Atmósfera (Journal)
Not a member yet
881 research outputs found
Sort by
Water-soluble components in PM10 aerosols over an urban and a suburban site in the city of Sfax (Tunisia).
Get PDFThis study examines the influence of source and meteorological factors on the physico-chemical characteristics of atmospheric aerosols collected at two sampling sites, urban and suburban, in the city of Sfax (Tunisia) during the year of 2004. Atmospheric aerosols were further analyzed for their chemical composition and spatio-temporal evolution was investigated. Based on particle content distribution, the species studied were classified into distinct groups with different content and temporal distribution. A principal component analysis (PCA) revealed a clear relationship between the behavior of the constituents of each group and their corresponding source and meteorological factors. The findings provide sheer evidence for a marked intra-site enrichment that depended on the soil state, the frequency of exposition to the industrial plumes and the transport phenomena. Source apportionment revealed three major groupings. Group I consisted of a natural source including maritime (Cl- et Na+) and crustal (Ca++, Mg++, Fe(2;3)+ and K+) elements. Group II is associated with a “primary” anthropic source attributed to the local effect of industrial plume fallouts which threatens the urban site. This mainly concerns the PO43- compound. The third group is explained by a “secondary” anthropic source that included NH4+, NO3- and SO4= compounds resulting from the effect of gas/particles conversion processes.ATMOSPHERIC AEROSOLS COLLECTED AT TWO SAMPLING SITES, URBAN AND SUBURBAN, IN THE CITY OF SFAX (TUNISIA) DURING THE YEAR OF 2004. ATMOSPHERIC AEROSOLS WERE FURTHER ANALYZED FOR THEIR CHEMICAL COMPOSITION AND SPATIO-TEMPORAL EVOLUTION WAS INVESTIGATED. BASED ON PARTICLE CONTENT DISTRIBUTION, THE SPECIES STUDIED WERE CLASSIFIED INTO DISTINCT GROUPS WITH DIFFERENT CONTENT AND TEMPORAL DISTRIBUTION. A PRINCIPAL COMPONENT ANALYSIS (PCA) REVEALED A CLEAR RELATIONSHIP BETWEEN THE BEHAVIOR OF THE CONSTITUENTS OF EACH GROUP AND THEIR CORRESPONDING SOURCE AND METEOROLOGICAL FACTORS. THE FINDINGS PROVIDE SHEER EVIDENCE FOR A MARKED INTRA-SITE ENRICHMENT THAT DEPENDED ON THE SOIL STATE, THE FREQUENCY OF EXPOSITION TO THE INDUSTRIAL PLUMES AND THE TRANSPORT PHENOMENA. SOURCE APPORTIONMENT REVEALED THREE MAJOR GROUPINGS. GROUP I CONSISTED OF A NATURAL SOURCE INCLUDING MARITIME (CL- ET NA+) AND CRUSTAL (CA++, MG++, FE(2;3)+ AND K+) ELEMENTS. GROUP II IS ASSOCIATED WITH A “PRIMARY” ANTHROPIC SOURCE ATTRIBUTED TO THE LOCAL EFFECT OF INDUSTRIAL PLUME FALLOUTS WHICH THREATENS THE URBAN SITE. THIS MAINLY CONCERNS THE PO43- COMPOUND. THE THIRD GROUP IS EXPLAINED BY A “SECONDARY” ANTHROPIC SOURCE THAT INCLUDED NH4+, NO3- AND SO4= COMPOUNDS RESULTING FROM THE EFFECT OF GAS/PARTICLES CONVERSION PROCESSES
Changing rainfall in the Palakkad plains of South India
Get PDFAnalysis of the general rainfall trend is vital in understanding the underlying features, for the purpose of forecasting and in identifying the changes and impacts that are very crucial for an agro-based economy like the one of India. Situated on the western side of the Palakkad Gap, the Palakkad plains connect the state of Kerala in India to the plains of Tamil Nadu and Deccan. The geographical location results in an environmental realm in the Palakkad plains that is different from the rest of Kerala. The present study examines the general trend of rainfall in the Palakkad