Atmósfera (Journal)
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Synoptic climatology associated with heavy rainfall events in the Itajaí Valley region, Brazil
Full text linkThis study presents a synoptic climatology of heavy rainfall events (HRE) in the Itajaí Valley region (IVr) in the eastern Santa Catarina (SC) state between 2000 and 2022. A total of 195 HRE were identified, corresponding to accumulations greater than 27 mm per day. The mean synoptic pattern associated with HRE showed the presence of a cold front over the study region and a low-pressure system over northeastern Argentina and Paraguay that promoted warm advection over much of the SC state. This pattern was also observed at the 850 hPa level, where a cyclonic circulation centered over Paraguay two days before the HRE (day –2) intensified the moisture transport from the Amazon region over SC. On day 0, a trough in the middle and upper troposphere was observed over Argentina, Uruguay, and parts of southern Brazil, showing a typical mid-latitude dynamic system that reflects the cold front observed at the surface. The synoptic classification identified four main surface synoptic patterns associated with HRE in the IVr. The most frequent pattern was related to the presence of the South Atlantic Subtropical Anticyclone (SASA) with blocking characteristics. Two patterns were related to a typical cold front, and the last was associated with a cyclogenetic process. No correlation was found between the sea surface temperature (SST) and the occurrence of HRE in the IVr; however, the SST anomaly gradient observed around 35º S suggested that cold fronts may be anchoring over the region of anomalously cold waters over the coast of the south of Brazil
Chemical and isotopic composition of rainwater in the eastern Yucatan peninsula, Mexico (edited by Dr. Iván Y. Hernández Paniagua)
No full textGiven that rain is the component of precipitation that reaches the surface of the earth, and aiming to contribute to the global efforts of rainwater monitoring, we present information regarding the origin of ions and their relationship with isotopic patterns and the source of moisture for rainwater in the Mexican Caribbean, which not only may be useful for pollution and atmospheric studies, but also for estimating groundwater recharges, understanding dust nuisances, and offering information about water quality for rainwater harvesting. In this paper, we describe the chemical composition of rainwater in terms of major ions, isotopic composition, and the most probable sources of moisture in the Caribbean coastal zone of Mexico, considering the three main climatic seasons in this area. The chemistry of rainwater displayed a noticeable influence from sea-salt spray, land-blown dust, and anthropogenic impacts such as agriculture and biomass burning. We identified the predominant terrestrial origin of calcium, namely anthropogenic contributions of sulfates and nitrates, plus potassium from sea spray and anthropogenic emissions. The local meteoric water line is δ2H = 8.2 δ18O + 13.8 (R² = 0.9601) suggesting enrichment due to evaporative losses, various moisture sources and local climatic effects. Although isotope composition was not different by site, it was by season, as opposed to water chemistry. We conclude that the water chemistry responds to the local conditions of the air column below the clouds, while the isotope composition is influenced by the origin of moisture and the physical conditions in which water evaporates and condenses as well
Carbonaceous particles and PM2.5 optical properties in Mexico City during the ACU15 campaign
Full text linkWe measured the optical properties of aerosols with two photoacoustic spectrometers operating at 532 and 870 nm wavelengths and sampled PM2.5 to analyze the organic carbon (OC) and elemental carbon (EC) content. The measuring site was in the southwest corner of Mexico City. We sorted the data by OC/EC ratios and calculated four mass absorption efficiencies (MAEs) for each wavelength with linear regressions. The MAEs ranged from 2.27 to 19.75 and 2.03 to 15.26 m2 g–1 at 532 and 870 nm, respectively, with determination coefficients above 0.88, showing that the amount of OC modifies the absorption properties of particles, sometimes underestimating or overestimating the black carbon concentration. It is possible to choose the MAE based on the daily median O3 concentration when there is no information about the EC and OC composition
Trend analysis and forecast of annual precipitation and temperature series in the Eastern Mediterranean region
Full text linkThe present study aims to examine the current trend of annual precipitation and temperature series referred to the Eastern Mediterranean basin on a national basis, including the annual variability of sea surface temperature anomalies and the connection effect with the North Atlantic Oscillation and the Mediterranean Oscillation indices (NAOI and MOI, respectively). The period under consideration is mainly the last 32 years, from 1990 to 2021. Additionally, the prediction of monthly and yearly temperature and precipitation series, based on the autoregressive integrated moving average model on a national base, for the next four or eight years, is another interesting feature of the present study. Results indicate rising trends in the annual precipitation during 1990-2021, mostly non-significant and significant warming trends in the annual temperature, including sea surface temperature. The NAOI is highly correlated mostly with annual temperature, whereas the MOI does not affect the variation of annual precipitation and temperature. The results of the present study are in general agreement with the results of available studies in the literature, and they could be of high interest to national authorities and environmental unions/organizations, to help decision-makers face climate change
