Hasil untuk "Meteorology. Climatology"

José P. Vega-Camarena, Luis Brito-Castillo, Luis M. Farfán et al.

Due to the lack of in situ observations in mountainous locations, the use of remote sensing data is an alternative to analyze rainfall distribution patterns during the passage of major hurricanes. In this work, gridded precipitation data from the CHIRPS database are evaluated by comparing with observations from weather stations during the passage of category 3–5 hurricanes for the period 1980–2024. The comparison between estimated and observed values is performed by regression analysis and the use of <i>K</i> and <i>K</i>₀ coefficients. An advantage of using K-ratio and K₀-ratio is the identification of overestimated or underestimated precipitation in the pixel records. The distribution of daily precipitation helped in a more concise way to better understand how well CHIRPS reproduced the observed rainfall patterns. Results show that correlations between observations and database estimates are in the range of 0.40–0.76, for eastern Pacific hurricanes, and 0.49–0.78 for Atlantic hurricanes, all of which are statistically significant; however, these results do not imply congruence between observations and estimates since CHIRPS fails to adequately reproduce the position of the highest precipitation core. In the initial stages of a tropical cyclone, near-zero correlations between observations and estimates indicate that CHIRPS is not able to reproduce the observed rainfall. It is recommended to use CHIRPS with caution when the focus is on analyzing rainfall patterns during the development of intense tropical cyclones.

K. Marvel, B. Cook, E. Weng et al.

<p>An understanding of Earth's past climate can help put current and future changes into historical context. Widely used tree ring-based drought atlases generally target the Palmer Drought Severity Index or other metrics of soil moisture and/or drought risk. These indices reflect contemporaneous meteorological conditions, and it is possible to extract information about temperature and precipitation given the existing reconstructions. Here, we present a fully Bayesian inverse method that infers a joint posterior for monthly mean temperature and precipitation given tree ring-based PDSI reconstructions from the North American Drought Atlas. The method is skillful at reconstructing early twentieth century conditions when compared to instrumental measurements from the CRU TS dataset. Moreover, the reconstructions can capture the complex temporal and multivariate covariance structure between monthly regional temperatures and precipitation. By reconstructing regional temperature and precipitation for the last millennium, we identify the driest and wettest years and decades in each region. Our results highlight the unique nature of the 1930s Dust Bowl drought in central Kansas and the late twentieth century pluvial in the North American southwest.</p>

Noé Lugaz

Abstract Are we moving into a new reality where the next human stepping onto a different world will utter “That's one small step for me, a giant leap for my country”? Is further tightening Heliophysics and space weather research to military endeavors the solution to the decrease in federal funding for Heliophysics in the US and the worldwide increase in military budget? I invite researchers to take the time to contemplate those issues and to continue pushing for an ethical, peaceful, cooperative, and curiosity‐driven space science and space weather research.

Aysha Fleming, Simon Fielke, Emma Jakku et al.

Tiejun Xie, Hui Gao, Ting Ding et al.

Abstract It was found that the Central-eastern China’s summer extreme heat (CECSH) has a decadal variability with a cycle of about 70 years and is significantly positively correlated with the Atlantic Multidecadal Oscillation (AMO) core area sea surface temperature (SST; AMOCORE) and the tropical western Pacific SST (WPSST) in boreal summer. Diagnostic analyses such as synergistic diagnostic and linear baroclinic model (LBM) experiments show that the warm AMOCORE and WPSST in boreal summer can generate the localized heat dome (HD) over Mongolia to northeast China by exciting local convection and subsequent propagation, respectively, which in turn directly influences the CECSH decadal variability through compression of the atmosphere and temperature transport. The empirical models of the CECSH decadal variability were constructed based on the AMOCORE or the WPSST separately and synergistically considering both, and the empirical model considering the synergistic effects of the AMOCORE and the WPSST had better simulation capability.

