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Nitrogen oxides are among the most important pollutants in the troposphere. They are emitted in many anthropogenic activities such as fossil fuel use for energy production and transportation or agricultural burning. At high concentrations, nitrogen oxides are a health hazard. They also are involved in the formation of tropospheric ozone and acid rain.There are many different ways to measure nitrogen oxides in the atmosphere. Satellite observations of NO2 are one of the most powerful as they provide excellent coverage. However, the spatial resolution is limited and in the case of measurements from low-earth satellites, there is only one measurement per day. The latter problem can be overcome by using geostationary satellites, and the Korean GEMS instrument is the first to provide hourly NO2 observations over Asia.In this study, a full year of tropospheric NO2 columns are retrieved from GEMS observations. Different retrieval settings are applied and the results compared with a particular emphasis on the analysis of the diurnal variation of NO2. Sensitivity tests include correction for the polarisation sensitivity of the GEMS instrument, different stratospheric correction schemes, different surface reflectances and different a priori profiles. While all of these parameters affect the retrieved NO2 columns, the pattern of the diurnal variation of the retrieved tropospheric columns appears to be robust, at least over regions with large pollution signals.

Recent works on using Machine Learning methods for deriving estimates of the NO2 concentration at the Earth's surface from satellite observations exploit measurements taken from low Earth orbits, e.g. from the TROPOMI instrument on the Copernicus Sentinel-5P satellite. However, given geographic location, the time resolution is quite low, with a single measurement per day, which leads to rather small data sets. In order to increase the performance of Machine Learning methods, large data sets would be desirable.Launched in 2019, the Korean Geostationary Environmental Monitoring Spectrometer (GEMS) mission has been the first geostationary satellite mission for observing trace gas concentrations in the Earth's atmosphere over Asia. Geostationary orbits allows for hourly measurements, which leads to a much higher temporal resolution compared to measurements taken from low Earth orbits. Within the next years, two further geostationary missions will follow: NASA‘s TEMPO and ESA‘s Sentinel-4 mission, providing additional data with high temporal resolution over North America and Europe.One of the GEMS level-2 data products is the NO2 tropospheric vertical column density (VCD). In our research project we discuss and develop Deep Learning methods that use not only these NO2 VCDs, but also additional data such as meteorological and geographical data, to derive estimates of the NO2 surface concentration in high spatial as well as high temporal resolution, enabled by the geostationary GEMS measurements mentioned above. The validation of the network‘s prediction is realized by the consideration of in-situ NO2 observations from the air quality network of South Korea.

GEMS (Geostationary Environmental Monitoring Spectrometer), the world’s first geostationary environmental satellite was successfully launched in February 2020 and keeps monitoring the trace gases around East Asia. For improving the GEMS retrieval algorithms and validation of the products, NIER (National Institute of Environmental Research) organized two international field campaigns in Korea: GMAP2021 (GEMS MAP of Air Pollution) and SIJAQ2022 (Satellite Integrated Joint monitoring of Air Quality), respectively in winter and summer season. In the framework of these campaigns, to fill the gap of the reference ground remote sensing observation network, additional Pandora and MAX-DOAS instruments were installed in SMA (Seoul Metropolitan Area), Ulsan, and Busan. In addition, we operated Car-DOAS and GCAS (GeoCAPE Airborne Simulator) flight measurements around the SMA and the Southeastern region to catch the detailed distribution of emission sources. Preliminary results indicate different diurnal variation patterns of NO2 columns in SMA and the Southeastern region, visible both in ground-based and GEMS data. Car-DOAS measurements show a detailed distribution of trace gases at city level and for a few days during the summer season (SIJAQ2022), Car-DOAS even caught some well-synchronized high SO2 and HCHO signals with NO2, which can be related to anthropogenic emissions around the industrial area and in the case of the SMA emission estimation measurement, nice plumes were observed along the wind direction on good meteorological condition days.

