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2018
2018
Monitoring of the atmospheric ozone layer and natural ultraviolet radiation: Annual report 2017.
This report summarizes the results from the Norwegian monitoring programme on stratospheric ozone and UV radiation measurements. The ozone layer has been measured at three locations since 1979: in Oslo, Tromsø/Andøya and Ny-Ålesund. The UV measurements started in 1995. The results show that there was a significant decrease in stratospheric ozone above Norway between 1979 and 1997. After that the ozone layer stabilized at a level ~2% below pre-1980 level. There are large inter-annual variations and in 2017 there were relatively low values at all the three Norwegian stations during the winter. However, the ozone situation normalized towards the end of spring.
NILU
2018
Monitoring of greenhouse gases and aerosols at Svalbard and Birkenes in 2017 - Annual report
The report summaries the activities and results of the greenhouse gas monitoring at the Zeppelin Observatory situated on Svalbard in Arctic Norway during the period 2001-2017, and the greenhouse gas monitoring and aerosol observations from Birkenes for 2009-2017.
NILU
2018
Energetic electrons from the magnetosphere deposit their energy in the atmosphere and lead to production of nitric oxide (NO) in the mesosphere and lower thermosphere. We study the atmospheric NO response to a geomagnetic storm in April 2010 with WACCM (Whole Atmosphere Community Climate Model). Modeled NO is compared to observations by Solar Occultation For Ice Experiment/Aeronomy of Ice in the Mesosphere at 72–82°S latitudes. We investigate the modeled NOs sensitivity to changes in energy and chemistry. The electron energy model input is either a parameterization of auroral electrons or a full range energy spectrum (1–750 keV) from National Oceanic and Atmospheric Administration/Polar Orbiting Environmental Satellites and European Organisation for the Exploitation of Meteorological Satellites/Meteorological Operational satellites. To study the importance of ion chemistry for the production of NO, WACCM‐D, which has more complex ion chemistry, is used. Both standard WACCM and WACCM‐D underestimate the storm time NO increase in the main production region (90–110 km), using both electron energy inputs. At and below 80 km, including medium‐energy electrons (>30 keV) is important both for NO directly produced at this altitude region and for NO transported from other regions (indirect effect). By using WACCM‐D the direct NO production is improved, while the indirect effects on NO suffer from the downward propagating deficiency above. In conclusion, both a full range energy spectrum and ion chemistry is needed throughout the mesosphere and lower thermosphere region to increase the direct and indirect contribution from electrons on NO.
2018
Accurate gas velocity measurements in emission plumes are highly desirable for various atmospheric remote sensing applications. The imaging technique of UV SO2 cameras is commonly used to monitor SO2 emissions from volcanoes and anthropogenic sources (e.g. power plants, ships). The camera systems capture the emission plumes at high spatial and temporal resolution. This allows the gas velocities in the plume to be retrieved directly from the images. The latter can be measured at a pixel level using optical flow (OF) algorithms. This is particularly advantageous under turbulent plume conditions. However, OF algorithms intrinsically rely on contrast in the images and often fail to detect motion in low-contrast image areas. We present a new method to identify ill-constrained OF motion vectors and replace them using the local average velocity vector. The latter is derived based on histograms of the retrieved OF motion fields. The new method is applied to two example data sets recorded at Mt Etna (Italy) and Guallatiri (Chile). We show that in many cases, the uncorrected OF yields significantly underestimated SO2 emission rates. We further show that our proposed correction can account for this and that it significantly improves the reliability of optical-flow-based gas velocity retrievals.
In the case of Mt Etna, the SO2 emissions of the north-eastern crater are investigated. The corrected SO2 emission rates range between 4.8 and 10.7 kg s−1 (average of 7.1 ± 1.3 kg s−1) and are in good agreement with previously reported values. For the Guallatiri data, the emissions of the central crater and a fumarolic field are investigated. The retrieved SO2 emission rates are between 0.5 and 2.9 kg s−1 (average of 1.3 ± 0.5 kg s−1) and provide the first report of SO2 emissions from this remotely located and inaccessible volcano.
2018
Influence of solar wind energy flux on the interannual variability of ENSO in the subsequent year
Previous studies have tended to adopt the quasi-decadal variability of the solar cycle (e.g. sunspot number (SSN) or solar radio flux at 10.7 cm (F10.7) to investigate the effect of solar activity on El Niño–Southern Oscillation (ENSO). As one of the major terrestrial energy sources, the effect of solar wind energy flux in Earth’s magnetosphere (Ein) on the climate has not drawn much attention, due to the big challenge associated with its quantitative estimation. Based on a new Ein index estimated by three-dimensional magnetohydrodynamic simulations from a previous study, this study reveals that Ein exhibits both quasi-decadal variability (periodic 11-year) and interannual (2–4 years) variability, which has rarely before been detected by SSN and F10.7. A significant interannual relationship between the annual mean Ein and subsequent early-winter ENSO is further revealed. Following high Ein, the sea level pressure in the subsequent early winter shows significant positive anomalies from Asia southward to the Maritime Continent, and significant negative anomalies over the Southeast and Northeast Pacific, resembling the Southern Oscillation. Meanwhile, significant upper-level anomalous convergence and divergence winds appear over the western and eastern Pacific, which is configured with significant lower-level anomalous divergence and convergence, indicating a weakening of the Walker circulation. Consequently, notable surface easterly wind anomalies prevail over the eastern tropical Pacific, leading to El Niño-like sea surface temperature anomalies. It is suggested that better describing the processes in the solar wind–magnetosphere–ionosphere coupled system is essential to understand the solar influence on climate change.
