Marine versus Continental Sources of Iodine and Selenium in Rainfall at Two European High-Altitude Locations.

The essential elements selenium (Se) and iodine (I) are often present in low levels in terrestrial diets, leading to potential deficiencies. Marine I and Se emissions and subsequent atmospheric wet deposition has been suggested to be an important source of I and Se to soils and terrestrial food chains. However, the contribution of recycled moisture of continental origin to I and Se to precipitation has never been analyzed. Here we report concentrations and speciation of I and Se, as well as of bromine (Br), sulfur (S), and DOC-δ13C signatures for weekly collected precipitation samples (in the period of April 2015 to September 2016) at two high altitude sites, i.e., Jungfraujoch (JFJ; Switzerland) and Pic du Midi (PDM; France). Analysis of precipitation chemistry and moisture sources indicate combined marine and continental sources of precipitation and Se, I, Br, and S at both sites. At JFJ, concentrations of I and Se were highest when continental moisture sources were dominant, indicating important terrestrial sources for these elements. Furthermore, correlations between investigated elements and DOC-δ13C, particularly when continental moisture source contributions were high, indicate a link between these elements and the source of dissolved organic matter, especially for I (JFJ and PDM) and Se (JFJ).

Extraction and Visual Analysis of Potential Vorticity Banners around the Alps.

Potential vorticity is among the most important scalar quantities in atmospheric dynamics. For instance, potential vorticity plays a key role in particularly strong wind peaks in extratropical cyclones and it is able to explain the occurrence of frontal rain bands. Potential vorticity combines the key quantities of atmospheric dynamics, namely rotation and stratification. Under suitable wind conditions elongated banners of potential vorticity appear in the lee of mountains. Their role in atmospheric dynamics has recently raised considerable interest in the meteorological community for instance due to their influence in aviation wind hazards and maritime transport. In order to support meteorologists and climatologists in the analysis of these structures, we developed an extraction algorithm and a visual exploration framework consisting of multiple linked views. For the extraction we apply a predictor-corrector algorithm that follows streamlines and realigns them with extremal lines of potential vorticity. Using the agglomerative hierarchical clustering algorithm, we group banners from different sources based on their proximity. To visually analyze the time-dependent banner geometry, we provide interactive overviews and enable the query for detail on demand, including the analysis of different time steps, potentially correlated scalar quantities, and the wind vector field. In particular, we study the relationship between relative humidity and the banners for their potential in indicating the development of precipitation. Working with our method, the collaborating meteorologists gained a deeper understanding of the three-dimensional processes, which may spur follow-up research in the future.

Effects of black carbon and mineral dust on glacial melting on the Muz Taw glacier, Central Asia.

Light-absorbing impurities (LAIs), including black carbon (BC) and mineral dust, in snow can trigger a positive feedback. In this study, we estimate the contribution of BC and dust to glacial melting in Central Asia. Average BC and dust concentrations in the surface snow of the Muz Taw glacier are 1788 ± 1754 ng g-1 and 172 ± 178 µg g-1, respectively. Simulation using the Snow Ice and Aerosol Radiation (SNICAR) model indicates that the combined effect of BC and dust reduces the snow albedo by approximately 6.24% to 50.4% relative to clean snow. Radiative forcing (RF) induced by BC and dust deposited in snow ranges from 1.61 to 32.69 W m-2, with an average of 16.74 W m-2 for the central scenario. Thus, glacier melting can be enhanced by 36.37 cm w.e. by BC and dust in snow, accounting for about 16.3% of the total glacier melt. LAIs deposited on the Muz Taw glacier mostly originate from Central Asia, West Siberia and local emissions during the study period. More than 80% of BC deposited is attributed to anthropogenic emissions. These results strengthen the important role of BC and dust in glacier melting in Central Asia, and further highlights the potential benefits of mitigation of BC emissions.

Data on DOC and N from the Muz taw glacier in Central Asia.

This Data in Brief article provides a supplementary information to the dissolved organic carbon and nitrogen from the snow of Muz taw glacier in the Central Asia, which is related to the scientific article titled with "Characterization, sources and transport of dissolved organic carbon and nitrogen from a glacier in the Central Asia"[1]. Meanwhile, major ions (including Na+, K +, NH4 +, Ca2+, Mg2+, Cl-, SO4 2-, NO3 -, and NO2 -) were also reported. These data were analysed using descriptive statistics such as correlations and principle component analysis. Additionally, we conducted a literature review on DOC and N concentrations for the comparison. This article also presents the analysis data of the mass absorption cross section of DOC in snow.

Characterization, sources and transport of dissolved organic carbon and nitrogen from a glacier in the Central Asia.

Glacier melting represents an important flux of carbon and nitrogen (N) and affects the hydrological cycle. In this study, we presented the features of dissolved organic carbon (DOC) and N concentrations, their potential sources and export from the Muz Taw glacier in Central Asia. The average DOC and total dissolved nitrogen concentrations were 1.12 ± 1.66 and 0.62 ± 0.59 mg L-1 in surface snow and 0.21 ± 0.04 and 0.31 ± 0.10 mg L-1 in snowpit samples, respectively. The values from snowpit of the Muz Taw glacier were comparable to data reported from glaciers in the Tibetan Plateau but were considerably higher than those from polar regions. The C/N ratios in snow ranged from 0.7 to 11.7, indicating the high bioavailability of DOC. Mass absorption cross section of DOC at 365 nm in snow indicated that during the snow melting process, light-absorbing DOC was prone to be attached to particles, especially in the ablation zone of the Muz Taw glacier. Radiative forcing caused by DOC contributed approximately 38 ± 26% and 18 ± 9.8% of that caused by black carbon for surface snow and snowpit samples, respectively. DOC and N deposition on the glacier surface were influenced by the combined sources from anthropogenic input, wild biomass burning emission, and dust input from local regions and long range transport. Export of DOC and N from the Muz Taw glacier was estimated to be 3.47-18.5 t C yr-1 and 5.11-10.23 t N yr-1 respectively, based on their concentrations and current glacier mass balance. These results enhanced our understanding of the sources and cycle of DOC and N released from glaciers in Central Asia, where glacier meltwater can protect the population from drought stress.

