Past changes in the vertical distribution of ozone – Part 3: Analysis and interpretation of trends Atmospheric Chemistry and Physics DOI 10.5194/acp-15-9965-2015 7 September 2015 Trends in the vertical distribution of ozone are reported for new and recently revised data sets. The amount of ozone-depleting compounds in the stratosphere peaked in the second half of the 1990s. We examine the trends before and after that peak to see if any change in trend is discernible. The previously reported decreases are confirmed. Furthermore, the downward trend in upper stratospheric ozone has not continued. The possible significance of any increase is discussed in detail. Read more
Diesel-related hydrocarbons can dominate gas phase reactive carbon in megacities Atmospheric Chemistry and Physics DOI 10.5194/acp-15-9983-2015 7 September 2015 Technological shifts between fuel sources have had unexpected impacts on atmospheric composition and these significant changes can go undetected if source-specific monitoring infrastructure is not in place. We present chemically comprehensive, continuous measurements of organic compounds in a developed megacity (London), that show diesel-related hydrocarbons can dominate reactive carbon and ozone formation potential, highlighting a serious underestimation of this source in emission inventories. Read more
Retrieving the paleoclimatic signal from the deeper part of the EPICA Dome C ice core The Cryosphere DOI 10.5194/tc-9-1633-2015 20 August 2015 The oldest paleoclimatic information is buried within the lowermost layers of deep ice cores. It is therefore essential to judge how deep these records remain unaltered. We study the bottom 60 meters of the EPICA Dome C ice core from central Antarctica to show that the paleoclimatic signal is only affected at the small scale (decimeters) in terms of some of the global ice properties. However our data suggest that the time scale has been considerably distorted by mechanical stretching. Read more
Observation of a new type of low-frequency waves at comet 67P/Churyumov-Gerasimenko Annales Geophysicae DOI 10.5194/angeo-33-1031-2015 19 August 2015 We present a first report on magnetic field measurements made in the coma of comet 67P/C-G in its low activity state. The plasma environment is dominated by quasi-coherent, large-amplitude, compressional magnetic field oscillations around 40 mHz, differing from the observations at strongly active comets where waves at the cometary ion gyro-frequencies are the main feature. We propose a cross-field current instability associated with the newborn cometary ions as a possible source mechanism. Read more
Century-scale simulations of the response of the West Antarctic Ice Sheet to a warming climate The Cryosphere DOI 10.5194/tc-9-1579-2015 18 August 2015 We used a high resolution ice sheet model capable of resolving grouding line dynamics (BISICLES) to compute responses of the major West Antarctic ice streams to projections of ocean and atmospheric warming. This is computationally demanding, and although other groups have considered parts of West Antarctica, we think this is the first calculation for the whole region at the sub-kilometer resolution that we show is required. Read more
Tropospheric ozone and its precursors from the urban to the global scale from air quality to short-lived climate forcer Atmospheric Chemistry and Physics DOI 10.5194/acp-15-8889-2015 13 August 2015 Ozone holds a certain fascination in atmospheric science. It is ubiquitous in the atmosphere, central to tropospheric oxidation chemistry, and yet harmful to human and ecosystem health as well as being an important greenhouse gas. It is not emitted into the atmosphere but is a byproduct of the very oxidation chemistry it largely initiates. This review examines current understanding of the processes regulating tropospheric ozone at global to local scales from both measurements and models. Read more
Impact of model developments on present and future simulations of permafrost in a global land-surface model The Cryosphere DOI 10.5194/tc-9-1505-2015 7 August 2015 In this paper we use a global land-surface model to study the dynamics of Arctic permafrost. We examine the impact of new and improved processes in the model, namely soil depth and resolution, organic soils, moss and the representation of snow. These improvements make the simulated soil temperatures and thaw depth significantly more realistic. Simulations under future climate scenarios show that permafrost thaws more slowly in the new model version, but still a large amount is lost by 2100. Read more
