1.86 ng (ΣMCCPs)) and particle (MQL: 500 pg (ΣSCCPs), 1.72 ng (ΣMCCPs) phases. Good repeatability was observed between parallel indoor measurements (RSD ≤ 9.3% (gas), RSD ≤ 14% (particle)) with no breakthrough/saturation observed after a week of continuous sampling. For indoor air sampling, SCCPs were dominant within the gas phase (17 ± 4.9 ng/m3) compared to MCCPs (2.7 ± 0.8 ng/m3) while the opposite was observed in the particle bound fraction (0.28 ± 0.11 ng/m3 (ΣSCCPs) vs. 2.7 ± 1.0 ng/m3 (ΣMCCPs)). Only SCCPs in the gas phase could be detected reliably during outdoor sampling and were considerably lower compared to indoor concentrations (0.27 ± 0.10 ng/m3). Separation of the gas and particle bound phase was found to be crucial in applying the appropriate response factors for quantification based on the deconvoluted S/MCCP sample profile, thus avoiding over- (gas phase) or underestimation (particle phase) of reported concentrations. Very short chain chlorinated paraffins (vSCCPs, C5-C9) were also detected at equal or higher abundance compared to SCCP congener groups (C10-C13) congener groups, indicating an additional human indoor inhalation risk.
2021
Microfibers (MF) are one of the major classes of microplastic found in the marine environment on a global scale. Very little is known about how they move and distribute from point sources such as wastewater effluents into the ocean. We chose Adventfjorden near the settlement of Longyearbyen on the Arctic Svalbard archipelago as a case study to investigate how microfibers emitted with untreated wastewater will distribute in the fjord, both on a spatial and temporal scale. Fiber abundance in the effluent was estimated from wastewater samples taken during two one-week periods in June and September 2017. Large emissions of MFs were detected, similar in scale to a modern WWTP serving 1.3 million people and providing evidence of the importance of untreated wastewater from small settlements as major local sources for MF emissions in the Arctic. Fiber movement and distribution in the fjord mapped using an online-coupled hydrodynamic-drift model (FVCOM-FABM). For parameterizing a wider spectrum of fibers from synthetic to wool, four different density classes of MFs, i.e., buoyant, neutral, sinking, and fast sinking fibers are introduced to the modeling framework. The results clearly show that fiber class has a large impact on the fiber distributions. Light fibers remained in the surface layers and left the fjord quickly with outgoing currents, while heavy fibers mostly sank to the bottom and deposited in the inner parts of the fjord and along the northern shore. A number of accumulation sites were identified within the fjord. The southern shore, in contrast, was much less affected, with low fiber concentrations throughout the modeling period. Fiber distributions were then compared with published pelagic and benthic fauna distributions in different seasons at selected stations around the fjord. The ratios of fibers to organisms showed a very wide range, indicating hot spots of encounter risk for pelagic and benthic biota. This approach, in combination with in-situ ground-truthing, can be instrumental in understanding microplastic pathways and fate in fjord systems and coastal areas and help authorities develop monitoring and mitigation strategies for microfiber and microplastic pollution in their local waters.
2021
High levels of organochlorines (OCs) have been measured in arctic char (Salvelinus alpinus) from Lake Ellasjøen on Bjørnøya, Norway (74.30°N, 19.0°E). In a nearby lake, Laksvatn, the OC-levels in arctic char were low. A previous study has shown that char from Ellasjøen had significantly higher levels of DNA double strand breaks (DSBs) than char from Lake Laksvatn. Even though there is increasing evidence of the genotoxic effects of OCs, little is known about the effects of OCs on the DNA repair system. The aim of the present study was to determine if the two main DNA DSB repair mechanisms, homologous recombination (HR) and non-homologous end-joining (NHEJ), are affected by the higher OC and DSB level in char from Ellasjøen. This was analysed by comparing the transcript level of 11 genes involved in DNA DSB repair in char liver samples from Ellasjøen (n = 9) with char from Laksvatn (n = 12). Six of the investigated genes were significantly upregulated in char from Ellasjøen. As the expression of DNA DSB repair genes was increased in the contaminant-exposed char, it is likely that the DNA DSB repair capacity is induced in these individuals. This induction was positively correlated with the DNA DSB and negatively correlated with one or several OCs for four of these genes. However, the strongest predictor variable for DNA repair genes was habitat, indicating genetic differences in repair capacity between populations. As char from Ellasjøen still had significantly higher levels of DSBs compared to char from Laksvatn, it is possible that chronic exposure to OCs and continued production of DSB has caused selective pressure within the population for fixation of adaptive alleles. It is also possible that DSB production was exceeding the repair capacity given the prevailing conditions, or that the OC or DSB level was above the threshold value of inhibition of the DNA repair system resulting in the rate of DNA damage exceeding the rate of repair.
