Calibration of River Gauge at Afdeyu Research Station, Eritrea: A study conducted by MOA NARI and SLM

Afdeyu Station is one of the few river gauging stations in the highlands of Eritrea where daily measurements are taken. As a result of damages, the station was refurbished, and the cross section of the gauge was changed to have better control of minimal runoff. The gauge therefore had to be re-calibrated. This publication documents this process and also provides the new calibration curve, based on extensive field work carried out in the rainy season 2009

Meteorological and Hydrological Data collected at Gununo SCRP Research Station from 1996 to 2004

Nine years of meteorological and hydrological data collected at Gununo SCRP Research Station are ecoded and available

Quand les greniers se remplissent: Les bénéfices du partenariat entre la recherche agronomique, la vulgarisation agricole et des organisations paysannes au Mali

This publication is a collation and summary of the major achievements of the Agricultural Research Station of Cinzana (SRAC) and the Capacity Building for Sustainable Agriculture Project (PRECAD). Both projects, created in 1983 and 2006, respectively, have been developed through close collaboration between the Rural Economy Institute (IER) responsible for agricultural research in Mali and the Syngenta Foundation for Sustainable Agriculture (SFSA), formerly the Ciba-Geigy Foundation. The publication covers the period from 1979 to 2009 and includes, where available, some key information for the year 2010. It is aimed at a wide audience and provides an overview of the work carried out in Mali by an agricultural research station and an extension project. It highlights the obstacles and opportunities encountered by the SRAC and PRECAD, as well as the successes and difficulties arising from their work.

Ground-based and airborne in-situ measurements of the Eyjafjallajökull volcanic aerosol plume in Switzerland in spring 2010

The volcanic aerosol plume resulting from the Eyjafjallajökull eruption in Iceland in April and May 2010 was detected in clear layers above Switzerland during two periods (17–19 April 2010 and 16–19 May 2010). In-situ measurements of the airborne volcanic plume were performed both within ground-based monitoring networks and with a research aircraft up to an altitude of 6000 m a.s.l. The wide range of aerosol and gas phase parameters studied at the high altitude research station Jungfraujoch (3580 m a.s.l.) allowed for an in-depth characterization of the detected volcanic aerosol. Both the data from the Jungfraujoch and the aircraft vertical profiles showed a consistent volcanic ash mode in the aerosol volume size distribution with a mean optical diameter around 3 ± 0.3 μm. These particles were found to have an average chemical composition very similar to the trachyandesite-like composition of rock samples collected near the volcano. Furthermore, chemical processing of volcanic sulfur dioxide into sulfate clearly contributed to the accumulation mode of the aerosol at the Jungfraujoch. The combination of these in-situ data and plume dispersion modeling results showed that a significant portion of the first volcanic aerosol plume reaching Switzerland on 17 April 2010 did not reach the Jungfraujoch directly, but was first dispersed and diluted in the planetary boundary layer. The maximum PM10 mass concentrations at the Jungfraujoch reached 30 μgm−3 and 70 μgm−3 (for 10-min mean values) duri ng the April and May episode, respectively. Even low-altitude monitoring stations registered up to 45 μgm−3 of volcanic ash related PM10 (Basel, Northwestern Switzerland, 18/19 April 2010). The flights with the research aircraft on 17 April 2010 showed one order of magnitude higher number concentrations over the northern Swiss plateau compared to the Jungfraujoch, and a mass concentration of 320 (200–520) μgm−3 on 18 May 2010 over the northwestern Swiss plateau. The presented data significantly contributed to the time-critical assessment of the local ash layer properties during the initial eruption phase. Furthermore, dispersion models benefited from the detailed information on the volcanic aerosol size distribution and its chemical composition.

Prevalence and time course of acute mountain sickness in older children and adolescents after rapid ascent to 3450 meters

OBJECTIVE: Acute mountain sickness is a frequent and debilitating complication of high-altitude exposure, but there is little information on the prevalence and time course of acute mountain sickness in children and adolescents after rapid ascent by mechanical transportation to 3500 m, an altitude at which major tourist destinations are located throughout the world. METHODS: We performed serial assessments of acute mountain sickness (Lake Louise scores) in 48 healthy nonacclimatized children and adolescents (mean +/- SD age: 13.7 +/- 0.3 years; 20 girls and 28 boys), with no previous high-altitude experience, 6, 18, and 42 hours after arrival at the Jungfraujoch high-altitude research station (3450 m), which was reached through a 2.5-hour train ascent. RESULTS: We found that the overall prevalence of acute mountain sickness during the first 3 days at high altitude was 37.5%. Rates were similar for the 2 genders and decreased progressively during the stay (25% at 6 hours, 21% at 18 hours, and 8% at 42 hours). None of the subjects needed to be evacuated to lower altitude. Five subjects needed symptomatic treatment and responded well. CONCLUSION: After rapid ascent to high altitude, the prevalence of acute mountain sickness in children and adolescents was relatively low; the clinical manifestations were benign and resolved rapidly. These findings suggest that, for the majority of healthy nonacclimatized children and adolescents, travel to 3500 m is safe and pharmacologic prophylaxis for acute mountain sickness is not needed.

