Analytically tractable climate–carbon cycle feedbacks under 21st century anthropogenic forcing Earth System Dynamics DOI 10.5194/esd-9-507-2018 17 May 2018 Around half of the carbon that humans emit into the atmosphere each year is taken up on land (by trees) and in the ocean (by absorption). We construct a simple model of carbon uptake that, unlike the complex models that are usually used, can be analysed mathematically. Our results include that changes in atmospheric carbon may affect future carbon uptake more than changes in climate. Our simple model could also study mechanisms that are currently too uncertain for complex models. Read more
Random and externally controlled occurrences of Dansgaard–Oeschger events Climate of the Past DOI 10.5194/cp-14-609-2018 16 May 2018 The climate of the last glacial period was frequently interrupted by rapid warming events, the cause of which is still unknown. One open question is whether the occurrence of events is random or externally controlled. We studied the temporal characteristics of warm and cold phases using statistical null models and find that they are well described as random processes modulated by two different external climate factors. This may help distinguish physical mechanisms for rapid climate change. Read more
Effects of climatic seasonality on the isotopic composition of evaporating soil waters Hydrology and Earth System Sciences DOI 10.5194/hess-22-2881-2018 15 May 2018 Evaporation causes the isotopic composition of soil water to become different from that of the original precipitation source. If multiple samples originating from the same source are available, they can be used to reconstruct the original source composition. However, soil water is influenced by seasonal variability in both precipitation sources and evaporation patterns. We show that this variability, if not accounted for, can lead to biased estimates of the precipitation source water. Read more
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. PAGES 2k special issue">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