Navaporn Kanjanasiranont

Concentrations of PM₁₀, PM_2.5, and the BTEX chemical group were studied in Nakhon Pathom, Thailand. The occupational health risk for workers (security guards and printing machine operators) was estimated against exposure to these pollutants. The average levels of PM₁₀, PM_2.5, and BTEX (benzene, toluene, ethylbenzene, and xylenes) were 67.32, 40.21, and 80.93 µg/m³, respectively. Among the BTEX group, toluene was the most prevalent at all the sampling sites, with mean levels of 55.71 µg/m³. The measured toluene/benzene ratios (T/B) indicated that the potential sources of BTEX at EG, CP1, and CP2 sites were influenced by vehicular or traffic sources. The level of benzene was utilized for evaluating the risk of cancer, whereas toluene and PM_2.5 were estimated for non-cancer health risk. According to the health risk assessment (at the 95% CI), security guards tended to have higher cancer risk values due to benzene (4.04 × 10⁻⁵) when compared to printing machine operators (2.41 × 10⁻⁵) due to their frequent exposure to particular sources of high concentration. Meanwhile, the non-cancer risk values were at an acceptable level for security guards and copy center employees. In order to lower the overall cancer risk levels of workers, the most effective method is to reduce the chemical concentration.

Daniel Martín Pérez, Emily Gleeson, Panu Maalampi et al.

Near real-time aerosol fields from the Copernicus Atmospheric Monitoring Services (CAMS), operated by the European Centre for Medium-Range Weather Forecasts (ECMWF), are configured for use in the HARMONIE-AROME Numerical Weather Prediction model. Aerosol mass mixing ratios from CAMS are introduced in the model through the first guess and lateral boundary conditions and are advected by the model dynamics. The cloud droplet number concentration is obtained from the aerosol fields and used by the microphysics and radiation schemes in the model. The results show an improvement in radiation, especially during desert dust events (differences of nearly 100 W/m² are obtained). There is also a change in precipitation patterns, with an increase in precipitation, mainly during heavy precipitation events. A reduction in spurious fog is also found. In addition, the use of the CAMS near real-time aerosols results in an improvement in global shortwave radiation forecasts when the clouds are thick due to an improved estimation of the cloud droplet number concentration.

Engineer Bainomugisha, Joel Ssematimba, Deo Okure

With rapid urbanization, hazardous environmental exposures such as air, noise, plastic, soil and water pollution have emerged as a major threat to urban health. Recent studies show that 9 out of 10 people worldwide breathe contaminated air contributing to over 7 million premature deaths annually. Internet of Things (IoT) and Artificial Intelligence (AI)-based environmental sensing and modelling systems have potential for contributing low-cost and effective solutions by providing timely data and insights to inform mitigation and management actions. While low and middleincome countries are among those most affected by environmental health risks, the appropriateness and deployment of IoT and AI systems in low-resource settings is least understood. Motivated by this knowledge gap, this paper presents a design space for a custom environmental sensing and management system designed and developed to fill the data gaps in low-resource urban settings with a particular focus on African cities. The paper presents the AirQo system, which is the first instance of the design space requirements. The AirQo system includes: (1) autonomous AirQo sensors designed and customised to be deployed in resource constrained environments (2) a distributed sensor network that includes over 120 static and mobile nodes for air quality sensing (3) AirQo network manager tool for tracking and management of installation and maintenance of nodes, (4) AirQo platform that provides calibration, data access and analytics tools to support usage among policy makers and citizens. Case studies from African cities that are using the data and insights for education, awareness and policy are presented. The paper provides a template for designing and deploying a technology-driven solution for cities in low resource settings.

Jiuwei Zhao, Mi-Kyung Sung, Jae-Heung Park et al.

Abstract Owing to the significant influence of El Niño-Southern Oscillation (ENSO) on global climate, how ENSO events are initiated is an intriguing issue. The North Pacific Oscillation (NPO), a primary atmospheric variability over the midlatitude, is a well-known trigger for ENSO events, but the physical linkage is not yet fully understood. Based on observational analyses, in Part I, we proposed a new mechanism that the NPO-related wave activity flux (WAF) could directly induce the equatorial wind anomalies in both upper and lower levels. In this study, we substantiate the impacts of the WAF on tropical circulations using climate models participating in the Coupled Model Intercomparison Project phases 5 and 6 (CMIP5/6). We found that the intensity of the southward WAF over the central Pacific is a paramount factor resulting in intermodel diversity in simulating the NPO–ENSO linkage. By classifying the models into two groups of strong and weak meridional WAF (MWAF), we reveal that the strong MWAF models simulate stronger upper- and lower-level equatorial winds and precipitation anomalies that facilitate the ENSO in subsequent winter. We also reveal that the magnitude of the MWAF is closely related to the model’s climatological meridional wind and meridional shear of climatological zonal wind, emphasizing the role of systematic bias on the ENSO simulation. A comparison of the MWAF impact and seasonal footprinting mechanism demonstrates the dominant influence of the MWAF in determining the diversity of NPO–ENSO relationships.

