Crossing the chasm: how to develop weather and climate models for next generation computers? Geoscientific Model Development DOI 10.5194/gmd-11-1799-2018 8 May 2018 Weather and climate models consist of complex software evolving in response to both scientific requirements and changing computing hardware. After years of relatively stable hardware, more diversity is arriving. It is possible that this hardware diversity and the pace of change may lead to an inability for modelling groups to manage their software development. This “chasm” between aspiration and reality may need to be bridged by large community efforts rather than traditional “in-house” efforts. Read more
Contrails and their impact on shortwave radiation and photovoltaic power production – a regional model study Atmospheric Chemistry and Physics DOI 10.5194/acp-18-6393-2018 7 May 2018 A numerical model also used for operational weather forecast was applied to investigate the impact of contrails and contrail cirrus on the radiative fluxes at the earth’s surface. Accounting for contrails produced by aircraft enables the model to simulate high clouds that are otherwise missing. In a case study, we find that the effect of these extra clouds is to reduce the incoming shortwave radiation at the surface as well as the production of photovoltaic power by up to 10 %. Read more
Technical note: Open-paleo-data implementation pilot – the PAGES 2k special issue Climate of the Past DOI 10.5194/cp-14-593-2018 3 May 2018 We explain the procedure used to attain a high and consistent level of data stewardship across a special issue of the journal Climate of the Past. We discuss the challenges related to (1) determining which data are essential for public archival, (2) using data generated by others, and (3) understanding data citations. We anticipate that open-data sharing in paleo sciences will accelerate as the advantages become more evident and as practices that reduce data loss become the accepted convention. Read more
Vertical wind velocity measurements using a five-hole probe with remotely piloted aircraft to study aerosol–cloud interactions Atmospheric Measurement Techniques DOI 10.5194/amt-11-2583-2018 3 May 2018 Remotely piloted aircraft systems (RPAS), commonly called UAVs, are used in atmospheric science for in situ measurements. The presented work shows wind measurements from a five-hole probe on an RPAS. Comparisons with other instruments (sonic anemometer and cloud radar) show good agreement, validating the RPAS measurements. In situ vertical wind measurements at cloud base are highlighted because they are a major parameter needed for simulating aerosol–cloud interactions, though rarely collected. Read more
Brief communication: Unabated wastage of the Juneau and Stikine icefields (southeast Alaska) in the early 21st century The Cryosphere DOI 10.5194/tc-12-1523-2018 27 April 2018 Two recent studies suggested a slowdown in mass loss after 2000 of the Juneau and Stikine icefields, accounting for 10% of the total ice cover in Alaska. Here, the ASTER-based geodetic mass balances are revisited, carefully avoiding the use of the SRTM DEM, because of the unknown penetration depth of the SRTM C-band radar signal. We find strongly negative mass balances from 2000 to 2016 for both icefields, in agreement with airborne laser altimetry. Mass losses are thus continuing unabated. Read more
A new method, with application, for analysis of the impacts on flood risk of widely distributed enhanced hillslope storage Hydrology and Earth System Sciences DOI 10.5194/hess-22-2589-2018 27 April 2018 Flooding is a significant hazard and extreme events in recent years have focused attention on effective means of reducing its risk. An approach known as natural flood management (NFM) seeks to increase flood resilience by a range of measures that work with natural processes. The paper develops a modelling approach to assess one type NFM of intervention – distributed additional hillslope storage features – and demonstrates that more strategic placement is required than has hitherto been applied. Read more
Adaption of an array spectroradiometer for total ozone column retrieval using direct solar irradiance measurements in the UV spectral range Atmospheric Measurement Techniques DOI 10.5194/amt-11-2477-2018 27 April 2018 A compact array spectroradiometer technology that enables precise and robust measurements of UV spectral irradiance is presented. We show that this instrument can retrieve total ozone column (TOC) accurately. The internal stray light, which is often the limiting factor for measurements in the UV spectral range, is physically reduced so that no other stray-light reduction methods are needed. During an international total ozone measurement intercomparison, the high quality was verified. Read more
Global evaluation and calibration of a passive air sampler for gaseous mercury Atmospheric Chemistry and Physics DOI 10.5194/acp-18-5905-2018 26 April 2018 A new passive air sampler for gaseous mercury was tested at 20 sites on four continents. These sites have in common that they use the state-of-the-art active air sampling technique for gaseous mercury on a continuous basis and therefore allow for an evaluation and calibration of the passive sampler. The sampler proved to work exceptionally well, with a precision and accuracy on par with the active instrument and better than what has previously been achieved with passive samplers. Read more
Novel pathway of SO2 oxidation in the atmosphere: reactions with monoterpene ozonolysis intermediates and secondary organic aerosol Atmospheric Chemistry and Physics DOI 10.5194/acp-18-5549-2018 24 April 2018 Synergistic effects between SOA formation and SO2 oxidation through Criegee chemistry and reactive uptake by organic peroxides were observed. The relative importance of these two pathways (Criegee vs. peroxide) varies with relative humidity. The latter SO2 loss mechanism to organic peroxides in SOA has not previously been identified. Our results suggest a new pathway of atmospheric SO2 oxidation, which may contribute to the missing mechanisms of high-sulfate production in the polluted areas. Read more
Using satellite measurements of N2O to remove dynamical variability from HCl measurements Atmospheric Chemistry and Physics DOI 10.5194/acp-18-5691-2018 24 April 2018 Detecting trends in short data sets of stratospheric molecules is difficult because of variability due to dynamical fluctuations. We suggest that one way around this difficulty is using the measurements of one molecule to remove dynamical variability from the measurements of another molecule. We illustrate this using Aura MLS measurements of N2O to help us sort out issues in the determination of trends in HCl. This shows that HCl is decreasing throughout the middle stratosphere as expected. Read more