Regional Antarctic snow accumulation over the past 1000 years Climate of the Past DOI 10.5194/cp-13-1491-2017 10 November 2017 Regional Antarctic snow accumulation derived from 79 ice core records is evaluated as part of the PAGES Antarctica 2k working group. Our results show that surface mass balance for the total Antarctic ice sheet has increased at a rate of 7 ± 0.13 Gt dec-1 since 1800 AD, representing a net reduction in sea level of ~ 0.02 mm dec-1 since 1800 and ~ 0.04 mm dec-1 since 1900 AD. The largest contribution is from the Antarctic Peninsula. Read more
Towards representing human behavior and decision making in Earth system models – an overview of techniques and approaches Earth System Dynamics DOI 10.5194/esd-8-977-2017 8 November 2017 Today, human interactions with the Earth system lead to complex feedbacks between social and ecological dynamics. Modeling such feedbacks explicitly in Earth system models (ESMs) requires making assumptions about individual decision making and behavior, social interaction, and their aggregation. In this overview paper, we compare different modeling approaches and techniques and highlight important consequences of modeling assumptions. We illustrate them with examples from land-use modeling. Read more
Making better sense of the mosaic of environmental measurement networks: a system-of-systems approach and quantitative assessment Geoscientific Instrumentation, Methods and Data Systems DOI 10.5194/gi-6-453-2017 6 November 2017 The term system-of-systems with respect to observational capabilities is frequently used, but what does it mean and how can it be assessed? Here, we define one possible interpretation of a system-of-systems architecture that is based upon demonstrable aspects of observing capabilities. We develop a set of assessment strands and then apply these to a set of atmospheric observational networks to decide which observations may be suitable for characterising satellite platforms in future work. Read more
Methanesulfonic acid (MSA) migration in polar ice: data synthesis and theory The Cryosphere DOI 10.5194/tc-11-2439-2017 3 November 2017 We combine a synthesis of 22 ice core records and a model of soluble impurity transport to investigate the enigmatic, post-depositional migration of methanesulfonic acid in polar ice. Our findings suggest that migration may be universal across coastal regions of Greenland and Antarctica, though it is mitigated at sites with higher accumulation and (or) lower impurity content. Records exhibiting severe migration may still be useful for inferring decadal and lower-frequency climate variability. Read more
Global consequences of afforestation and bioenergy cultivation on ecosystem service indicators Biogeosciences DOI 10.5194/bg-14-4829-2017 3 November 2017 Many climate change mitigation scenarios require negative emissions from land management. However, environmental side effects are often not considered. Here, we use projections of future land use from two land-use models as input to a vegetation model. We show that carbon removal via bioenergy production or forest maintenance and expansion affect a range of ecosystem functions. Largest impacts are found for crop production, nitrogen losses, and emissions of biogenic volatile organic compounds. Read more
Is there 1.5-million-year-old ice near Dome C, Antarctica? The Cryosphere DOI 10.5194/tc-11-2427-2017 2 November 2017 The oldest dated deep ice core drilled in Antarctica has been retrieved at EPICA Dome C (EDC), reaching ~ 800 000 years. Obtaining an older palaeoclimatic record from Antarctica is one of the greatest challenges of the ice core community. Here, we estimate the age of basal ice in the Dome C area. We find that old ice (> 1.5 Myr) likely exists in two regions a few tens of kilometres away from EDC:Little Dome C PatchandNorth Patch. Read more
The Palaeoclimate and Terrestrial Exoplanet Radiative Transfer Model Intercomparison Project (PALAEOTRIP): experimental design and protocols Geoscientific Model Development DOI 10.5194/gmd-10-3931-2017 1 November 2017 We provide the experimental designs and protocols for a community experiment to compare radiative transfer codes used for past climate on Earth, and for exoplanets. Read more
Impact of agricultural emission reductions on fine-particulate matter and public health Atmospheric Chemistry and Physics DOI 10.5194/acp-17-12813-2017 27 October 2017 This study shows that agricultural emissions are important for air quality and their reduction can effectively reduce the concentration of fine particles and their associated premature mortality. Therefore, emission control policies, especially in North America and Europe, should also involve strong ammonia emission decreases to optimally reduce fine-particle concentration. Read more
