The 22 December 2018 Mount Anak Krakatau volcanogenic tsunami on SundaStrait coasts, Indonesia: tsunami and damage characteristics Natural Hazards and Earth System Sciences DOI 10.5194/nhess-20-549-2020 3 March 2020 On 22 December 2018, a tsunami was generated from the Mount Anak Krakatau area that was caused by volcanic flank failures. The tsunami had severe impacts on the western coasts of Banten and the southern coasts of Lampung in Indonesia. A series of surveys to measure the impacts of the tsunami was started 3 d after the tsunami and lasted for 10 d. This paper provides insights from the tsunami-affected area in terms of distribution of tsunami flow depths, boulders and building damage. Read more
No nitrogen fixation in the Bay of Bengal? Biogeosciences DOI 10.5194/bg-17-851-2020 27 February 2020 Oxygen minimum zones (OMZs) are ocean areas severely depleted in oxygen as a result of physical, chemical, and biological processes. Biologically, organic material is produced in the sea surface and exported to deeper waters, where it respires. In the Bay of Bengal (BoB), an OMZ is present, but there are traces of oxygen left. Our study now suggests that this is because one key process, nitrogen fixation, is absent in the BoB, thus preventing primary production and consecutive respiration. Read more
The millennium-old hydrogeology textbook The Extraction of Hidden Waters by the Persian mathematician and engineer Abubakr Mohammad Karaji (953 CE–1029 CE) Hydrology and Earth System Sciences DOI 10.5194/hess-24-761-2020 27 February 2020 We revisit and shed light on the textbook The Extraction of Hidden Waters by the Persian mathematician and engineer Abubakr Mohammad Karaji. Ground-breaking ideas and descriptions of hydrological and hydrogeological perceptions such as components of the hydrological cycle, groundwater quality and driving factors for groundwater flow were presented in the book. We speculate that Karaji’s book is the first of its kind to provide a construction and maintenance manual for an engineering project. Read more
Cryoconite: an efficient accumulator of radioactive fallout in glacialenvironments The Cryosphere DOI 10.5194/tc-14-657-2020 25 February 2020 Cryoconite is the sediment found on the surface of glaciers. The paper presents cryoconite as an environmental matrix able to accumulate natural and artificial radioactivity with unprecedented efficiency. Only samples from sites where nuclear accidents and explosions occurred present a stronger radioactive contamination. The peculiarities of glacial environments are responsible for this extreme feature, making cryoconite a useful tool tool for the monitoring of environmental radioactivity. Read more
Quantifying hail size distributions from the sky – application of drone aerial photogrammetry Atmospheric Measurement Techniques DOI 10.5194/amt-13-747-2020 25 February 2020 Collecting measurements of hail size and shape is difficult due to the infrequent and dangerous nature of hailstorms. To improve upon this, a new technique called HailPixel is introduced for measuring hail using aerial imagery collected by a drone. A combination of machine learning and computer vision methods is used to extract the shape of thousands of hailstones from the aerial imagery. The improved statistics from the much larger HailPixel dataset show significant benefits. Read more
Surface water as a cause of land degradation from dryland salinity Hydrology and Earth System Sciences DOI 10.5194/hess-24-717-2020 25 February 2020 Secondary dryland salinity is a global land degradation issue. Our understanding of causal processes is adapted from wet and hydrologically connected landscapes and concludes that low end-of-catchment runoff indicates land clearing alters water balance in favour of increased infiltration and rising groundwater that bring salts to the surface causing salinity. This study shows surface flows play an important role in causing valley floor recharge and dryland salinity in low-gradient landscapes. Read more
Variations in soil chemical and physical properties explain basin-wideAmazon forest soil carbon concentrations SOIL DOI 10.5194/soil-6-53-2020 20 February 2020 Amazon soils hold as much carbon © as is contained in the vegetation. In this work we sampled soils across 8 different Amazonian countries to try to understand which soil properties control current Amazonian soil C concentrations. We confirm previous knowledge that highly developed soils hold C through clay content interactions but also show a previously unreported mechanism of soil C stabilization in the younger Amazonian soil types which hold C through aluminium organic matter interactions. Read more
A multi-model analysis of teleconnected crop yield variability in a range of cropping systems Earth System Dynamics DOI 10.5194/esd-11-113-2020 20 February 2020 In this study, we analyse the impacts of three major climate oscillations on global crop production. Our results show that maize, rice, soybean, and wheat yields are influenced by climate oscillations to a wide extent and in several important crop-producing regions. We observe larger impacts if crops are rainfed or fully fertilized, while irrigation tends to mitigate the impacts. These results can potentially help to increase the resilience of the global food system to climate-related shocks. Read more
Modal shift in North Atlantic seasonality during the last deglaciation Climate of the Past DOI 10.5194/cp-16-265-2020 18 February 2020 Here, mid-ocean seasonality is resolved through time, using differences in the oxygen isotope composition between individual shells of the commonly used (sub)polar planktonic foraminifera species in ocean-climate reconstruction, N. pachyderma and G. bulloides . Single-specimen isotope measurements during the deglacial period revealed a surprising bimodality, the cause of which was investigated. Read more
Dimensions of marine phytoplankton diversity Biogeosciences DOI 10.5194/bg-17-609-2020 18 February 2020 Phytoplankton are an essential component of the marine food web and earth’s carbon cycle. We use observations, ecological theory and a unique trait-based ecosystem model to explain controls on patterns of marine phytoplankton biodiversity. We find that different dimensions of diversity (size classes, biogeochemical functional groups, thermal norms) are controlled by a disparate combination of mechanisms. This may explain why previous studies of phytoplankton diversity had conflicting results. Read more