Ships are important emission sources of nitrogen oxides (NOx), which are relevant pollutants in the atmosphere affecting the environment and human health. For decades, some of the busiest shipping lines have been tracked by satellites from space. With TROPOMI aboard the first European Sentinel satellite for monitoring the composition of the Earth’s atmosphere, the Sentinel 5-Precursor (S5P), the potential for detecting shipping emissions has increased due to its low noise and high spatial resolution of 5.5 x 3.5 km2. Previous studies have shown that even individual ship plumes can be identified from TROPOMI data.In this study, we evaluate the shipping emissions on a global scale in an attempt to identify as many signals as possible from the TROPOMI data. One important aspect is to focus on finding real shipping signals and avoiding inadvertently interpreting a priori information. The aim of this study is to contribute to the progress of satellite remote sensing of shipping emissions and to better understand air pollution caused by the shipping sector and its effect on the environment.

Nitrogen oxides (NOx) play an important role in tropospheric chemistry and are key pollutants in particular in industrialised regions. While some natural emission sources exist such as lightning and bacterial soil activities, anthropogenic emissions dominate, mainly from transport, energy production, heating and industrial sources. To better understand the role of nitrogen oxides in the troposphere and to monitor the effects of measures taken to reduce emissions, continuous and global measurements of NO2 abundances in the troposphere are needed.Passive remote sensing of NO2 from space is possible as it has strong and structured absorption features in the UV and visible part of the solar spectrum. Global measurements of tropospheric NO2 have been achieved from a series of instruments including GOME, SCIAMACHY, GOME2, OMI and TROPOMI. While these data sets provide a wealth of information on NO2, they all are from satellites in sun-synchronous orbits and provide little insight into the diurnal evolution of NO2. This has changed with the launch of the Korean GEMS instrument that is the first to provide hourly NO2 measurements over Asia.In this study, spectra from the GEMS instrument were analysed for tropospheric NO2 using the IUP-Bremen NO2 retrieval code developed as breadboard algorithm for the upcoming European geostationary instrument Sentinel-4. Very good agreement is found between GEMS and concurrent measurements from TROPOMI. Validation using ground based MAX-DOAS measurements in Incheon, Republic of Korea during the GMAP-2021 campaign shows good correlation but a systematic underestimation, similar to what is reported for TROPOMI data. A number of sensitivity studies have been performed to explore the changes of the retrievals when using different stratospheric correction schemes, different a priori NO2 profiles, and different surface reflectivity assumptions. The results will be presented and discussed, in particular in view of their impact on the diurnal variations retrieved for NO2 over different cities in Asia.

South Korea’s Geostationary Environment Monitoring Spectrometer (GEMS) instrument was launched in February 2020 for monitoring of air quality above Asia on an hourly basis. During multiple validation campaigns the data quality of GEMS is being evaluated. Between September and November 2021, the GEMS Map of Air Pollution (GMAP 2021) campaign was supported by mobile car DOAS measurements with two main goals: Determining the general agreement between satellite and ground based measurements with a focus on the intra-pixel variability and assessing the nitrogen oxides (NOx) emission strength of Seoul.Mobile zenith sky DOAS observations from three instruments are combined and analyzed for Nitrogen Dioxide (NO2), Formaldehyde (HCHO) and Sulphur Dioxide (SO2). Emission estimates are performed for NO2 only, as the signal-to-noise of the other trace gases is too low. For the intra-pixel variability study, direct comparisons with NO2 vertical column densities as derived from the GEOstationary Coastal and Air Pollution Events (GEO-CAPE) Airborne Simulator (GCAS, operated by NASA) and GEMS measurements are performed.

Luftverschmutzung durch Stickoxide ist in industrialisierten Gebieten ein wichtiges Problem da sie direkte negative Auswirkungen auf die menschliche Gesundheit haben und indirekt an der Entstehung weiterer Luftschadstoffe wie Ozon und Partikeln beteiligt sind. Während die Emission von Stickoxiden meist in der Form von NO erfolgt, bildet sich in der Atmosphäre rasch ein Gleichgewicht zwischen NO2 und NO. Stickstoffdioxid (NO2) kann aufgrund seines strukturierten Absorptionsspektrums in der Atmosphäre mit spektroskopischen Methoden nachgewiesen und quantifiziert werden. Dies ist insbesondere auch von Satelliteninstrumenten wie GOME, SCIAMACHY, OMI und TROPOMI möglich, wodurch globale Karten der NO2-Verschmutzung erstellt werden können. Ein Nachteil bisheriger Satellitenmessungen ist die geringe zeitliche Auflösung von meist nur einer Messung pro Tag. Dies lässt sich durch den Einsatz von geostationären Satelliten verbessern, die für ein begrenztes Gebiet mehrere Messungen pro Tag erlauben. Solche Messungen sollen in Zukunft über Europa mit dem Sentinel-4-Instrument erfolgen und über Nordamerika mit dem TEMPO-Instrument. Über Asien sind solche Messungen vom Koreanischen Satelliten GEMS bereits verfügbar und erlauben einen ersten Einblick in das Potential geostationärer NO2-Messungen. In diesem Beitrag wird das am IUP-Bremen entwickelte NO2-Produkt für GEMS vorgestellt, die Genauigkeit der abgeleiteten Säulen untersucht und die aus den schon verfügbaren Daten bestimmte räumliche und zeitliche Variabilität diskutiert. Neben den Ergebnissen über Asien wird auch ein Ausblick auf die zu erwartenden Sentinel-4 Messungen über Europa gegeben.

