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
Cold-to-warm flow regime transition in snow avalanches The Cryosphere DOI 10.5194/tc-12-3759-2018 30 November 2018 Snow avalanches show complicated flow behaviour, characterized by several flow regimes which coexist in one avalanche. In this work, we analyse flow regime transitions where a powder snow avalanche transforms into a plug flow avalanche by incorporating warm snow due to entrainment. Prediction of such a transition is very important for hazard mitigation, as the efficiency of protection dams are strongly dependent on the flow regime, and our results should be incorporated into avalanche models. Read more
Solar wind and kinetic heliophysics Annales Geophysicae DOI 10.5194/angeo-36-1607-2018 30 November 2018 This paper originated from the lecture I gave as the Hannes Alfvén medalist at the EGU General Assembly in Vienna in spring 2018. The paper reviews various aspects of modern solar wind physics and elucidates the role Alfvén waves play in solar wind acceleration and turbulence, which prevail in the low corona and inner heliosphere. Our understanding of the solar wind has recently made considerable progress based on remote sensing, in situ measurements, kinetic simulation and fluid modeling. Read more
What can seabirds tell us about the tide? Ocean Science DOI 10.5194/os-14-1483-2018 29 November 2018 This paper describes a feasibility study carried out to determine if information gathered for one discipline could berepurposedto provide insight in another. Data gathered during a study of bird distribution were used to investigate whether these same data could be used to measure tidal current velocities and direction. The paper concludes that there is potential to use GPS-tagged birds asdrifters of opportunityand that interdisciplinary sharing of data can provide additional insight. Read more
Field survey of Typhoon Hato (2017) and a comparison with storm surge modeling in Macau Natural Hazards and Earth System Sciences DOI 10.5194/nhess-18-3167-2018 29 November 2018 Typhoon Hato was one of the most damaging natural disaster events in the western Pacific region in 2017. It caused the the worst flooding in Macau since its instrumental records began in 1925. We present a high-resolution survey map recording inundation depths and distances at 278 sites in Macau. We provide a series of inundation maps under different tidal and sea levels. The maps that highlight adaptive strategies are essential in order to keep up with the pace of rising sea level. Read more
Carbon burial in deep-sea sediment and implications for oceanic inventories of carbon and alkalinity over the last glacial cycle Climate of the Past DOI 10.5194/cp-14-1819-2018 28 November 2018 A data-based reconstruction of carbon-bearing deep-sea sediment shows significant changes in the global burial rate over the last glacial cycle. We calculate the impact of these deep-sea changes, as well as hypothetical changes in continental shelf burial and volcanic outgassing. Our results imply that these geological fluxes had a significant impact on ocean chemistry and the global carbon isotopic ratio, and that the natural carbon cycle was not in steady state during the Holocene. Read more
Connecting the Greenland ice-core and U/Th timescales via cosmogenic radionuclides: testing the synchroneity of Dansgaard–Oeschger events Climate of the Past DOI 10.5194/cp-14-1755-2018 20 November 2018 The last glacial period was characterized by a number of rapid climate changes seen, for example, as abrupt warmings in Greenland and changes in monsoon rainfall intensity. However, due to chronological uncertainties it is challenging to know how tightly coupled these changes were. Here we exploit cosmogenic signals caused by changes in the Sun and Earth magnetic fields to link different climate archives and improve our understanding of the dynamics of abrupt climate change. Read more
Mesospheric bores at southern midlatitudes observed by ISS-IMAP/VISI: a first report of an undulating wave front Atmospheric Chemistry and Physics DOI 10.5194/acp-18-16399-2018 19 November 2018 Spatial structures of wave disturbances in the upper atmosphere were investigated with space-borne imaging from the International Space Station. The wave disturbance occurred around an altitude of 100 km, and is called a mesospheric bore. The large-scale structure of mesospheric bores has not been fully captured by previous ground-based imagers, but the space-borne imaging captured a bore with a wide field of view, and showed that bores can have a large undulating wave front as long as 2000 km. ISS-IMAP/VISI: a first report of an undulating wave front">Read more
Distribution and cycling of terrigenous dissolved organic carbon in peatland-draining rivers and coastal waters of Sarawak, Borneo Biogeosciences DOI 10.5194/bg-15-6847-2018 16 November 2018 The carbon cycle is a key control for the Earth’s climate. Every year rivers deliver a lot of organic carbon to coastal seas, but we do not know what happens to this carbon, particularly in the tropics. We show that rivers in Borneo deliver carbon from peat swamps to the sea with at most minimal biological or chemical alteration in estuaries, but sunlight can rapidly oxidise this carbon to CO2. This means that south-east Asian seas are likely hotspots of terrestrial carbon decomposition. Read more