plains using monthly rainfall data, almost spanning a century, collected from four rain gauge stations available in the area. The annual rainfall pattern of all the stations showed a trend of significant decline, as the years proceed. Changes in the rainfall may have implications on local ecology as well as in agricultural productivity. The decrement in rainfall may reflect the actual regional level climate changes compounded by various anthropogenic factors.EL ANÁLISIS DE LAS TENDENCIAS GENERALES DE LA PRECIPITACIÓN ES VITAL PARA ENTENDER SUS CARACTERÍSTICAS SUBYACENTES CON EL PROPÓSITO DE PRONOSTICAR E IDENTIFICAR LOS CAMBIOS E IMPACTOS QUE SON CRUCIALES PARA UNA ECONOMÍA BASADA EN LA AGRICULTURA COMO LA DE LA INDIA. LAS PLANICIES DE PALAKKAD, SITUADAS AL LADO OESTE DE LA BRECHA DE PALAKKAD, COMUNICAN AL ESTADO DE KERALA, EN LA INDIA, CON LAS PLANICIES DE TAMIL NADU Y DECCAN. SU UBICACIÓN GEOGRÁFICA RESULTA EN UN AMBIENTE DIFERENTE DEL RESTO DE KERALA. LA INVESTIGACIÓN PRESENTE ANALIZA LA TENDENCIA GENERAL DE LA PRECIPITACIÓN EN LAS PLANICIES DE PALAKKAD UTILIZANDO DATOS MENSUALES DE PRECIPI¬TACIÓN, CORRESPONDIENTES A CASI UN SIGLO, TOMADOS DE LA RED DE ESTACIONES DISPONIBLES EN EL ÁREA. EL PATRÓN ANUAL DE PRECIPITACIÓN EN TODAS LAS ESTACIONES MUESTRA UNA TENDENCIA SIGNIFICATIVA DE DECLINACIÓN CON EL PASO DE LOS AÑOS. LOS CAMBIOS EN LA PRECIPITACIÓN PUEDEN TENER IMPLICACIONES EN LA ECOLOGÍA LOCAL ASÍ COMO EN LA PRODUCTIVIDAD AGRÍCOLA. EL DECREMENTO DE LA PRECIPITACIÓN PODRÍA SER REFLEJO DE LOS CAMBIOS CLIMÁTICOS A NIVEL LOCAL OCASIONADOS POR VARIOS FACTORES ANTRÓPICOS
Chemical composition of rainwater in northeastern México
Get PDFThe present study reports the chemical composition of atmospheric wet deposition in Monterrey, capital of the state of Nuevo León and the most important industrial city in northeastern México, where air quality presents a serious problem due to dust particles emitted. The sampling period was from January to December 2007. The station was mounted on the roof of the College of Chemical Sciences at the University of Nuevo León which is located in the north of the Metropolitan Area. Thirty-two samples of rain were collected with an automatic sampler and analyzed for pH, ion concentrations (SO4-2, NO3-, Cl-, Ca2+, Na+, K+, NH4+) and conductivity. The results show that the average weighted pH value of the rainwater was 6.58 due to neutralization. Rainwater chemistry showed high contribution of Ca2+ and Mg+2 in cations and SO4-2 and Cl- in anionic species. Low concentration of H+ found in rainwater samples from Monterrey N.L. suggests that an important portion of H2SO4 and HNO3 have been neutralized by alkaline particles in the atmosphere. In order to find possible association between ions in precipitation, and consequently, the possible sources of pollutants correlation study was applied using the program SPSS v.12. Weak correlations were found between the H+ ions and SO4-2 or NO3-1 because of neutralization. The local dust cement factories and surrounding limestone environment might be causing high concentration of Ca+2 and Mg+2. The results of this research will be used to evaluate the composition of atmospheric deposition, to evaluate air quality and to develop strategies to implement preventive measures and control of the atmospheric emissions in Nuevo Leon. This work represents the first study of rainwater chemical composition in the northeast of México.EN EL PRESENTE TRABAJO SE INVESTIGÓ LA COMPOSICIÓN QUÍMICA DEL DEPÓSITO ATMOSFÉRICO HÚMEDO EN