Mapping snow depth from manned aircraft on landscape scales at centimeter resolution using structure-from-motion photogrammetry The Cryosphere DOI 10.5194/tc-9-1445-2015 5 August 2015 This paper presents a photogrammetric method for measuring topography from manned aircraft with an accuracy of 30 cm and repeatability of 8 cm, at significantly lower cost than other methods. Here we created difference maps to demonstrate that we could measure snow depth with an accuracy of 10 cm compared to over 6000 snow-probe measurements on the ground, but do so over entire watersheds at 10-20 cm spatial resolution rather than just a few transects. Read more
EMPOWER-1.0: an Efficient Model of Planktonic ecOsystems WrittEn in R Geoscientific Model Development DOI 10.5194/gmd-8-2231-2015 24 July 2015 Ecosystem models provide a powerful tool for simulating ocean biology. Care must be exercised when selecting appropriate equations and parameter values to represent chosen marine ecosystems. Here, we present an efficient plankton model testbed, using simplified physics and coded in the freely available language R. Multiple runs can be undertaken for different ocean sites, permitting thorough evaluation of ecosystem model performance. The testbed also serves as an excellent resource for teaching. Read more
Evidence for biological shaping of hair ice Biogeosciences DOI 10.5194/bg-12-4261-2015 22 July 2015 We investigated an unusual ice type, called hair ice. It grows on the surface of dead wood of broad-leaf trees at temperatures slightly below 0°C.We describe this phenomenon and present our biological, physical and chemical investigations to gain insight in the properties and processes related to hair ice: we found, that a winter-acive fungus in the wood is required. Ice segregation is the common mechanism. Chemical analyses show a complex mixture of several thousand lignin/tannin compounds. Read more
Mapping gas-phase organic reactivity and concomitant secondary organic aerosol formation: chemometric dimension reduction techniques for the deconvolution of complex atmospheric data sets Atmospheric Chemistry and Physics DOI 10.5194/acp-15-8077-2015 22 July 2015 This paper describes a new ensemble methodology for the statistical analysis of atmospheric gas- & particle-phase composition data sets. The methodology reduces the huge amount of data derived from many chamber experiments to show that organic reactivity & resultant particle formation can be mapped into unique clusters in statistical space. The model generated is used to map more realistic plant mesocosm oxidation data, the projection of which gives insight into reactive pathways & precursors. Read more
14C-age tracers in global ocean circulation models Geoscientific Model Development DOI 10.5194/gmd-8-2079-2015 16 July 2015 The natural abundance of 14C in CO2 dissolved in seawater is often used to evaluate circulation and age in the ocean and in ocean models. We study limitations of using natural 14C to determine the time elapsed since water had contact with the atmosphere. We find that, globally, bulk 14C age is dominated by two equally important components, (1) the time component of circulation and (2) the “preformed 14C-age”. Considering preformed 14C-age is critical for an assessment of circulation in models. Read more
Decomposing uncertainties in the future terrestrial carbon budget associated with emission scenarios, climate projections, and ecosystem simulations using the ISI-MIP results Earth System Dynamics DOI 10.5194/esd-6-435-2015 13 July 2015 Our MS focused on uncertainties terrestrial C cycling under newly developed scenarios with CMIP 5 experiment. This study is first results to figure out the relative uncertainties of projected terrestrial C cycling in multiple projection components. Only using our new model inter-comparison project datasets enables us to evaluate various uncertainty sources in projection periods. The information about relative uncertainties are useful for climate science and the climate change impact evaluation. Read more
A contribution to the selection of tsunami human vulnerability indicators: conclusions from tsunami impacts in Sri Lanka and Thailand (2004), Samoa (2009), Chile (2010) and Japan (2011) Natural Hazards and Earth System Sciences DOI 10.5194/nhess-15-1493-2015 3 July 2015 Human vulnerability indicators used by the scientific community are validated in light of past tsunamis (2011 Japan, 2010 Chile, 2009 Samoa, 2004 Indian Ocean). Temporal exposure depends on livelihoods, traditions and gender roles. Vulnerable age groups are the elderly (highest mortality rates) and children. Female mortality is not always higher. There is a high correlation between damaged buildings and victims; distance to the sea, building materials and water depths determine type of damage. Read more
