Atmósfera (Journal)
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Feasibility assessment of machine learning for predicting heatwaves in Bangladesh
Full text linkAs extreme weather phenomena, heatwaves bring severe risks to human health, society, and ecosystems. Over the past few years, Bangladesh has experienced heatwaves that are becoming more frequent and intense. Early warning systems (EWS) can help to minimize the potential damage from these events by providing sufficient time for thorough and effective preparation. Traditionally, numerical weather prediction (NWP) is employed for heatwave forecasting, but it is both expensive and time-consuming. This study explores the potential of using machine learning as a faster and more cost-effective alternative to NWP. Specifically, we focus on building an artificial neural network (ANN) to predict heatwaves three days in advance over Bangladesh. Our model utilizes 28 features to predict a binary target value (0 for no heatwave, 1 for heatwave). The results are promising, with the model achieving an accuracy of 91% in distinguishing heatwave and non-heatwave days. This suggests that machine learning can be a valuable tool for large-scale heatwave prediction in Bangladesh
Regionalization of precipitation in Guatemala in climatology and El Niño-Southern Oscillation in its Niño, Niña, and neutral phases
Full text linkThe regionalization of precipitation is a vital tool for understanding hydrological phenomena, particularly in the context of the El Niño-Southern Oscillation (ENSO) phases (El Niño, La Niña, neutral, and climatology) in Guatemala. This study introduces a novel framework that defines previously diffuse regional boundaries, revealing the dynamic nature of precipitation patterns across the country. The findings demonstrate how regional boundaries shift in response to ENSO phases, as well as under climatology and neutral conditions. These insights highlight the importance of considering dynamic regionalization to accurately analyze climatic impacts and precipitation variability, providing a foundation for more effective climate adaptation strategies
Surface water assessment availability and potential impacts on Mexico’s 757 hydrographic basins for future hydroelectric development
Full text linkThis study evaluates Mexico’s surface water availability across 757 hydrographic basins, organized into 37 hydrological regions, projecting scenarios for 2034. Using NOM-011-CONAGUA-2015 methodology, availability was determined by subtracting downstream commitments from runoff volume, analyzing historical climate (1976-2018) and water use trends. Significant regional disparities exist. Northern basins, like those in HR 8 (Sonora Norte) and 24 (Río Bravo Conchos), face severe water stress, with availability as low as 050 Hm3/year. Southern regions, such as HR 30 (Grijalva-Usumacinta), have higher availability, exceeding 10 000 Hm3 year–1. Projected scenarios for 2034, using Turc’s formula and the runoff coefficient (Rc), indicate 154 (Turc) and 103 (Rc) basins will face water scarcity. Northwest basins, including HR 9 (Sonora South) and 25 (San Fernando Soto la Marina), are projected to have availability below 100 Hm3 year–1, exacerbating stress. South-central basins, like HR 18 (Balsas) and HR 30 are expected to maintain high availability, exceeding 500 Hm3 year–1. The study also identified basins suitable for hydroelectric development, focusing on flows above 2 m3 s–1 and slopes over 2%. However, ecological and legal constraints, like protected areas and environmental flow requirements, limit development, especially in HR 30. These findings underscore the need for integrated water management to address regional disparities, promote sustainability, and mitigate the impacts of climate variability on Mexico’s water resources
Predictive models of incident solar radiation and its reflectance on surfaces with anti-weed screens
Full text linkIn agriculture, the wavelengths of interest are UV A + B radiation and photosynthetically active radiation. Different techniques can be used by farmers to enhance radiation distribution on crops, with one alternative being the installation of polypropylene anti-weed nets. The analysis of the radiation balance can be performed using different predictive methods, which are a function of solar geometry, climate, and weather variables. The objective of this research was to develop multiple regression models for comparison with the Holt-Winters model in time series to analyze and estimate incident radiation and its reflectance on surfaces covered with white and black polypropylene anti-weed nets and soil without cover. The results indicate an increase in radiation and temperature between Julian days 116 and 273, decreasing significantly with cloud cover. The white polypropylene anti-weed nets reflected a higher amount of solar radiation. On the other hand, the multiple regression models presented better accuracy for the prediction of incident solar radiation and its reflectance compared to the Holt Winters time series model. However, each model provides a different analysis of radiation, so that they can be complementary in decision making for agricultural purposes