Since May 2017 and August 2018, two ground-based MAX-DOAS (multi-axis differential optical absorption spectroscopy) instruments have been continuously recording daytime spectral UV–visible measurements in the northwest (University of Natural Resources and Life Sciences (BOKU) site) and south (Arsenal site), respectively, of the Vienna city center (Austria). In this study, vertical aerosol extinction (AE) profiles, aerosol optical depth (AOD), and near-surface AE are retrieved from MAX-DOAS measurements recorded on cloud-free days applying the Bremen Optimal estimation REtrieval for Aerosols and trace gaseS (BOREAS) algorithm. Measurements of atmospheric profiles of pressure and temperature obtained from routinely performed sonde ascents are used to calculate box-air-mass factors and weighting functions for different seasons. The performance of BOREAS was evaluated against co-located ceilometer, sun photometer, and in situ instrument observations covering all four seasons. The results show that the vertical AE profiles retrieved from the BOKU UV–visible MAX-DOAS observations are in very good agreement with data from the co-located ceilometer, reaching correlation coefficients (R) of 0.936–0.996 (UV) and 0.918–0.999 (visible) during the fall, winter, and spring seasons. Moreover, AE extracted using the lowest part of MAX-DOAS vertical profiles (up to 100 m above ground) is highly consistent with near-surface ceilometer AE (R>0.865 and linear regression slopes of 0.815–1.21) during the fall, winter, and spring seasons. A strong correlation is also found for the BOREAS-based AODs when compared to the AERONET ones. Notably, the highest correlation coefficients (R=0.953 and R=0.939 for UV and visible, respectively) were identified for the fall season. While high correlation coefficients are generally found for the fall, winter, and spring seasons, the results are less reliable for measurements taken during summer. For the first time, the spatial variability of AOD and near-surface AE over the urban environment of Vienna is assessed by analyzing the retrieved and evaluated BOREAS aerosol profiling products in terms of different azimuth angles of the two MAX-DOAS instruments and for different seasons. We found that the relative differences of averaged AOD between different azimuth angles are 7–13 %, depending on the season. Larger relative differences of up to 32 % are found for near-surface AE in the different azimuthal directions. This study revealed the strong capability of BOREAS to retrieve AE profiles, AOD, and near-surface AE over urban environments and demonstrated its use for identifying the spatial variability of aerosols in addition to the temporal variation.

Satellite observations of the high-resolution TROPOspheric Monitoring Instrument (TROPOMI) on Sentinel-5 Precursor can be used to observe nitrogen dioxide (NO2) at city scales to quantify short time variability of nitrogen oxide (NOx) emissions and lifetimes on a daily and seasonal basis. In this study, 2 years of TROPOMI tropospheric NO2 columns, having a spatial resolution of up to 3.5 km × 5.5 km, have been analyzed together with wind and ozone data. NOx lifetimes and emission fluxes are estimated for 50 different NOx sources comprising cities, isolated power plants, industrial regions, oil fields, and regions with a mix of sources distributed around the world. The retrieved NOx emissions are in agreement with other TROPOMI-based estimates and reproduce the variability seen in power plant stack measurements but are in general lower than the analyzed stack measurements and emission inventory results. Separation into seasons shows a clear seasonal dependence of NOx emissions with in general the highest emissions during winter, except for isolated power plants and especially sources in hot desert climates, where the opposite is found. The NOx lifetime shows a systematic latitudinal dependence with an increase in lifetime from 2 to 8 h with latitude but only a weak seasonal dependence. For most of the 50 sources including the city of Wuhan in China, a clear weekly pattern of NOx emissions is found, with weekend-to-weekday ratios of up to 0.5 but with a high variability for the different locations. During the Covid-19 lockdown period in 2020, strong reductions in the NOx emissions were observed for New Delhi, Buenos Aires, and Madrid.