2018
In birds, incubation‐related behaviors and brood patch formation are influenced by hormonal regulation such as prolactin secretion. Brood patch provides efficient heat transfer between the incubating parent and the developing embryo in the egg. Importantly, several environmental contaminants are already known to have adverse effects on avian reproduction. However, relatively little is known about the effect of contaminants on incubation temperature (Tinc) in wild birds. By using temperature thermistors placed into artificial eggs, we investigated whether the most contaminated parent birds are less able to provide appropriate egg warming and thus less committed to incubating their clutch. Specifically, we investigated the relationships among 3 groups of contaminants (organochlorines, perfluoroalkyl substances [PFASs], and mercury [Hg]) with Tinc and also with prolactin concentrations and brood patch size in incubating Arctic black‐legged kittiwakes (Rissa tridactyla). Our results reveal that among the organochlorines considered, only blood levels of oxychlordane, the main metabolite of chlordane, a banned pesticide, were negatively related to the minimum incubation temperature in male kittiwakes. Levels of PFASs and Hg were unrelated to Tinc in kittiwakes. Moreover, our study suggests a possible underlying mechanism: since we reported a significant and negative association between blood oxychlordane concentrations and the size of the brood patch in males. Finally, this reduced Tinc in the most oxychlordane‐contaminated kittiwakes was associated with a lower egg hatching probability.
2018
2018
Satellite data inclusion and kernel based potential improvements in NO2 mapping
European Topic Centre on Air Pollution and Climate Change Mitigation
2018
Svevestøvmåling i bydel Fana langs FV546. 23. desember 2016 - 31. desember 2017.
På oppdrag fra Statens vegvesen Region vest har NILU utført målinger av PM10 og PM2.5 ved et boligområde ved Fanavegen (Bergen kommune). Støvende aktivitet i forbindelse med anleggsarbeid genererer svevestøv til sjenanse for berørte naboer. Målingene pågikk i perioden 23. desember 2016 – 31. desember 2017. Resultatene ble rapportert hver måned. Årsmiddel-konsentrasjonene for PM10 og PM2.5 i 2017 var langt under respektive grenseverdier. I måleperioden ble det observert 3 døgn med PM10-døgnmiddelverdier over grenseverdien på 50 μg/m3. Det er tillatt med 30 døgnverdier over dette nivået. Årsaken til høy PM10-konsentrasjon var oppvirvling av svevestøv fra kjørebanen. Så lenge tiltak for å dempe støvoppvirvling ble iverksatt tidsnok, var svevestøvkonsentrasjonen innenfor varslingsklassen for liten eller ingen helserisiko.
NILU
2018
Assessment of heavy metal transboundary pollution on global, regional and national scales
Meteorological Synthesizing Centre - East (MSC-E)
2018
2018
2018
Comparison of dust-layer heights from active and passive satellite sensors
Aerosol-layer height is essential for understanding the impact of aerosols on the climate system. As part of the European Space Agency Aerosol_cci project, aerosol-layer height as derived from passive thermal and solar satellite sensors measurements have been compared with aerosol-layer heights estimated from CALIOP measurements. The Aerosol_cci project targeted dust-type aerosol for this study. This ensures relatively unambiguous aerosol identification by the CALIOP processing chain. Dust-layer height was estimated from thermal IASI measurements using four different algorithms (from BIRA-IASB, DLR, LMD, LISA) and from solar GOME-2 (KNMI) and SCIAMACHY (IUP) measurements. Due to differences in overpass time of the various satellites, a trajectory model was used to move the CALIOP-derived dust heights in space and time to the IASI, GOME-2 and SCIAMACHY dust height pixels. It is not possible to construct a unique dust-layer height from the CALIOP data. Thus two CALIOP-derived layer heights were used: the cumulative extinction height defined as the height where the CALIOP extinction column is half of the total extinction column, and the geometric mean height, which is defined as the geometrical mean of the top and bottom heights of the dust layer. In statistical average over all IASI data there is a general tendency to a positive bias of 0.5–0.8 km against CALIOP extinction-weighted height for three of the four algorithms assessed, while the fourth algorithm has almost no bias. When comparing geometric mean height there is a shift of −0.5 km for all algorithms (getting close to zero for the three algorithms and turning negative for the fourth). The standard deviation of all algorithms is quite similar and ranges between 1.0 and 1.3 km. When looking at different conditions (day, night, land, ocean), there is more detail in variabilities (e.g. all algorithms overestimate more at night than during the day). For the solar sensors it is found that on average SCIAMACHY data are lower by −1.097 km (−0.961 km) compared to the CALIOP geometric mean (cumulative extinction) height, and GOME-2 data are lower by −1.393 km (−0.818 km).
2018