Abstract
Understanding how aerosols affect cloud cover is critical for reducing the large uncertainty of the aerosol-cloud interaction (ACI). The 2014 Holuhraun effusive eruption in Iceland resulted in a significant increase in cloud drop number concentration (N
d
) relative to the climatological N
d
observed during periods of relatively infrequent volcanic activity. Previous studies show a significant “Twomey” effect during this eruption; however, aerosol-induced changes in cloud fraction (Cf) appeared negligible. This leads to the question of why changes in aerosols do not cause Cf changes. To address this question, prediction models were derived to predict Cf based on N
d
and meteorological parameters. These validated models allow us to investigate aerosol perturbations on Cf in various N
d
scenarios by controlled meteorological conditions. Here our analysis unveiled that the increase in N
d
was primarily observed under polluted conditions where N
d
surpassing the threshold of 60 cm−3. After this point, cloud cover stops increasing even as N
d
increases. On the contrary, the cloud cover did increase by 9.0% under conditions of clean backgrounds (N
d
< 60 cm−3). Accordingly, the aerosol-driven cloud adjustment is hidden behind the seemingly insignificant cloud cover effect in areas with large background N
d
. These findings provide insights into the importance of considering background N
d
and the saturation status of cloud covers in ACI studies.
Abstract
Researchers have recently focused on the interplay of the urban heat island (UHI) effect and heat waves (HWs). However, the synergies of these two phenomena remains inconclusive at present. To address this gap, this study investigated UHIs and HWs synergies during the last 30 years in the Tokyo metropolitan area, through a unique and novel approach named Land-Surface-Physics-Based Downscaling (LSP-DS). LSP-DS integrates the widely used Noah-Multiparameterization (Noah-MP) land-surface model coupled with urban canopy-process physics, aiming to conduct high-resolution, long-term urban-specific simulations with much less computational resources. Our comprehensive analysis combining observation data and numerous LSP-DS simulations confirms exacerbated UHIs during HWs. Specifically, HWs amplify the temperature differences between urban and rural environments, which is quantified by UHI intensity (UHII). During HWs, UHII increased more at night in inland areas and more during daytime in coastal areas. HWs present especially a heightened threat to coastal regions where daytime UHII increased by approximately 1°C during HWs. The Bowen ratio can explain the increase in the daytime UHII, and the daytime accumulated storage heat increase during HWs can explain the increase in nighttime UHII. Based on future projections of the increasing frequency of high temperatures, our findings highlight the impending heat-related health challenges faced by urban residents.
Toward on-demand measurements of greenhouse gas emissions using an uncrewed aircraft AirCore system
Zihan Zhu, Javier González-Rocha, Yifan Ding, Isis Frausto-Vicencio, Sajjan Heerah, Akula Venkatram, Manvendra Dubey, Don Collins, and Francesca M. Hopkins
Atmos. Meas. Tech., 17, 3883–3895, https://doi.org/10.5194/amt-17-3883-2024, 2024
Increases in agriculture, oil and gas, and waste management activities have contributed to the increase in atmospheric methane levels and resultant climate warming. In this paper, we explore the use of small uncrewed aircraft systems (sUASs) and AirCore technology to detect and quantify methane emissions. Results from field experiments demonstrate that sUASs and AirCore technology can be effective for detecting and quantifying methane emissions in near real time.
Fast retrieval of XCO2 over east Asia based on Orbiting Carbon Observatory-2 (OCO-2) spectral measurements
Fengxin Xie, Tao Ren, Changying Zhao, Yuan Wen, Yilei Gu, Minqiang Zhou, Pucai Wang, Kei Shiomi, and Isamu Morino
Atmos. Meas. Tech., 17, 3949–3967, https://doi.org/10.5194/amt-17-3949-2024, 2024
This study demonstrates a new machine learning approach to efficiently and accurately estimate atmospheric carbon dioxide levels from satellite data. Rather than using traditional complex physics-based retrieval methods, neural network models are trained on simulated data to rapidly predict CO2 concentrations directly from satellite spectral measurements.
Transferability of machine-learning-based global calibration models for NO2 and NO low-cost sensors
Ayah Abu-Hani, Jia Chen, Vigneshkumar Balamurugan, Adrian Wenzel, and Alessandro Bigi
Atmos. Meas. Tech., 17, 3917–3931, https://doi.org/10.5194/amt-17-3917-2024, 2024
This study examined the transferability of machine learning calibration models among low-cost sensor units targeting NO2 and NO. The global models were evaluated under similar and different emission conditions. To counter cross-sensitivity, the study proposed integrating O3 measurements from nearby reference stations, in Switzerland. The models show substantial improvement when O3 measurements are incorporated, which is more pronounced when in regions with elevated O3 concentrations.