Vertical segregation among pathways mediating nitrogen loss (N2 and N2O production) across the oxygen gradient in a coastal upwelling ecosystem Biogeosciences DOI 10.5194/bg-14-4795-2017 26 October 2017 This investigation characterizes the variability of pathways involved in N loss in the water column over the continental shelf off central Chile during the development of the upwelling season. Our results highlight the links between several pathways involved in N removal, and considering the extreme variation in oxygen observed could help to understand the ecological and biogeochemical implications due to global warming when intensification and/or expansion of the oceanic OMZs are projected. Read more
Expansion of oil palm and other cash crops causes an increase of the land surface temperature in the Jambi province in Indonesia Biogeosciences DOI 10.5194/bg-14-4619-2017 25 October 2017 From the analysis of MODIS and Landsat satellite data of the Jambi province in Indonesia, this first study on the effects of oil palm expansion on the surface temperature in Indonesia shows shows a local and regional warming effect caused by the expansion of oil palm plantations and other cash or tree crops between 2000 and 2015. The observed warming effects may affect ecosystem services, reduce water availabilty in the dry period and increase the vulnerability to fires in the province. Read more
The CAMELS data set: catchment attributes and meteorology for large-sample studies Hydrology and Earth System Sciences DOI 10.5194/hess-21-5293-2017 20 October 2017 We introduce a data set describing the landscape of 671 catchments in the contiguous USA: we synthesized various data sources to characterize the topography, climate, streamflow, land cover, soil, and geology of each catchment. This extends the daily time series of meteorological forcing and discharge provided by an earlier study. The diversity of these catchments will help to improve our understanding and modeling of how the interplay between catchment attributes shapes hydrological processes. Read more
Revisiting the synoptic-scale predictability of severe European winter storms using ECMWF ensemble reforecasts Natural Hazards and Earth System Sciences DOI 10.5194/nhess-17-1795-2017 19 October 2017 The predictability of 25 historical winter storms over Europe is revisited by taking advantage of a homogeneous dataset of retrospective forecasts for the 1995–2015 period. The forecasts well predict the storms up to 2–4 days ahead only but also show clear potential for the early warning of storms up to 10 days ahead. However, the predictability of individual storms exhibits large variability and physical characteristics are identified for outliers with a poor predictability. Read more
Automated mineralogy based on micro-energy-dispersive X-ray fluorescence microscopy (µ-EDXRF) applied to plutonic rock thin sections in comparison to a mineral liberation analyzer Geoscientific Instrumentation, Methods and Data Systems DOI 10.5194/gi-6-429-2017 18 October 2017 This work describes a new approach to use fast X-ray fluorescence mapping as a tool for automated mineralogy applied on thin sections of plutonic rocks. Using a supervised classification of the spectral information, mineral maps are obtained for modal mineralogy and image analysis. The results are compared to a conventional method for automated mineralogy, which is scanning electron microscopy with mineral liberation analyzer, showing a good overall accuracy of 76 %. Read more
Seismic monitoring of small alpine rockfalls – validity, precision and limitations Earth Surface Dynamics DOI 10.5194/esurf-5-653-2017 16 October 2017 We use a seismometer network to detect and locate rockfalls, a key process shaping steep mountain landscapes. When tested against laser scan surveys, all seismically detected events could be located with an average deviation of 81 m. Seismic monitoring provides insight to the dynamics of individual rockfalls, which can be as small as 0.0053 m3. Thus, seismic methods provide unprecedented temporal, spatial and kinematic details about this important process. Read more
