Deconvolution of boundary layer depth and aerosol constraints on cloud water path in subtropical stratocumulus decks Atmospheric Chemistry and Physics DOI 10.5194/acp-20-3609-2020 3 April 2020 Cloud water content and the number of droplets inside clouds covary with boundary layer depth. This covariation may amplify the change in water content due to a change in droplet number inferred from long-term observations. Taking this into account shows that the change in water content for increased droplet number in observations and high-resolution simulations agrees in shallow boundary layers. Meanwhile, deep boundary layers are under-sampled in process-scale simulations and observations. Read more
Back to the future II: tidal evolution of four supercontinent scenarios Earth System Dynamics DOI 10.5194/esd-11-291-2020 31 March 2020 We have confirmed that there is a supertidal cycle associated with the supercontinent cycle. As continents drift due to plate tectonics, oceans also change size, controlling the strength of the tides and causing periods of supertides. In this work, we used a coupled tectonic–tidal model of Earth’s future to test four different scenarios that undergo different styles of ocean closure and periods of supertides. This has implications for the Earth system and for other planets with liquid oceans. Read more
Scaling carbon fluxes from eddy covariance sites to globe: synthesis andevaluation of the FLUXCOM approach Biogeosciences DOI 10.5194/bg-17-1343-2020 26 March 2020 We test the approach of producing global gridded carbon fluxes based on combining machine learning with local measurements, remote sensing and climate data. We show that we can reproduce seasonal variations in carbon assimilated by plants via photosynthesis and in ecosystem net carbon balance. The ecosystem’s mean carbon balance and carbon flux trends require cautious interpretation. The analysis paves the way for future improvements of the data-driven assessment of carbon fluxes. Read more
“This bookmark gauges the depths of the human”: how poetry can help to personalise climate change Geoscience Communication DOI 10.5194/gc-3-35-2020 24 March 2020 To many non-specialists, the science behind climate change can appear confusing and alienating, yet in order for global mitigation efforts to be successful it is not just scientists who need to take action, but rather society as a whole. This study shows how poets and poetry offer a method of communicating the science of climate change to the wider society using language that they not only better understand, but which also has the potential to stimulate accountability and inspire action. Read more
Methanethiol, dimethyl sulfide and acetone over biologically productive waters in the southwest Pacific Ocean Atmospheric Chemistry and Physics DOI 10.5194/acp-20-3061-2020 24 March 2020 Methanethiol (MeSH) is a reduced sulfur gas originating from phytoplankton, with a global ocean source of ~ 17 % of dimethyl sulfide (DMS). It has been little studied and is rarely observed over the ocean. In this work, MeSH was measured at much higher levels than previously observed (3–36 % of parallel DMS mixing ratios). MeSH could be a significant source of atmospheric sulfur over productive regions of the ocean, but its distribution, and its atmospheric impact, requires more investigation. Read more
Changing suspended sediment in United States rivers and streams: linking sediment trends to changes in land use/cover, hydrology and climate Hydrology and Earth System Sciences DOI 10.5194/hess-24-991-2020 17 March 2020 Between 1992 and 2012, concentrations of suspended sediment decreased at about 60 % of 137 US stream sites, with increases at only 17 % of sites. Sediment trends were primarily attributed to changes in land management, but streamflow changes also contributed to these trends at > 50 % of sites. At many sites, decreases in sediment occurred despite small-to-moderate increases in the amount of anthropogenic land use, suggesting sediment reduction activities across the US may be seeing some success. Read more
Assimilation of surface observations in a transient marine ice sheet model using an ensemble Kalman filter The Cryosphere DOI 10.5194/tc-14-811-2020 17 March 2020 Marine-based sectors of the Antarctic Ice Sheet are increasingly contributing to sea-level rise. The basal conditions exert an important control on the ice dynamics. For obvious reasons of inaccessibility, they are an important source of uncertainties in numerical ice flow models used for sea-level projections. Here we assess the performance of an ensemble Kalman filter for the assimilation of transient observations of surface elevation and velocities in a marine ice sheet model. Read more
Time-lapse monitoring of root water uptake using electrical resistivitytomography and mise-à-la-masse: a vineyard infiltration experiment SOIL DOI 10.5194/soil-6-95-2020 17 March 2020 The use of non-invasive geophysical imaging of root system processes is of increasing interest to study soil–plant interactions. The experiment focused on the behaviour of grapevine plants during a controlled infiltration experiment. The combination of the mise-à-la-masse (MALM) method, a variation of the classical electrical tomography map (ERT), for which the current is transmitted directly into the stem, holds the promise of being able to image root distribution. Read more
Ultra-clean and smoky marine boundary layers frequently occur in the same season over the southeast Atlantic Atmospheric Chemistry and Physics DOI 10.5194/acp-20-2341-2020 12 March 2020 Using observations from instruments deployed to a small island in the southeast Atlantic, we study days when the atmospheric concentrations of particles near the surface are exceptionally low. Interestingly, these ultra-clean boundary layers occur in the same months as the smokiest boundary layers associated with biomass burning in Africa. We find evidence that enhancements in drizzle scavenging, on top of a seasonal maximum in cloudiness and precipitation, likely drive these conditions. Read more
Temperature controls production but hydrology regulates export of dissolved organic carbon at the catchment scale Hydrology and Earth System Sciences DOI 10.5194/hess-24-945-2020 12 March 2020 Lateral carbon fluxes from terrestrial to aquatic systems remain central uncertainties in determining ecosystem carbon balance. This work explores how temperature and hydrology control production and export of dissolved organic carbon (DOC) at the catchment scale. Results illustrate the asynchrony of DOC production, controlled by temperature, and export, governed by flow paths; concentration–discharge relationships are determined by the relative contribution of shallow versus groundwater flow. Read more