Modulation of snow reflectance and snowmelt from Central Asian glaciers by anthropogenic black carbon.

Deposited mineral dust and black carbon are known to reduce the albedo of snow and enhance melt. Here we estimate the contribution of anthropogenic black carbon (BC) to snowmelt in glacier accumulation zones of Central Asia based on in-situ measurements and modelling. Source apportionment suggests that more than 94% of the BC is emitted from mostly regional anthropogenic sources while the remaining contribution comes from natural biomass burning. Even though the annual deposition flux of mineral dust can be up to 20 times higher than that of BC, we find that anthropogenic BC causes the majority (60% on average) of snow darkening. This leads to summer snowmelt rate increases of up to 6.3% (7 cm a-1) on glaciers in three different mountain environments in Kyrgyzstan, based on albedo reduction and snowmelt models.

Characteristics of black carbon in snow from Laohugou No. 12 glacier on the northern Tibetan Plateau.

Black carbon (BC) emitted from the incomplete combustion of biomass and fossil fuel impacts the climate system, cryospheric change, and human health. This study documents black carbon deposition in snow from a benchmark glacier on the northern Tibetan Plateau. Significant seasonality of BC concentrations indicates different input or post-depositional processes. BC particles deposited in snow had a mass volume median diameter slightly larger than that of black carbon particles typically found in the atmosphere. Also, unlike black carbon particles in the atmosphere, the particles deposited in snow did not exhibit highly fractal morphology by Scanning Transmission Electron Microscope. Footprint analysis indicated BC deposited on the glacier in summer originated mainly from Central Asia; in winter, the depositing air masses generally originated from Central Asia and Pakistan. Anthropogenic emissions play an important role on black carbon deposition in glacial snow, especially in winter. The mass absorption efficiency of BC in snow at 632nm exhibited significantly seasonality, with higher values in summer and lower values in winter. The information on black carbon deposition in glacial snow provided in this study could be used to help mitigate the impacts of BC on glacier melting on the northern Tibetan Plateau.

A High-Resolution Analysis on the Meteorological Influences on Spontaneous Intracerebral Hemorrhage Incidence.

OBJECTIVE: To investigate the influence of meteorological factors on the incidence of intracerebral hemorrhage (ICH). METHODS: We included 295 ICH admissions between 2005 and 2013. The hourly meteorological parameters considered were surface pressure, temperature, relative humidity, wind gusts, and precipitation. To minimize confounding effects of seasonality, data were analyzed with the following 3 complementary statistical approaches: 1) deviation of daily measure from the 10-year monthly mean at the day of ictus; 2) deviation from monthly average with respect to changes in daily measures between the day of ictus and 2 days before; and 3) evolution of daily measures from 5 days before to 5 days after the ICH occurred. For 1) and 2), the statistical significance of the results was determined with a Monte Carlo simulation combined with a resampling technique (1000×). RESULTS: Regarding all patients, no statistically significant and meteorologically meaningful signal could be found. With respect to subgroup-analysis, ICH related to vascular pathologies occurred significantly more frequently at days with especially low relative humidity, whereas an opposite relation was present in patients with cerebral amyloid angiopathy. However, as absolute deviations were small, a strong functional effect is questionable. With respect to seasonal distribution, a greater incidence of ICH could be detected during the cold season, in line with previous reports. CONCLUSIONS: By using high-quality meteorological data analyzed with a sophisticated and robust statistical method that minimizes the confounding effect of seasonality, no clearly identifiable meteorological influence for the ICH events considered can be found.

Meteorological influences on the incidence of aneurysmal subarachnoid hemorrhage - a single center study of 511 patients.

OBJECTIVE: To assess the potential meteorological influence on the incidence of aneurysmal subarachnoid hemorrhage (SAH). Previous studies used inhomogeneous patient groups, insufficient study periods or inappropriate statistics. PATIENTS AND METHODS: We analyzed 511 SAH admissions between 2004 and 2012 for which aneurysmal rupture occurred within the Zurich region. The hourly meteorological parameters considered are: surface pressure, 2-m temperature, relative humidity and wind gusts, sunshine, and precipitation. For all parameters we investigate three complementary statistical measures: i) the time evolution from 5 days before to 5 days after the SAH occurrence; ii) the deviation from the 10-year monthly mean; and iii) the change relative to the parameter's value two days before SAH occurrence. The statistical significance of the results is determined using a Monte Carlo simulation combined with a re-sampling technique (1000×). RESULTS: Regarding the meteorological parameters considered, no statistically significant signal could be found. The distributions of deviations relative to the climatology and of the changes during the two days prior to SAH events agree with the distributions for the randomly chosen days. The analysis was repeated separately for winter and summer to exclude compensating effects between the seasons. CONCLUSION: By using high-quality meteorological data analyzed with a sophisticated and robust statistical method no clearly identifiable meteorological influence for the SAH events considered can be found. Further studies on the influence of the investigated parameters on SAH incidence seem redundant.