A growing threat to the ozone layer from short-lived anthropogenic chlorocarbons Atmospheric Chemistry and Physics DOI 10.5194/acp-17-11929-2017 12 October 2017 We have observed large amounts of man-made chlorine compounds in E and SE Asia and in the upper tropical troposphere. These relatively short-lived compounds are not controlled by the Montreal Protocol, but if significant quantities were able to reach the stratosphere, the long-term recovery of stratospheric ozone would be delayed. We have also identified an important atmospheric transport mechanism that can rapidly transport these chemicals from E Asia to the upper troposphere via the tropics. Read more
Balanced source terms for wave generation within the Hasselmann equation Nonlinear Processes in Geophysics DOI 10.5194/npg-24-581-2017 9 October 2017 The Hasselmann equation (HE) is the basis of modern surface ocean wave prediction models. Currently, they operate in theblack box with the tuning knobsmodes, since there is no consensus on universal wind input and wave-breaking dissipation source terms, and require re-tuning for different boundary and external conditions. We offer a physically justified framework able to reproduce theoretical properties of the HE and experimental field data without re-tuning of the model. Read more
Improving calibration and validation of cosmic-ray neutron sensors in the light of spatial sensitivity Hydrology and Earth System Sciences DOI 10.5194/hess-21-5009-2017 6 October 2017 A field-scale average of near-surface water content can be sensed by cosmic-ray neutron detectors. To interpret, calibrate, and validate the integral signal, it is important to account for its sensitivity to heterogeneous patterns like dry or wet spots. We show how point samples contribute to the neutron signal based on their depth and distance from the detector. This approach robustly improves the sensor performance and data consistency, and even reveals otherwise hidden hydrological features. Read more
Boundary layer models for calving marine outlet glaciers The Cryosphere DOI 10.5194/tc-11-2283-2017 5 October 2017 We show mathematically and computationally how discharge of ice from ocean-terminating glaciers is controlled by a combination of different forces acting on ice near the grounding line of a glacier and how that combination of forces is affected by the process of iceberg formation, which limits the length of floating ice tongues extending in front of the glacier. We show that a deeper fjord may lead to a longer ice tongue providing greater drag on the glacier, slowing the rate of ice discharge. Read more
Complex relationship between seasonal streamflow forecast skill and value in reservoir operations Hydrology and Earth System Sciences DOI 10.5194/hess-21-4841-2017 28 September 2017 This study investigates the relationship between skill and value of ensemble seasonal streamflow forecasts. Using data from a modern forecasting system, we show that skilled forecasts are more likely to provide benefits for reservoirs operated to maintain a target water level rather than reservoirs operated to satisfy a target demand. We identify the primary causes for this behaviour and provide specific recommendations for assessing the value of forecasts for reservoirs with supply objectives. Read more
The Plio-Pleistocene climatic evolution as a consequence of orbital forcing on the carbon cycle Climate of the Past DOI 10.5194/cp-13-1259-2017 25 September 2017 Ice ages are paced by astronomical parameters. On longer timescales, the astronomy also acts on climate, as evidenced by the 400 kyr signature observed in carbon isotopic records. In this paper, I present a conceptual model that links the astronomy to the dynamics of organic carbon in coastal areas. The model reproduces the carbon isotopic records and a two-step decrease in atmospheric CO2that would explain the Pleistocene (~ 2.8 Myr BP) and mid-Pleistocene (~ 0.8 Myr BP) transition. Read more
An explanation for the different climate sensitivities of land and ocean surfaces based on the diurnal cycle Earth System Dynamics DOI 10.5194/esd-8-849-2017 25 September 2017 We provide an explanation why land temperatures respond more strongly to global warming than ocean temperatures, a robust finding in observations and models that has so far not been understood well. We explain it by the different ways by which ocean and land surfaces buffer the strong variation in solar radiation and demonstrate this with a simple, physically based model. Our explanation also illustrates why nighttime temperatures warm more strongly, another robust finding of global warming. Read more