MONTERREY CAPITAL DEL ESTADO DE NUEVO LEÓN LA CIUDAD INDUSTRIAL MÁS IMPORTANTE DEL NORESTE DE MÉXICO, Y DONDE LA CALIDAD DEL AIRE PRESENTA SERIOS PROBLEMAS DEBIDO A LAS PARTÍCULAS SUSPENDIDAS. EL PERÍODO DE MUESTREO FUE DE ENERO A DICIEMBRE DE 2007. LA ESTACIÓN SE LOCALIZA EN LA AZOTEA DE LA FACULTAD DE CIENCIAS QUÍMICAS DE LA UNIVERSIDAD AUTÓNOMA DE NUEVO LEÓN LA CUAL ESTÁ LOCALIZADA AL NORTE DEL ÁREA METROPOLITANA DE MONTERREY. TREINTA Y DOS MUESTRAS DE DEPÓSITO HÚMEDO FUERON RECOLECTADAS UTILIZANDO UN MUESTREADOR AUTOMÁTICO ANALIZANDO CONCENTRACIÓN DE IONES (SO4-2,NO3-,CL-,CA2+, NA+,K+,NH4+) Y CONDUCTIVIDAD. LOS RESULTADOS MUESTRAN QUE EL VALOR DE PH PROMEDIO PONDERADO FUE DE 6.58 DEBIDO A LA NEUTRALIZACIÓN. LA QUÍMICA DEL AGUA DE LLUVIA MUESTRA UNA ALTA CONCENTRACIÓN DE CA+2 Y MG+2 COMO ESPECIES CATIÓNICAS Y DE SO4-2 Y CL- COMO ESPECIES ANIÓNICAS. LA BAJA CONCENTRACIÓN DE H+ ENCONTRADA EN LAS MUESTRAS DE AGUA DE LLUVIA DE MONTERREY N.L. SUGIERE QUE UNA PARTE IMPORTANTE DE H2SO4 Y DE HNO3 FUE NEUTRALIZADA POR PARTÍCULAS ALCALINAS PRESENTES EN LA ATMÓSFERA. PARA ANALIZAR LA POSIBLE ASOCIACIÓN ENTRE LOS IONES EN LAS MUESTRAS DE LLUVIA Y CONSECUENTEMENTE LA CORRELACIÓN CON FUENTES DE EMISIÓN SE APLICÓ EL PROGRAMA ESTADÍSTICO SPSS V.12. SE ENCONTRÓ UNA BAJA CORRELACIÓN ENTRE LOS IONES H+, SO4-2 Y NO3- POSIBLEMENTE DEBIDO A LA NEUTRALIZACIÓN. LAS PEDRERAS UBICADAS EN LA LOCALIDAD Y LA COMPOSICIÓN PROPIA DE LAS MONTAÑAS PUEDEN ESTAR CONTRIBUYENDO A LAS ALTAS CONCENTRACIONES DE CA+2 Y MG+2. LOS RESULTADOS DE ESTA INVESTIGACIÓN SERÁN UTILIZADOS PARA EVALUAR LA COMPOSICIÓN DE LA DEPOSITACIÓN ATMOSFÉRICA, LA CALIDAD DEL AIRE Y PARA DESARROLLAR ESTRATEGIAS PARA IMPLEMENTAR MEDIDAS DE CONTROL DE LAS EMISIONES ATMOSFÉRICAS EN EL ESTADO. EL PRESENTE TRABAJO REPRESENTA LA PRIMERA CONTRIBUCIÓN DE LA QUÍMICA DEL AGUA DE LLUVIA EN EL NORESTE DE MÉXICO
Simulation of high impact convective events over Indian region by ARPS model with assimilation of Doppler weather radar radial velocity and reflectivity
Get PDFIn this paper, impact of assimilation of Indian Doppler Weather Radar (DWR) data has been assessed by numerical weather prediction system (ARPS) at 9 km horizontal resolution. The radial velocity and reflectivity observations from two DWR stations namely, Chennai (Lat. 13.0° N and Long. 80.0° E) and Machilipatnam (Lat. 16.5° N and Long. 81.3° E) are assimilated using the ARPS Data Assimilation System (ADAS) and cloud analysis scheme of the model. Two case studies selected are 1) Bay of Bengal Tropical Cyclone Ogni of October 2006 and 2) A local thunderstorm event of 5 June 2009 over the southeast parts of India. The study shows that the model at 9 km resolution with the assimilation of DWR observations (Chennai) could simulate mesoscale features such as: number of cells, spiral rain band structure, location of the center, strengthening of the lower tropospheric winds and northerly movement of the small size cyclonic storm in the analysis as well as in the forecasts. The model with DWR assimilation could retain the intensity of the cyclone up to 6 hours of forecasts. Thereafter the cyclone showed a weakening trend when it was drifting away from the radar site. In case of thunderstorm, the model with the DWR assimilation could capture the convective precipitation in the right location. The DWR assimilation could realistically reproduce the development process and south-westward movement of thunderstorm cells
Measurements of polycyclic aromatic hydrocarbons in an urban atmosphere of Agra, India.
