A shape model of internally mixed soot particles derived from artificial surface tension Atmospheric Measurement Techniques DOI 10.5194/amt-12-107-2019 7 January 2019 We developed a shape model of coated soot particles and created a dataset of their optical properties. To simulate the detailed shape properties of mixtures of soot aggregates and adhered water-soluble substances, we propose a simple model of surface tension derived from the artificial surface potential. The results of some single-scattering properties including lidar backscattering were discussed. Read more
ESD Ideas: Photoelectrochemical carbon removal as negative emission technology Earth System Dynamics DOI 10.5194/esd-10-1-2019 4 January 2019 Current CO2 emission rates are incompatible with the 2 °C target for global warming. Negative emission technologies are therefore an important basis for climate policy scenarios. We show that photoelectrochemical CO2 reduction might be a viable, high-efficiency alternative to biomass-based approaches, which reduce competition for arable land. To develop them, chemical reactions have to be optimized for CO2 removal, which deviates from energetic efficiency optimization in solar fuel applications. Read more
What climate signal is contained in decadal- to centennial-scale isotope variations from Antarctic ice cores? Climate of the Past DOI 10.5194/cp-14-2053-2018 20 December 2018 Proxy data on climate variations contain noise from many sources and, for reliable estimates, we need to determine those temporal scales at which the climate signal in the proxy record dominates the noise. We developed a method to derive timescale-dependent estimates of temperature proxy signal-to-noise ratios, which we apply and discuss in the context of Antarctic ice-core records but which in general are applicable to a large set of palaeoclimate records. Read more
Photochemical box modelling of volcanic SO2 oxidation: isotopic constraints Atmospheric Chemistry and Physics DOI 10.5194/acp-18-17909-2018 18 December 2018 Volcanic sulfur can have climatic impacts for the planet via sulfate aerosol formation, leading also to pollution events. We provide model constraints on tropospheric volcanic sulfate formation, with implications for its lifetime and impacts on regional air quality. Oxygen isotope investigations from our model suggest that in the poor tropospheric plumes of halogens, the O2/TMI sulfur oxidation pathway might significantly control sulfate production. The produced sulfate has no isotopic anomaly. Read more
Retreat of Thwaites Glacier, West Antarctica, over the next 100 years using various ice flow models, ice shelf melt scenarios and basal friction laws The Cryosphere DOI 10.5194/tc-12-3861-2018 11 December 2018 Thwaites Glacier, West Antarctica, has experienced rapid grounding line retreat and mass loss in the past decades. In this study, we simulate the evolution of Thwaites Glacier over the next century using different model configurations. Overall, we estimate a 5 mm contribution to global sea level rise from Thwaites Glacier in the next 30 years. However, a 300% uncertainty is found over the next 100 years, ranging from 14 to 42 mm, depending on the model setup. Read more
The impact of mineral dust on cloud formation during the Saharan dust event in April 2014 over Europe Atmospheric Chemistry and Physics DOI 10.5194/acp-18-17545-2018 11 December 2018 The impact of desert dust on cloud formation is investigated for a major Saharan dust event over Europe by interactive regional dust modeling. Dust particles are very efficient ice-nucleating particles promoting the formation of ice crystals in clouds. The simulations show that the observed extensive cirrus development was likely related to the above-average dust load. The interactive dust–cloud feedback in the model significantly improves the agreement with aircraft and satellite observations. Read more
ESM-SnowMIP: assessing snow models and quantifying snow-related climate feedbacks Geoscientific Model Development DOI 10.5194/gmd-11-5027-2018 10 December 2018 This paper provides an overview of a coordinated international experiment to determine the strengths and weaknesses in how climate models treat snow. The models will be assessed at point locations using high-quality reference measurements and globally using satellite-derived datasets. How well climate models simulate snow-related processes is important because changing snow cover is an important part of the global climate system and provides an important freshwater resource for human use. Read more
Hydro-climatic variability in the southwestern Indian Ocean between 6000 and 3000 years ago Climate of the Past DOI 10.5194/cp-14-1881-2018 7 December 2018 The 4.2 ka eventbetween 4.2 and 3.9 ka has been widely discussed in the Northern Hemsiphere but less reported in the Southern Hemisphere. Here, we use speleothem records from Rodrigues in the southwestern Indian Ocean spanning from 6000 to 3000 years ago to investigate the regional hydro-climatic variability. Our records show no evidence for an unusual climate anomaly between 4.2 and 3.9 ka. Instead, it shows a multi-centennial drought between 3.9 and 3.5 ka. Read more
Light absorption by marine cyanobacteria affects tropical climate mean state and variability Earth System Dynamics DOI 10.5194/esd-9-1283-2018 5 December 2018 We use an Earth system model to study the effects of light absorption by marine cyanobacteria on climate. We find that cyanobacteria have a considerable cooling effect on tropical SST with implications for ocean and atmosphere circulation patterns as well as for climate variability. The results indicate the importance of considering phytoplankton light absorption in climate models, and specifically highlight the role of cyanobacteria due to their regulative effect on tropical SST and climate. Read more
Seasonal to decadal variability in ice discharge from the Greenland Ice Sheet The Cryosphere DOI 10.5194/tc-12-3813-2018 3 December 2018 We derive the first continuous record of total ice discharged from all large Greenland outlet glaciers over the 2000–2016 period, resolving a distinct pattern of seasonal variability. We compare these results to glacier retreat and meltwater runoff and find that while runoff has a limited impact on ice discharge in summer, long-term changes in discharge are highly correlated to retreat. These results help to better understand Greenland outlet glacier sensitivity over a range of timescales. Read more