Sensitivity of thermodynamic profiles retrieved from ground-based microwave and infrared observations to additional input data from active remote sensing instruments and numerical weather prediction models
Laura Bianco, Bianca Adler, Ludovic Bariteau, Irina V. Djalalova, Timothy Myers, Sergio Pezoa, David D. Turner, and James M. Wilczak
Atmos. Meas. Tech., 17, 3933–3948, https://doi.org/10.5194/amt-17-3933-2024, 2024
The Tropospheric Remotely Observed Profiling via Optimal Estimation physical retrieval is used to retrieve temperature and humidity profiles from various combinations of passive and active remote sensing instruments, surface platforms, and numerical weather prediction models. The retrieved profiles are assessed against collocated radiosonde in non-cloudy conditions to assess the sensitivity of the retrievals to different input combinations. Case studies with cloudy conditions are also inspected.
A 2-year intercomparison of three methods for measuring black carbon concentration at a high-altitude research station in Europe
Sarah Tinorua, Cyrielle Denjean, Pierre Nabat, Véronique Pont, Mathilde Arnaud, Thierry Bourrianne, Maria Dias Alves, and Eric Gardrat
Atmos. Meas. Tech., 17, 3897–3915, https://doi.org/10.5194/amt-17-3897-2024, 2024
The three most widely used techniques for measuring black carbon (BC) have been deployed continuously for 2 years at a French high-altitude research station. Despite a similar temporal variation in the BC load, we found significant biases by up to a factor of 8 between the three instruments. This study raises questions about the relevance of using these instruments for specific background sites, as well as the processing of their data, which can vary according to the atmospheric conditions.
Automatic adjoint-based inversion schemes for geodynamics: reconstructing the evolution of Earth's mantle in space and time
Sia Ghelichkhan, Angus Gibson, D. Rhodri Davies, Stephan C. Kramer, and David A. Ham
Geosci. Model Dev., 17, 5057–5086, https://doi.org/10.5194/gmd-17-5057-2024, 2024
We introduce the Geoscientific ADjoint Optimisation PlaTform (G-ADOPT), designed for inverse modelling of Earth system processes, with an initial focus on mantle dynamics. G-ADOPT is built upon Firedrake, Dolfin-Adjoint and the Rapid Optimisation Library, which work together to optimise models using an adjoint method, aligning them with seismic and geologic datasets. We demonstrate G-ADOPT's ability to reconstruct mantle evolution and thus be a powerful tool in geosciences.
Validating a microphysical prognostic stratospheric aerosol implementation in E3SMv2 using observations after the Mount Pinatubo eruption
Hunter York Brown, Benjamin Wagman, Diana Bull, Kara Peterson, Benjamin Hillman, Xiaohong Liu, Ziming Ke, and Lin Lin
Geosci. Model Dev., 17, 5087–5121, https://doi.org/10.5194/gmd-17-5087-2024, 2024
Explosive volcanic eruptions lead to long-lived, microscopic particles in the upper atmosphere which act to cool the Earth's surface by reflecting the Sun's light back to space. We include and test this process in a global climate model, E3SM. E3SM is tested against satellite and balloon observations of the 1991 eruption of Mt. Pinatubo, showing that with these particles in the model we reasonably recreate Pinatubo and its global effects. We also explore how particle size leads to these effects.
Risk reduction through managed retreat? Investigating enabling conditions and assessing resettlement effects on community resilience in Metro Manila
Hannes Lauer, Carmeli Marie C. Chaves, Evelyn Lorenzo, Sonia Islam, and Jörn Birkmann
Nat. Hazards Earth Syst. Sci., 24, 2243–2261, https://doi.org/10.5194/nhess-24-2243-2024, 2024
In many urban areas, people face high exposure to hazards. Resettling them to safer locations becomes a major strategy, not least because of climate change. This paper dives into the success factors of government-led resettlement in Manila and finds surprising results which challenge the usual narrative and fuel the conversation on resettlement as an adaptation strategy. Contrary to expectations, the location – whether urban or rural – of the new home is less important than safety from floods.
Abstract
Dissolved organic matter (DOM) is a key component of the global carbon cycle, with rivers delivering significant amounts of DOM to oceans. Urbanization and agricultural land-use alter the age and chemical composition of riverine DOM, which likely impact the downstream bioavailability of riverine DOM. Here, we use bioreactor incubations of a marine bacterium (Pseudoalteromonas sp. 3D05) to investigate DOM bioavailability from two distinct rivers: the Suwannee River (natural, non-urbanized), and the Upper Mississippi River Basin (anthropogenically influenced). We measured rates of microbial CO2 production and radiocarbon ages (as Δ14C) to assess DOM remineralization. We observed nearly identical cell densities and degradation patterns for both riverine DOM incubations. Respired DOM Δ14C values were also similar and decreased over time indicative of preferential utilization of recently synthesized “modern” substrates. These findings reveal unexpected similarities in riverine DOM bioavailability, indicating similar short term biological reactivity despite large DOM compositional differences.