A new look at the environmental conditions favorable to secondary ice production Atmospheric Chemistry and Physics DOI 10.5194/acp-20-1391-2020 13 February 2020 This study attempts identification of mechanisms of secondary ice production (SIP) based on the observation of small faceted ice crystals. It was found that in both mesoscale convective systems and frontal clouds, SIP was observed right above the melting layer and extended to the higher altitudes with colder temperatures. A principal conclusion of this work is that the freezing drop shattering mechanism is plausibly accounting for the measured ice concentrations in the observed condition. Read more
Machine learning and soil sciences: a review aided by machine learning tools SOIL DOI 10.5194/soil-6-35-2020 13 February 2020 The application of machine learning (ML) has shown an accelerated adoption in soil sciences. It is a difficult task to manually review all papers on the application of ML. This paper aims to provide a review of the application of ML aided by topic modelling in order to find patterns in a large collection of publications. The objective is to gain insight into the applications and to discuss research gaps. We found 12 main topics and that ML methods usually perform better than traditional ones. Read more
Global catchment modelling using World-Wide HYPE (WWH), open data, andstepwise parameter estimation Hydrology and Earth System Sciences DOI 10.5194/hess-24-535-2020 11 February 2020 How far can we reach in predicting river flow globally, using integrated catchment modelling and open global data? For the first time, a catchment model was applied world-wide, covering the entire globe with a relatively high resolution. The results show that stepwise calibration provided better performance than traditional modelling of the globe. The study highlights that open data and models are crucial to advance hydrological sciences by sharing knowledge and enabling transparent evaluation. Read more
Mapping the drivers of uncertainty in atmospheric selenium deposition with global sensitivity analysis Atmospheric Chemistry and Physics DOI 10.5194/acp-20-1363-2020 11 February 2020 The amount of the micronutrient selenium in food largely depends on the amount and form of selenium in soil. The atmosphere acts as a source of selenium to soils through deposition, yet little information is available about atmospheric selenium cycling. Therefore, we built the first global atmospheric selenium model. Through sensitivity and uncertainty analysis we determine that selenium can be transported thousands of kilometers and that measurements of selenium emissions should be prioritized. Read more
An urban ecohydrological model to quantify the effect of vegetation on urban climate and hydrology (UT&C v1.0) Geoscientific Model Development DOI 10.5194/gmd-13-335-2020 6 February 2020 We developed a novel urban ecohydrological model (UT&C v1.0) that is able to account for the effects of different plant types on the urban climate and hydrology, as well as the effects of the urban environment on plant well-being and performance. UT&C performs well when compared against energy flux measurements in three cities in different climates (Singapore, Melbourne, Phoenix) and can be used to assess urban climate mitigation strategies that aim at increasing or changing urban green cover. Read more
Identification of new microbial functional standards for soil quality assessment SOIL DOI 10.5194/soil-6-17-2020 6 February 2020 Soil quality depends on the functioning of soil microbiota. Only a few standardized methods are available to assess this as well as adverse effects of human activities. So we need to identify promising additional methods that target soil microbial function. Discussed are (i) molecular methods using qPCR for new endpoints, e.g. in N and P cycling and greenhouse gas emissions, (ii) techniques for fungal enzyme activities, and (iii) field methods on carbon turnover such as the litter bag test. Read more
A decade of variability on Jakobshavn Isbræ: ocean temperatures pace speedthrough influence on mélange rigidity The Cryosphere DOI 10.5194/tc-14-211-2020 27 January 2020 Jakobshavn Isbræ, considered to be Greenland’s fastest glacier, has varied its speed and thinned dramatically since the 1990s. Here we examine the glacier’s behaviour over the last decade to better understand this behaviour. We find that when the floating ice (mélange) in front of the glacier freezes in place during the winter, it can control the glacier’s speed and thinning rate. A recently colder ocean has strengthened this mélange, allowing the glacier to recoup some of its previous losses. Read more
Electron spin resonance (ESR) thermochronometry of the Hida range of the Japanese Alps: validation and future potential Geochronology DOI 10.5194/gchron-2-1-2020 27 January 2020 Rates of landscape evolution over the past million years are difficult to quantify. This study develops a technique which is able to measure changes in rock cooling rates (related to landscape evolution) over this timescale. The technique is based on the electron spin resonance dating of quartz minerals. Measurement protocols and new numerical models are proposed that describe these data, allowing for their translation into rock cooling rates. Read more
Altitude profiles of cloud condensation nuclei characteristics across the Indo-Gangetic Plainprior to the onset of the Indian summer monsoon Atmospheric Chemistry and Physics DOI 10.5194/acp-20-561-2020 27 January 2020 Concurrent measurements of the altitude profiles of the concentration of cloud condensation nuclei (CCNs), as a function of supersaturation (ranging from 0.2 % to 1.0 %), and aerosol optical properties were carried out aboard an instrumented aircraft across the Indo-Gangetic Plain (IGP) just prior to the onset of the 2016 Indian summer monsoon (ISM). A high CCN concentration is observed up to 2.5 km across the IGP, indicating the significant possibility of aerosol indirect effects. Read more
Why did deep convection persist over four consecutive winters (2015–2018) southeast of Cape Farewell? Ocean Science DOI 10.5194/os-16-99-2020 27 January 2020 The region south of Cape Farewell (SCF) is recognized as a deep convection site. Convection deeper than 1300 m occurred SCF in 2015 and persisted during three additional winters. Extreme air–sea buoyancy fluxes caused the 2015 event. For the following winters, air–sea fluxes were close to the climatological average, but local cooling above 800 m and the advection below 1200 m of a fresh anomaly from the Labrador Sea decreased stratification and allowed for the persistence of deep convection. Read more