Topoclimatological case-study of Alpine pastures near the Albula Pass in the eastern Swiss Alps

Alpine grasslands are an important source of fodder for the cattle of Alpine farmers. Only during the short summer season can these pastures be used for grazing. With the anticipated climate change, it is likely that plant production – and thus the fodder basis for the cattle – will be influenced. Investigating the dependence of biomass production on topoclimatic factors will allow us to better understand how anticipated climate change may influence this traditional Alpine farming system. Because small-scale topoclimatological variations of the main meteorological variables: temperature, humidity, precipitation, shortwave incoming radiation and wind speed are not easily derived from available long-term climate stations in mountainous terrain, it was our goal to investigate the topoclimatic variations over the pastures belonging to the Alp Weissenstein research station north of the Albula Pass in the eastern Swiss Alps. We present a basic assessment of current topoclimatic conditions as a site characterization for ongoing ecological climate change studies. To be able to link short-term studies with long-term climate records, we related agrometeorological measurements with those of surrounding long-term sites run by MeteoSwiss, both on valley bottoms (Davos, Samedan), and on mountain tops (Weissfluhjoch, Piz Corvatsch). We found that the Davos climate station north of the study area is most closely correlated with the local climate of Alp Weissenstein, although a much closer site (Samedan) exists on the other side of the Albula Pass. Mountain top stations, however, did not provide a convincing approximation for the climate at Alp Weissenstein. Direct comparisons of near-surface measurements from a set of 11 small weather stations distributed over the domain where cattle and sheep are grazed indicate that nocturnal minimum air temperature and minimum vapor pressure deficit are mostly governed by the altitudinal gradient, whereas daily maxima – including also wind speed – are more strongly depending on vegetation cover and less on the altitude.

Atmospheric CO₂, δ(O₂/N₂) and δ13CO2 measurements at Jungfraujoch, Switzerland: results from a flask sampling intercomparison program

We present results from an intercomparison program of CO2, δ(O2/N2) and δ13CO2 measurements from atmospheric flask samples. Flask samples are collected on a bi-weekly basis at the High Altitude Research Station Jungfraujoch in Switzerland for three European laboratories: the University of Bern, Switzerland, the University of Groningen, the Netherlands and the Max Planck Institute for Biogeochemistry in Jena, Germany. Almost 4 years of measurements of CO2, δ(O2/N2) and δ13CO2 are compared in this paper to assess the measurement compatibility of the three laboratories. While the average difference for the CO2 measurements between the laboratories in Bern and Jena meets the required compatibility goal as defined by the World Meteorological Organization, the standard deviation of the average differences between all laboratories is not within the required goal. However, the obtained annual trend and seasonalities are the same within their estimated uncertainties. For δ(O2/N2) significant differences are observed between the three laboratories. The comparison for δ13CO2 yields the least compatible results and the required goals are not met between the three laboratories. Our study shows the importance of regular intercomparison exercises to identify potential biases between laboratories and the need to improve the quality of atmospheric measurements.

GROMOS-C, a novel ground-based microwave radiometer for ozone measurement campaigns

Stratospheric ozone is of major interest as it absorbs most harmful UV radiation from the sun, allowing life on Earth. Ground-based microwave remote sensing is the only method that allows for the measurement of ozone profiles up to the mesopause, over 24 hours and under different weather conditions with high time resolution. In this paper a novel ground-based microwave radiometer is presented. It is called GROMOS-C (GRound based Ozone MOnitoring System for Campaigns), and it has been designed to measure the vertical profile of ozone distribution in the middle atmosphere by observing ozone emission spectra at a frequency of 110.836 GHz. The instrument is designed in a compact way which makes it transportable and suitable for outdoor use in campaigns, an advantageous feature that is lacking in present day ozone radiometers. It is operated through remote control. GROMOS-C is a total power radiometer which uses a pre-amplified heterodyne receiver, and a digital fast Fourier transform spectrometer for the spectral analysis. Among its main new features, the incorporation of different calibration loads stands out; this includes a noise diode and a new type of blackbody target specifically designed for this instrument, based on Peltier elements. The calibration scheme does not depend on the use of liquid nitrogen; therefore GROMOS-C can be operated at remote places with no maintenance requirements. In addition, the instrument can be switched in frequency to observe the CO line at 115 GHz. A description of the main characteristics of GROMOS-C is included in this paper, as well as the results of a first campaign at the High Altitude Research Station at Jungfraujoch (HFSJ), Switzerland. The validation is performed by comparison of the retrieved profiles against equivalent profiles from MLS (Microwave Limb Sounding) satellite data, ECMWF (European Centre for Medium-Range Weather Forecast) model data, as well as our nearby NDACC (Network for the Detection of Atmospheric Composition Change) ozone radiometer measuring at Bern.

Cosmogenic activation of xenon and copper

Rare event search experiments using liquid xenon as target and detection medium require ultra-low background levels to fully exploit their physics potential. Cosmic ray induced activation of the detector components and, even more importantly, of the xenon itself during production, transportation and storage at the Earth's surface, might result in the production of radioactive isotopes with long half-lives, with a possible impact on the expected background. We present the first dedicated study on the cosmogenic activation of xenon after 345 days of exposure to cosmic rays at the Jungfraujoch research station at 3470m above sea level, complemented by a study of copper which has been activated simultaneously. We have directly observed the production of 7Be, 101Rh, 125Sb, 126I and 127Xe in xenon, out of which only 125Sb could potentially lead to background for a multi-ton scale dark matter search. The production rates for five out of eight studied radioactive isotopes in copper are in agreement with the only existing dedicated activation measurement, while we observe lower rates for the remaining ones. The specific saturation activities for both samples are also compared to predictions obtained with commonly used software packages, where we observe some underpredictions, especially for xenon activation.