Abstract
Geothermal heat plays a vital role in Antarctic ice sheet stability. The continental geothermal heat flow distribution depends on lithospheric composition and ongoing tectonism. Heat-producing elements are unevenly enriched in the crust over deep time by various geological processes. The contribution of crustal heat production to geothermal heat flow is widely recognized; however, in Antarctica, crustal geology is largely hidden, and its complexity has frequently been excluded in thermal studies due to limited observations and oversimplified assumptions. Li and Aitken (2024), https://doi.org/10.1029/2023GL106201 take a significant step forward, focusing on Antarctic crustal radiogenic heat. Utilizing gravity inversion and rock composition data, they show that the crustal heterogeneity introduces considerable variability to heat flow. However, modeling crustal heat production proves challenging because it lacks distinct associations with geophysical observables and has a narrow spatial association. Robust quantification of geothermal heat production and heat flow must incorporate explicit aspects of geology.
Abstract
The cold surges have frequently attacked North America (NA) in recent decades, which has been tied to the diminished sea-ice over the Bering Sea. However, we find that the contribution of sea-ice loss to NA winter coldness is state-dependent on the Pacific Decadal Oscillation (PDO) phase. Using observations and CAM6 model simulations, we find that the phase regulates the atmospheric response to Bering ice loss. During the negative PDO phase (PDO−), there is an apparent eastward-propagating wave train, accompanied by a strengthened Alaskan ridge and NA cold high, resulting in a robust cold over Central NA. Meanwhile, enhanced upward-propagating planetary waves weaken the stratospheric polar vortex over the Pacific-NA regions. During the positive phase (PDO+), the NA temperature response to Bering ice loss is quite weak or even warm. We speculate that more NA cold extremes will appear as the PDO− continues and less as the PDO− shifts to PDO+.
Abstract
Dipolarization fronts (DFs), characterized by sharp increases in the northward magnetic field and usually preceded by magnetic dips, are suggested to play an important role in energy conversion and transport in the magnetotail. It has been documented that strong energy conversion typically develops right at the fronts. Here we present spacecraft observations of electron-scale energy conversion (EEC) developed inside the dip region ahead of a DF, by using high-cadence data from the Magnetospheric Multiscale Mission. The EEC, with magnitude comparable to that at the front, is primarily driven by ion current and electron-scale electric field. The electric field inside the dip is provided by electrostatic waves fed by lower hybrid drift instability, which experiences temporal decaying. Such decaying leads to nonhomogeneity of EEC along the dawn-dusk direction. These results, uncovering a new channel for DF-driven energy conversion, can provide important insights into understanding energy transport in the magnetotail.
Abstract
The Paradox Basin, straddling Utah, Colorado, Arizona, and New Mexico is characterized by an intricate amalgamation of evaporites and clastic layers and is dominated by prominent salt walls and related subsurface structures. Our research offers a new examination of the stress distribution across the basin, deriving from continuous and discrete stress measurements conducted in boreholes in the region and focal mechanism analysis, emphasizing variations over salt structures. Integrating Coulomb failure criteria with probabilistic methods, we assess potential fault movements resulting from fluid pressure alterations. Our approach provides a comprehensive understanding of the Paradox Basin's state of stress, showing a continuous change of the maximum horizontal stress orientation from N-S at the Wasatch Fault Zone to WNW-ESE in the northern part of the Paradox Basin and to WSW-ENE in the southern part of the basin. Further East, into the Colorado Plateau and the Uncompahgre Uplift, the S
Hmax orientation becomes E-W. Decoding stress orientation dynamics has enabled critical insights into fault slip potential, especially in the basin's northern region. The salt wall faults are less likely to slip, and the Paradox Formation's evaporite and clastic rock sequence can serve as a potential low seismic risk target for carbon storage and hydrocarbon extraction.
Abstract
During periods of increased geomagnetic activity, perturbations within the terrestrial magnetosphere are known to induce currents within conducting materials, at the surface of Earth through rapid changes in the local magnetic field over time (dB/dt). These currents are known as geomagnetically induced currents and have potentially detrimental effects on ground based infrastructure. In this study we undertake case studies of five geomagnetic storms, analyzing a total of 19 days of 1-s SuperMAG data in order to better understand the magnetic local time (MLT) distribution, size, and occurrence of “spikes” in dB/dt, with 131,447 spikes in dB/dt exceeding 5 nT/s identified during these intervals. These spikes were concentrated in clusters over three MLT sectors: two previously identified pre-midnight and dawn region hot-spots, and a third, lower-density population centered around 12 MLT (noon). The noon spike cluster was observed to be associated with pressure pulse impacts, however, due to incomplete magnetometer station coverage, this population is not observed for all investigated storms. The magnitude of spikes in dB/dt are determined to be greatest within these three “hot-spot” locations. These spike occurrences were then compared with field-aligned current (FAC) data, provided by the Active Magnetospheric Planetary Electrodynamic Response Experiment. Spikes are most likely to be co-located with upward FACs (56%) rather than downward FACs (30%) or no FACs (14%).