Response to Filchner–Ronne Ice Shelf cavity warming in a coupled ocean–ice sheet model – Part 1: The ocean perspective Ocean Science DOI 10.5194/os-13-765-2017 21 September 2017 A coupled model has been developed to study the interaction between the ocean and the Antarctic ice sheet. Simulations for present-day climate yield realistic ice-shelf melt rates and a grounding line position close to the observed state. In a warm-water-inflow scenario, the model suggests a substantial thinning of the ice shelf and a local retreat of the grounding line. The coupled model yields a stronger increase in ice-shelf basal melt rates than a fixed-geometry control experiment. Read more
Community climate simulations to assess avoided impacts in 1.5 and 2 ∘C futures Earth System Dynamics DOI 10.5194/esd-8-827-2017 19 September 2017 We present the results of a set of climate simulations designed to simulate futures in which the Earth’s temperature is stabilized at the levels referred to in the 2015 Paris Agreement. We consider the necessary future emissions reductions and the aspects of extreme weather which differ significantly between the 2 and 1.5 °C climate in the simulations. Read more
Combining ground-based microwave radiometer and the AROME convective scale model through 1DVAR retrievals in complex terrain: an Alpine valley case study Atmospheric Measurement Techniques DOI 10.5194/amt-10-3385-2017 18 September 2017 Microwave radiometers have the capability of observing temperature and humidity profiles with a few minute time resolution. This study investigates the potential benefit of this instrument to improve weather forecasts thanks to a better initialization of the model. Our results show that a significant improvement can be expected in the model initialization in the first 3 km with potential impacts on weather forecasts. Read more
A national-scale seasonal hydrological forecast system: development and evaluation over Britain Hydrology and Earth System Sciences DOI 10.5194/hess-21-4681-2017 15 September 2017 The research presented here provides the first evaluation of the skill of a seasonal hydrological forecast for the UK. The forecast scheme combines rainfall forecasts from the Met Office GloSea5 forecast system with a national-scale hydrological model to provide estimates of river flows 1 to 3 months ahead. The skill in the combined model is assessed for different seasons and regions of Britain, and the analysis indicates that Autumn/Winter flows can be forecast with reasonable confidence. Read more
Astronomical calibration of the Ypresian timescale: implications for seafloor spreading rates and the chaotic behavior of the solar system? Climate of the Past DOI 10.5194/cp-13-1129-2017 11 September 2017 We assembled a very accurate geological timescale from the interval 47.8 to 56.0 million years ago, also known as the Ypresian stage. We used cyclic variations in the data caused by periodic changes in Earthäs orbit around the sun as a metronome for timescale construction. Our new data compilation provides the first geological evidence for chaos in the long-term behavior of planetary orbits in the solar system, as postulated almost 30 years ago, and a possible link to plate tectonics events. Read more
An update on ozone profile trends for the period 2000 to 2016 Atmospheric Chemistry and Physics DOI 10.5194/acp-17-10675-2017 11 September 2017 Thanks to the 1987 Montreal Protocol and its amendments, ozone-depleting chlorine (and bromine) in the stratosphere has declined slowly since the late 1990s. Improved and extended long-term ozone profile observations from satellites and ground-based stations confirm that ozone is responding as expected and has increased by about 2 % per decade since 2000 in the upper stratosphere, around 40 km altitude. At lower altitudes, however, ozone has not changed significantly since 2000. Read more
Extracting real-crack properties from non-linear elastic behaviour of rocks: abundance of cracks with dominating normal compliance and rocks with negative Poisson ratios Nonlinear Processes in Geophysics DOI 10.5194/npg-24-543-2017 5 September 2017 A new method of analysing pressure wave dependences is presented and tested against the published experimental data. Upon the results of examination of more than 90 rock samples, it was found that a significant portion of rocks (~ 45 %) exhibit negative Poisson ratios at lower pressures. Such a significant number of naturally auxetic rocks suggests that the occurrence of negative Poisson ratios is not as exotic as assumed previously. Read more
