Surface impacts of the Quasi Biennial Oscillation Atmospheric Chemistry and Physics DOI 10.5194/acp-18-8227-2018 13 June 2018 A major phenomenon in the stratosphere is the Quasi Biennial Oscillation (QBO). Although a feature of the equatorial stratosphere, its influence extends to surface weather at both equatorial and mid latitudes. Improved knowledge of mechanisms of influence should help to improve weather forecasts. In this paper, QBO impacts at the surface are characterized and dominant mechanisms explored. Three pathways are identified, referred to as the tropical, subtropical and polar routes. Read more
On the Holocene evolution of the Ayeyawady megadelta Earth Surface Dynamics DOI 10.5194/esurf-6-451-2018 12 June 2018 Here we provide the first results on the evolution of the Ayeyarwady delta, the last unstudied megadelta of Asia. In addition to its intrinsic value as a founding study on the Holocene development of this region, we advance new ideas on the climate control of monsoonal deltas as well as describe for the first time a feedback mechanism between tectonics and tidal hydrodynamics that can explain the peculiarities of the Ayeyarwady delta. Read more
Airborne wind lidar observations over the North Atlantic in 2016 for the pre-launch validation of the satellite mission Aeolus Atmospheric Measurement Techniques DOI 10.5194/amt-11-3297-2018 11 June 2018 This work reports airborne wind lidar observations performed in a recent field campaign. The deployed lidar system serves as a demonstrator for the satellite instrument ALADIN on board Aeolus, which is scheduled for launch in 2018 and will become the first wind lidar in space. After presenting the measurement principle, operation procedures and wind retrieval algorithm, the obtained wind results are validated and discussed, providing valuable information in preparation for the satellite mission. Read more
Editorial: Geoscience Communication – Building bridges, not walls Geoscience Communication DOI 10.5194/gc-1-1-2018 11 June 2018 Welcome to the journal of Geoscience Communication! We decided to write this editorial in order to introduce ourselves (the executive editors of GC), to provide a history of its development, and to serve as a guideline for future authors who wish to submit to this journal. We hope that this article serves as a useful aid for people who are considering publishing in GC, as well as the wider geoscience community, and that it can act in the first instance as a FAQ for authors, editors, and readers alike. Read more
Two drastically different climate states on an Earth-like terra-planet Earth System Dynamics DOI 10.5194/esd-9-739-2018 7 June 2018 Using climate simulations, we investigate the role of water recycling in shaping the climate of low-obliquity Earth-like terra-planets. By such a mechanism feeding water back from the extra-tropics to the tropics, the planet can assume two drastically different climate states differing by more than 35 K in global temperature. We describe the bifurcation between the two states occurring upon changes in surface albedo and argue that the bistability hints at a wider habitable zone for such planets. Read more
Assessing the impact of a future volcanic eruption on decadal predictions Earth System Dynamics DOI 10.5194/esd-9-701-2018 6 June 2018 The likelihood of a large volcanic eruption in the future provides the largest uncertainty concerning the evolution of the climate system on the timescale of a few years, but also an excellent opportunity to learn about the behavior of the climate system, and our models thereof. So the following question emerges: how predictable is the response of the climate system to future eruptions? By this we mean to what extent will the volcanic perturbation affect decadal climate predictions and how does the pre-eruption climate state influence the impact of the volcanic signal on the predictions? Read more
High-resolution diapycnal mixing map of the Alboran Sea thermocline from seismic reflection images Ocean Science DOI 10.5194/os-14-403-2018 6 June 2018 The Alboran Sea is a dynamically active region. The interaction between Mediterranean and Atlantic water originates a set of sub-mesoscale structures and a complex sequence of processes that entail mixing close to the thermocline. Here we present a high-resolution map of the diapycnal diffusivity around the thermocline depth obtained using acoustic data recorded with a high-resolution multichannel seismic system. The map revels a patchy thermocline, with areas of strong diapycnal mixing. Read more
Snow depth on Arctic sea ice from historical in situ data The Cryosphere DOI 10.5194/tc-12-1867-2018 5 June 2018 In this paper we analyze snow data from Soviet airborne expeditions, Sever, which operated in late winter 1959-1986, in the Arctic and made snow measurements on the ice around plane landing sites. The snow measurements were made on the multiyear ice in the central Arctic and on the first-year ice in the Eurasian seas in the areas for which snow characteristics are poorly described in the literature. The main goal of this study is to produce an improved data set of snow depth on the sea ice. Read more
Consideration of various aspects in a drift study of MH370 debris Ocean Science DOI 10.5194/os-14-387-2018 4 June 2018 To assist in establishing the most likely location of the crash site of MH370, a Boeing 777 aircraft that went missing on March 7, 2014, a drift study was conducted by means of numerical modelling. Three elements were considered: (a) the efficacy of the aerial search; (b) water temperatures along the path of the flaperon; © beached debris distribution. The results obtained indicate the crash site is likely located between 25.5° S and 30.5° S along the so-called seventh arc in the Indian Ocean. Read more
On ozone trend detection: using coupled chemistry–climate simulations to investigate early signs of total column ozone recovery Atmospheric Chemistry and Physics DOI 10.5194/acp-18-7625-2018 1 June 2018 2017 marks the 30th anniversary of the Montreal Protocol, which was implemented to protect the stratospheric ozone layer from the harmful effects of synthetic ozone depleting substances. Since the late 1990s atmospheric concentrations of these species have begun to decline, and as a result ozone concentrations are expected to increase. In this study we use an ensemble of chemistry–climate simulations to investigate recent ozone trends and search for early signs of ozone recovery. Read more
Glacial isostatic adjustment modelling: historical perspectives, recent advances, and future directions Earth Surface Dynamics DOI 10.5194/esurf-6-401-2018 29 May 2018 This article is a contribution to a special issue onTwo centuries of modelling across scales. It describes the historical observations, evolving hypotheses, and early calculations that led to the development of the field of glacial isostatic sdjustment (GIA) modelling, which seeks to understand feedbacks between ice-sheet change, sea-level change, and solid Earth deformation. Recent and future advances are discussed. Future progress will likely involve an interdisciplinary approach. Read more
Aromatic acids in an Arctic ice core from Svalbard: a proxy record of biomass burning Climate of the Past DOI 10.5194/cp-14-637-2018 23 May 2018 This study presents organic acid levels in an ice core from Svalbard over the past 800 years. These acids are produced from wildfire emissions and transported as aerosol. Organic acid levels are high early in the record and decline until the 20th century. Siberia and Europe are likely the primary source regions of the fire emissions. The data are similar to those from a Siberian ice core prior to 1400 CE. The timing of the divergence after 1400 CE is similar to a shift in North Atlantic climate. Read more
Estimating sowing and harvest dates based on the Asian summer monsoon Earth System Dynamics DOI 10.5194/esd-9-563-2018 18 May 2018 Sowing and harvest dates are a significant source of uncertainty within crop models. South Asia is one region with a large uncertainty. We aim to provide more accurate sowing and harvest dates than currently available and that are relevant for climate impact assessments. This method reproduces the present day sowing and harvest dates for most parts of India and when applied to two future periods provides a useful way of modelling potential growing season adaptations to changes in future climate. Read more
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. 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