Abstract
The Nitric Oxide (NO) emission at 5.3 μm wavelength is a well-known coolant above 100 km. It effectively regulates thermospheric temperature during space weather events. We studied NO cooling emission over Tromsø (geographic:69.59°N, 19.22°E; cgm:66.58°,102.94°), Norway by using the Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIEGCM) simulation driven by both Heelis and Weimer models as sources of geomagnetic forcing during October–November 2003 storm. The Weimer driven TIEGCM significantly overestimates thermospheric Nitric Oxide and Atomic Oxygen densities and underestimates temperature as compared to the Heelis driven simulation. The density ratio between the Weimer and Heelis driven estimations decreases with increasing altitude for both NO and atomic oxygen densities. The Heelis driven Joule heating rate agrees very well with the European incoherent scatter (EISCAT) radar measurements. It peaks during the main phase of the storm with magnitude about 4–5 times higher than that driven by Weimer model which peaks during the recovery phase. The difference in Joule heating rates between the Heelis and Weimer driven models increases with storm intensity, reaching a peak discrepancy of about an order of magnitude during the October-November 2003 storm. An early and stronger NO cooling enhancement is predicted by Heelis driven TIEGCM simulation. It overestimates NO cooling emission by about 2–3 times as compared to SABER observations and about 4–5 times the Weimer driven calculation. This strong difference between the two models can be attributed to the model calculations of high latitude electric field and convection patterns.
Abstract
This paper presents the results of a nearly 2-year long campaign to detect and analyze meteor persistent trains (PTs)—self-emitting phenomena which can linger up to an hour after their parent meteor. The modern understanding of PTs has been primarily developed from the Leonid storms at the turn of the century; our goal was to assess the validity of these conclusions using a diverse sample of meteors with a wide range of velocities and magnitudes. To this end, year-round observations were recorded by the Widefield Persistent Train camera, 2nd edition (WiPT2) and were passed through a pipeline to filter out airplanes and flag potential meteors. These were classified by visual inspection based on the presence and duration of trains. Observed meteors were cross-referenced with the Global Meteor Network (GMN) database, which independently detects and calculates meteor parameters, enabling statistical analysis of PT-leaving meteors. There were 4,726 meteors codetected by the GMN, with 636 of these leaving trains. Among these were a large population of slow, dim meteors that left PTs; these slower meteors had a greater train production rate relative to their faster counterparts. Unlike prior research, we did not find a clear magnitude cutoff or a strong association with fast meteor showers. Additionally, we note several interesting trends not previously reported, which include PT eligibility being primarily determined by a meteor's terminal height and an apparent dynamical origin dependence that likely reflects physical meteoroid properties.
Abstract
Tree rings are the most widely-used proxy records for reconstructing Common Era temperatures. Tree-ring records correlate strongly with temperature on an interannual basis, but studies have found discrepancies between tree rings and climate models on longer timescales, indicating that low-frequency noise could be prevalent in these archives. Using a large network of temperature-sensitive tree-ring records, we partition timeseries variance into a common (i.e., “signal”) and non-climatic (i.e., “noise”) component using a frequency-resolved signal-to-noise ratio (SNR) analysis. We find that the availability of stored resources from prior years (i.e., biological “memory”) dampens the climate signal at high-frequencies, and that independent noise reduces the SNR on long timescales. We also find that well-replicated, millennial-length records had the strongest common signal across centuries. Our work suggests that low-frequency noise models are appropriate for use in pseudoproxy experiments, and speaks to the continued value of high-quality data development as a top priority in dendroclimatology.
Abstract
Estimates of radar attenuation in the shallow Martian subsurface are retrieved from RIMFAX soundings along the Perseverance rover traverse. Specifically, analyzed data is from the Hawksbill Gap area during the rover's first drives onto the Jezero Western Fan Front. The centroid frequency-shift method is employed to quantify attenuation in terms of the constant-Q approximation. Results are then compared with the amplitude decay method, which—in order to calculate attenuation—requires propagation velocities retrieved from radargram analysis. By verifying that results from two separate analyses are consistent, we ensure that quantified radar properties are well constrained. First estimate of constant-Q is 78.8 ± 11.6. For a subsurface propagation velocity of 0.113 m/ns, that equals an attenuation of −2.1 ± 0.4 dB/m at the RIMFAX 675 MHz center frequency. Results are consistent with dry sedimentary rocks, and are distinguishable from the magmatic lithologies on Jezero Crater Floor.