Observed interannual variability and projected scenarios of drought in the Chorotega region, Costa Rica
Full text linkThe observation-based analysis of drought development in the Chorotega region showed that, despite the area being relatively small, agricultural drought exhibits high spatial variability across the region. However, the lack of net radiation data hinders the capacity to provide reliable estimates of evapotranspiration (ET), affecting the assessment of drought occurrence, since its propagation across the hydrological system is very sensitive to the ET estimation method. The coarse resolution of satellite-derived Normalized Difference Vegetation Index (NDVI) products and the lack of information on irrigation in agricultural areas limits the ability to properly establish a relationship between drought and vegetation response. Based on the observations, the most prominent precipitation deficits occur between September and October (–100 mm on average), showing that changes in the large-scale circulation are responsible for the impact of severe drought in the region. In agreement with previous studies, El Niño-Southern Oscillation (ENSO) is the main modulator of the drought severity, with the warm ENSO phase favoring an enhanced drought development and its influence being more significant between August and October, displaying correlations greater than –0.6. The climate change projections under RCP4.5 and RCP8.5 scenarios suggest the intensification of drought events in the Chorotega region at mid-century, with the Tempisque-Bebedero basin being the most affected area in terms of precipitation decrease and warming. The projected scenarios correspond to an increase of 1 oC for mean temperature and more of 2 oC for minimum and maximum temperature in the 2050 horizon, as well as a decrease of 400 to 800 mm for annual precipitation under both RCPs
Influence of teleconnections on observations and projections of hydroclimatic extremes caused by tropical cyclones in the arid climate of Baja California Sur (edited by Dr. Matilde Rusticucci)
No full textThis study focuses on identifying modulations by large-scale synoptic, inter-annual, and decadal oscillations on the extreme rainfall in the state of Baja California Sur, and provides statistical models to forecast future evolution. The region is arid, with 70% of precipitation from July to October, and is affected by tropical systems that may lead to moderate and even intense precipitation. Seven clusters were obtained using the Ward method applied to quality-controlled climatological data from 1950 to 2014. Normalized extreme precipitation (95th percentile) shows an overall increase in the last decades (1995-2004 and 2005-2014), with total values much larger than in any of the previous 50 years. Multivariate linear models (MLMs) were developed based on indices for the Pacific Decadal Oscillation (PDO) and El Niño-Southern Oscillation (ENSO) in Region 3.4, which were shown to modulate extreme precipitation. The MLM based on PDO, ENSO, and the fraction of tropical cyclones (TC) within a radius of 300 km to the peninsula (M4), has a better correlation with observed rainfall than the historical simulations of the Coupled-Model Inter-comparison Project version 5 (CMIP5) models; moreover, M4 outperforms all other MLMs in six of the seven clusters. Projections were evaluated based on the MLMs and CMIP5 simulations under scenarios RCP4.5 and RCP8.5 for mid- and long-term horizons. Model M4 projects more extreme events than CMIP5, and all MLM projects negative trends in extreme precipitation from 2041 to 2100 under RCP8.5. This study provides valuable information on future extreme precipitation in an arid region in the presence of steep topography, which could result in potential damage to ecosystems and infrastructure
Monitoring of construction dust and assessment of probable increment in mortality risks for exposed construction workers at Kolkata, India
Full text linkThe present study assesses the construction dust pollution scenario and associated health risks for construction sites in the Kolkata metropolis. The generated PM levels well exceeded the daily and annual National Ambient Air Quality Standards (NAAQS) of India (214.78-12 202.28 and 424.64-20 403.81%, respectively for PM10 and 182.20-5847.92 and 323.29-8821.88%, respectively for PM2.5). Mortality risks associated with long-term exposure to such high PM levels are estimated for construction workers. The stochastic nature of the influencing variables while calculating health risks is handled through the Monte Carlo Simulation (MCS). The mortality risks for different causes due to elevated PM10 exposure (RR_Expos_PM10) ranged between 1.25 (±1.20) for the risk of stroke for earthwork workers to 75.89 (±46.87) for the risk of chronic obstructive pulmonary disease (COPD) for brick wall-cutting workers. The mortality risks for PM2.5 exposure (RR_Expos_PM2.5) ranged between 1.96 (±0.40) for the risk of non-malignant respiratory diseases for earthwork workers to 19.04 (±8.82) for the risk of acute lower respiratory infections (ALRI) for brick wall-cutting workers. A sensitivity analysis was also carried out, which showed that the mortality risk associated with PM10 and PM2.5 exposure is most sensitive to the PM10 concentration during construction activities and pooled relative risk for PM2.5. The mortality risk of exposed construction workers was alarmingly higher (14.68-3548.56% higher for PM10 and 61.60-1269.78% higher for PM2.5) than the average Kolkata City population. Policy-level and site-level interventions are necessary to control and mitigate the alarming scenario
