New insights for mesospheric OH: multi-quantum vibrational relaxation as a driver for non-local thermodynamic equilibrium Annales Geophysicae DOI 10.5194/angeo-36-13-2018 9 January 2018 The question of whether mesospheric rotational population distributions of vibrationally excited OH are in equilibrium with the local kinetic temperature has been debated over several decades. We examine the relationship of multi-quantum relaxation pathways with the behavior exhibited by OH(v) rotational population distributions and find that the effective rotational temperatures of mesospheric OH(v) deviate from local thermodynamic equilibrium for all observed vibrational levels. Read more
Invited perspectives: Hydrological perspectives on precipitation intensity-duration thresholds for landslide initiation: proposing hydro-meteorological thresholds Natural Hazards and Earth System Sciences DOI 10.5194/nhess-18-31-2018 4 January 2018 The vast majority of shallow landslides and debris flows are precipitation initiated and predicted using historical landslides plotted versus observed precipitation information. However, this approach has severe limitations. This is partly due to the fact that it is not precipitation that initiates a landslide or debris flow but rather the hydrological dynamics in the soil and slope. We propose to include hydrological information in the regional hydro-meteorological hazard assessment. Read more
The UKC2 regional coupled environmental prediction system Geoscientific Model Development DOI 10.5194/gmd-11-1-2018 3 January 2018 In the real world the atmosphere, oceans and land surface are closely interconnected, and yet prediction systems tend to treat them in isolation. Those feedbacks are often illustrated in natural hazards, such as when strong winds lead to large waves and coastal damage, or when prolonged rainfall leads to saturated ground and high flowing rivers. For the first time, we have attempted to represent some of the feedbacks between sky, sea and land within a high-resolution forecast system for the UK. Read more
Synergy between land use and climate change increases future fire risk in Amazon forests Earth System Dynamics DOI 10.5194/esd-8-1237-2017 20 December 2017 Fires damage large areas of eastern Amazon forests when ignitions from human activity coincide with droughts, while more humid central and western regions are less affected. Here, we use a fire model to estimate that fire activity could increase by an order of magnitude without climate mitigation. Our results show that avoiding further agricultural expansion can limit fire ignitions but that tackling climate change is essential to insulate the interior Amazon through the 21st century. Read more
The SPACE 1.0 model: a Landlab component for 2-D calculation of sediment transport, bedrock erosion, and landscape evolution Geoscientific Model Development DOI 10.5194/gmd-10-4577-2017 18 December 2017 Rivers control the movement of sediment and nutrients across Earth’s surface. Understanding how rivers change through time is important for mitigating natural hazards and predicting Earth’s response to climate change. We develop a new computer model for predicting how rivers cut through sediment and rock. Our model is designed to be joined with models of flooding, landslides, vegetation change, and other factors to provide a comprehensive toolbox for predicting changes to the landscape. Read more
Designing a network of critical zone observatories to explore the living skin of the terrestrial Earth Earth Surface Dynamics DOI 10.5194/esurf-5-841-2017 18 December 2017 The layer known as the critical zone extends from the tree tops to the groundwater. This zone varies globally as a function of land use, climate, and geology. Energy and materials input from the land surface downward impact the subsurface landscape of water, gas, weathered material, and biota – at the same time that differences at depth also impact the superficial landscape. Scientists are designing observatories to understand the critical zone and how it will evolve in the future. Read more
First tomographic observations of gravity waves by the infrared limb imager GLORIA Atmospheric Chemistry and Physics DOI 10.5194/acp-17-14937-2017 18 December 2017 Using the infrared limb imager GLORIA, the 3-D structure of mesoscale gravity waves in the lower stratosphere was measured for the first time, allowing for a complete 3-D characterization of the waves. This enables the precise determination of the sources of the waves in the mountain regions of Iceland with backward ray tracing. Forward ray tracing shows oblique propagation, an effect generally neglected in global atmospheric models. Read more
In situ nuclear magnetic resonance response of permafrost and active layer soil in boreal and tundra ecosystems The Cryosphere DOI 10.5194/tc-11-2943-2017 14 December 2017 Geophysical methods have wide applications to permafrost studies. We show that borehole nuclear magnetic resonance is a valuable geophysical tool to rapidly characterize the liquid water content and unfrozen pore space in warm permafrost through simulation and field study. This technique is also sensitive to the ice nucleation process in situ. This method, which is applicable in a variety of soil types, can be used for single observations or for time-lapse monitoring of permafrost changes. Read more
Continuous measurement of air–water gas exchange by underwater eddy covariance Biogeosciences DOI 10.5194/bg-14-5595-2017 11 December 2017 We use the aquatic eddy covariance technique – developed first for benthic O2flux measurements – right below the air–water interface (~ 4 cm) to determine gas exchange rates and coefficients. This use of the technique is particularly useful in studies of gas exchange and its dynamics and controls. The approach can thus help reduce the recognized problem of large uncertainties linked to gas exchange estimates in traditional aquatic ecosystem studies. Read more
Structure and functioning of the acid–base system in the Baltic Sea Earth System Dynamics DOI 10.5194/esd-8-1107-2017 11 December 2017 This review describes the general knowledge of the marine acid–base system as well as the peculiarities identified and reported for the Baltic Sea specifically. We discuss issues such as dissociation constants in the brackish water, the structure of the total alkalinity in the Baltic Sea, long-term changes in total alkalinity, and the acid–base effects of biomass production and mineralization. We identify research gaps and specify bottlenecks concerning the Baltic Sea acid–base system. Read more