Most of the anthropogenic emissions of nitrogen oxides (NOx = NO2 + NO) are linked to burning of fossil fuels for energy production, transportation or industrial processes. However, biomass burning and in particular large wild fires in tropical and sub-tropical regions can also be large sources of nitrogen oxides at least locally. Depending on the size of the fires, particles and gases can be lifted into the free troposphere and even higher, increasing the atmospheric lifetime of NOx and enabling long range transport.The TROPOMI instrument on board of Sentinel 5 precursor (S5p) is a nadir viewing UV/vis imaging spectrometer launched in October 2017 and operationally providing data since July 2018. One of the main products that can be retrieved from TROPOMI spectra is tropospheric and total column NO2. Compared to previous UV/vis satellite instruments such as GOME, SCIAMACHY, GOME2 and OMI, TROPOMI has a higher spatial resolution of 3.5 x 5.5 km2. This reduced foot print size enables detection and evaluation of more localised sources such as individual fires and their plumes, and better separation of different contributions to the overall NO2 loading.In this presentation, IUP-Bremen TROPOMI NO2 retrievals are evaluated for biomass burning signatures during the years 2018 to 2020, three years with very different burning seasons. The amounts and spatial distributions of NO2 from fires are compared between the years and between different fire regions, and their impact on regions downwind of the sources is investigated.

Airborne imaging DOAS and ground-based stationary and mobile DOAS measurements were conducted during the ESA funded S5P-VAL-DE-Ruhr campaign in September 2020 in the Ruhr area. The Ruhr area is located in Western Germany and is a pollution hotspot in Europe with urban character as well as large industrial emitters. The measurements are used to validate data from the Sentinel-5P TROPOspheric Monitoring Instrument (TROPOMI) with focus on the NO2 tropospheric vertical column product.Seven flights were performed with the airborne imaging DOAS instrument, AirMAP, providing continuous maps of NO2 in the layers below the aircraft. These flights cover many S5P ground pixels within an area of about 40 km side length and were accompanied by ground-based stationary measurements and three mobile car DOAS instruments. Stationary measurements were conducted by two Pandora, two zenith-sky and two MAX-DOAS instruments distributed over three target areas, partly as long-term measurements over a one-year period.Airborne and ground-based measurements were compared to evaluate the representativeness of the measurements in time and space. With a resolution of about 100 x 30 m2, the AirMAP data creates a link between the ground-based and the TROPOMI measurements with a resolution of 3.5 x 5.5 km2 and is therefore well suited to validate TROPOMI's tropospheric NO2 vertical column.The measurements on the seven flight days show strong variability depending on the different target areas, the weekday and meteorological conditions. We found an overall low bias of the TROPOMI operational NO2 data for all three target areas but with varying magnitude for different days. The campaign data set is compared to custom TROPOMI NO2 products, using different auxiliary data, such as albedo or a priori vertical profiles to evaluate the influence on the TROPOMI data product. Analyzing and comparing the different data sets provides more insight into the high spatial and temporal heterogeneity in NO2 and its impact on satellite observations and their validation.