Small-scale variation of atmospheric dynamics applying chaos theory, case study
Full text linkCharacterization and knowledge of the variability of atmospheric dynamics on a small scale in the city of Riobamba, Ecuador, are achieved through the chaos theory. Meteorological data is taken every hour during four years, including variables such as wind speed, wind direction, incident radiation, temperature, and humidity, from the ESPOCH, SAN JUAN, and QUIMIAG weather stations in the canton of Riobamba. The van Ulden and Hostlang models are used to calculate the Obukhov length, surface heat fluxes, and latent heat flux. The chaos theory is applied to study the variation of atmospheric microdynamics. The Lyapunov coefficients, Kolmogorov-Sinai entropy, and Kaplan-Yorke fractal dimension are determined. Before analysis, noise reduction is necessary due to the lack of correlation, especially in the Obukhov length. This research follows a longitudinal design and employs quantitative and explanatory methods based on data analysis, statistical-mathematical techniques, and inductive-deductive approaches. The results indicate a highly variable system, reflected in a high number of Lyapunov coefficients, fractional dimensions, and entropy variations. The microdynamic parameters exhibit hyperchaotic behavior, as indicated by the presence of more than one positive Lyapunov coefficient. The variables also demonstrate a fractional fractal dimension, highlighting the irregularity in the geometric representation of the system
An Index for Predicting Precipitation in the North Coast of Peru Using Logistic Regression
No full textThe northern coast of Perú has a desert-like climate. Since precipitation is so scarce, convective rainfall events have a major impact. However, little is known about these events and their prediction is complex. To date, anomalous convective activity has mainly been associated with warm sea surface temperature anomalies near the Peruvian coast. However, a more comprehensive analysis of atmospheric variables could shed light on how these precipitation events are triggered. To address this need, this study presents a new diagnostic index of precipitation using logistic regression. Satellite radar data are used as predictand and ERA5 reanalysis parameters are used as predictors. The new index includes the mixing ratio and divergence at different levels (950, 700 and 250 hPa) and the Galvez-Davison index. This combination yields a logistic regression equation that ultimately takes the form of a new index, which we call RAMI (Rivas, Anderson-Frey, McMurdie Index). The RAMI is useful for diagnosing rainfall in the northern coast of Peru and could be useful for forecasting in this area, region is devoid of surface radars or other severe weather instruments
Simulation of the Planetary Boundary Layer characteristics and its relation to air quality in the Metropolitan Area of Rio de Janeiro, Brazil
Full text linkFrequently in the Metropolitan Area of Rio de Janeiro (MARJ), air quality monitoring stations record concentrations of particulate matter (PM10) and ozone (O3) above the reference values proposed by the World Health Organization. In this region, weather conditions combined with high atmospheric pollutant emissions and complex topography favor the occurrence of high concentrations of pollutants such as PM10 and O3 for several consecutive days. Hence, this study evaluated 1) the Planetary Boundary Layer (PBL) conditions simulated by the Weather Research and Forecasting (WRF) model and b) its relation to the air quality recorded during days with high concentrations of O3 and PM10 in the MARJ. Two episodes, one during summertime when high O3 concentrations were registered and one during the winter with high PM10 concentrations, were considered. The study used the WRF model to simulate conditions during those periods. Upper air and surface observations, synoptic charts, and satellite images were used to verify WRF results. In both periods, it was possible to identify the influence of the South Atlantic Subtropical Anticyclone associated with clear sky conditions, slight air subsidence, and weaker winds. The comparison with observations showed the model simulated coherently local weather conditions. Weaker winds and the performance of the sea breeze during the afternoon favored the maintenance of pollutants and their transport to the northeast/northwest of the region. In general, WRF consistently represented the height of the PBL and atmospheric stability. Therefore, this study shows that WRF results can be used to simulate PBL conditions and could be used as a source of upper air information in the MARJ