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The nano-scanning electrical mobility spectrometer (nSEMS) and its application to size distribution measurements of 1.5–25 nm particles

We present the design, modeling, and experimental characterization of the nano-scanning electrical mobility spectrometer (nSEMS), a recently developed instrument that probes particle physical properties in the 1.5–25 nm range. The nSEMS has proven to be extremely powerful in examining atmospheric nucleation and the subsequent growth of nanoparticles in the CERN CLOUD experiment, which provides a valuable asset to study atmospheric nanoparticles and to evaluate their impact on climate.

Physical characteristics of frozen hydrometeors inferred with parameter estimation

Satellite observations sensitive to cloud and precipitation help improve the quality of weather forecasts. However, they are sensitive to things that models do not forecast, such as the shapes and sizes of snow and ice particles. These details can be estimated from the observations themselves and then incorporated in the satellite simulators used in weather forecasting. This approach, known as parameter estimation, will be increasingly useful to build models of poorly known physical processes.

Influence of the representation of convection on the mid-Holocene West African Monsoon

This paper investigates the impact of explicitly resolving convection on the mid-Holocene West African Monsoon rain belt by employing the ICON climate model in high resolution. While the spatial distribution and intensity of the precipitation are improved by this technique, the monsoon extents further north and the mean summer rainfall is higher in the simulation with parameterized convection.

Iodide CIMS and m∕z 62: the detection of HNO3 as NO3− in the presence of PAN, peroxyacetic acid and ozone

We demonstrate in laboratory experiments that the formation of IOx anions (formed in reactions of I− with O3) or acetate anions (formed e.g. by the reaction of I− with peracetic acid) results in unexpected sensitivity of an iodide chemical ionisation mass spectrometer (I-CIMS) to HNO3 at a mass-to-charge ratio of 62. This helps explain observations of apparent high daytime levels of N2O5. Airborne measurements using I-CIMS confirm these conclusions.

Recent degradation of interior Alaska permafrost mapped with ground surveys, geophysics, deep drilling, and repeat airborne lidar

The Cryosphere
DOI 10.5194/tc-15-3555-2021
10 September 2021

Permafrost is actively degrading across high latitudes due to climate warming. We combined thousands of end-of-summer active layer measurements, permafrost temperatures, geophysical surveys, deep borehole drilling, and repeat airborne lidar to quantify permafrost warming and thawing at sites across central Alaska. We calculate the mass of permafrost soil carbon potentially exposed to thaw over the past 7 years (0.44 Pg) is similar to the yearly carbon dioxide emissions of Australia.

Spatial and temporal subsidence characteristics in Wuhan (China), during 2015–2019, inferred from Sentinel-1 synthetic aperture radar (SAR) interferometry

Natural Hazards and Earth System Sciences
DOI 10.5194/nhess-21-2285-2021
8 September 2021

We mapped the subsidence of Wuhan using Sentinel-1 synthetic aperture radar (SAR) images acquired during 2015–2019. Overall subsidence coincides with the distribution of engineered geological regions with soft soils, while the subsidence centers shifted with urban construction activities. Correlation between karst subsidence and concentrated rainfall was identified in Qingling–Jiangdi. Results indicate that interferometric SAR can be employed to routinely monitor and identify geohazards.

Better representation of dust can improve climate models with too weak an African monsoon

Earth system models have persistent biases that impinge on our ability to make robust future regional predictions of precipitation. For the last 15 years, there has been little improvement in these biases. This work presents an accurate representation of dust absorption based upon observed dust mineralogical composition and size distribution. The striking result is that this more accurate representation improves tropical precipitations for climate models with too weak an African monsoon.

Characterization of dark current signal measurements of the ACCDs used on board the Aeolus satellite

This paper reports on dark current signal anomalies of the detectors used on board the ESA’s Earth Explorer satellite Aeolus during the first 1.5 years in orbit. After introducing sophisticated algorithms to classify dark current anomalies according to their characteristics, the impact of the different kinds of anomalies on wind measurements is discussed. In addition, mitigation approaches for the wind retrieval are presented and potential root causes are discussed.

Drought effects on leaf fall, leaf flushing and stem growth in the Amazon forest: reconciling remote sensing data and field observations

Satellite images show that the Amazon forest has greened up during past droughts. Measurements of tree stem growth and leaf litterfall upscaled using machine-learning algorithms show that leaf flushing at the onset of a drought results in canopy rejuvenation and green-up during drought while simultaneously trees excessively shed older leaves and tree stem growth declines. Canopy green-up during drought therefore does not necessarily point to enhanced tree growth and improved forest health.

Steepening of magnetosonic waves in the inner coma of comet 67P/Churyumov–Gerasimenko

Plasma waves are an integral part of cometary physics, as they facilitate the transfer of energy and momentum. From intermediate to strong activity, nonlinear asymmetric plasma and magnetic field enhancements dominate the inner coma of 67P/CG. We present a statistical survey of these structures from December 2014 to June 2016, facilitated by Rosetta’s unprecedented long mission duration. Using a 1D MHD model, we show they can be described as a combination of nonlinear and dissipative effects.