Get PDFSixteen polycyclic aromatic hydrocarbons (PAH) were measured in total suspended particulate matter (TSPM) samples collected at an urban and industrial cum residential site in Agra (India) from December 2005 to December 2006. The average total PAH concentration was found to be 115 ± 17 ng m-3. The measured concentrations were found to be lower than those reported from other cities in India like Chennai, Delhi, Kanpur, Mumbai and Kolkata. The mass distribution in air was dominated by high molecular weight compounds. PAH concentration showed a significant seasonal cycle during the year with greater concentration during the cold months due to changes in emission sources and meteorological factors. The presence of specific tracers and calculation of characteristic molecular diagnostic ratios revealed vehicular exhausts and emissions from coal and biofuel combustion as the major sources of these compoundsSIXTEEN POLYCYCLIC AROMATIC HYDROCARBONS (PAH) WERE MEASURED IN TOTAL SUSPENDED PARTICULATE MATTER (TSPM) SAMPLES COLLECTED AT AN URBAN AND INDUSTRIAL CUM RESIDENTIAL SITE IN AGRA (INDIA) FROM DECEMBER 2005 TO DECEMBER 2006. THE AVERAGE TOTAL PAH CONCENTRATION WAS FOUND TO BE 115 ± 17 NG M-3. THE MEASURED CONCENTRATIONS WERE FOUND TO BE LOWER THAN THOSE REPORTED FROM OTHER CITIES IN INDIA LIKE CHENNAI, DELHI, KANPUR, MUMBAI AND KOLKATA. THE MASS DISTRIBUTION IN AIR WAS DOMINATED BY HIGH MOLECULAR WEIGHT COMPOUNDS. PAH CONCENTRATION SHOWED A SIGNIFICANT SEASONAL CYCLE DURING THE YEAR WITH GREATER CONCENTRATION DURING THE COLD MONTHS DUE TO CHANGES IN EMISSION SOURCES AND METEOROLOGICAL FACTORS. THE PRESENCE OF SPECIFIC TRACERS AND CALCULATION OF CHARACTERISTIC MOLECULAR DIAGNOSTIC RATIOS REVEALED VEHICULAR EXHAUSTS AND EMISSIONS FROM COAL AND BIOFUEL COMBUSTION AS THE MAJOR SOURCES OF THESE COMPOUNDS
Sea surface temperature and mixed layer depth changes due to cold-air outbreak in the gulf of México
Get PDFThe impact of a cold-air outbreak (CAO) on the mixed layer in the Gulf of México (GoM), during the period 18-23 October 1999, is shown in this work. A numerical model, based on the thermal energy equation and the balance equation between the thermal and mechanical energies, is used for computing both, the sea surface temperature (SST) and the sea mixed layer depth (MLD) changes due to atmospheric forcing before and during the CAO. The importance of the contributions to the temperature tendency by thermal forcing at the surface, the vertical entrainment of cold water from the thermocline, the horizontal transport of thermal energy by ocean currents and by turbulent eddies in the mixed layer are analyzed, as well as the contributions to the entrainment velocity by deepening of the mixed layer and the Ekman's pumping velocity. During the passage of the CAO on the Gulf of México the SST changes were markedly influenced by the increase in the surface wind speed. At the end of the period the experiments show that the vertical entrainment turned out to be the most determining process in the cooling of the mixed layer, even overhead of the latent and sensible heat fluxes and the horizontal transport by ocean currents and by turbulent eddies.Se muestra el impacto de un frente frío o Norte en la capa de mezcla marina del Golfo de México (GoM) durante el periodo 18-23 de octubre de 1999. Un modelo numérico basado en la ecuación de la energía térmica y en la ecuación de balance entre la energía térmica y la energía mecánica, es usado para calcular los cambios en la temperatura de la superficie marina y los cambios en la profundidad de la capa de mezcla marina, debidos al forzamiento atmosférico producido antes y durante el frente frío en estudio. Se analiza la