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
On the alignment of velocity and magnetic fields within magnetosheath jets Annales Geophysicae DOI 10.5194/angeo-38-287-2020 12 March 2020 Jets of solar-wind plasma commonly hit the Earth’s magnetosphere. Using data from the four Magnetospheric Multiscale (MMS) spacecraft, we show statistically that within jets the magnetic field is more aligned with the plasma flow direction than outside of these jets. Our study confirms prior simulation results, but it also shows that the average effect is moderate. The jets’ magnetic field is important with respect to their impact on space weather. Read more
Earth system data cubes unravel global multivariate dynamics Earth System Dynamics DOI 10.5194/esd-11-201-2020 10 March 2020 The ever-growing availability of data streams on different subsystems of the Earth brings unprecedented scientific opportunities. However, researching a data-rich world brings novel challenges. We present the concept of Earth system data cubes to study the complex dynamics of multiple climate and ecosystem variables across space and time. Using a series of example studies, we highlight the potential of effectively considering the full multivariate nature of processes in the Earth system. Read more
Modelling global tropical cyclone wind footprints Natural Hazards and Earth System Sciences DOI 10.5194/nhess-20-567-2020 10 March 2020 Assessing tropical cyclone (TC) wind risk is challenging due to a lack of historical TC wind data. This paper presents a novel approach to simulating landfalling TC winds anywhere on Earth. It captures local features such as high winds over coastal hills and lulls over rough terrain. A dataset of over 700 global historical wind footprints has been generated to provide new views of historical events. This dataset can be used to advance our understanding of overland TC wind risk. Read more
The substructure of extremely hot summers in the Northern Hemisphere Weather and Climate Dynamics DOI 10.5194/wcd-1-45-2020 10 March 2020 In this study we quantify how much the coldest, middle and hottest third of all days during extremely hot summers contribute to their respective seasonal mean anomaly. This extreme-summer substructure varies substantially across the Northern Hemisphere and is directly related to the local physical drivers of extreme summers. Furthermore, comparing re-analysis (i.e. measurement-based) and climate model extreme-summer substructures reveals a remarkable level of agreement. Read more
Measuring compound flood potential from river discharge and storm surge extremes at the global scale Natural Hazards and Earth System Sciences DOI 10.5194/nhess-20-489-2020 3 March 2020 When a high river discharge coincides with a high storm surge level, this can exarcebate flood level, depth, and duration, resulting in a so-called compound flood event. These events are not currently included in global flood models. In this research, we analyse the timing and correlation between modelled discharge and storm surge level time series in deltas and estuaries. Our results provide a first indication of regions along the global coastline with a high compound flooding potential. Read more
TRAPPIST-1 Habitable Atmosphere Intercomparison (THAI):motivations and protocol version 1.0 Geoscientific Model Development DOI 10.5194/gmd-13-707-2020 3 March 2020 Atmospheric characterization of rocky exoplanets orbiting within the habitable zone of nearby M dwarf stars is around the corner with the James Webb Space Telescope (JWST), expected to be launch in 2021. Global climate models (GCMs) are powerful tools to model exoplanet atmospheres and to predict their habitability. However, intrinsic differences between the models can lead to various predictions. This paper presents an experiment protocol to evaluate these differences. Read more