2021
Eastward-propagating planetary waves prior to the January 2009 sudden stratospheric warming
Eastward-propagating planetary waves (EPWs) were investigated prior to the boreal January 2009 major sudden stratospheric warming (SSW) event simulated by the National Center for Atmospheric Research's Whole Atmosphere Community Climate Model with specified dynamics. About 22 days before SSW onset, a background flow with jet maxima around the upper polar stratosphere and subtropical mesosphere developed due to the net forcing by gravity and planetary waves. The mesospheric wind structure was largely unstable and supported a wave geometry conducive to overreflection. With a zonal phase speed of ∼10 m s−1, EPWs appeared near their turning and critical layers as wavenumber-2 perturbations in the stratosphere and mesosphere. Accompanied by upward EPW activity from the lower stratosphere, EPW growth exhibited characteristics of wave instability and overreflection.
2021
The Arctic middle atmosphere was affected by major sudden stratospheric warmings (SSW) in February 2018 and January 2019, respectively. In this article, we report for the first time the impact of these two events on the middle atmospheric nitric oxide (NO) abundance. The study is based on measurements obtained during two dedicated observation campaigns, using the Sub-Millimetre Radiometer (SMR) aboard the Odin satellite, measuring NO globally since 2003. The SSW of February 2018 was similar to other, more dynamically quiet, Arctic winters in term of NO downward transport from the upper mesosphere–lower thermosphere to lower altitudes (referred to as energetic particle precipitation indirect effect EPP-IE). On the contrary, the event of January 2019 led to one of the strongest EPP-IE cases observed within the Odin operational period. Important positive NO anomalies were indeed observed in the lower mesosphere–upper stratosphere during the three months following the SSW onset, corresponding to NO volume mixing ratios more than 50 times higher than the climatological values. These different consequences on the middle atmospheric composition are explained by very different dynamical characteristics of these two SSW events.
2021
The 11 year solar cycle UV irradiance effect and its dependency on the Pacific Decadal Oscillation
The stratospheric, tropospheric and surface impacts from the 11 year ultraviolet solar spectral irradiance (SSI) variability have been extensively studied using climate models and observations. Here, we demonstrate using idealized model simulations that the Pacific Decadal Oscillation (PDO), which has been shown to impact the tropospheric and stratospheric circulation from sub-decadal to multi-decadal timescales, strongly modulates the solar-induced atmospheric response. To this end, we use a high-top version of the coupled ocean–atmosphere Norwegian Climate Prediction Model forced by the SSI dataset recommended for Coupled Model Intercomparison Project 6. We perform a 24-member ensemble experiment over the solar cycle 23 in an idealized framework. To assess the PDO modulation of the solar signal, we divide the model data into the two PDO phases, PDO+ and PDO−, for each solar (maximum or minimum) phase. By compositing and combining the four categories, we hence determine the component of the solar signal that is independent of the PDO and the modulation of the solar signal by the PDO, along with the solar signal in each PDO phase. Reciprocally, we determine the PDO effect in each solar phase. Our results show that the intensification of the polar vortex under solar maximum is much stronger in the PDO− phase. This signal is transferred into the troposphere, where we find a correspondingly stronger polar jet and weaker Aleutian Low. We further show that the amplification of the solar signal by the PDO− phase is driven by anomalous meridional advection of solar-induced temperature anomalies over northern North America and the North Pacific, which contributes to a decreased meridional eddy heat flux and hence to a decreased vertical planetary wave flux into the stratosphere.
2021
Fluorescent Nanocomposites: Hollow Silica Microspheres with Embedded Carbon Dots
Intrinsically fluorescent carbon dots may form the basis for a safer and more accurate sensor technology for digital counting in bioanalytical assays. This work presents a simple and inexpensive synthesis method for producing fluorescent carbon dots embedded in hollow silica particles. Hydrothermal treatment at low temperature (160 °C) of microporous silica particles in presence of urea and citric acid results in fluorescent, microporous and hollow nanocomposites with a surface area of 12 m2/g. High absolute zeta potential (−44 mV) at neutral pH demonstrates the high electrosteric stability of the nanocomposites in aqueous solution. Their fluorescence emission at 445 nm is remarkably stable in aqueous dispersion under a wide pH range (3–12) and in the dried state. The biocompatibility of the composite particles is excellent, as the particles were found to show low genotoxicity at exposures up to 10 μg/cm2.