importancia de cada una de las diferentes contribuciones a la tendencia de la temperatura como son el forzamiento térmico en la superficie, la penetración vertical de agua fría desde la termoclina, el transporte horizontal de energía térmica por corrientes y turbulencia en la capa de mezcla. Durante el paso del frente frío los cambios en la temperatura de la superficie marina estuvieron marcadamente influenciados por el incremento en la rapidez del viento a nivel de superficie. Los experimentos mostraron que la penetración vertical de agua fría a través de la termoclina resultó ser el proceso determinante en el enfriamiento de la capa de mezcla, aún por encima de los flujos de calor latente y sensible y del transporte horizontal por corrientes oceánicas y por remolinos turbulentos
Air pollution from fireworks during festival of lights (Deepawali) in Howrah, India - a case study
Get PDFFireworks display during festive celebrations can cause acute short term air pollution. Deepawali –the festival of light– is celebrated in India, every year during October or November with great fireworks display. Concentration of air pollutants such as SPM (suspended particulate matter), PM10, PM2.5, SO2 y NO2 were monitored for six consecutive days during Deepawali in Salkia, a densely populated residential area near Kolkata, India, for assessing the impacts of fireworks on ambient air quality. The pollutant concentrations as recorded on Deepawali were found to be several times higher (6.44 times for SPM, 7.16 times for PM10, 5.35 times for PM2.5, 1.73 times for SO2 and 1.27 times for NO2) compared to a typical winter day value. The results indicated the huge contribution of fireworks on the pollutant levels. The particulate concentrations on Deepawali exceeded its respective 24 hour residential standards by several times (11.6 times for SPM, 22.3 times for PM10, and 34.3 times for PM2.5). Concentrations of metals like Ba, Cu, Cd, Pb, Hg, Al in collected PMPM2.5 were found to be increased by many times on Deepawali (56.72, 79.00, 16.67, 14.86, 12.00 and 6.26 times, respectively) compared to the previous day. The probable health impact of this huge though short-lived deterioration of the ambient air quality is estimated through Monte Carlo's simulation in terms of increase in relative risk of mortality and morbidity in exposed individuals and found to be extremely high. It suggests some controls on fireworks during festive celebrations.La actividad de “pirotecnia” durante las celebraciones festivas locales pueden causar una contaminación del aire intensa y a corto plazo. Deepawali (fiesta de la luz) es una fiesta anual que se celebra en la India durante los meses de octubre o noviembre, con gran actividad en la atmósfera de fuegos artificiales. La concentración de contaminantes atmosféricos tales como SPM (partículas en suspensión), PM10, PM2.5, SO2 y NO2 fue monitoreada durante seis días consecutivos en Salkia, una zona densamente poblada y residencial, cerca de Calcuta en la India, con el fin de evaluar el impacto que los fuegos artificiales presentan sobre la calidad del aire. Las concentraciones de contaminantes registradas fueron varias veces superiores a lo habitual con referencia a un típico día de invierno (6.44 veces superior para SPM, 7.16 veces para PM10, 5.35 veces para PM2.5, 1.73 veces para SO2 y 1.27 veces para NO2). Los resultados han mostrado la gran aportación que los fuegos artificiales generan en los niveles de concentración de los diferentes contaminantes atmosféricos. Las concentraciones de partículas superaron ampliamente sus respectivos valores normales, en promedio de 24 horas, (11.6 veces para SPM, 22.3 veces para PM10, y 34.3 veces para PM2.5). Además