Development of a Global Fire Weather Database Natural Hazards and Earth System Sciences DOI 10.5194/nhess-15-1407-2015 30 June 2015 The authors of this study have developed a global database of daily, gridded Fire Weather Index System calculations beginning in 1980. Input data and two different estimates of precipitation from rain gauges were obtained from the NASA Modern Era Retrospective-Analysis for Research and Applications. This data set can be used for analyzing historical relationships between fire weather and fire activity, and in identifying large-scale atmosphere–ocean controls on fire weather. Read more
A ground temperature map of the North Atlantic permafrost region based on remote sensing and reanalysis data The Cryosphere DOI 10.5194/tc-9-1303-2015 23 June 2015 The authors of this paper use remotely sensed land surface temperature and land cover in conjunction with air temperature and snowfall from a reanalysis product as input for a simple permafrost model. The scheme is applied to the permafrost regions bordering the North Atlantic. A comparison with ground temperatures in boreholes suggests a modeling accuracy of 2 to 2.5 °C. Read more
Towards observation-based gridded runoff estimates for Europe Hydrology and Earth System Sciences DOI 10.5194/hess-19-2859-2015 22 June 2015 Water storages and fluxes on land are key variables in the earth system. To provide context for local investigations and to understand phenomena that emerge at large spatial scales, information on continental freshwater dynamics is needed. This paper presents a methodology to estimate continental scale runoff on a 0.5° spatial grid, which combines the advantages of in-situ observations with the power of machine learning regression. The resulting runoff estimates compare well with observations. Read more
Dynamics of the Oso-Steelhead landslide from broadband seismic analysis Natural Hazards and Earth System Sciences DOI 10.5194/nhess-15-1265-2015 17 June 2015 We carry out a study of the seismic signals generated by the devastating Oso-Steelhead landslides. We invert the long-period seismic signals generated by the first main event and obtain estimates of its trajectory, kinematics and mass. No distinct long-period surface waves were recorded for the second failure, which prevents inversion for its source parameters. However, from the comparison of the energy of the short-period waves generated by both events, we can estimate the volume of the second. Read more
Technical Note: How accurate can stalagmite formation temperatures be determined using vapour bubble radius measurements in fluid inclusions? Climate of the Past DOI 10.5194/cp-11-905-2015 17 June 2015 Fluid inclusions inside stalagmites retain information on the cave temperature at the time they formed and thus can be used to reconstruct the continental climate of the past. A method for extracting this information based on a thermodynamic model and size measurements of femtosecond-laser-induced vapour bubbles is presented. Applying our method to stalagmites taken from the Milandre cave in the Swiss Jura Mountains demonstrate that palaeotemperatures can be determined with an accuracy of ±1°C. Read more
Brief Communication: Newly developing rift in Larsen C Ice Shelf presents significant risk to stability The Cryosphere DOI 10.5194/tc-9-1223-2015 15 June 2015 Within the last year, a large rift in the southern part of the Larsen C Ice Shelf, Antarctic Peninsula, propagated towards the inner part of the ice shelf. In this study we present the development of the rift as derived from remote sensing data and assess the impact of possible calving scenarios on the future stability of the Larsen C Ice Shelf, using a numerical model. We find that the calving front is likely to become unstable after the anticipated calving events. Read more
Large-basin hydrological response to climate model outputs: uncertainty caused by internal atmospheric variability Hydrology and Earth System Sciences DOI 10.5194/hess-19-2737-2015 15 June 2015 Our paper is one of very few studies where the influence of stochastic internal atmospheric variability (IAV) on the hydrological response is analyzed. On the basis of ensemble experiments with GCM and hydrological models, we found, e.g., that averaging over ensemble members filters the stochastic term related to IAV, and that a considerable portion of the simulated trend in annual Lena R. runoff can be explained by the externally forced signal (global SST and SIC changes in our experiments). Read more
