Publications Highlight articles

European Geosciences Union

www.egu.eu

Highlight articles

Some features of our web site require JavaScript to function properly. Please enable JavaScript in your browser.

2043 items found

10 20 50

First assessment of the earth heat inventory within CMIP5 historical simulations

The current radiative imbalance at the top of the atmosphere is increasing the heat stored in the oceans, atmosphere, continental subsurface and cryosphere, with consequences for societies and ecosystems (e.g. sea level rise). We performed the first assessment of the ability of global climate models to represent such heat storage in the climate subsystems. Models are able to reproduce the observed atmosphere heat content, with biases in the simulation of heat content in the rest of components.

Captive Aerosol Growth and Evolution (CAGE) chamber system to investigate particle growth due to secondary aerosol formation

The newly developed portable 1 m3 CAGE chamber systems were characterized using data acquired during a 2-month field study in 2016 in a forested area north of Houston, TX, USA. Concentrations of several oxidant and organic compounds measured in the chamber were found to closely agree with those calculated with a zero-dimensional model. By tracking the modes of injected monodisperse particles, a pattern change was observed for hourly averaged growth rates between late summer and early fall.

Assimilation of DAWN Doppler wind lidar data during the 2017 Convective Processes Experiment (CPEX): impact on precipitation and flow structure

The assimilation of airborne-based three-dimensional winds into a mesoscale weather forecast model resulted in better agreement with airborne radar-derived precipitation 3-D structure at later model time steps. More importantly, there was also a discernible impact on the resultant wind and moisture structure, in accord with independent analysis of the wind structure and external satellite observations.

Glacier detachments and rock-ice avalanches in the Petra Pervogo range, Tajikistan (1973–2019)

Natural Hazards and Earth System Sciences
DOI 10.5194/nhess-21-1409-2021
24 June 2021

A cluster of 13 large mass flow events including five detachments of entire valley glaciers was observed in the Petra Pervogo range, Tajikistan, in 1973–2019. The local clustering provides additional understanding of the influence of temperature, seismic activity, and geology. Most events occurred in summer of years with mean annual air temperatures higher than the past 46-year trend. The glaciers rest on weak bedrock and are rather short, making them sensitive to friction loss due to meltwater.

Regional variation in the effectiveness of methane-based and land-based climate mitigation options

We model greenhouse gas emission scenarios consistent with limiting global warming to either 1.5 or 2 °C above pre-industrial levels. We quantify the effectiveness of methane emission control and land-based mitigation options regionally. Our results highlight the importance of reducing methane emissions for realistic emission pathways that meet the global warming targets. For land-based mitigation, growing bioenergy crops on existing agricultural land is preferable to replacing forests.

Atmospheric extremes caused high oceanward sea surface slope triggering the biggest calving event in more than 50 years at the Amery Ice Shelf

The unexpected September 2019 calving event from the Amery Ice Shelf, the largest since 1963 and which occurred almost a decade earlier than expected, was triggered by atmospheric extremes. Explosive twin polar cyclones provided a deterministic role in this event by creating oceanward sea surface slope triggering the calving. The observed record-anomalous atmospheric conditions were promoted by blocking ridges and Antarctic-wide anomalous poleward transport of heat and moisture.

Heterogeneous interactions between SO2 and organic peroxides in submicron aerosol

Discrepancies between atmospheric modeling and field observations, especially in highly polluted cities, have highlighted the lack of understanding of sulfate formation mechanisms and kinetics. Here, we directly quantify the reactive uptake coefficient of SO2 onto organic peroxides and study the important governing factors. The SO2 uptake rate was observed to depend on RH, peroxide amount and reactivity, pH, and ionic strength, which provides a framework to better predict sulfate formation.

On the phenomenon of the blue sun

This study investigates the physical processes leading to the rare phenomenon of the sun appearing blue or green. The phenomenon is caused by anomalous scattering by, e.g., volcanic or forest fire aerosols. Unlike most other studies, our study includes a full treatment of the effect of Rayleigh scattering on the colour of the sun. We investigate different factors and revisit a historic example, i.e. the Canadian forest fires in 1950, that led to blue sun events in different European countries.

Effects of Earth system feedbacks on the potential mitigation of large-scale tropical forest restoration

Estimates of large-scale tree planting and forest restoration as a carbon sequestration tool typically miss a crucial aspect: the Earth system response to the increased land carbon sink from new vegetation. We assess the impact of tropical forest restoration using an Earth system model under a scenario that limits warming to 2 °C. Almost two-thirds of the carbon impact of forest restoration is offset by negative carbon cycle feedbacks, suggesting a more modest benefit than in previous studies.

