Browsing by Author "Karam, Hugo Abi"
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Item Open Access Estimación de la turbidez atmosférica usando el modelo IQC en el área metropolitana de Huancayo – Perú(Universidade Federal do Rio de Janeiro, 2020) Suazo Angeles, Julio Miguel; Rocha Condor, Alicia G.; Rosales Aylas, Georgynio Y.; Flores Rojas, José Luis; Angeles Vasquez, Roberto; Suazo, Nataly A.; Karam, Hugo AbiPor naturaleza el cielo no es totalmente limpio, sin embargo cuando la concentración de partículas es mayor a la normal puede atenuar con mayor intensidad la de radiación solar. Por lo que la cantidad de radiación solar que llega hasta la superficie terrestre depende en gran medida de la turbidez atmosférica. De esta manera, el objetivo de este trabajo fue estimar los valores óptimos diarios de la turbidez atmosférica y parámetros radiativos de superficie tales como: el coeficiente de turbidez de Angstrom (β), exponente de longitud de onda de Angstrom (α), el albedo de dispersión simple (ω₀) y dispersión ascendente (Fc). Mediante mediciones de radiación solar incidente (global, directa y difusa), realizadas entre junio y julio del 2019 en la Provincia de Huancayo-Perú, se realizó los cálculos de los parámetros antes presentados. El modelo numérico usado para calcular los componentes de radiación solar directa, difusa y global, es el modelo numérico de parametrización de banda ancha para cielo despejado; IQC (Iqbal, 1993) el cual se basa en información sinóptica. Los resultados muestran valores de β y α de 0.16 y 1.3 respectivamente, sugiriendo una atmósfera parcialmente contaminada.Item Open Access Isla de calor urbana superficial para tres megaciudades en África(Universidade Federal do Rio de Janeiro, 2020-03-16) Angeles Suazo, Julio Miguel; Flores Rojas, José Luis; Karam, Hugo AbiEsta contribución estima la intensidad de la isla de calor urbano superficial (ICUS) durante el período 2001-2016 para las áreas metropolitanas de El Cairo (CMA), Johannesburgo (JMA) y Lagos (LMA), ubicadas en África. Para cuantificar el SUHI se utilizaron dos métodos: el método Gaussiano y el método Quantiles. Ambos métodos utilizan datos de teledetección de temperatura superficial mensual (ST) y un producto anual del tipo de cobertura terrestre a una resolución de 0.05°, obtenidos del sensor del Espectrorradiómetro de imágenes de resolución MODerada (MODIS) a bordo de los satélites TERRA y AQUA. En los resultados obtenidos para el método gaussiano, el IICUS diurno máximo se presentó en el AML con 4.82°C y el mínimo en el AML con 0.01°C. Por la noche, la máxima encontrada fue en AMC con 4.64°C y la mínima en AMJ con 1.30°C. Para el método Quantiles, el IICUS diurno mensual máximo que se encuentra en el AML es de 5.78 ° C y el mínimo en el AMC es de -1.56°C. Por la noche, la ICUS máximo fue en AMC con 4.88°C y mínimo en AML con 2.05°C.Item Open Access Modeling the Effects of Explicit Urban Canopy Representation on the Development of Thunderstorms above a Tropical Mega City(MDPI, 2019-06-27) Flores Rojas, José Luis; Pereira Filho, Augusto José; Karam, Hugo Abi; Vemando, Felipe; Masson, Valéry; Silva Vidal, YaminaThe effects of an explicit three dimensional (3D) urban canopy representation on the development of convective thunderstorms were analyzed with the tropical town energy budget (tTEB) scheme integrated into the advanced regional prediction system (ARPS). The study provides a detailed description of the procedure to couple the system ARPS-tTEB and analyzed the simulation results of the 12 January 2015 sea-breeze event that developed a severe thunderstorm above the metropolitan area of São Paulo (MASP), Brazil. The simulation used realistic boundary and initial conditions from the Global Forecast System (GFS) and sea surface temperature (SST) from the Tropical Rainfall Measurement Mission (TRMM). The system ARPS-tTEB runs of up to 3 km horizontal resolution were carried out with high resolution topography features and land-use types currently available for Southeastern Brazil. The simulated spatial distribution of precipitation was verified against the Climate Prediction Center Morphing Technique (CMORPH), the Global Precipitation Measurement (GPM) and the São Paulo weather radar (SPWR) precipitation estimates by indexes scores. Time series of grid precipitation estimates (ARPS-tTEB and SPWR) and point measurements (rain gauges) were evaluated with a Bayesian statistical method. Results indicate that the urban area of the MASP modulates the precipitation spatial distribution over it. Furthermore, phase and amplitude precipitation accuracy increased with the 3D urban canyon and the urban energy budget scheme in relationship to control runs without urban environment effects.Item Restricted On the dynamic mechanisms of intense rainfall events in the central Andes of Peru, Mantaro valley(Elsevier, 2021-01-15) Flores Rojas, José Luis; Moya Álvarez, Aldo Saturnino; Valdivia Prado, Jairo Michael; Piñas-Laura, Manuel; Kumar, Shailendra; Karam, Hugo Abi; Villalobos Puma, Elver Edmundo; Martínez Castro, Daniel; Silva Vidal, YaminaThe present study was aimed at analysing the main atmospheric dynamic mechanisms associated with the occurrence of intense rainfall events above the Huancayo observatory (12.05°S, 75.32°W, 3313 m asl) in the central Andes of Perú (Mantaro valley) from January 2018 to April 2019. To identify the rainfall events, we used a set of instruments from the laboratory of physics, microphysics and radiation (LAMAR) composed by in-situ pluviometric observations, satellite remote sensing data (GPM), Cloud Radar (MIRA-35c), Boundary Layer Tropospheric Radar (BLTR) and downscaling model simulations with WRF (resolutions: 18 km, 6 km and 2 km) and ARPS (0.5 km) models to analyse the dynamics of the atmosphere for the synoptic, meso and local processes that control the occurrence of these rainfall events. The results showed that all intense rainfall events are associated with the presence of thermal meso-scale circulations that transport moisture fluxes through passes with gentle slopes along both sides of the Andes. The easterly moisture fluxes come in from the South America Low Level Jet (SALLJ) and the westerly moisture fluxes from the Pacific Ocean. The arrival of these moisture flows to regions within the Mantaro valley depends on their coupling with the circulations at medium and high levels of the atmosphere. At the synoptic scale, the results show that the rainfall events can be separated into two groups: the first one associated with westerly circulations (WC) at the mid and upper levels of the atmosphere, generated by the weakening and eastern displacement of the anticyclonic Bolivian high-North east low (BH-NE) system, and the second associated with easterly circulations (EC) at the mid and upper levels of the atmosphere, generated by the intensification of the BH-NE system. The observed and simulated results showed that multicell convective systems of WC events are more extensive and deeper than EC events. This situation can be explained as the convergence of moisture fluxes from opposite directions occurred within the Mantaro basin for WC events. In contrast, for EC events, the convergence develops at the east Andes mountain range, following which the multicell storm system propagates westward, driven by easterly circulations. The EC events occur mostly in the summer months, while the WC events occur mostly in the autumn and spring months. Moreover, apparently the inertia gravity waves (IGWs) formed in the Amazon basin transport moisture and energy to the central Andes plateau and intensify the convection processes.