Launched in October 2017, the TROPOspheric Monitoring Instrument (TROPOMI) aboard Sentinel-5 Precursor provides the potential to monitor air quality over point sources across the globe with a spatial resolution as high as 5.5 km × 3.5 km (7 km × 3.5 km before 6 August 2019). The nitrogen dioxide (NO2) retrieval algorithm for the TROPOMI instrument consists of three steps: the spectral fitting of the slant column, the separation of stratospheric and tropospheric contributions, and the conversion of the slant column to a vertical column using an air mass factor (AMF) calculation. In this work, an improved tropospheric NO2 retrieval algorithm from TROPOMI measurements over Europe is presented. The stratospheric estimation is implemented using the STRatospheric Estimation Algorithm from Mainz (STREAM), which was developed as a verification algorithm for TROPOMI and does not require chemistry transport model data as input. A directionally dependent STREAM (DSTREAM) is developed to correct for the dependency of the stratospheric NO2 on the viewing geometry by up to 2 × 1014 molec/cm2. Applied to synthetic TROPOMI data, the uncertainty in the stratospheric column is 3.5 × 1014 molec/cm2 for polluted conditions. Applied to actual measurements, the smooth variation of stratospheric NO2 at low latitudes is conserved, and stronger stratospheric variation at higher latitudes are captured. For AMF calculation, the climatological surface albedo data is replaced by geometry-dependent effective Lambertian equivalent reflectivity (GE_LER) obtained directly from TROPOMI measurements with a high spatial resolution. Mesoscale-resolution a priori NO2 profiles are obtained from the regional POLYPHEMUS/DLR chemistry transport model with the TNO-MACC emission inventory. Based on the latest TROPOMI operational cloud parameters, a more realistic cloud treatment is provided by a clouds-as-layers (CAL) model, which treats the clouds as uniform layers of water droplets, instead of the clouds-as-reflecting-boundaries (CRB) model, in which clouds are simplified as Lambertian reflectors. For the error analysis, the tropospheric AMF uncertainty, which is the largest source of NO2 uncertainty for polluted scenarios, ranges between 20 % and 50 %, leading to a total uncertainty in the tropospheric NO2 column in the 30–60 % range. From a validation performed with ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) measurements, the improved tropospheric NO2 data shows good correlations for nine European urban/suburban stations with an average correlation coefficient of 0.78. The implementation of the algorithm improvements leads to a decrease of the relative difference from −55.3 % to −34.7 % on average.

Within the project VINDOBONA (VIenna horizontal aNd vertical Distribution OBservations Of Nitrogen dioxide and Aerosols), a method was developed to retrieve the spatial distribution of trace gases using data from three ground based MAX-DOAS instruments and was applied on the example of NO2. At three different locations in Vienna (Austria) MAX-DOAS instruments were installed performing measurements in the visible and UV spectral range. Currently, each instrument is set up to determine the column densities in different azimuthal directions and low elevation angles within approximately a horizontal plane. The different lines of sight of the three instruments intersect horizontally and can be used to estimate the horizontal spatial distribution of trace gases. With the knowledge of vertical profiles, even the vertical distribution can be estimated using this method. The intersections of the different lines of sight define segments along the slant columns for which the mass concentrations can be estimated. Knowledge about the vertical profiles for a chosen trace gas can be used to correct the retrieved trace gas concentration to specific altitudes above ground. Such corrections are also required since the three instruments were set up at different heights above ground, at different altitudes relative to sea level and with different elevation angles of the lowest viewing direction. One open issue for the retrieval process is the terrain in Vienna in combination with the prevailing wind condition that impacts the horizontal and vertical trace gas distribution and make the retrieval challenging.

Most of the anthropogenic emissions of nitrogen oxides (NOx = NO2 + NO) are linked to burning of fossil fuels for energy production, transportation or industrial processes. However, biomass burning and in particular large wild fires in tropical and sub-tropical regions can also be important sources of nitrogen oxides, at least locally. Depending on the size of the fires, particles and gases are lifted into the free troposphere and even higher, increasing the atmospheric lifetime of NOx in these plumes and enabling long range transport.The TROPOMI instrument on board of Sentinel 5 precursor (S5p) is a nadir viewing UV/vis imaging spectrometer launched in October 2017 and operationally providing data since July 2018. One of the main products that can be retrieved from TROPOMI spectra is tropospheric and total column NO2. Compared to previous UV/vis satellite instruments such as GOME, SCIAMACHY, GOME2 and OMI, TROPOMI has a higher spatial resolution of 3.5 x 5.5 km2. This reduced foot print size enables detection and evaluation of more localised sources such as individual fires and their plumes, and better separation of different contributions to the overall NO2 loading.In this presentation, IUP-Bremen TROPOMI NO2 retrievals are evaluated for biomass burning signatures during 2018 and 2019, two years with very different burning seasons. The amounts and spatial distributions of NO2 from fires are compared between the two years and between different fire regions, and their impact on regions downwind of the sources is investigated.