Controls on the rates and products of particle attrition by bed-load collisions

The authors of this paper conducted experiments to investigate the mechanics of sediment attrition due to collisions with the channel bed during downstream transport. During this process, the grains become rounder and smaller, changing the overall distribution of sediment in the river. In this work the authors examine how material properties play a role in the breakdown of sediment due to energetic collisions and the fine particles that are produced when chipped off of larger grains.

fv3gfs-wrapper: a Python wrapper of the FV3GFS atmospheric model

FV3GFS is a weather and climate model written in Fortran. It uses Fortran so that it can run fast, but this makes it hard to add features if you do not (or even if you do) know Fortran. We have written a Python interface to FV3GFS that lets you import the Fortran model as a Python package. We show examples of how this is used to write “model” scripts, which reproduce or build on what the Fortran model can do. You could do this same wrapping for any compiled model, not just FV3GFS.

Invited perspectives: The ECMWF strategy 2021–2030 challenges in the area of natural hazards

Natural Hazards and Earth System Sciences
DOI 10.5194/nhess-21-2163-2021
23 August 2021

The European Centre for Medium-Range Weather Forecasts mission is to deliver high-quality global medium‐range (3–15 d ahead of time) weather forecasts and monitoring of the Earth system. We have published a new strategy, and in this paper we discuss what this means for forecasting and monitoring natural hazards.

Nonstationary weather and water extremes: a review of methods for their detection, attribution, and management

Weather and water extremes have devastating effects each year. One of the principal challenges for society is understanding how extremes are likely to evolve under the influence of changes in climate, land cover, and other human impacts. This paper provides a review of the methods and challenges associated with the detection, attribution, management, and projection of nonstationary weather and water extremes.

Thaw-driven mass wasting couples slopes with downstream systems, and effects propagate through Arctic drainage networks

Climate-driven landslides are transforming glacially conditioned permafrost terrain, coupling slopes with aquatic systems, and triggering a cascade of downstream effects. Nonlinear intensification of thawing slopes is primarily affecting headwater systems where slope sediment yields overwhelm stream transport capacity. The propagation of effects across watershed scales indicates that western Arctic Canada will be an interconnected hotspot of thaw-driven change through the coming millennia.

Additional carbon inputs to reach a 4 per 1000 objective in Europe: feasibility and projected impacts of climate change based on Century simulations of long-term arable experiments

Increasing soil organic carbon (SOC) stocks is beneficial for climate change mitigation and food security. One way to enhance SOC stocks is to increase carbon input to the soil. We estimate the amount of carbon input required to reach a 4 % annual increase in SOC stocks in 14 long-term agricultural experiments around Europe. We found that annual carbon input should increase by 43 % under current temperature conditions, by 54 % for a 1 °C warming scenario and by 120 % for a 5 °C warming scenario.

Tropical deoxygenation sites revisited to investigate oxygen and nutrient trends

Six tropical areas in the Pacific, Atlantic and Indian oceans were investigated for trends for the years since 1950 for temperature, salinity, oxygen and nutrients at 50 to 300 m and 300 to 700 m depth. Generally, temperature increases, oxygen decreases and nutrients often increase. Overlain variability on the trends seem to be related to climate modes. Different trends indicate that oxygen and nutrient trends cannot by completely explained by local warming.

Disparities in particulate matter (PM10) origins and oxidative potential at a city scale (Grenoble, France) – Part 2.

With an enhanced source apportionment obtained in a companion paper, this paper acquires more understanding of the spatiotemporal associations of the sources of PM to oxidative potential (OP), an emerging health-based metric. Multilayer perceptron neural network analysis was used to apportion OP from PM sources. Results showed that such a methodology is as robust as the linear classical inversion and permits an improvement in the OP prediction when local features or non-linear effects occur.

Continental-scale controls on soil organic carbon across sub-Saharan Africa

SOIL
DOI 10.5194/soil-7-305-2021
9 August 2021

We investigated various soil and climate properties that influence soil organic carbon (SOC) concentrations in sub-Saharan Africa. Our findings indicate that climate and geochemistry are equally important for explaining SOC variations. The key SOC-controlling factors are broadly similar to those for temperate regions, despite differences in soil development history between the two regions.

Investigations on the anthropogenic reversal of the natural ozone gradient between northern and southern midlatitudes

The few ozone measurements made before the 1980s indicate that industrial development increased ozone concentrations by a factor of ~ 2 at northern midlatitudes, which are now larger than at southern midlatitudes. This difference was much smaller, and likely reversed, in the pre-industrial atmosphere. Earth system models find similar increases, but not higher pre-industrial ozone in the south. This disagreement may indicate that modeled natural ozone sources and/or deposition loss are inadequate.