Comparison of meteorological indices for drought assessment and monitoring: A case study from the Tafna watershed, Northwestern Algeria
Full text linkDrought is a complex phenomenon that includes meteorological, agricultural, and hydrological aspects. It is characterized by an extended period of insufficient rainfall that adversely impacts civilization‘s economic, social, and environmental aspects. This study compares four meteorological indices, including the Standardized Precipitation Index (SPI), China-Z index (CZI), Modified China Z Index (MCZI), and Z-Score Index (ZSI), to identify the most suitable drought indices (DIs) for assessing drought in the Tafna watershed. Monthly rainfall data from 14 stations (1970-2019) were used to calculate drought events on 1-, 3-, and 12-month time scales. On the 1- and 3-month time scales, the frequency of total drought for SPI-1 and CZI-1 is higher than for MCZI-1 and ZSI-1. At the 12-month time scale, all DIs showed the same frequency of total drought for most stations. The highest Pearson correlation coefficient is observed between SPI-1 and CZI-1 on a 1-month scale, with values exceeding 0.939 across all stations. Additionally, 57 and 71% of stations exhibit the highest correlation between SPI and CZI, with coefficients exceeding 0.963 and 0.999 at 3- and 12-month scales, respectively. Most stations do not show any trend (increase or decrease) using the Mann-Kendall trend test in all index values at 1- and 3-month scales. On a 12-month scale, most stations showed an increase in the values of all DIs. The results reported in this study provide valuable insights that can enhance the management of water resources and improve preparedness for drought events in the Tafna watershed, particularly in the context of climate change
Regional frequency analysis of daily rainfall extremes using L-moments approach
Full text linkDaily extreme precipitation values are among environmental events with the most disastrous consequences for human society. Information on the magnitudes and frequencies of extreme precipitations is essential for sustainable water resources management, planning for weather-related emergencies, and design of hydraulic structures. In the present study, regional frequency analysis of maximum daily rainfalls was investigated for Golestan province located in the northeastern Iran. This study aimed to find appropriate regional frequency distributions for maximum daily rainfalls and predict the return values of extreme rainfall events (design rainfall depths) for the future. L-moment regionalization procedures coupled with an index rainfall methodwere applied to maximum rainfall records of 47 stations across the study area. Due to complex geographicand hydro-climatological characteristics of the region, an important research issue focused on breaking downthe large area into homogeneous and coherent sub-regions. The study area was divided into five homogeneousregions, based on the cluster analysis of site characteristics and tests for the regional homogeneity.The goodness-of-fit results indicated that the best fitting distribution is different for individual homogeneousregions. The difference may be a result of the distinctive climatic and geographic conditions. The estimatedregional quantiles and their accuracy measures produced by Monte Carlo simulations demonstrate that theestimation uncertainty as measured by the RMSE values and 90% error bounds is relatively low when returnperiods are less than 100 years. But, for higher return periods, rainfall estimates should be treated withcaution. More station years, either from longer records or more stations in the regions, would be required forrainfall estimates above T=100 years. It was found from the analyses that, the index rainfall (at-site averagemaximum rainfall) can be estimated reasonably well as a function of mean annual precipitation in Golestanprovince. Index rainfalls combined with the regional growth curves, can be used to estimate design rainfallsat ungauged sites. Overall, it was found that cluster analysis together with the L-moments based regional frequencyanalysis technique could be applied successfully in deriving design rainfall estimates for northeasternIran. The approach utilized in this study and the findings are of great scientific and practical merit, particularlyfor the purpose of planning for weather-related emergencies and design of hydraulic engineering structuresLos valores extremos de precipitación