Abstract
Over the past century, rapid urbanization has greatly altered landscapes and affected atmospheric conditions causing impacts across a wide range of sectors including human welfare, infrastructure, and ecosystems. As a result, there is a growing imperative to improve understanding of urbanization impacts on local and regional weather events and hydroclimates. This study investigates how urbanization affects precipitation and cloud fraction (CF) in the vicinity of Indianapolis. We employ multi-month simulations using the Weather Research and Forecasting model to: (a) assess the impact of an urban area on precipitation and CF, (b) quantify how this impact varies with urban growth, and (c) examine the main mechanisms through which the city alters the local hydroclimate. Specifically, two perturbed simulations, where the urban land cover is either replaced by croplands or is increased in size, are also performed for the two rainiest months. Comparisons of the control run with no city against the perturbed runs indicate statistically significant impacts of the urban area in enhancing precipitation amounts, frequency and low-level CF, particularly within the first 100 km radius downwind of the city boarder. The urban environment is found to increase precipitation efficiency over the city and in downwind regions. Temperature at 2 m height, planetary boundary layer height, turbulent kinetic energy, and convective available potential energy, are also enhanced in the perturbed runs and drive changes in vertical mixing, downwind precipitation amounts, frequency and low-level height CF. All these changes appear to be a non-linear function of the city size.
Abstract
While the Department of Defense (DoD) infrastructure is no stranger to extremes, recent events have been unprecedented, with climate change acting as a growing risk multiplier. To assess the level of exposure of DoD installations to extreme weather and climate events, site-specific climate information is needed. One way to bridge the scale gap between outputs from existing global climate models (GCMs) and sites is climate downscaling. This makes the information more relevant for impact assessment at the DoD installation and facility scale. However, downscaling GCMs is beset by a myriad of challenges and sources of uncertainty, and downscaling methods were not designed with specific infrastructure planning and design needs in mind. Here, we evaluate state-of-the-science dynamical downscaling and statistical downscaling and bias correction for climate variables (i.e., temperature and precipitation) at the daily scale. We also combine downscaling approaches in novel ways to optimize computational efficiency and reduce uncertainty. Furthermore, we examine the sensitivity of the downscaled outputs to the choice of reference data and quantify the relative uncertainty related to downscaling approach, reference data, and other factors across the climate variables and aggregation scales. Results show that empirical quantile mapping (EQM), a statistical downscaling, consistently performs well and has less sensitivity to the choice of reference data. Moreover, the hybrid downscaling that leverages EQM improves the performance of dynamical downscaling. Our findings highlight that the choice of reference data dominates uncertainties in temperature downscaling, while their role is more muted for precipitation but still non-negligible.
Abstract
Despite the importance of understanding the urban emission characteristics of greenhouse gases (GHGs) and air pollutants, few studies have conducted integrated assessments across diverse urban environments. Herein, we conducted a comprehensive evaluation of the emission characteristics of GHGs and air pollutants in seven cities in the Northern Hemisphere using ground-based Fourier transform spectrometers. Our analysis primarily focused on emission ratios of excess column-averaged dry-air mole fractions of carbon monoxide (CO) to carbon dioxide (CO2) (∆XCO:∆XCO2) and those of methane (CH4) to CO2 (∆XCH4:∆XCO2). We found that the emission ratios varied significantly across cities. Xianghe (China) and Pasadena (USA), known for severe air pollution, showed the highest emission ratios. Notably, Seoul (South Korea) showed lower ∆XCO:∆XCO2 (3.32 ± 0.10 ppb/ppm) but relatively higher ∆XCH4:∆XCO2 (4.85 ± 0.04 ppb/ppm), which was comparable to the ∆XCH4:∆XCO2 value of Xianghe (5.15 ± 0.10 ppb/ppm), suggesting that targeted CH4 reduction strategies may be required for climate change mitigation in Seoul.
Abstract
Dr. Jennifer Gannon passed away suddenly on 2024 May 2 in Greenbelt, MD. Dr. Gannon had served as an editor for the Space Weather journal since April 2019, and she was the longest-serving editor on the current board, having started under the previous editor-in-chief, Dr. Delores Knipp.
