Abstract
The potential of deep learning for the investigation of medium scale traveling ionospheric disturbances (MSTIDs) has been exploited through the Sodankylä rapid-run ionosonde in this statistical study. The complementing observations of the Sodankylä ionosonde with those of the Sodankylä meteor radar reveals the diurnal and seasonal occurrence rate of high-latitude MSTIDs in the recent low solar activity period, 2018–2020. In our results, the daytime, nighttime and dusk MSTIDs are predominantly identified during winter, summer, and equinoctial months, respectively. The winter daytime higher (lower) occurrence rate is well correlated with the lower (higher) altitude of the height of the F2-layer peak (hmF2), and the low occurrence rate of the summer daytime is well correlated with the mesosphere-lower-thermosphere wind shear and higher gradient of temperature. Relatively high occurrence rate (>0.4) of summer nighttime MSTIDs has a general—but not one-to-one agreement—with post-noon to evening IU (eastward auroral current index) inferred ionospheric conductivity. Rather, we see a one-to-one relationship between the summer nighttime MSTIDs and zonal wind shear suggesting that the wind shear-induced electrodynamic processes could play significant roles for higher occurrence rate of MSTIDs. Furthermore, significant MSTIDs with ∼0.4 occurrence rate are so far revealed during spring and autumn transition periods. The enhanced nighttime MSTID amplitudes during the equinox are observed to be well correlated with IL index (westward auroral current indicator) suggesting that the particle precipitation during substorms could be the primary cause.
Globally, last year was the warmest for thousands of years, with a globally averaged temperature of at least 1.45°C greater than pre-industrial times. The year also saw an unprecedented string of extreme weather and climate events in many parts of the world, including heat waves, torrential rainfall, transitions from drought to floods, wildfires, and sandstorms.
A team of international scientists involving the Durham University Geography department has unveiled a new map of the geological provinces hidden beneath the Greenland Ice Sheet.
CLASH – Climate-responsive Land Allocation model with carbon Storage and Harvests
Tommi Ekholm, Nadine-Cyra Freistetter, Aapo Rautiainen, and Laura Thölix
Geosci. Model Dev., 17, 3041–3062, https://doi.org/10.5194/gmd-17-3041-2024, 2024
CLASH is a numerical model that portrays land allocation between different uses, land carbon stocks, and agricultural and forestry production globally. CLASH can help in examining the role of land use in mitigating climate change, providing food and biogenic raw materials for the economy, and conserving primary ecosystems. Our demonstration with CLASH confirms that reduction of animal-based food, shifting croplands and storing carbon in forests are effective ways to mitigate climate change.
Much of Earth's water is hidden hundreds of meters beneath our feet, among soil particles and deep within rock pores and fractures.
The High lAtitude sNowfall Detection and Estimation aLgorithm for ATMS (HANDEL-ATMS): a new algorithm for snowfall retrieval at high latitudes
Andrea Camplani, Daniele Casella, Paolo Sanò, and Giulia Panegrossi
Atmos. Meas. Tech., 17, 2195–2217, https://doi.org/10.5194/amt-17-2195-2024, 2024
The paper describes a new machine-learning-based snowfall retrieval algorithm for Advanced Technology Microwave Sounder observations developed to retrieve high-latitude snowfall events. The main novelty of the approach is the radiometric characterization of the background surface at the time of the overpass, which is ancillary to the retrieval process. The algorithm shows a unique capability to retrieve snowfall in the environmental conditions typical of high latitudes.
Next-generation radiance unfiltering process for the Clouds and the Earth's Radiant Energy System instrument
Lusheng Liang, Wenying Su, Sergio Sejas, Zachary Eitzen, and Norman G. Loeb
Atmos. Meas. Tech., 17, 2147–2163, https://doi.org/10.5194/amt-17-2147-2024, 2024
This paper describes an updated process to obtain unfiltered radiation from CERES satellite instruments by incorporating the most recent developments in radiative transfer modeling and ancillary input datasets (e.g., realistic representation of land surface radiation and climatology of surface temperatures and aerosols) during the past 20 years. The resulting global mean of instantaneous SW and LW fluxes is changed by less than 0.5 W m−2 with regional differences as large as 2.0 W m−2.
Development of a cascade impactor optimized for size-fractionated analysis of aerosol metal content by total reflection X-ray fluorescence spectroscopy (TXRF)
Claudio Crazzolara and Andreas Held
Atmos. Meas. Tech., 17, 2183–2194, https://doi.org/10.5194/amt-17-2183-2024, 2024
Our paper describes the development of a collection device that can be used to collect airborne dust particles classified according to their size. This collection device is optimized for a special analysis method based on X-ray fluorescence so that particles can be collected from the air and analyzed with high sensitivity. This enables the determination of the content of heavy metals in the airborne particle fraction, which are of health-relevant significance.
Improved rain event detection in commercial microwave link time series via combination with MSG SEVIRI data
Maximilian Graf, Andreas Wagner, Julius Polz, Llorenç Lliso, José Alberto Lahuerta, Harald Kunstmann, and Christian Chwala
Atmos. Meas. Tech., 17, 2165–2182, https://doi.org/10.5194/amt-17-2165-2024, 2024
Commercial microwave links (CMLs) can be used for rainfall retrieval. The detection of rainy periods in their attenuation time series is a crucial processing step. We investigate the usage of rainfall data from MSG SEVIRI for this task, compare this approach with existing methods, and introduce a novel combined approach. The results show certain advantages for SEVIRI-based methods, particularly for CMLs where existing methods perform poorly. Our novel combination yields the best performance.