diaria se encuentran entre los sucesos ambientales con consecuencias más desastrosas para la sociedad. La información sobre las magnitudes y frecuencias de las precipitaciones extremas es vital para el manejo sostenible de los recursos hídricos, la planeación de emergencias vinculadas con el clima y el diseño de estructuras hidráulicas. En este trabajo se analiza la frecuencia de precipitaciones diarias máximas en la provincia de Golestán, localizada en el noreste de Irán. Se trataron de encontrar distribuciones de frecuencias regionales adecuadas para precipitaciones máximas diarias y de predecir los valores de retorno de episodios extremos de precipitación (diseño de la profundidad de la precipitación). Se aplicó la regionalización de procedimientos de momentos-L, en conjunto con un método de indización de las precipitaciones, a los registros máximos de precipitación de 47 estaciones en el área de estudio. Debido a las complejas características geográficas e hidroclimatológicas de la región, un aspecto importante de la investigación fue la desagregación del área en subregiones coherentes y homogéneas. Así, se dividió el área de estudio en cinco regiones homogéneas con base en análisis de conglomerados de las características locales y en pruebas de homogeneidad regional. Los resultados de la precisión del ajuste indicaron que la mejor distribución es diferente para cada región homogénea. La diferencia puede deberse a las condiciones climáticas y geográficas distintivas de cada región. Los cuantiles regionales estimados y sus medidas de precisión, obtenidas mediante simulaciones de Monte Carlo, demuestran que la estimación de incertidumbre mediante valores de la raíz cuadrada del error cuadrático medio (RMSE, por sus siglas en inglés) y límites del error estadístico de 90%, es relativamente baja cuando los periodos de retorno son menores de 100 años. Sin embargo, para periodos más largos, las estimaciones de precipitación deben tomarse con cautela. Más años por estación, ya sea por registros más largos o por más estaciones en las regiones, se requerirían para estimaciones de precipitación mayores a T = 100 años. El análisis encontró que el índice de precipitación (promedio in situ de la máxima precipitación) puede estimarse razonablemente bien como una función de la precipitación media anual en la provincia de Golestán. Pueden utilizarse índices de precipitación combinados con curvas de crecimiento regional para calcular precipitaciones de diseños en sitios carentes de sistemas de medición. En general se encontró que el análisis de conglomerados, en conjunto con la técnica de análisis regional de frecuencias basada en momentos-L, puede aplicarse de manera exitosa para obtener estimados de precipitaciones de diseño en el noreste de Irán. El enfoque de este trabajo y sus resultados tienen gran importancia científica y mérito práctico, en particular para la planeación de emergencias relacionadas con el clima y el diseño de estructuras hidráulicas
Diurnal to seasonal meteorological cycles along an equatorial Andean elevational gradient
Full text linkThe climate of the Andean equatorial mountains has a pronounced spatiotemporal variability, which, coupled with limited meteorological monitoring, hampers our understanding of the regional and local atmospheric processes that govern this variability. To deepen our understanding of this region’s climate, we analyzed diurnal to seasonal meteorological patterns of the main meteorological variables: precipitation, air temperature, relative humidity, incident solar radiation, and wind speed and direction. We used a unique 10-year high-resolution dataset from March 2013 to February 2023 along an elevation gradient located in southern Ecuador. Our analyses reveal a trimodal regime of precipitation; two wet seasons are associated with convective processes influenced by the position of the Intertropical Convergence Zone (ITCZ) over the study area during the equinoxes, and the less humid season is due to the intensification of the Walker circulation, which produces subsidence over the study area. The relative humidity shows distinct daily and seasonal variations, reaching minimum daily values around noon when the air temperature is the highest, and an annual minimum in November. Incident solar radiation reaches its maximum values around the equinoxes when sunlight is almost perpendicular, which produces greater heating on the surface and, hence, a more humid atmosphere. The meridional displacement of the ITCZ around the year influences the climate, increasing humidity from March to May and wind speed from April to July. Our research reveals significant differences between diurnal and seasonal meteorological cycles, highlighting the importance of altitude, topography, and wind patterns in the climate dynamics of the equatorial Andes