Helko Borsdorf, Maja Bentele, Michael Müller et al.

Ambient atmospheric concentrations of isoprene and monoterpenes were measured at two forest sites, one deciduous and one coniferous, over the year 2022. Both sites in a regional area were sampled monthly between April and September. The samples were taken using sorbent tubes and analyzed with thermal desorption–gas chromatography–mass spectrometry. The highest concentrations were determined in August at both sites. While isoprene is the most abundant compound at the deciduous forest with an average concentration of 5.59 µg m⁻³ in August, α-pinene and β-pinene dominate throughout the year at the coniferous forest with the highest concentrations also in August (3.44 µg m⁻³ and 1.51 µg m⁻³). Because other monoterpenes (camphene, sabinene, 3-carene, p-cymene and limonene) are also emitted in significant amounts, the total concentration measured in the coniferous forest is higher (7.96 µg m⁻³ in August) in comparison to the deciduous forest (6.08 µg m⁻³). Regarding the detected monoterpenes in the deciduous forest, sabinene is the dominant monoterpene in addition to α-pinene and is sometimes present in higher (July) or equal (August) concentrations. The seasonal and diurnal concentrations of all monoterpenes correlate very well with each other at both sites. An exception is sabinene with a diurnal concentration profile similar to isoprene.

Yu-Chiao Liang, Lorenzo M. Polvani, Ivan Mitevski

Abstract Arctic amplification (AA), the larger warming of the Arctic compared to the rest of the planet, is widely attributed to the increasing concentrations of atmospheric CO2, and is caused by local and non-local mechanisms. In this study, we examine AA, and its seasonal cycle, in a sequence of abrupt CO2 forcing experiments, spanning from 1 to 8 times pre-industrial CO2 levels, using a state-of-the-art global climate model. We find that increasing CO2 concentrations give rise to stronger Arctic warming but weaker AA, owing to relatively weaker warming of the Arctic in comparison with the rest of the globe due to weaker sea-ice loss and atmosphere-ocean heat fluxes at higher CO2 levels. We further find that the seasonal peak in AA shifts gradually from November to January as CO2 increases. Finally, we show that this seasonal shift in AA emerges in the 21st century in high-CO2 emission scenario simulations. During the early-to-middle 21st century AA peaks in November–December but the peak shifts to December-January at the end of the century. Our findings highlight the role of CO2 forcing in affecting the seasonal evolution of amplified Arctic warming, which carries important ecological and socio-economic implications.

Malika Menoud, Carina van der Veen, Bert Scheeren et al.

Despite the importance of methane for climate change mitigation, uncertainties regarding the temporal and spatial variability of the emissions remain. Measurements of CH4 isotopic composition are used to partition the relative contributions of different emission sources. We report continuous isotopic measurements during 5 months at the Lutjewad tower (north of the Netherlands). Time-series of χ(CH4), δ13C-CH4, and δD-CH4 in ambient air were analysed using the Keeling plot method. Resulting source signatures ranged from −67.4 to −52.4‰ vs V-PDB and from −372 to −211‰ vs V-SMOW, for δ13C and δD respectively, indicating a prevalence of biogenic sources. Analysis of isotope and wind data indicated that (i) emissions from off-shore oil and gas platforms in the North Sea were not detected during this period, (ii) CH4 from fossil fuel related sources was usually advected from the east, pointing towards the Groningen gas field or regions further east in Germany. The results from two atmospheric transport models, CHIMERE and FLEXPART-COSMO, using the EDGAR v4.3.2 and TNO-MACC III emission inventories, reproduce χ(CH4) variations relatively well, but the isotope signatures were over-estimated by the model compared to the observations. Accounting for geographical variations of the δ13C signatures from fossil fuel emissions improved the model results significantly. The difference between model and measured isotopic signatures was larger when using TNO-MACC III compared to EDGAR v4.3.2 inventory. Uncertainties in the isotope signatures of the sources could explain a significant fraction of the discrepancy, thus a better source characterisation could further strengthen the use of isotopes in constraining emissions.