SummaryThe prominent Pamir plateau holds considerable significance in comprehending the processes of Asian continental collisional orogeny. However, due to harsh natural conditions and low seismic activity within the Pamir hinterland, our understanding of this region remains deficient. Recent major events and the accumulation of geodetic observations present a rare opportunity for us to get insights into the tectonic activities and orogenic processes occurring in this region. Firstly, employing Sentinel-1 and ALOS-2 SAR images, we acquire coseismic displacements associated with the most recent earthquakes in 2015 and 2023. Subsequently, we conduct the souce models inversion with the constraints of surface displacements based on a finite-fault model. Our results reveal displacements ranging from -0.8 m to 0.8 m for the 2015 Mw 7.2 Tajik earthquake and -0.25 m to 0.25 m for the 2023 Mw 6.9 Murghob event, respectively. The optimal three-segment model for the 2015 event ruptured a fault length of 89 km with a surface rupture extending 59 km along the Sarez-Karakul fault (SKF), characterized predominantly by left-lateral strike-slip motion, with a maximum slip of 3.5 m. Meanwhile, our preferred uniform slip model suggests that the 2023 event ruptured an unmapped fault in the southern Pamir region with a strike angle of 31° and a dip angle of 76.8°. The distributed slip model indicates that the 2023 event ruptured a fault length of 32 km, resulting in an 8 km surface rupture. This event is characterized by left-lateral strike slip, with a peak slip of 2.2 m. Secondly, the Coulomb stress calculations demonstrate that the 2023 event was impeded by the 2015 event. Finally, interseismic GPS data reveals a relative motion of 3.4–5.7 mm/yr in the N-S component and 3.2–3.8 mm/yr in the E-W component along the SKF in the Pamir hinterland, respectively. These N-S direction strike-slip activities and slip behaviors support an ongoing strong shear and extension in the Pamir regime, which is a response to the oblique convergence between the Indian and Eurasian plates.
SummaryIn this study, we present the results of palaeomagnetic research conducted on Jurassic units of the Cañadón Asfalto Basin (CAB) in Patagonia, formed during Gondwana breakup. This basin is a key locality for understanding intra-plate deformation within Patagonia during the Jurassic. The nature of this basin has been a subject of debate, based on the dynamics of the blocks that constitute its depocentres. In this context, the palaeomagnetic study of the Jurassic units of this basin provides a unique methodology to characterise the tectonic motions of its crustal blocks during its formation and development. To achieve this, we collected 350 samples from 53 sites in the sedimentary units of Las Leoneras (ca. 189 Ma) and Cañadón Calcáreo Formations (ca. 160 Ma – 157 Ma), as well as the volcanic Lonco Trapial Group (ca. 185 Ma – 172 Ma). The palaeomagnetic results from the sedimentary units show a regional remagnetisation due to hydrothermal activity that obliterated the original remanence and overprinted a new one, simultaneously imprinting a secondary remanence in the volcanic units of the Lonco Trapial Group. When comparing the direction of the palaeomagnetic pole obtained from the remagnetised units with respect to average poles of equivalent ages, it is observed that the remagnetisation must have occurred during the Late Jurassic (ca. 145 Ma). The age range in which this process occurred (Oxfordian to Aptian) and the direction of the calculated pole dispute a monster polar shift postulated for Late Jurassic to Early Cretaceous times. In addition, the primary magnetisation recorded in the units of the Lonco Trapial Group indicates a counterclockwise rotation of the studied crustal blocks between 21º and 11º, which, in line with previous studies, refutes large-scale dextral motion along the Gastre Fault System since the Jurassic. Similar counterclockwise rotations of equivalent magnitudes are found along the units overlying the Palaeozoic Central Patagonian Igneous-Metamorphic Belt, which represents the opposite shear sense compared to the Jurassic units beyond this belt. This is interpreted as a reactivation of the Palaeozoic belt structures in the opposite sense, from transpressive during the Palaeozoic to transtensive during the Mesozoic.
SummaryWe propose a novel method for three-dimensional (3D) magnetotelluric (MT) forward modeling based on hybrid meshless and finite-element (FE) methods. This method divides the earth model into a central computational region and an expansion one. For the central region, we adopt scatter points to discretize the model, which can flexibly and accurately characterize the complex structures without generating unstructured mesh. The meshless method using compact support radial basis function is applied to simulate this area's electromagnetic (EM) field. While in the expansion region, to avoid the heavy time consumption and numerical error of the meshless method caused by non-uniform nodes, we adopt a node-based finite-element method with regular hexahedral mesh for stability. Finally, the two discretized systems are coupled at the interface nodes according to the continuity conditions of vector and scalar potentials. Considering that the normal electric field is discontinuous at the interface with resistivity discontinuity, while the shape functions for the meshless method are continuous, we further adopt the visibility criterion in constructing the support region. Numerical experiments on typical models show that using the same degree of freedom (DOF), the hybrid meshless-FEM (HMF) algorithm has higher accuracy than the node-based finite element method (FEM) and meshless method. In addition, the electric field discontinuity at interfaces is well preserved, which proves the effectiveness of the visibility criterion method. In general, compared to the conventional grid-based method, this new approach doesn't need the complex mesh generation for complex structures and can achieve high accuracy, thus it has the potential to become a powerful 3D MT forward modeling technique.