A large-scale simulation model to assess karstic groundwater recharge over Europe and the Mediterranean Geoscientific Model Development DOI 10.5194/gmd-8-1729-2015 11 June 2015 We present a new approach to assess karstic groundwater recharge over Europe and the Mediterranean. Cluster analysis is used to subdivide all karst regions into four typical karst landscapes and to simulate karst recharge with a process-based karst model. We estimate its parameters by a combination of a priori information and observations of soil moisture and evapotranspiration. Independent observations of recharge that present large-scale models significantly under-estimate karstic recharge. Read more
Twelve thousand years of dust: the Holocene global dust cycle constrained by natural archives Climate of the Past DOI 10.5194/cp-11-869-2015 11 June 2015 We propose an innovative framework to organize paleodust records, formalized in a publicly accessible database, and discuss the emerging properties of the global dust cycle during the Holocene by integrating our analysis with simulations performed with the Community Earth System Model. We show how the size distribution of dust is intrinsically related to the dust mass accumulation rates and that only considering a consistent size range allows for a consistent analysis of the global dust cycle. Read more
A 50 % increase in the mass of terrestrial particles delivered by the Mackenzie River into the Beaufort Sea (Canadian Arctic Ocean) over the last 10 years Biogeosciences DOI 10.5194/bg-12-3551-2015 9 June 2015 Eleven years (2003-2013) of satellite data were processed to observe the variations in suspended particulate matter concentrations at the mouth of the Mackenzie River and estimate the fluxes exported into the Canadian Arctic Ocean. Results show that these concentrations at the river mouth, in the delta zone and in the river plume have increased by 46%, 71% and 33%, respectively, since 2003. This corresponds to a more than 50% increase in particulate export from the river into the Beaufort Sea. Read more
Emergence of multiple ocean ecosystem drivers in a large ensemble suite with an Earth system model Biogeosciences DOI 10.5194/bg-12-3301-2015 3 June 2015 A large initial-condition ensemble suite of simulations with an Earth system model is applied to evaluate emergence characteristics of four ocean ecosystem drivers under climate change. The drivers considered are warming, acidification, deoxygenation, and perturbations to biological productivity. The spatial and temporal hierarchies of the emergence of these drivers are considered, using concepts of both time of emergence and confidence intervals. Read more
Ideas and perspectives: on the emission of amines from terrestrial vegetation in the context of new atmospheric particle formation Biogeosciences DOI 10.5194/bg-12-3225-2015 3 June 2015 In this article we summarise recent science which shows how airborne amines, specifically methylamines (MAs), play a key role in new atmospheric particle formation (NPF) by stabilising small molecule clusters. Read more
Snowfall in the Himalayas: an uncertain future from a little-known past The Cryosphere DOI 10.5194/tc-9-1147-2015 2 June 2015 Snow and ice provide large amounts of meltwater to the Indus, Ganges and Brahmaputra rivers. In this study we show that climate change will reduce the amount of snow falling in the Himalayas, Hindu Kush and Karakoram substantially. The limited number of observations in remote upper-level terrain makes it difficult to get a complete overview of the situation today, but our results indicate that by 2071–2100 snowfall may be reduced by 30–70% with the strongest anthropogenic forcing scenario. Read more
Reliable, robust and realistic: the three R’s of next-generation land-surface modelling Atmospheric Chemistry and Physics DOI 10.5194/acp-15-5987-2015 29 May 2015 Land surface models (LSMs) describe how carbon and water fluxes react to environmental change. They are key component of climate models, yet they differ enormously. Many perform poorly, despite having many parameters. We outline a development strategy emphasizing robustness, reliability and realism, none of which is guaranteed by complexity alone. We propose multiple constraints, benchmarking and data assimilation, and representing unresolved processes stochastically, as tools in this endeavour. Read more