JRAero: the Japanese Reanalysis for Aerosol v1.0 Geoscientific Model Development DOI 10.5194/gmd-10-3225-2017 4 September 2017 A global aerosol reanalysis product named the Japanese Reanalysis for Aerosol (JRAero) was constructed by the Meteorological Research Institute (MRI) of the Japan Meteorological Agency. The reanalysis employs a global aerosol transport model developed by MRI and a two-dimensional variational data assimilation method. It assimilates maps of aerosol optical depth (AOD) from MODIS onboard the Terra and Aqua satellites every 6 h and has a TL159 horizontal resolution (approximately 1.1° × 1.1°). Read more
The electric current approach in the solar–terrestrial relationship Annales Geophysicae DOI 10.5194/angeo-35-965-2017 21 August 2017 The sequence of phenomena consisting of solar flares, coronal mass ejections (CMEs), auroral substorm, and geomagnetic storms is mostly a manifestation of electromagnetic energy dissipation. Thus, first of all, it is natural to consider each of them in terms of a sequence of power supply (dynamo), power transmission (electric currents/circuits), and dissipation (mostly observed phenomena), i.e., as an input–output process and the electric current line approach. Read more
Simultaneous measurements of new particle formation at 1 s time resolution at a street site and a rooftop site Atmospheric Chemistry and Physics DOI 10.5194/acp-17-9469-2017 8 August 2017 This study reports the distinct effects of street canyons on new particle formation (NPF) under warm or cold ambient temperature conditions because of on-road vehicle emissions; i.e., stronger condensation sinks are responsible for the reduced NPF in the springtime, but efficient nucleation and partitioning of gaseous species contribute to the enhanced NPF in the wintertime. The oxidization of biogenic organics is suggested to play an important role in growing new particles. Read more
Has dyke development in the Vietnamese Mekong Delta shifted flood hazard downstream? Hydrology and Earth System Sciences DOI 10.5194/hess-21-3991-2017 7 August 2017 In this study we provide a numerical quantification of changes in flood hazard in the Vietnamese Mekong Delta as a result of dyke development. Other important drivers to the alteration of delta flood hazard are also investigated, e.g. tidal level. The findings of our study are substantial valuable for the decision makers in Vietnam to develop holistic and harmonized floods and flood-related issues management plan for the whole delta. Read more
NOx emission trends over Chinese cities estimated from OMI observations during 2005 to 2015 Atmospheric Chemistry and Physics DOI 10.5194/acp-17-9261-2017 1 August 2017 We assess NOx emission trends over Chinese cities based on satellite NO2 observations using a method independent of chemical transport models. NOx emissions over 48 Chinese cities have decreased significantly since 2011. Cities with different dominant emission sources (i.e. power, industrial, and transportation sectors) showed variable emission decline timelines that corresponded to the schedules for emission control in different sectors. Read more
An intercomparison of approaches for improving operational seasonal streamflow forecasts Hydrology and Earth System Sciences DOI 10.5194/hess-21-3915-2017 31 July 2017 Water supply forecasts are critical to support water resources operations and planning. The skill of such forecasts depends on our knowledge of (i) future meteorological conditions and (ii) the amount of water stored in a basin. We address this problem by testing several approaches that make use of these sources of predictability, either separately or in a combined fashion. The main goal is to understand the marginal benefits of both information and methodological complexity in forecast skill. Read more
Every apple has a voice: using stable isotopes to teach about food sourcing and the water cycle Hydrology and Earth System Sciences DOI 10.5194/hess-21-3799-2017 25 July 2017 Fruits take up soil water as they grow, and thus the fruit water is related to the rain or irrigation the crop receives. We used a novel sampling system to measure the stable isotopes of H and O in the fruit water to determine its geographic origin by comparing it to maps of isotopes in rain. We used this approach to teach an audience of science students and teachers about water cycle concepts and how humans may modify the water cycle through agriculture and irrigation water diversions. Read more