To investigate solar activity dependence of the coupling between medium-scale traveling ionosphere disturbance (MSTID) and sporadic E (Es) layer, we analyzed the total electron content (TEC) obtained from a Japan...
Nature Geoscience, Published online: 21 June 2024; doi:10.1038/s41561-024-01468-4
The fate of water carried by subducted slabs to the deep Earth remains unclear. Experiments suggest that water is unlikely to escape the slabs when they reach the core–mantle boundary despite high pressures and temperatures.
Nature Geoscience, Published online: 21 June 2024; doi:10.1038/s41561-024-01476-4
Machine learning analyses of global datasets of radiocarbon in river particles and coastal sediments reveal different patterns of organic carbon transfer and accumulation across the land–ocean continuum worldwide.
Nature Geoscience, Published online: 21 June 2024; doi:10.1038/s41561-024-01464-8
Water-bearing subducted slabs may not dehydrate and contribute to chemical heterogeneities at the core–mantle boundary, according to high-pressure and high-temperature melting experiments.
Nature Geoscience, Published online: 21 June 2024; doi:10.1038/s41561-024-01467-5
Millennial-scale trends in cosmogenic radionuclide production rates through the Holocene are largely the result of variations in geomagnetic field and not solar activity, according to an analysis of several radionuclide records and geomagnetic field models.
Comparison of the LEO and CPMA-SP2 techniques for black-carbon mixing-state measurements
Arash Naseri, Joel C. Corbin, and Jason S. Olfert
Atmos. Meas. Tech., 17, 3719–3738, https://doi.org/10.5194/amt-17-3719-2024, 2024
It is crucial to accurately measure the mixing states of light-absorbing carbon particles from emission sources like wildfires and biomass combustion to decrease climate forcing uncertainties. This study compares methods that measure light-absorbing carbon in the atmosphere. The CPMA-SP2 method offers more accurate results than traditional light-scattering methods, such as the leading-edge-only (LEO) method, thereby enhancing the accuracy of measuring the mixing states of light-absorbing carbon.
Cost-effective off-grid automatic precipitation samplers for pollutant and biogeochemical atmospheric deposition
Alessia A. Colussi, Daniel Persaud, Melodie Lao, Bryan K. Place, Rachel F. Hems, Susan E. Ziegler, Kate A. Edwards, Cora J. Young, and Trevor C. VandenBoer
Atmos. Meas. Tech., 17, 3697–3718, https://doi.org/10.5194/amt-17-3697-2024, 2024
A new modular and affordable instrument was developed to automatically collect wet deposition continuously with an off-grid solar top-up power package. Monthly collections were performed across the Newfoundland and Labrador Boreal Ecosystem Latitudinal Transect of experimental forest sites from 2015 to 2016. The proof-of-concept systems were validated with baseline measurements of pH and conductivity and then applied to dissolved organic carbon as an analyte of emerging biogeochemical interest.
Modeling biochar effects on soil organic carbon on croplands in a microbial decomposition model (MIMICS-BC_v1.0)
Mengjie Han, Qing Zhao, Xili Wang, Ying-Ping Wang, Philippe Ciais, Haicheng Zhang, Daniel S. Goll, Lei Zhu, Zhe Zhao, Zhixuan Guo, Chen Wang, Wei Zhuang, Fengchang Wu, and Wei Li
Geosci. Model Dev., 17, 4871–4890, https://doi.org/10.5194/gmd-17-4871-2024, 2024
The impact of biochar (BC) on soil organic carbon (SOC) dynamics is not represented in most land carbon models used for assessing land-based climate change mitigation. Our study develops a BC model that incorporates our current understanding of BC effects on SOC based on a soil carbon model (MIMICS). The BC model can reproduce the SOC changes after adding BC, providing a useful tool to couple dynamic land models to evaluate the effectiveness of BC application for CO2 removal from the atmosphere.
Hector V3.2.0: functionality and performance of a reduced-complexity climate model
Kalyn Dorheim, Skylar Gering, Robert Gieseke, Corinne Hartin, Leeya Pressburger, Alexey N. Shiklomanov, Steven J. Smith, Claudia Tebaldi, Dawn L. Woodard, and Ben Bond-Lamberty
Geosci. Model Dev., 17, 4855–4869, https://doi.org/10.5194/gmd-17-4855-2024, 2024
Hector is an easy-to-use, global climate–carbon cycle model. With its quick run time, Hector can provide climate information from a run in a fraction of a second. Hector models on a global and annual basis. Here, we present an updated version of the model, Hector V3. In this paper, we document Hector’s new features. Hector V3 is capable of reproducing historical observations, and its future temperature projections are consistent with those of more complex models.
