A new diagnostic for tropospheric ozone production Atmospheric Chemistry and Physics DOI 10.5194/acp-17-13669-2017 17 November 2017 Understanding tropospheric ozone chemistry has been at the centre of the field of atmospheric chemistry for the last 30 years. However, our conceptual approach to diagnosing ozone production in global models has not advanced in this time. Our work presents a new and powerful approach for diagnosing tropospheric ozone production, providing a significant enhancement in our ability to understand the processes controlling ozone and how we can validate our assessment of these processes. Read more
Reviews and syntheses: on the roles trees play in building and plumbing the critical zone Biogeosciences DOI 10.5194/bg-14-5115-2017 17 November 2017 This review represents the outcome from an invigorating workshop discussion that involved tree physiologists, geomorphologists, ecologists, geochemists, and hydrologists and developed nine hypotheses that could be tested. We argue these hypotheses point to the essence of issues we must explore if we are to understand how the natural system of the earth surface evolves, and how humans will affect its evolution. This paper will create discussion and interest both before and after publication. Read more
Basin-scale heterogeneity in Antarctic precipitation and its impact on surface mass variability The Cryosphere DOI 10.5194/tc-11-2595-2017 15 November 2017 In this CESM modeling study, we uncover regional relationships in snowfall across Antarctica that are corroborated by regional modeling and ice core records. These relationships are driven by variability in large-scale atmospheric moisture transport and dampen overall Antarctic snowfall variability, with implications for Antarctic-sourced sea level variability and detection of an emergent anthropogenic signal in Antarctic mass trends. Read more
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