Modelling glacier change in the Everest region, Nepal Himalaya The Cryosphere DOI 10.5194/tc-9-1105-2015 27 May 2015 A glacier mass balance and redistribution model that integrates field observations and downscaled climate fields is developed to examine glacier sensitivity to future climate in the Everest region of Nepal. The modelled sensitivity of glaciers to future climate change is high, and glacier mass loss is sustained through the 21st century for both middle- and high-emission scenarios. Projected temperature increases will expose large glacier areas to melt and reduce snow accumulations. Read more
Local and regional scale measurements of CH4, δ13CH4, and C2H6 in the Uintah Basin using a mobile stable isotope analyzer Atmospheric Measurement Techniques DOI 10.5194/amtd-8-4859-2015 13 May 2015 We describe an innovative instrument based on cavity ring down spectroscopy that analyzes the stable isotopes of methane in the ambient atmosphere. This instrument was used to study atmospheric emissions from oil and gas extraction activities in the Uintah Basin in Utah. These measurements suggest that 86 ± 7% of the total emissions in the basin are from natural gas production. The easy field deployment of this instrument can enable similar regional attribution studies across the world. Read more
Oceanic and atmospheric forcing of Larsen C Ice-Shelf thinning The Cryosphere DOI 10.5194/tc-9-1005-2015 13 May 2015 Antarctic Peninsula ice shelves have collapsed in recent decades. The surface of Larsen C Ice Shelf is lowering, but the cause of this has not been understood. This study uses eight radar surveys to show that the lowering is caused by both ice loss and a loss of air from the ice shelf’s snowpack. At least two different processes are causing the lowering. The stability of Larsen C may be at risk from an ungrounding of Bawden Ice Rise or ice-front retreat past a ‘compressive arch’ in strain rates. Read more
The GAMDAM glacier inventory: a quality-controlled inventory of Asian glaciers The Cryosphere DOI 10.5194/tc-9-849-2015 6 May 2015 We present a new glacier inventory for high-mountain Asia named Glacier Area Mapping for Discharge from the Asian Mountains (GAMDAM). Glacier outlines were delineated manually using 356 Landsat ETM+ scenes in 226 path-row sets from the period 1999–2003, in conjunction with a digital elevation model and high-resolution Google EarthTM imagery. Our GAMDAM Glacier Inventory includes 87,084 glaciers covering a total area of 91,263 ± 13,689 km2 throughout high-mountain Asia. Read more
Open ocean dead zones in the tropical North Atlantic Ocean Biogeosciences DOI 10.5194/bg-12-2597-2015 30 April 2015 This study is the first report of the formation of dead zones in the open ocean. A combination of multiple ocean observing system elements (mooring, floats, satellites, ships) allowed us to reconstruct the generation of the dead zones and to connect the formation to enhanced respiration within mesoscale ocean eddies. The dead zones present specific threats to the ecosystem, such as the interruption of the diurnal migration of zooplankters. Read more
Storm type effects on super Clausius–Clapeyron scaling of intense rainstorm properties with air temperature Hydrology and Earth System Sciences DOI 10.5194/hess-19-1753-2015 16 April 2015 We present an empirical study of the rates of increase in precipitation intensity with air temperature using high-resolution 10 min precipitation records in Switzerland. We estimated the scaling rates for lightning (convective) and non-lightning event subsets and show that scaling rates are between 7 and 14%/C for convective rain and that mixing of storm types exaggerates the relations to air temperature. Doubled CC rates reported by other studies are an exception in our data set. Read more
Field survey report and satellite image interpretation of the 2013 Super Typhoon Haiyan in the Philippines Natural Hazards and Earth System Sciences DOI 10.5194/nhess-15-805-2015 10 April 2015 Super Typhoon Haiyan devastated the Eastern Visayas islands of the Philippines on 8 November 2013. The International Research Institute of Disaster Science (IRIDeS) at Tohoku University in Sendai, Japan, deployed several teams for damage recognition, relief support and collaboration with regard to this event. In this paper, we summarize the rapid damage assessment from satellite imagery conducted days after the event and report on the inundation measurements and damage surveyed in the field. Read more