2021
Information Requirements under the Essential-Use Concept: PFAS Case Studies
Per- and polyfluoroalkyl substances (PFAS) are a class of substances for which there are widespread concerns about their extreme persistence in combination with toxic effects. It has been argued that PFAS should only be employed in those uses that are necessary for health or safety or are critical for the functioning of society and where no alternatives are available (“essential-use concept”). Implementing the essential-use concept requires a sufficient understanding of the current uses of PFAS and of the availability, suitability, and hazardous properties of alternatives. To illustrate the information requirements under the essential-use concept, we investigate seven different PFAS uses, three in consumer products and four industrial applications. We investigate how much information is available on the types and functions of PFAS in these uses, how much information is available on alternatives, their performance and hazardous properties and, finally, whether this information is sufficient as a basis for deciding on the essentiality of a PFAS use. The results show (i) the uses of PFAS are highly diverse and information on alternatives is often limited or lacking; (ii) PFAS in consumer products often are relatively easy to replace; (iii) PFAS uses in industrial processes can be highly complex and a thorough evaluation of the technical function of each PFAS and of the suitability of alternatives is needed; (iv) more coordination among PFAS manufacturers, manufacturers of alternatives to PFAS, users of these materials, government authorities, and other stakeholders is needed to make the process of phasing out PFAS more transparent and coherent.
2021
The study aimed at investigating the concentrations and geographical patterns of 11 polychlorinated biphenyls (PCBs) and 15 organochlorine pesticides (OCPs) in reindeer muscle samples (n = 100) collected from 10 grazing districts in Norway, 2009. Concentrations were examined for patterns related to geographical region as well as age and sex of animals. Concentrations measured for PCBs and OCPs in reindeer meat samples were generally low. Geographical patterns were revealed and districts with previous mining activities, military trenches, or those that were in the vicinity of the Russian border exhibited slightly elevated concentrations compared to other districts. Calves (10 months) exhibited higher concentrations than young (1.5 year) and old animals (>2 years) adjusted for sex, whereas males exhibited higher concentrations than females, adjusted for age. All PCB congeners inter-correlated strongly with each other, whereas oxy-chlordane and heptachlor epoxide were the strongest inter-correlated OCP compounds. Concentrations of PCBs and OCPs in reindeer meat were all considerably lower than the maximum levels set for those contaminants in foodstuffs for safe human consumption by the European Commission. Thus, reindeer meat is not likely to be a substantial contributor to the human body burden of persistent organic pollutants.
2021
Exposure to mercury (Hg) is a global concern, particularly among Arctic populations that rely on the consumption of marine mammals and fish which are the main route of Hg exposure for Arctic populations.The MercuNorth project was created to establish baseline Hg levels across several Arctic regions during the period preceding the Minamata Convention. Blood samples were collected from 669 pregnant women, aged 18–44 years, between 2010 and 2016 from sites across the circumpolar Arctic including Alaska (USA), Nunavik (Canada), Greenland, Iceland, Norway, Sweden, Northern Lapland (Finland) and Murmansk Oblast (Russia). Descriptive statistics were calculated, multiple pairwise comparisons were made between regions, and unadjusted linear trend analyses were performed.Geometric mean concentrations of total Hg were highest in Nunavik (5.20 µg/L) and Greenland (3.79 µg/L), followed by Alaska (2.13 µg/L), with much lower concentrations observed in the other regions (ranged between 0.48 and 1.29 µg/L). In Nunavik, Alaska and Greenland, blood Hg concentrations have decreased significantly since 1992, 2000 and 2010 respectively with % annual decreases of 4.7%, 7.5% and 2.7%, respectively.These circumpolar data combined with fish and marine mammal consumption data can be use
2021
Observational studies suggest that part of the North Atlantic Oscillation (NAO) variability may be attributed to the spectral ultra-violet (UV) irradiance variations associated to the 11-year solar cycle. The observed maximum surface pressure response in the North Atlantic occurs 2–4 years after solar maximum, and some model studies have identified that atmosphere–ocean feedbacks explain the multi-year lag. Alternatively, medium-to-high energy electron (MEE) precipitation, which peaks in the declining phase of the solar cycle, has been suggested as a potential cause of this lag. We use a coupled (ocean–atmosphere) climate prediction model and a state-of-the-art MEE forcing to explore the respective roles of irradiance and MEE precipitation on the NAO variability. Three decadal ensemble experiments were conducted over solar cycle 23 in an idealized setting. We found a weak ensemble-mean positive NAO response to the irradiance. The simulated signal-to-noise ratio remained very small, indicating the predominance of internal NAO variability. The lack of multi-annual lag in the NAO response was likely due to lagged solar signals imprinted in temperatures below the oceanic mixed-layer re-emerging equatorward of the oceanic frontal zones, which anchor ocean–atmosphere feedbacks. While there is a clear, yet weak, signature from UV irradiance in the atmosphere and upper ocean over the North Atlantic, enhanced MEE precipitation on the other hand does not lead to any systematic changes in the stratospheric circulation, despite its marked chemical signatures.