The potamochemical symphony: new progress in the high-frequency acquisition of stream chemical data Hydrology and Earth System Sciences DOI 10.5194/hess-21-6153-2017 7 December 2017 We present a new prototypelab in the fieldnamed River Lab (RL) designed for water quality monitoring to perform a complete analysis at sub-hourly frequency of major dissolved species in river water. The article is an analytical paper to present the proof of concept, its performances and improvements. Our tests reveal a significant improvement of reproducibility compared to conventional analysis in the laboratory. First results are promising for understanding the critical zone. Read more
DCMIP2016: a review of non-hydrostatic dynamical core design and intercomparison of participating models Geoscientific Model Development DOI 10.5194/gmd-10-4477-2017 6 December 2017 Atmospheric dynamical cores are a fundamental component of global atmospheric modeling systems and are responsible for capturing the dynamical behavior of the Earth’s atmosphere. To better understand modern dynamical cores, this paper aims to provide a comprehensive review of 11 dynamical cores, drawn from modeling centers and groups that participated in the 2016 Dynamical Core Model Intercomparison Project (DCMIP) workshop and summer school. Read more
Impact of asymmetric uncertainties in ice sheet dynamics on regional sea level projections Natural Hazards and Earth System Sciences DOI 10.5194/nhess-17-2125-2017 4 December 2017 This paper provides a full range of possible future sea levels on a regional scale, since it includes extreme, but possible, contributions to sea level change from dynamical mass loss from the Greenland and Antarctica ice sheets. In contrast to the symmetric distribution used in the IPCC report, it is found that an asymmetric distribution toward high sea level change values locally can increase the mean sea level by 1.8 m this century. Read more
Simulation of climate, ice sheets and CO2 evolution during the last four glacial cycles with an Earth system model of intermediate complexity Climate of the Past DOI 10.5194/cp-13-1695-2017 29 November 2017 Ice cores reveal that atmospheric CO2 concentration varied synchronously with the global ice volume. Explaining the mechanism of glacial–interglacial variations of atmospheric CO2 concentrations and the link between CO2 and ice sheets evolution still remains a challenge. Here using the Earth system model of intermediate complexity we performed for the first time simulations of co-evolution of climate, ice sheets and carbon cycle using the astronomical forcing as the only external forcing. Read more
The role of meteorological conditions and pollution control strategies in reducing air pollution in Beijing during APEC 2014 and Victory Parade 2015 Atmospheric Chemistry and Physics DOI 10.5194/acp-17-13921-2017 23 November 2017 The generalized linear regression model (GLM), even based only on meteorological parameters, could be satisfactory to estimate the contribution of meteorological conditions in reducing air pollution and hence the contribution of control strategies in reducing air pollution. Using the GLM, we found that the meteorological conditions and pollution control strategies contributed 30% and 28% to the reduction of the PM2.5 concentration during APEC 2014 and 38% and 25% during Parade 2015. Read more
Latest Permian carbonate carbon isotope variability traces heterogeneous organic carbon accumulation and authigenic carbonate formation Climate of the Past DOI 10.5194/cp-13-1635-2017 22 November 2017 Stratigraphic trends in the carbon isotope composition of calcium carbonate rock can be used as a stratigraphic tool. An important assumption when using these isotope chemical records is that they record a globally universal signal of marine water chemistry. We show that carbon isotope scatter on a confined centimetre stratigraphic scale appears to represent a signal of microbial activity. However, long-term carbon isotope trends are still compatible with a primary isotope imprint. Read more
When probabilistic seismic hazard climbs volcanoes: the Mt. Etna case, Italy – Part 1: Model components for sources parameterization Natural Hazards and Earth System Sciences DOI 10.5194/nhess-17-1981-2017 22 November 2017 The volcanic region of Mt. Etna (Sicily, Italy) represents a perfect lab for testing innovative approaches to seismic hazard assessment. We present here the model components and the procedures adopted for defining seismic sources to be used in a new generation of probabilistic seismic hazard assessment, the first results and maps of which are presented in a companion paper, Peruzza et al. (2017). Read more
When probabilistic seismic hazard climbs volcanoes: the Mt. Etna case, Italy – Part 2: Computational implementation and first results Natural Hazards and Earth System Sciences DOI 10.5194/nhess-17-1999-2017 22 November 2017 It is well known that volcanoes and earthquakes are associated, and some active volcanoes cause damaging earthquakes. Nonetheless, volcanoes usually are not pinpointed on a hazard map, as the effects of shallow, volcanic earthquakes can be overshadowed by stronger tectonic earthquakes in the region, particularly when long exposure periods are considered. In this study we faced some challenges with software implementations and original concept scheme for an original PSHA at Mt. Etna, Italy. Read more
Climate of migration? How climate triggered migration from southwest Germany to North America during the 19th century Climate of the Past DOI 10.5194/cp-13-1573-2017 21 November 2017 This paper presents the extent to which climate, harvest and prices influenced the major migration waves from southwest Germany into North America during the 19th century, a century of dramatic climatic and societal changes. Read more
A multilayer physically based snowpack model simulating direct and indirect radiative impacts of light-absorbing impurities in snow The Cryosphere DOI 10.5194/tc-11-2633-2017 20 November 2017 Light-absorbing impurities deposited on snow, such as soot or dust, strongly modify its evolution. We implemented impurity deposition and evolution in a detailed snowpack model, thereby expanding the reach of such models into addressing the subtle interplays between snow physics and impurities’ optical properties. Model results were evaluated based on innovative field observations at an Alpine site. This allows future investigations in the fields of climate, hydrology and avalanche prediction. Read more