Analysis of extreme events: Large coverage drought and daily precipitation events in Jalisco, Mexico
Full text linkThe objectives of the present study are to analyze: (1) drought events with large coverage and their possible response to El Niño Southern Oscillation (ENSO) and (2) extreme daily precipitation (EDP) events, both during the 1980-2019 period considering daily precipitation data from climatological stations during the summer months (July-September) in the state of Jalisco, Mexico. For the first objective, a drought analysis was performed using the Standardized Precipitation Index (SPI) at time scales of three (SPI-3) and 12 months (SPI-12), calculating seasonal (July-September) and annual (January-December) series. For the second objective, an EDP event was defined by filtering records greater than 30 mm from the selected stations, then adjusting them to a probability distribution to obtain the 99th percentile (P99) of each series. Values above P99 were identified as EDP events. The results indicate that drought events with large coverage (SPI-12) occurred under La Niña conditions in the 1989-1990 and 2011-2012 periods, affecting 71.4 and 64.3% of the state, respectively, where the coastal region was the least affected. A total of 57 EDP events were identified, but no particular ENSO pattern was determined. The most frequent peak activity occurred in 1987, 1999, 2010, and 2013, representing 31.6%, concentrated in 11 out of 28 climatological stations. While ENSO influences are weaker in these regions, other drivers, such as tropical cyclones, need adaptive disaster preparedness measures. Strengthening early warning systems, improving urban drainage infrastructure, and updating zoning regulations can mitigate flood impacts, reduce economic losses, and protect lives
Effect of green corridors on the mitigation of the urban heat island (UHI) in the district of Lince, Lima, Peru
Full text linkIn Peru, various studies on canopy urban heat islands (CUHI) show their effects on the health and habitability of cities. In the case of Lima, various effects have been analyzed. However, the analysis of the mitigation mechanisms of urban heat islands is still limited. Therefore, information on the mitigation potential of such measures is also limited. The main objective of this work is to evaluate the effect of green corridors on Arequipa Avenue in the city of Lima with respect to the mitigation of CUHI. The work was carried out by recording temperatures and relative humidity between August and September 2022, using fixed stations, through determined observation points, and numerical atmospheric modelling. The results show that the maximum temperatures reached in areas without a corridor are higher than those in areas with a green corridor by up to 5.4 ºC. On the other hand, there are significant differences in the intensity of CUHI between areas inside and outside the corridor. CUHI values within the corridor, ranging from 0.4 to 0.6 ºC, are lower than those found outside, indicating the positive effect of the green corridors in mitigating the CUHI impact. The analysis of the data allows us to evaluate the effectiveness of this intervention proposed in the Strategic evaluation of measures to reduce the urban heat island in the Province of Lima, prepared by the Metropolitan Municipality of Lima
Intensities of the 2023 and 2024 heatwaves in different local climate zones of the city of Puebla (Mexico)
Full text linkIn 2023 and 2024, Mexico experienced intense heatwaves that affected large areas of the country. This article evaluates the differentiated responses of three events in 2023 and four in 2024 in five local climate zones (LCZ) in the city of Puebla (Mexico). Heatwaves were identified based on the criterion of five consecutive days in which daily temperatures exceeded the 90th percentile, applied to the maximum temperature (27.4 ºC) for diurnal waves and to the minimum temperatures (17.4 ºC) for nocturnal waves. When thermal thresholds were exceeded during both day and night over the same period, waves were classified as circadian. To achieve greater precision, the wave’s intensity was calculated in degree-days and degree-hours. Additionally, the Humidex index was applied to estimate the bioclimatic effects in degree-hours above the preferred Humidex value. The findings indicate that nocturnal waves in the city center are more intense, partly due to the urban heat island effect, and that LCZ with greater vegetation show increased wave intensity when atmospheric humidity is included in the analysis. Thermohygrometric data recorded every 15 min at five meteorological stations throughout 2023, and six months of 2024, were used. Given the limited number of studies in Mexico evaluating the spatially differentiated effects of heatwaves within urban areas, this study adopts a localized approach