A directional surface reflectance climatology determined from TROPOMI observations
Lieuwe G. Tilstra, Martin de Graaf, Victor J. H. Trees, Pavel Litvinov, Oleg Dubovik, and Piet Stammes
Atmos. Meas. Tech., 17, 2235–2256, https://doi.org/10.5194/amt-17-2235-2024, 2024
This paper introduces a new surface albedo climatology of directionally dependent Lambertian-equivalent reflectivity (DLER) observed by TROPOMI on the Sentinel-5 Precursor satellite. The database contains monthly fields of DLER for 21 wavelength bands at a relatively high spatial resolution of 0.125 by 0.125 degrees. The anisotropy of the surface reflection is handled by parameterisation of the viewing angle dependence.
Radiative closure tests of collocated hyperspectral microwave and infrared radiometers
Lei Liu, Natalia Bliankinshtein, Yi Huang, John R. Gyakum, Philip M. Gabriel, Shiqi Xu, and Mengistu Wolde
Atmos. Meas. Tech., 17, 2219–2233, https://doi.org/10.5194/amt-17-2219-2024, 2024
We conducted a radiance closure experiment using a unique combination of two hyperspectral radiometers, one operating in the microwave and the other in the infrared. By comparing the measurements of the two hyperspectrometers to synthetic radiance simulated from collocated atmospheric profiles, we affirmed the proper performance of the two instruments and quantified their radiometric uncertainty for atmospheric sounding applications.
Atmospheric propane (C3H8) column retrievals from ground-based FTIR observations at Xianghe, China
Minqiang Zhou, Pucai Wang, Bart Dils, Bavo Langerock, Geoff Toon, Christian Hermans, Weidong Nan, Qun Cheng, and Martine DeMaziere
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2024-67,2024
Preprint under review for AMT (discussion: open, 0 comments)
Solar absorption spectra near 2967 cm−1 recorded by a ground-based FTIR with a high spectral resolution of 0.0035 cm-1 are applied to retrieve C3H8 columns for the first time at Xianghe, China, within the NDACC-IRWG. The mean and standard deviation of the C3H8 columns are 1.80±0.81(1σ) × 10 molecules / cm2. Good correlations are found between C3H8 and other non-methane hydrocarbons, such as C2H6 (R=0.84) and C2H2 (R=0.79), as well as between C3H8 and CO (R=0.72).
Abstract
Crack interactions leading to shear localization were quantified using microstructural analysis for brittle faults and high-temperature ductile faults formed during experiments on quartz sandstone. In both faulting regimes, the nucleation of macroscopic faults results from the interactions of microfractures at two length scales in ensemble. Brittle faults nucleate when the longest mesoscale shear fractures and transgranular tensile cracks critically interact. In contrast, ductile faults nucleate when the longest mesoscale shear fractures and multi-grain scale intergranular shear cracks critically interact. For both faulting regimes, we conclude the interaction and coalescence of the longest mesoscale shear fractures is the fundamental process responsible for fault nucleation. Hence, mesoscale shear fractures, which accommodate the majority of axial strain prior to shear localization in both faulting regimes, also serve as the nucleus of macroscopic faults. Locally, the growth of the mesoscale shear fractures is promoted by the interaction and coalescence of the multi-grain scale cracks in both faulting regimes. We hypothesize that attainment of a critical microstructure for shear localization (i.e., local clustering of the longest microfractures) requires a characteristic amount of plastic axial strain, which depends on deformation conditions. In brittle faulting, distributed microfracturing is confined within limited regions of the rock volume, which expedites crack clustering and fault nucleation at low characteristic strains. In ductile faulting, distributed microfracturing occurs more uniformly throughout the rock volume, delaying shear localization to high characteristic strains. Accurate prediction of shear localization requires models that describe crack interactions of the largest flaws that account for crack clustering.
The drying up of the Aral Sea has made Central Asia 7% dustier in the last 30 years. Between 1984 and 2015, dust emissions from the growing desert almost doubled from 14 to 27 million tons. This is the result of a study by the Leibniz Institute for Tropospheric Research (TROPOS) and the Free University of Berlin.
As carbon dioxide accumulates in the atmosphere, the Earth will get hotter. But exactly how much warming will result from a certain increase in CO2 is under study. The relationship between CO2 and warming, known as climate sensitivity, determines what future we should expect as CO2 levels continue to climb.
Factors of influence on flood risk perceptions related to Hurricane Dorian: an assessment of heuristics, time dynamics, and accuracy of risk perceptions
Laurine A. de Wolf, Peter J. Robinson, W. J. Wouter Botzen, Toon Haer, Jantsje M. Mol, and Jeffrey Czajkowski
Nat. Hazards Earth Syst. Sci., 24, 1303–1318, https://doi.org/10.5194/nhess-24-1303-2024, 2024
An understanding of flood risk perceptions may aid in improving flood risk communication. We conducted a survey among 871 coastal residents in Florida who were threatened to be flooded by Hurricane Dorian. Part of the original sample was resurveyed after Dorian failed to make landfall to investigate changes in risk perception. We find a strong influence of previous flood experience and social norms on flood risk perceptions. Furthermore, flood risk perceptions declined after the near-miss event.
Each summer, a hypoxic dead zone forms in the Gulf of Mexico, making some marine habitats unlivable. The dead zone is caused by nutrients—primarily from agricultural fertilizers—flowing into the Gulf from the Mississippi River. Restoring wetlands at field margins has been proposed to intercept some of the runoff, as wetland plants and soils are capable of absorbing nutrients like a living sponge. But estimates of nutrient removal by restored wetlands have varied widely.