Revision of the World Meteorological Organization Global Atmosphere Watch (WMO/GAW) CO2 calibration scale

We have recently revised the carbon dioxide calibration scale used by numerous laboratories that measure atmospheric CO2. The revision follows from an improved understanding of the manometric method used to determine the absolute amount of CO2 in an atmospheric air sample. The new scale is 0.18 μmol mol−1 (ppm) greater than the previous scale at 400 ppm CO2. While this difference is small in relative terms (0.045 %), it is significant in terms of atmospheric monitoring.

Observing the timescales of aerosol–cloud interactions in snapshot satellite images

Cloud responses to aerosol are time-sensitive, but this development is rarely observed. This study uses isolated aerosol perturbations from ships to measure this development and shows that macrophysical (width, cloud fraction, detectability) and microphysical (droplet number) properties of ship tracks vary strongly with time since emission, background cloud and meteorological state. This temporal development should be considered when constraining aerosol–cloud interactions with observations.

On the attribution of industrial-era glacier mass loss to anthropogenic climate change

The worldwide retreat of mountain glaciers and consequent loss of ice mass is one of the most obvious signs of a changing climate and has significant implications for the hydrology and natural hazards in mountain landscapes. Consistent with our understanding of the human role in temperature change, we demonstrate that the central estimate of the size of the human-caused mass loss is essentially 100 % of the observed loss. This assessment resolves some important inconsistencies in the literature.

Development of smart boulders to monitor mass movements via the Internet of Things: a pilot study in Nepal

We use long-range smart sensors connected to a network based on the Internet of Things to explore the possibility of detecting hazardous boulder movements in real time. Prior to the 2019 monsoon season we inserted the devices in 23 boulders spread over debris flow channels and a landslide in northeastern Nepal. The data obtained in this pilot study show the potential of this technology to be used in remote hazard-prone areas in future early warning systems.

Robust increase of Indian monsoon rainfall and its variability under future warming in CMIP6 models

All state-of-the-art global climate models that contributed to the latest Coupled Model Intercomparison Project (CMIP6) show a robust increase in Indian summer monsoon rainfall that is even stronger than in the previous intercomparison (CMIP5). Furthermore, they show an increase in the year-to-year variability of this seasonal rainfall that crucially influences the livelihood of more than 1 billion people in India.

Uncertainties in the Emissions Database for Global Atmospheric Research (EDGAR) emission inventory of greenhouse gases

We conducted an extensive analysis of the structural uncertainty of the Emissions Database for Global Atmospheric Research (EDGAR) emission inventory of greenhouse gases, which adds a much needed reliability dimension to the accuracy of the emission estimates. The study undertakes in-depth analyses of the implication of aggregating emissions from different sources and/or countries on the accuracy. Results are presented for all emissions sectors according to IPCC definitions.

Snapshots of mean ocean temperature over the last 700 000 years using noble gases in the EPICA Dome C ice core

Using the temperature-dependent solubility of noble gases in ocean water, we reconstruct global mean ocean temperature (MOT) over the last 700 kyr using noble gas ratios in air enclosed in polar ice cores. Our record shows that glacial MOT was about 3 °C cooler compared to the Holocene. Interglacials before 450 kyr ago were characterized by about 1.5 °C lower MOT than the Holocene. In addition, some interglacials show transient maxima in ocean temperature related to changes in ocean circulation.

Pervasive diffusion of climate signals recorded in ice-vein ionic impurities

Current theory predicts climate signals in the vein chemistry of ice cores to migrate, hampering their dating. I show that the Gibbs–Thomson effect, which has been overlooked, causes fast diffusion that prevents signals from surviving into deep ice. Hence the deep climatic peaks in Antarctic and Greenlandic ice must be due to impurities in the ice matrix (outside veins) and safe from migration. These findings reset our understanding of postdepositional changes of ice-core climate signals.

FES2014 global ocean tide atlas: design and performance

Since the mid-1990s, a series of FES (finite element solution) global ocean tidal atlases has been produced with the primary objective to provide altimetry missions with a tidal de-aliasing correction. We describe the underlying hydrodynamic/data assimilation design and accuracy assessments for the FES2014 release. The FES2014 atlas shows overall improved performance and has consequently been integrated in satellite altimetry and gravimetric data processing and adopted in ITRF standards.

A Dark Target research aerosol algorithm for MODIS observations over eastern China: increasing coverage while maintaining accuracy at high aerosol loading

Due to fast industrialization and development, China has been experiencing haze pollution episodes with both high frequencies and severity over the last 3 decades. This study improves the accuracy and data coverage of measured aerosol from satellites, which help quantify, characterize, and understand the impact of the haze phenomena over the entire East Asia region.

Introducing hydrometeor orientation into all-sky microwave and submillimeter assimilation

Oriented nonspherical ice particles induce polarization that is ignored when cloud-sensitive satellite observations are used in numerical weather prediction systems. We present a simple approach for approximating particle orientation, requiring minor adaption of software and no additional calculation burden. With this approach, the system realistically simulates the observed polarization patterns, increasing the physical consistency between instruments with different polarizations.