The double high tide at Port Ellen: Doodson’s criterion revisited Ocean Science DOI 10.5194/os-13-599-2017 20 July 2017 Some places experience double high tides, where the tide starts to ebb for a short while, only to briefly flood again before finally receding. The result is a very long high tide with weak currents, and is important for navigational purposes. The existing theory for when and where double high tides occur does not always capture them, and it can only be applied to double highs occurring on a twice-daily tide. Here, the criterion has been generalized to capture all double high or low tides. Read more
Reviews and syntheses: Systematic Earth observations for use in terrestrial carbon cycle data assimilation systems Biogeosciences DOI 10.5194/bg-14-3401-2017 19 July 2017 This paper briefly reviews data assimilation techniques in carbon cycle data assimilation and the requirements of data assimilation systems on observations. We provide a non-exhaustive overview of current observations and their uncertainties for use in terrestrial carbon cycle data assimilation, focussing on relevant space-based observations. Read more
The CarbonTracker Data Assimilation Shell (CTDAS) v1.0: implementation and global carbon balance 2001–2015 Geoscientific Model Development DOI 10.5194/gmd-10-2785-2017 18 July 2017 The CarbonTracker Data Assimilation Shell (CTDAS) is the new modular implementation of the CarbonTracker Europe (CTE) data assimilation system. We present and document CTDAS and demonstrate its ability to estimate global carbon sources and sinks. We present the latest CTE results including the distribution of the carbon sinks over the hemispheres and between the land biosphere and the oceans. We show the versatility of CTDAS with an overview of the wide range of other applications. Read more
Periodic input of dust over the Eastern Carpathians during the Holocene linked with Saharan desertification and human impact Climate of the Past DOI 10.5194/cp-13-897-2017 18 July 2017 We present the first record of dust input into an eastern European bog over the past 10 800 years. We find significant changes in past dust deposition, with large inputs related to both natural and human influences. We show evidence that Saharan desertification has had a significant impact on dust deposition in eastern Europe for the past 6100 years. Read more
Young people’s burden: requirement of negative CO2 emissions Earth System Dynamics DOI 10.5194/esd-8-577-2017 18 July 2017 Global temperature now exceeds +1.25 °C relative to 1880–1920, similar to warmth of the Eemian period. Keeping warming less than 1.5 °C or CO2 below 350 ppm now requires extraction of CO2 from the air. If rapid phaseout of fossil fuel emissions begins soon, most extraction can be via improved agricultural and forestry practices. In contrast, continued high emissions places a burden on young people of massive technological CO2 extraction with large risks, high costs and uncertain feasibility. Read more
Analysis of single-Alter-shielded and unshielded measurements of mixed and solid precipitation from WMO-SPICE Hydrology and Earth System Sciences DOI 10.5194/hess-21-3525-2017 14 July 2017 Precipitation measurements were combined from eight separate precipitation testbeds to create multi-site transfer functions for the correction of unshielded and single-Alter-shielded precipitation gauge measurements. Site-specific errors and more universally applicable corrections were created from these WMO-SPICE measurements. The importance and magnitude of such wind speed corrections were demonstrated. Read more
Update of the Polar SWIFT model for polar stratospheric ozone loss (Polar SWIFT version 2) Geoscientific Model Development DOI 10.5194/gmd-10-2671-2017 13 July 2017 The Polar SWIFT model is a fast scheme for calculating the chemistry of stratospheric ozone depletion in polar winter. It is intended for use in global climate models (GCMs) and Earth system models (ESMs) to enable the simulation of mutual interactions between the ozone layer and climate. Read more
Exploring gravity wave characteristics in 3-D using a novel S-transform technique: AIRS/Aqua measurements over the Southern Andes and Drake Passage Atmospheric Chemistry and Physics DOI 10.5194/acp-17-8553-2017 13 July 2017 We introduce a novel 3-D method of measuring atmospheric gravity waves, based around a 3-D Stockwell transform. Our method lets us measure new properties, including wave intrinsic frequencies and phase and group velocities. We apply it to data from the AIRS satellite instrument over the Southern Andes for two consecutive winters. Our results show clear evidence that the waves measured are primarily orographic in origin, and that their group velocity vectors are focused into the polar night jet. Read more