Satellite observations of the high-resolution instrument TROPOMI on Sentinel-5P make it possible to measure nitrogen dioxide (NO2) at city level and even to quantify the variability of NOx emissions and lifetimes on a seasonal and daily basis.NO2 is an air pollutant and especially in cities of particular importance due to the large number and strength of emission sources in combination with people living nearby exposing their health to the polluted air. To quantify nitrogen oxide emissions and lifetimes with their variability in space and time, satellite data is especially suited as it provides daily global coverage and large number of measurements. The TROPOspheric Monitoring Instrument (TROPOMI) on Sentinel-5P, launched in October 2017, provides, thanks to its higher spatial resolution when compared to previous satellite instruments, the possibility of detailed investigations on lifetimes and emissions of air pollutants.Two years of TROPOMI NO2 data with a spatial resolution of up to 3.5 km x 5.5 km together with ECMWF ERA5 wind data are analyzed. The NO2 data around a source is linked to the ERA5 wind data and rotated to a uniform wind direction to get clear emission patterns. Out of these two-dimensional maps of the mean NO2 distribution, one dimensional line densities are calculated by integration across wind direction. Lifetimes and emission fluxes are calculated for different NOx sources such as cities and power plants distributed over the world. They are compared among each other and to bottom-up emission inventories. Seasonal variability and weekday versus weekend effects in lifetimes and emissions are discussed.

As part of the German project MeSMarT (Measurements of shipping emissions in the marine troposphere, a cooperation between the University of Bremen and the German Federal Maritime and Hydrographic Agency) and the EU LIFE project CLINSH (Clean Inland Shipping,) numerous mobile measurements of atmospheric trace gases and aerosols have been carried out.For both projects one main objective is to investigate the general impact of shipping emissions on the air quality in regions with high marine traffic. In order to do this in areas where no permanent monitoring systems are available, in 2015 a mobile lab has been set up, which includes among other instrumentation for air pollution and meteorological parameters a scientific-grade MAX-DOAS system as well as in situ instruments for nitrogen oxides, ozone, carbon monoxide and sulfur dioxide (trace level).In this study we present intercomparison results between the different instruments onboard the mobile lab as well as the interpretation of the results using complementary data sets at different locations including the Lower Rhine and Waal area and several regions in Northern Germany. For some places close to the banks of the Rhine more than 70% of the nitrogen oxides are related to shipping emissions. Emission factors for different ship types have been calculated and compared to recent studies and emission inventories.

Within the scope of the VINDOBONA (VIenna horizontal aNd vertical Distribution OBservations Of Nitrogen dioxide and Aerosols) project, spectral UV/vis measurements at selected viewing directions are performed with three MAX-DOAS (Multi AXis Differential Optical Absorption Spectroscopy) instruments, which are located in the northeast, northwest, and south of the city center of Vienna, Austria. The selection of viewing directions of the three instruments was chosen in a way to provide data for the retrieval of horizontal and vertical trace gas and aerosol distributions, in particular over the urban core.In the present work, the profile retrieval algorithm BOREAS (Bremen Optimal estimation REtrieval for Aerosols and trace gaseS) is used to retrieve aerosol and NO2 vertical profiles as well as accompanying parameters aerosol optical depth, tropospheric NO2 vertical columns (TVC NO2), and near-surface NO2 on days with cloudless conditions. The retrieval results are compared with co-located ceilometer, sun photometer, surface air quality, and TVC NO2 measurements, with the latter being obtained by applying the geometrical approximation and converting zenith-sky NO2 measurements.

ZusammenfassungDie Vitamin-D3-gewichtete UV-Exposition eines aufrecht stehenden Menschen wurde für ausgewählte urbane Umgebungen bestimmt, um den Einfluss der Verschattung durch Gebäude oder Bewuchs auf die Exposition zu untersuchen. Die Exposition wird berechnet unter Berücksichtigung der Strahldichte, also der Strahlungsenergie von direkter Sonnenstrahlung und diffuser Himmelsstrahlung aus verschiedenen Einfalls- und Azimutwinkeln und der 3 D-Geometrie eines Modellmenschen. Die Verschattung wird durch Hemisphären-Bilder bestimmt, die mithilfe einer Fotokamera mit Fischaugenobjektiv aufgenommen wurden, wobei angenommen wird, dass die Strahlung verschatteter Himmelssegmente vernachlässigbar klein ist. Dadurch werden den Himmel verdeckende Hindernisse räumlich hochaufgelöst erfasst und als Input in das Expositionsmodell eingegeben. Die Vitamin-D3-gewichtete Exposition betrug an einer bebauten Straße am 21. Dezember zu Sonnenhöchststand ungefähr 50 % und am 21. März 70 % von der Exposition einer hindernisfreien Umgebung.

