Revisiting the differential freezing nucleus spectra derived from drop-freezing experiments: methods of calculation, applications, and confidence limits Atmospheric Measurement Techniques DOI 10.5194/amt-12-1219-2019 26 February 2019 The abundance of freezing nuclei in water samples is routinely determined by experiments involving the cooling of sample drops and observing the temperatures at which the drops freeze. This is used for characterizing the nucleating abilities of materials in laboratory preparations or to determine the numbers of nucleating particles in rain, snow, river water or other natural waters. The evaluation of drop-freezing experiments in terms of differential nucleus spectra is advocated in the paper. Read more
The role of moisture transport for precipitation in the inter-annual and inter-daily fluctuations of the Arctic sea ice extension Earth System Dynamics DOI 10.5194/esd-10-121-2019 21 February 2019 Ice melting at the scale of inter-annual fluctuations against the trend is favoured by an increase in moisture transport in summer, autumn, and winter and a decrease in spring. On a daily basis extreme humidity transport increases the formation of ice in winter and decreases it in spring, summer, and autumn; in these three seasons it thus contributes to Arctic sea ice melting. These patterns differ sharply from that linked to decline, especially in summer when the opposite trend applies. Read more
Identifying and improving AGU collaborations using network analysis and scientometrics Geoscience Communication DOI 10.5194/gc-2-55-2019 20 February 2019 The American Geophysical Union (AGU) is an Earth and space science professional society. Research conducted by AGU members ranges from the Earth’s deep interior to the outer planets of our solar system. However, little research exists on the AGU meeting itself. We apply network analysis and scientometrics to 17 years of AGU Fall Meetings to examine the network structure of the AGU and explore how data science can facilitate better scientific communication and collaboration. AGU collaborations using network analysis and scientometrics">Read more
Harmonising plant functional type distributions for evaluating Earth system models Climate of the Past DOI 10.5194/cp-15-335-2019 18 February 2019 A simple but powerful method for the biomisation of plant functional type distributions is introduced and tested for six different dynamic global vegetation models based on pre-industrial and palaeo-simulations. The method facilitates the direct comparison between vegetation distributions simulated by different Earth system models and between model results and the pollen-based biome reconstructions. It is therefore a powerful tool for the evaluation of Earth system models. Read more
Thaw processes in ice-rich permafrost landscapes represented with laterally coupled tiles in a land surface model The Cryosphere DOI 10.5194/tc-13-591-2019 18 February 2019 Many permafrost landscapes contain large amounts of excess ground ice, which gives rise to small-scale elevation differences. This results in lateral fluxes of snow, water, and heat, which we investigate and show how it can be accounted for in large-scale models. Using a novel model technique which can account for these differences, we are able to model both the current state of permafrost and how these landscapes change as permafrost thaws, in a way that could not previously be achieved. Read more
Towards a more complete quantification of the global carbon cycle Biogeosciences DOI 10.5194/bg-16-831-2019 14 February 2019 Globally, C is added to the atmosphere from fossil fuels and deforestation, balanced by ocean uptake and atmospheric increase. The difference (residual sink) is equated to plant uptake. But this omits cement carbonation; transport to oceans by dust; riverine organic C and volatile organics; and increased C in plastic, bitumen, wood, landfills, and lakes. Their inclusion reduces the residual sink from 3.6 to 2.1 GtC yr-1 and thus the inferred ability of the biosphere to alter human C emissions. Read more
A simple topography-driven and calibration-free runoff generation module Hydrology and Earth System Sciences DOI 10.5194/hess-23-787-2019 13 February 2019 Supported by large-sample ecological observations, a novel, simple and topography-driven runoff generation module (HSC-MCT) was created. The HSC-MCT is calibration-free, and therefore it can be used to predict in ungauged basins, and has great potential to be generalized at the global scale. Also, it allows us to reproduce the variation of saturation areas, which has great potential to be used for broader hydrological, ecological, climatological, and biogeochemical studies. Read more
Mineral formation induced by cable bacteria performing long-distance electron transport in marine sediments Biogeosciences DOI 10.5194/bg-16-811-2019 13 February 2019 Multicellular cable bacteria form long filaments that can reach lengths of several centimeters. They affect the chemistry and mineralogy of their surroundings and vice versa. How the surroundings affect the cable bacteria is investigated. They show three different types of biomineral formation: (1) a polymer containing phosphorus in their cells, (2) a sheath of clay surrounding the surface of the filament and (3) the encrustation of a filament via a solid phase containing iron and phosphorus. Read more
Evidence for a major missing source in the global chloromethane budget from stable carbon isotopes Atmospheric Chemistry and Physics DOI 10.5194/acp-19-1703-2019 8 February 2019 Chloromethane is the most important natural carrier of chlorine to the stratosphere. From a newly determined carbon isotope effect of −11.2 ‰ for the tropospheric loss of CH3Cl we derive a tropical rainforest CH3Cl source of 670 ± 200 Gg a−1, 60 % smaller than previous estimates. A revision of previous bottom-up estimates using above-ground biomass instead of rainforest area strongly supports this lower estimate. Our results suggest a large unknown tropical value of 1530 ± 200 Gg a−1. Read more
Four decades of Antarctic surface elevation changes from multi-mission satellite altimetry The Cryosphere DOI 10.5194/tc-13-427-2019 5 February 2019 We developed an approach to combine measurements of seven satellite altimetry missions over the Antarctic Ice Sheet. Our resulting monthly grids of elevation changes between 1978 and 2017 provide unprecedented details of the long-term and interannual variation. Derived mass changes agree well with contemporaneous data of surface mass balance and satellite gravimetry and show which regions were responsible for the significant accelerations of mass loss in recent years. Read more