On producing sea ice deformation data sets from SAR-derived sea ice motion The Cryosphere DOI 10.5194/tc-9-663-2015 9 April 2015 We present a new method to compute sea ice deformation fields from satellite-derived motion. The method particularly reduces the artificial noise that arises along discontinuities in the sea ice motion field. We estimate that this artificial noise may cause an overestimation of about 60% of sea ice opening and closing. The constant overestimation of the opening and closing could have led in previous studies to a large overestimation of freezing in leads, salt rejection and sea ice ridging. Read more
Rapid transport of East Asian pollution to the deep tropics Atmospheric Chemistry and Physics DOI 10.5194/acp-15-3565-2015 31 March 2015 We use observations and model calculations to show that “cold surges” occurring during Northern Hemisphere winter can rapidly transport East Asian pollution to equatorial Southeast Asia. As well as affecting atmospheric composition near the surface, we argue that strong convection can subsequently lift the polluted air masses to the tropical upper troposphere. This suggests a potentially important connection between midlatitude pollution sources and the lower stratosphere. Read more
Intercomparison of vertically resolved merged satellite ozone data sets: interannual variability and long-term trends Atmospheric Chemistry and Physics DOI 10.5194/acp-15-3021-2015 17 March 2015 Understanding ozone trends in the vertical are vital in terms of assessing the success of the Montreal Protocol. This paper compares and analyses the long-term trends in stratospheric ozone from seven new merged satellite data sets. The data sets largely agree well with each other, particularly for the negative trends seen in the early period 1984-1997. For the 1998-2011 period there is less agreement, but a clear shift from negative to mostly positive trends. Read more
Continuous and discontinuous variation in ecosystem carbon stocks with elevation across a treeline ecotone Biogeosciences DOI 10.5194/bg-12-1615-2015 12 March 2015 Here we investigate how ecosystem carbon stocks vary with elevation shifting from the closed forest to open alpine tundra, in the mountains of southern Norway. Above-ground carbon stocks decreased with elevation, with a clear breakpoint at the forest line, while the organic horizon soil carbon stocks increased linearly with elevation. Overall, ecosystem carbon stocks increased with elevation above the treeline and decreased with elevation below, demonstrating the importance of the treeline. Read more
A novel algorithm for detection of precipitation in tropical regions using PMW radiometers Atmospheric Measurement Techniques DOI 10.5194/amt-8-1217-2015 12 March 2015 The CCA algorithm is applicable to any modern passive microwave radiometer on board polar orbiting satellites; it has been developed using a data set of co-located SSMIS and TRMM-PR measurements and AMSU-MHS and TRMM-PR measurements. The algorithm shows a small rate of false alarms and superior detection capability and can efficiently detect (POD between 0.55 and 0.71) minimum rain rate varying from 0.14 mm/h (AMSU over ocean) to 0.41 (SSMIS over coast). Read more
The soil N cycle: new insights and key challenges SOIL DOI 10.5194/soil-1-235-2015 11 March 2015 Here, we review important insights with respect to the soil N cycle that have been made over the last decade, and present a personal view on the key challenges of future research. Read more
Improved routines to model the ocean carbonate system: mocsy 2.0 Geoscientific Model Development DOI 10.5194/gmd-8-485-2015 9 March 2015 We provide improved routines to model the ocean carbonate system, i.e., to compute ocean pH and related variables from dissolved inorganic carbon and total alkalinity. These routines (1) rely on the fastest available algorithm to solve the alkalinity-pH equation, which converges even under extreme conditions; (2) avoid common model approximations that lead to errors of 3% or more in computed variables; and (3) account for large pressure effects on subsurface pCO2, unlike other packages. Read more
Use of Ra isotopes to deduce rapid transfer of sediment-derived inputs off Kerguelen Biogeosciences DOI 10.5194/bg-12-1415-2015 5 March 2015 We investigated the origin and mechanisms of the natural iron fertilization that sustains a phytoplankton bloom downstream of the Kerguelen Islands. We used radium isotopes to trace the fate of shelf waters that may transport iron and other micronutrients towards offshore waters. We show that shelf waters are rapidly transferred offshore and may be transported across the polar front (PF). The PF may thus not be a strong physical barrier for chemical elements released by the shelf sediments. Read more