Solar spectral irradiance measured by two recently developed array spectroradiometers (called UV-BTS and VIS-BTS) are compared to the results of a scanning double monochromator system which is certified as a travelling reference instrument by the Network for the detection of atmospheric composition change (NDACC) and fulfils the specifications of S-2 UV instruments of the world meteorological organization (WMO). The comparison took place between 15 and 18 May 2017 at the Institute of Meteorology and Climatology of the University of Hanover (IMuK) between 4:00 and 17:00UTC. The UV-BTS array spectroradiometer is equipped with special hardware to significantly reduce internal stray light which has been the limiting factor of many array spectroradiometers in the past. It covers a wavelength range of 200 nm-430 nm. The VIS-BTS covers a wider spectral range from 280 nm up to 1050 nm, and stray light reduction is achieved by mathematical methods. For the evaluation, wavelength integrated quantities and spectral global irradiance are compared. The deviation for UV index measured by the UV-BTS, is within ±1% for solar zenith angles (SZA) below 70° and increased to a maximum of ±3% for SZA between 70° and 85° when synchronisation between measurements was possible. The deviation of global spectral irradiance is smaller ±2.5% in the spectral range from 300 nm to 420 nm (evaluated for SZA < 70°). The VIS-BTS achieved the same deviation for blue light hazard as the UV-BTS for the UV index. The evaluations of global spectral irradiance data of the VIS-BTS show a deviation smaller than ±2% in the spectral range from 365 nm to 900 nm (evaluated for SZA < 70°). Below 365 nm, the deviation rises up to ±7% at 305 nm due to remaining stray light. The agreement within the limited time of the intercomparison is considered to be satisfactory for a number of applications and provides a good basis for further investigations. © 2018 IOP Publishing Ltd.

The vitamin D3-weighted UV exposure of a human with vertical posture was calculated for urban locations to investigate the impact of orientation and obstructions on the exposure. Human exposure was calculated by using the 3D geometry of a human and integrating the radiance, i.e., the radiant energy from the direct solar beam and the diffuse sky radiation from different incident and azimuth angles. Obstructions of the sky are derived from hemispherical images, which are recorded by a digital camera with a fisheye lens. Due to the low reflectivity of most surfaces in the UV range, the radiance from obstructed sky regions was neglected. For spring equinox (21 March), the exposure of a human model with winter clothing in an environment where obstructions cover 40% of the sky varies by up to 25%, depending on the orientation of the human model to the sun. The calculation of the accumulated vitamin D3-weighted exposure of a human with winter clothing walking during lunch break shows that human exposure is reduced by the obstruction of buildings and vegetation by 40%.

The vitamin D3-weighted UV exposure of a human with vertical posture was calculated for urban locations to investigate the impact of orientation and obstructions on the exposure. Human exposure was calculated by using the 3D geometry of a human and integrating the radiance, i.e., the radiant energy from the direct solar beam and the diffuse sky radiation from different incident and azimuth angles. Obstructions of the sky are derived from hemispherical images, which are recorded by a digital camera with a fisheye lens. Due to the low reflectivity of most surfaces in the UV range, the radiance from obstructed sky regions was neglected. For spring equinox (21 March), the exposure of a human model with winter clothing in an environment where obstructions cover 40% of the sky varies by up to 25%, depending on the orientation of the human model to the sun. The calculation of the accumulated vitamin D3-weighted exposure of a human with winter clothing walking during lunch break shows that human exposure is reduced by the obstruction of buildings and vegetation by 40%.