se midieron concentraciones de metales tales como Ba, Cu, Cd, Pb, Hg, encontrándose un intenso incremento en sus valores promedios diarios con respecto al día anterior (56.72, 79.00, 16.67, 14.86, 12.00, 6.26 veces respectivamente). El probable impacto sobre la salud de los habitantes de la zona de análisis debido al incremento de los contaminantes atmosféricos, a pesar de ser un episodio de corta duración, se estima mediante una simulación de Monte Carlo con la determinación del índice de riesgo relativo respecto de la mortalidad y morbilidad en los individuos expuestos y resultó ser sumamente alto. Finalmente se sugiere realizar algún tipo de control o disminución de los fuegos artificiales durante estas celebraciones, con el fin de disminuir los riesgos en la población
Atmospheric boundary layer height calculation in México City derived by applying the individual Eulerian box model
Get PDFEthylene emissions are characteristic of primary exhalations of vehicular combustion processes. Their reaction with hydroxyl radicals in the presence of solar UV radiation promotes the production of ozone. Previously, our research group reported the measurement of real-time profiles of ethylene concentration (EC) in the atmosphere of the Metropolitan Zone of México City (MZMC) by means of laser photoacoustic system, based on 12C16O2. In this work, we applied the Euler box photochemical model to fit the time-dependent experimental ethylene concentration profiles recorded in the working week February 19-23, 2001. Those profiles allowed us to calculate the continuous variation of the atmospheric boundary layer (HABL) between 5:00 and 21:00 h, under stable atmospheric conditions. From the fitting function C(t), we identified the corresponding HABL temporal curves for the entire week of the campaign. Also, the emission ethylene rate general profile q(t) was determined, presenting three maximum peaks. The values of the HABL height ranged between 169 and 357 m in the morning and between 2700 and 3869 m in the afternoon. The Euler model, applied under atmospheric stable conditions, predicts the shifts of the three q(t) maximum center peaks depending on rush hours, Euler box volume, and –OH and ethene reactions.LAS EMISIONES DE ETILENO SON CARACTERÍSTICAS DE LAS EXHALACIONES PRIMARIAS DE LOS PROCESOS DE COMBUSTIÓN VEHICULAR. SU REACCIÓN CON RADICALES HIDROXILO EN PRESENCIA DE RADIACIÓN SOLAR UV PROMUEVE LA PRODUCCIÓN DE OZONO. EN INVESTIGACIONES ANTERIORES NUESTRO GRUPO REPORTÓ LA MEDICIÓN DE LOS PERFILES EN TIEMPO REAL DE LA CONCENTRACIÓN DE ETILENO EN LA ATMÓSFERA DE LA ZONA METROPOLITANA DE LA CIUDAD DE MÉXICO MEDIANTE UN SISTEMA LÁSER FOTOACÚSTICO DE 12C16O2. EN ESTE TRABAJO, APLICAMOS EL MODELO FOTOQUÍMICO DE LA CAJA DE EULER PARA AJUSTAR LAS CURVAS DE CONCENTRACIÓN DE ETILENO EXPERIMENTAL DEPENDIENTES DEL TIEMPO REGISTRADAS EN LA SEMANA LABORABLE DEL 19 AL 23 DE FEBRERO DE 2001. ELLO PERMITIÓ CALCULAR LA VARIACIÓN CONTINUA DE LA ALTURA DE LA CAPA DE MEZCLA (HABL) COMPRENDIDA ENTRE LAS 5:00 Y LAS 21:00 H, EN CONDICIONES ATMOSFÉRICAS ESTABLES. DE DICHO PERFIL, SE DETERMINARON LAS CORRESPONDIENTES CURVAS TEMPORALES DE HABL PARA TODA LA SEMANA DE CAMPAÑA Y EL PERFIL GENERAL, DE TRES PICOS MÁXIMOS, DE LA RAZÓN DE EMISIÓN DE ETILENO POR UNIDAD DE ÁREA Q(T). EL RANGO DE VALORES DE LA ALTURA DE LA CAPA DE MEZCLA INICIAL, POR LA MAÑANA, OSCILÓ ENTRE 169 Y 357 M; MIENTRAS QUE POR LA TARDE FUE ENTRE 2700 Y 3869 M. EL MODELO DE EULER APLICADO BAJO ESTAS CONDICIONES PREDICE CORRIMIENTOS DE LOS TRES PICOS MÁXIMOS EN FUNCIÓN DE LAS HORAS DE MAYOR TRÁFICO EN LA CAJA DE EULER
The interannual variability of midwestern temperatures and precipitation as related to the ENSO and PDO.