2021
Fate of Springtime Atmospheric Reactive Mercury: Concentrations and Deposition at Zeppelin, Svalbard
Mid-latitude atmospheric elemental mercury (Hg) emissions undergo extensive oxidation to reactive Hg (RM) compounds during Arctic polar sunrise, resulting in enhanced atmospheric deposition that impacts Arctic marine wildlife and humans. It has been difficult to estimate RM dry deposition, because RM concentrations, compounds, and their deposition velocities are ill-defined. Here, we investigate RM concentrations sampled with membrane-based methods and find these to exceed denuder-based RM detection by 5 times at the Zeppelin Observatory on Svalbard (March 26–July 24, 2019). Measured dry deposition of gaseous oxidized Hg was about half of the modeled RM deposition, demonstrating that particulate-bound Hg was an important component of dry deposition. Using thermal membrane desorption, RM chemistry was found to be dominated by Hg–Cl/Br (51%) and Hg–N (45%) compounds. Back-trajectory analysis indicated that Hg–Br/Cl compounds were predominantly advected from within the marine boundary layer (sea ice exposure), while Hg–N originated from the free troposphere. Weekly average RM compound-specific dry deposition velocities ranged from 0.12 to 0.49 cm s–1, with a net RM dry deposition of 1.9 μg m–2 (1.5–2.5 μg m–2; 95% confidence interval) that exceeds the mean annual Hg wet deposition flux in Svalbard. Overall, we find that springtime atmospheric RM deposition has been underestimated in the Arctic marine environment.
2021
Calibration and assessment of electrochemical low-cost sensors in remote alpine harsh environments
This work presents results from an original open-source low-cost sensor (LCS) system developed to measure tropospheric O3 in a remote high altitude alpine site. Our study was conducted at the Col Margherita Observatory (2543 m above sea level), in the Italian Eastern Alps. The sensor system mounts three commercial low-cost O3/NO2 sensors that have been calibrated before field deployment against a laboratory standard (Thermo Scientific; 49i-PS), calibrated against the standard reference photometer no. 15 calibration scale of the World Meteorological Organization (WMO). Intra- and intercomparison between the sensors and a reference instrument (Thermo Scientific; 49c) have been conducted for 7 months from May to December 2018. The sensors required an individual calibration, both in laboratory and in the field. The sensor's dependence on the environmental meteorological variables has been considered and discussed. We showed that it is possible to reduce the bias of one LCS by using the average coefficient values of another LCS working in tandem, suggesting a way forward for the development of remote field calibration techniques. We showed that it is possible reconstruct the environmental ozone concentration during the loss of reference instrument data in situations caused by power outages. The evaluation of the analytical performances of this sensing system provides a limit of detection (LOD) <5 ppb (parts per billion), limit of quantification (LOQ) <17 ppb, linear dynamic range (LDR) up to 250 ppb, intra-Pearson correlation coefficient (PCC) up to 0.96, inter-PCC >0.8, bias >3.5 ppb and ±8.5 at 95 % confidence. This first implementation of a LCS system in an alpine remote location demonstrated how to obtain valuable data from a low-cost instrument in a remote environment, opening new perspectives for the adoption of low-cost sensor networks in atmospheric sciences.
2021
Extreme precipitation events in Norway in all seasons are often linked to atmospheric rivers (AR). We show that during the period 1979–2018 78.5% of the daily extreme precipitation events in Southwestern Norway are linked to ARs, this percentage decreasing to 59% in the more northern coastal regions and ~40% in the inland regions. The association of extreme precipitation with AR occurs most often in fall for the coastal areas and in summer inland. All Norwegian regions experience stronger winds and 1–2°C increase of the temperature at 850 hPa during AR events compared to the climatology, the extreme precipitation largely contributing to the wet climatology (only considering rainy days) in Norway but also in Denmark and Sweden when the rest of Europe is dry. A cyclone is found nearby the AR landfall point in 70% of the cases. When the cyclone is located over the British Isles, as it is typically the case when ARs reach Southeastern Norway, it is associated with cyclonic Rossby wave breaking whereas when the ARs reach more northern regions, anticyclonic wave breaking occurs over Northern Europe. Cyclone-centered composites show that the mean sea level pressure is not significantly different between the eight Norwegian regions, that baroclinic interaction can still take place although the cyclone is close to its decay phase and that the maximum precipitation occurs ahead of the AR. Lagrangian air parcel tracking shows that moisture uptake mainly occurs over the North Atlantic for the coastal regions with an additional source over Europe for the more eastern and inland regions.
2021