BackgroundScales are widely used in psychiatric assessments following self-harm. Robust evidence for their diagnostic use is lacking.AimsTo evaluate the performance of risk scales (Manchester Self-Harm Rule, ReACT Self-Harm Rule, SAD PERSONS scale, Modified SAD PERSONS scale, Barratt Impulsiveness Scale); and patient and clinician estimates of risk in identifying patients who repeat self-harm within 6 months.MethodA multisite prospective cohort study was conducted of adults aged 18 years and over referred to liaison psychiatry services following self-harm. Scale a priori cut-offs were evaluated using diagnostic accuracy statistics. The area under the curve (AUC) was used to determine optimal cut-offs and compare global accuracy.ResultsIn total, 483 episodes of self-harm were included in the study. The episode-based 6-month repetition rate was 30% (n = 145). Sensitivity ranged from 1% (95% CI 0–5) for the SAD PERSONS scale, to 97% (95% CI 93–99) for the Manchester Self-Harm Rule. Positive predictive values ranged from 13% (95% CI 2–47) for the Modified SAD PERSONS Scale to 47% (95% CI 41–53) for the clinician assessment of risk. The AUC ranged from 0.55 (95% CI 0.50–0.61) for the SAD PERSONS scale to 0.74 (95% CI 0.69–0.79) for the clinician global scale. The remaining scales performed significantly worse than clinician and patient estimates of risk (P < 0.001).ConclusionsRisk scales following self-harm have limited clinical utility and may waste valuable resources. Most scales performed no better than clinician or patient ratings of risk. Some performed considerably worse. Positive predictive values were modest. In line with national guidelines, risk scales should not be used to determine patient management or predict self-harm.

General hospital clinicians frequently deal with injecting drug users because substance use has diverse medical and psychiatric complications. Non-specialist clinicians often initiate management when specialist consultation is not available or accepted by the patient. Here, we summarise evidence for the management of hospitalised injecting drug users. The first challenge is to engage a drug user into medical care. A non-judgmental approach towards patients and acceptance of their lifestyle choices facilitates engagement. Pragmatic clinical goals can be negotiated and achieved. We also describe common conditions of injecting drug users. Accurate diagnosis and appropriate management focus on common issues such as intoxication, withdrawal, pain management, drug seeking, psychological comorbidity, behavioural difficulties, and pregnancy. Effective management can reduce the medical and social effect of these conditions and is not difficult.

Background The neural correlates of anxiety associated with obsessive-compulsive symptomlike provocation in normal volunteers are unknown. Methods Ten healthy volunteers participated in four functional magnetic resonance experiments. Subjects were scanned while viewing alternating blocks of emotional (normally aversive, washing-relevant, checking-relevant, or hoarding-relevant pictures) and neutral pictures, and imagining scenarios related to the content of each picture type. Nonparametric brain mapping analyses were used. Results In response to the provocative pictures in all experiments, increases in subjective anxiety and activation in bilateral ventral prefrontal, limbic, dorsal prefrontal, and visual regions were demonstrated. Anxiety related to different symptom dimensions was associated with different patterns of activation: provocation of washing-relevant anxiety predominantly activated dorsal and ventral prefrontal regions; checking-relevant anxiety predominantly activated dorsal prefrontal regions; and hoarding-relevant anxiety predominantly activated ventral prefrontal regions and the left amygdala. Conclusions Our findings support a dimensional model of obsessive-compulsive disorder (OCD) whereby 1) the brain systems implicated in the mediation of anxiety in response to symptom-related material in normal subjects are similar to those identified in OCD patients during symptom provocation, and 2) anxiety associated with different symptom dimensions is associated with differential patterns of activation of these neural systems. Further investigation of the neural basis of OCD symptom dimensions is required.

Background The amygdala, hippocampus, ventral, and dorsal prefrontal cortices have been demonstrated to be involved in the response to fearful facial expressions. Little is known, however, about the effect of task instructions upon the intensity of responses within these regions to fear-inducing stimuli. Methods Using functional magnetic resonance imaging, we examined neural responses to alternating, 30-sec blocks of fearful and neutral expressions in nine right-handed male volunteers during three different 5-min conditions: 1) passive viewing; 2) performance of a gender-decision task, with no explicit judgment of facial emotion; 3) performance of an emotionality judgment task — an explicitly emotional task. Results There was a significant effect of task upon activation within the left hippocampus and the left inferior occipital gyrus, and upon the magnitude of response within the left hippocampus, with maximal activation in these regions occurring during passive viewing, and minimal during performance of the explicit task. Performance of the gender-decision and explicit tasks, but not passive viewing, was also associated with activation within ventral frontal cortex. Conclusions Neural responses to fearful facial expressions are modulated by task instructions.