Using results from the PlioMIP ensemble to investigate the Greenland Ice Sheet during the mid-Pliocene Warm Period Climate of the Past DOI 10.5194/cp-11-403-2015 5 March 2015 Climate and ice sheet models are often used to predict the nature of ice sheets in Earth history. It is important to understand if such predictions are consistent between different models, especially in warm periods of relevance to the future. We use input from 15 different climate models to run one ice sheet model and compare the predictions over Greenland. We find that there are large differences between the predicted ice sheets for the warm Pliocene (c. 3 million years ago). Read more
Evaluation of coral reef carbonate production models at a global scale Biogeosciences DOI 10.5194/bg-12-1339-2015 4 March 2015 Production of calcium carbonate by coral reefs is important in the global carbon cycle. Using a global framework we evaluate four models of reef calcification against observed values. The temperature-only model showed significant skill in reproducing coral calcification rates. The absence of any predictive power for whole reef systems highlights the importance of coral cover and the need for an ecosystem modelling approach accounting for population dynamics in terms of mortality and recruitment. Read more
Does temperature affect the accuracy of vented pressure transducer in fine-scale water level measurement? Geoscientific Instrumentation, Methods and Data Systems DOI 10.5194/gi-4-65-2015 3 March 2015 This paper discussed the effect of temperature on the accuracy of submersible strain gauge pressure transducers. The results show that rapid change of temperature introduces errors in the water level reading while the absolute temperature is also related to the sensor errors. The former is attributed to venting and the latter is attributed to temperature compensation effects in the strain gauges. Performance tests are necessary before field deployment to ensure the data quality. Read more
Persistent after-effects of heavy rain on concentrations of ice nuclei and rainfall suggest a biological cause Atmospheric Chemistry and Physics DOI 10.5194/acp-15-2313-2015 3 March 2015 We show that atmospheric load of ice nuclei is enhanced for up to 20 days after key rainfall events. The rate of enhancement decreases exponentially with time. Rainfall quantity and frequency are increased for a similar duration and with similar exponential decreases thereby supporting the notion of rainfall feedback. We reveal series of significant feedback in rainfall patterns across Australia over the past century and marked changes in feedback patterns, and we indicate their locations. Read more
Quantitative high-resolution observations of soil water dynamics in a complicated architecture using time-lapse ground-penetrating radar Hydrology and Earth System Sciences DOI 10.5194/hess-19-1125-2015 2 March 2015 In this study, we analyze a set of high-resolution, surface-based, 2-D Ground-Penetrating Radar (GPR) observations of artificially induced subsurface water dynamics. In particular, we place close scrutiny on the evolution of the capillary fringe in a highly dynamic regime with surface based time-lapse GPR. We thoroughly explain all observed phenomena based on theoretical soil physical considerations and numerical simulations of both subsurface water flow and the expected GPR response. Read more
Identification and quantification of gaseous organic compounds emitted from biomass burning using two-dimensional gas chromatography–time-of-flight mass spectrometry Atmospheric Chemistry and Physics DOI 10.5194/acp-15-1865-2015 23 February 2015 This work represents the first application of two-dimensional gas chromatography to broadly characterize the gas-phase emissions of biomass burning, including comparisons among the emissions from burns of selected conifer, grass, crop residue, and peat fuel types. In these smoke samples, over 700 compounds were detected, which are discussed in the context of potential secondary organic aerosol formation. Read more
A 3-D shear velocity model of the southern North American and Caribbean plates from ambient noise and earthquake tomography Solid Earth DOI 10.5194/se-6-271-2015 20 February 2015 We compute a velocity model of the crust and uppermost mantle of Southern North America, Mexico and the Caribbean. We use a recent technique based on ‘ambient noise’ – or continuous seismic records – and a traditional one using earthquakes. Both techniques, together with the increased number of seismic stations in the region, allow us to obtain greater resolution than previous works. Some of its applications are to localize regional earthquakes and simulate ground motions. Read more