On the long-range offshore transport of organic carbon from the Canary Upwelling System to the open North Atlantic Biogeosciences DOI 10.5194/bg-14-3337-2017 13 July 2017 We find that a big portion of the phytoplankton, zooplankton, and detrital organic matter produced near the northern African coast is laterally transported towards the open North Atlantic. This offshore flux sustains a relevant part of the biological activity in the open sea and reaches as far as the middle of the North Atlantic. Our results, obtained with a state-of-the-art model, highlight the fundamental role of the narrow but productive coastal ocean in sustaining global marine life. Read more
HESS Opinions: A planetary boundary on freshwater use is misleading Hydrology and Earth System Sciences DOI 10.5194/hess-21-3455-2017 12 July 2017 In 2009, the “planetary boundaries” were introduced. They consist of nine global control variables and corresponding “thresholds which, if crossed, could generate unacceptable environmental change”. The idea has been very successful, but also controversial. This paper picks up the debate with regard to the boundary on “global freshwater use”: it argues that such a boundary is based on mere speculation, and that any exercise of assigning actual numbers is arbitrary, premature, and misleading. Read more
Efficient retention of mud drives land building on the Mississippi Delta plain Earth Surface Dynamics DOI 10.5194/esurf-5-387-2017 12 July 2017 Our work presents a novel method of measuring the capacity of deltaic landforms to trap and retain river-borne sediments, and we demonstrate that sediment retention is closely connected to sedimentary composition. Our results, supported by a unique high-resolution coring dataset in a major crevasse splay, show that finer sediments are a much larger component of the Mississippi Delta than is often acknowledged and that their abundance indicates exceptionally high rates of sediment retention. Read more
River logjams cause frequent large-scale forest die-off events in southwestern Amazonia Earth System Dynamics DOI 10.5194/esd-8-565-2017 11 July 2017 In lowland Bolivia, satellite images show rivers collapsing and the replacement of forest with savannah. This was first described in 1996 as the result of logjams (river dams created by fallen trees). I have investigated how the logjams form and affect the forest through remote sensing and fieldwork. Logjams occur nearly every year and propagate upriver until the river changes course. This region offers a unique opportunity to study how frequent forest die-off events affect biodiversity. Read more
Detectability of Arctic methane sources at six sites performing continuous atmospheric measurements Atmospheric Chemistry and Physics DOI 10.5194/acp-17-8371-2017 11 July 2017 Atmospheric methane simulations in the Arctic have been made for 2012 and compared to continuous observations at six measurement sites. All methane sources significantly affect the measurements at all stations, at least at the synoptic scale, except for biomass burning. An appropriate modelling framework combined with continuous observations of atmospheric methane enables us to gain knowledge on regional methane sources, including those which are usually poorly represented, such as freshwater. Read more
Geomorphometric delineation of floodplains and terraces from objectively defined topographic thresholds Earth Surface Dynamics DOI 10.5194/esurf-5-369-2017 10 July 2017 Floodplains and fluvial terraces can provide information about current and past river systems, helping to reveal how channels respond to changes in both climate and tectonics. We present a new method of identifying these features objectively from digital elevation models by analysing their slope and elevation compared to the modern river. We test our method in eight field sites, and find that it provides rapid and reliable extraction of floodplains and terraces across a range of landscapes. Read more
A weekly Arctic sea-ice thickness data record from merged CryoSat-2 and SMOS satellite data The Cryosphere DOI 10.5194/tc-11-1607-2017 6 July 2017 We developed the first merging of CryoSat-2 and SMOS sea-ice thickness retrievals. ESA’s Earth Explorer SMOS satellite can detect thin sea ice, whereas its companion CryoSat-2, designed to observe thicker perennial sea ice, lacks sensitivity. Using these satellite missions together completes the picture of the changing Arctic sea ice and provides a more accurate and comprehensive view on the actual state of Arctic sea-ice thickness. Read more