Get PDFLong-term temperature and precipitation records in the Midwest are examined in order to determine if interdecadal variability associated with the Pacific Decadal Oscillation (PDO) acts to modulate the El Niño Southern Oscillation (ENSO) related interannual variability of Midwestern climates. Power spectrum analysis demonstrates that significant ENSO related variability between 3 and 7 years as well as significant interdecadal variability between 12-15 years and at approximately 21 year time periods exist within these time series. This interdecadal variability is suggested to represent the time periods in which the PDO acts to modulate the ENSO-related variability of Midwestern climates. In addition, it was determined in this study that the ENSO-related variability of Midwestern climates was very high during the +PDO periods (e.g., 1925-1946 and 1977-1999) and was much lower during the -PDO (e.g., 1900-1924, 1947-1976, and 2000 to present) periods. These results suggest that the ENSO-related impacts on Midwestern climates change on interdecadal time scales. Further, the seasonal climates experienced during a particular ENSO event may not necessarily mimic those of another similar ENSO event in the future. Thus, from an operational point of view, in order to obtain more skillful seasonal long-term forecasts, the interdecadal variability should be considered as being superimposed upon the interannual variations.SE EXAMINARON REGISTROS HISTÓRICOS DE TEMPERATURA Y PRECIPITACIÓN EN LA REGIÓN DEL MEDIO OESTE DE LOS EUA A FIN DE DETERMINAR SI LA VARIABILIDAD INTERDECADAL ASOCIADA CON LA OSCILACIÓN DECADAL DEL PACÍFICO (PDO POR SUS SIGLAS EN INGLÉS) MODULA LA VARIABILIDAD INTERANUAL DE LOS CLIMAS DE ESTA REGIÓN ASOCIADOS CON LA OSCILACIÓN DEL SUR EL NIÑO (ENSO POR SUS SIGLAS EN INGLÉS). EL ANÁLISIS DE ESPECTRO DE PODER DEMUESTRA QUE EXISTEN VARIABILIDADES SIGNIFICATIVAS ASOCIADAS AL ENSO EN SERIES TEMPORALES DE 3 A 7 AÑOS E INTERDECADALES ENTRE 12 Y 15 AÑOS; HAY ADEMÁS UN PERÍODO DE APROXIMADAMENTE 21 AÑOS ENTRE ESTAS SERIES TEMPORALES. SE SUGIERE QUE ESTA VARIABILIDAD INTERDECADAL REPRESENTA PERIODOS TEMPORALES EN LOS CUALES LA PDO ACTÚA COMO MODULADOR DE LA VARIABILIDAD DE LOS CLIMAS DEL MEDIO OESTE ASOCIADA AL ENSO. ASÍ MISMO, EN ESTE ESTUDIO SE DETERMINÓ QUE LA VARIABILIDAD DE LOS CLIMAS DEL MEDIO OESTE ASOCIADA CON EL ENSO ERA BASTANTE PRONUNCIADA DURANTE LOS PERÍODOS (P. EJ., 1925-1946 Y 1977-1999) Y MUCHO MENOR DURANTE LOS PERÍODOS -PDO (P. EJ., 1900-1924; 1947-1976; AND 2000 AL PRESENTE). ESTOS RESULTADOS SUGIEREN QUE LOS IMPACTOS DEL ENSO EN LOS CLIMAS DEL MEDIO OESTE VARÍAN EN ESCALAS INTERDECADALES. MÁS AÚN, LOS CLIMAS ESTACIONALES REGISTRADOS DURANTE UN ENSO EN PARTICULAR, NO NECESARIAMENTE SE REPETIRAN EN OTROS ENSO SIMILARES POSTERIORES. EN CONSECUENCIA, DESDE UNA PERSPECTIVA OPERACIONAL, LA VARIABILIDAD INTERDECADAL DEBER SER CONSIDERADA COMO SOBREPUESTA A LAS VARIACIONES INTERANUALES A FIN DE OBTENER PRONÓSTICOS ESTACIONALES DE LARGO PLAZO MÁS PRECISOS
The role of convective parameterization in the simulation of a cyclone over the South Atlantic
Get PDFNumerical simulations are carried out to examine the role of the Kuo and Kain-Fritsch (KF) cumulus parameterization schemes and dry dynamics on a cyclone development, in a weak baroclinic atmosphere, over subtropical South Atlantic Ocean. The initial phase of the cyclone development is investigated with a coarse horizontal mesh (75 km) and when the cyclone reaches the mature stage two different horizontal resolutions are used (75 and 25 km). The best performance simulation for the cyclone initial phase occurs when the Kuo convective scheme is applied, and this may be attributed to a greater diabatic warming in the troposphere. On the other hand, the dry simulation is not capable of simulating the correct location and intensity of the cyclone in its initial phase. During the mature phase, a cyclone over deepening occurs in the Kuo scheme experiment associated with larger latent heat release in a deep vertical column. The presence of downdraft currents in the KF scheme, which acts to cool and dry the lower levels, is essential to stabilize the atmosphere and to reproduce the nearest observation cyclone deepening rate. The largest cyclone deepening is found in the Kuo scheme high resolution experiment. This suggests that the KF convective scheme is less sensitive to the horizontal grid resolution. It was also revealed that the diabatic processes are crucial to simulate the observed features of this marine cyclone over subtropical region