Jing Qian, Qiming Zhou, Xi Chen et al.

Investigation of urban expansion can provide a better understanding of the urbanization process and its driving forces, which is critical for environmental management and land use planning. Total of 514 sampling points from the aerial photos and field sampling were applied to assess the image accuracy. A Conversion of Land Use and its Effect at Small Region Extent (CLUE-S) model was established to simulate the urbanization process at the township level in the North Xinjiang Economic Zone (NXEZ) of western China. Historical land use and land cover changes with multi-temporal remote sensing data were retrieved, and the underlying driving forces were explored by training the CLUE-S model. Moreover, future changes in urban development were simulated under different scenarios. Results showed that the overall accuracy reaches larger than 80% for the years of 2002, 2005, and 2007, and the corresponding kappa coefficient is bigger than 0.8. The NXEZ is at a premature development stage compared with urban clusters in eastern China. Before 1999, the driving force in this region was primary industry development. In recent years, secondary industries started to show significance in urbanization. These findings indicate that the industrial base and economic development in the NXEZ are still relatively weak and have not taken a strong leading role. When industry and population become the main driving factors, the regional economy will enter a new stage of leap-forward development, which in turn will stimulate a new round of rapid urbanization.

Men Xia, Weihao Wang, Zhe Wang et al.

The uptake of dinitrogen pentoxide (N₂O₅) on aerosols affects the nocturnal removal of NO_x and particulate nitrate formation in the atmosphere. This study investigates N₂O₅ uptake processes using field observations from an urban site in Beijing during April&#8211;May 2017, a period characterized by dry weather conditions. For the first time, a very large N₂O₅ uptake rate (<i>k</i>(N₂O₅) up to ~0.01 s^&#8722;1) was observed during a sand storm event, and the uptake coefficient (&#947;(N₂O₅)) was estimated to be 0.044. The &#947;(N₂O₅) in urban air masses was also determined and exhibited moderate correlation (r = 0.68) with aerosol volume to surface ratio (V_a/S_a), but little relation to aerosol water, nitrate, and chloride, a finding that contrasts with previous results. Several commonly used parameterizations of &#947;(N₂O₅) underestimated the field-derived &#947;(N₂O₅). A new parameterization is suggested for dry conditions, which considers the effect of V_a/S_a, temperature, and relative humidity.

Zamantha Nadir Z. Martin, Imee Su Martinez, Ricky B. Nellas

The Classical Nucleation Theory (CNT) has been a dominant model in understanding the self-assembly of new thermodynamic phases. CNT provides significant explanations to processes such as aerosol formation and cloud condensation. In this work, we generated the nucleation free energy profiles of normal alkanes (n-propane, n-octane and n-dodecane) at five different temperatures using the grand-canonical version of the nucleation algorithm. From these free energy profiles, characteristic $ \Omega $ ($ \equiv $$ \sigma /\rho ^{2/3} $) values were obtained. Using the density, $ \rho $ values from United-Atom Transferable Potentials for Phase Equilibria (TraPPE-UA) force field and the obtained $ \Omega $ values, we calculated the corresponding surface tension, $ \sigma $ values of these n-alkane systems at different temperatures. Values obtained are within reasonable agreement with experimental data.

Ivana Stiperski, Stefano Serafin, Alexandre Paci et al.

In this article, we present an overview of the HyIV-CNRS-SecORo (Hydralab IV-CNRS-Secondary Orography and Rotors Experiments) laboratory experiments carried out in the CNRM (Centre National de Recherches Météorologiques) large stratified water flume. The experiments were designed to systematically study the influence of double obstacles on stably stratified flow. The experimental set-up consists of a two-layer flow in the water tank, with a lower neutral and an upper stable layer separated by a sharp density discontinuity. This type of layering over terrain is known to be conducive to a variety of possible responses in the atmosphere, from hydraulic jumps to lee waves and highly turbulent rotors. In each experiment, obstacles were towed through the tank at a constant speed. The towing speed and the size of the tank allowed high Reynolds-number flow similar to the atmosphere. Here, we present the experimental design, together with an overview of laboratory experiments conducted and their results. We develop a regime diagram for flow over single and double obstacles and examine the parameter space where the secondary obstacle has the largest influence on the flow. Trapped lee waves, rotors, hydraulic jumps, lee-wave interference and flushing of the valley atmosphere are successfully reproduced in the stratified water tank. Obstacle height and ridge separation distance are shown to control lee-wave interference. Results, however, differ partially from previous findings on the flow over double ridges reported in the literature due to the presence of nonlinearities and possible differences in the boundary layer structure. The secondary obstacle also influences the transition between different flow regimes and makes trapped lee waves possible for higher Froude numbers than expected for an isolated obstacle.

David Rayner, Christine Achberger, Deliang Chen

This paper describes a new weather generator – the 10-state empirical model – that combines a 10-state, first-order Markov chain with a non-parametric precipitation amounts model. Using a doubly-stochastic transition-matrix results in a weather generator for which the overall precipitation distribution (including both wet and dry days) and the temporal-correlation can be modified independently for climate change studies. This paper assesses the ability of the 10-state empirical model to simulate daily area-average precipitation in the Torne River catchment in northern Sweden/western Finland in the context of 3 other models: a 10-state model with a parametric (Gamma) amounts model; a wet/dry chain with the empirical amounts model; and a wet/dry chain with the parametric amounts model. The ability to accurately simulate the distribution of multi-day precipitation in the catchment is the primary consideration. Results showed that the 10-state empirical model represented accumulated 2- to 14-day precipitation most realistically. Further, the distribution of precipitation on wet days in the catchment is related to the placement of a wet day within a wet-spell, and the 10-state models represented this realistically, while the wet/dry models did not. Although all four models accurately reproduced the annual and monthly averages in the training data, all models underestimated inter-annual and inter-seasonal variance. Even so, the 10-state empirical model performed best. We conclude that the multi-state model is a promising candidate for hydrological applications, as it simulates multi-day precipitation well, but that further development is required to improve the simulation of interannual variation.

E.S. Takle

Qun’ou Jiang, Chengcai Tang, Enjun Ma et al.

This study applies the Dynamics of Land System (DLS) model to simulating the land cover under the designed scenarios and then analyzes the effects of land cover conversion on energy flux in the semiarid grassland area of China with the Weather Research and Forecasting (WRF) model. The results indicate that the grassland will show a steadily upgrowing trend under the coordinated environmental sustainability (CES) scenario. Compared to the CES scenario, the rate of increase in grassland cover is lower, while the rate of increase in urban land cover will be higher under the rapid economic growth (REG) scenario. Although the conversion from cropland to grassland will reduce the energy flux, the expansion of urban area and decreasing of forestry area will bring about more energy flux. As a whole, the energy flux of near surface will obviously not change under the CES scenario, and the climate therefore will not be possible to be influenced greatly by land cover change. The energy flux under the REG scenario is higher than that under the CES scenario. Those research conclusions can offer valuable information for the land use planning and climate change adaptation in the semiarid grassland area of China.

LÁZÁR I., CSÁKBERÉNYI-NAGY G., TÚRI Z. et al.

his study is concerned with the examination of roughness factor affecting wind potential in low built-up urban areas (e.g. subdivision, light industrial area). The test interval is the transition between summer and winter, as a secondary wind maximum period. The ten-minute data-pairs empirical distribution was approached by several theoretical distributions where a fitting test research was also performed. Extrapolation to higher levels is possible by defining the Hellmann exponent. The wind speed in respective height and the specific wind power are derived from it. Knowing the daily progress of the Hellmann exponent value, more accurate estimation can be given of the wind potential calculated to different heights according to the measuring point. The results were compared to the surface cover of the surrounding area as well as to the literary alpha values.