Showing papers in "Atmosfera in 2008"

Seasonal and spatial variation of atmospheric particulate matter in a developing megacity, the Greater Cairo, Egypt

Abstract: As an example of a developing megacity the Greater Cairo (GC) area in Egypt has been evaluated with respect to atmospheric particulate matter (PM) and lead (Pb). Particulate matter was collected during 2001-2002 in the two size fractions PM 2.5 and PM 10 at 17 sites representing different activities (industrial, urban, residential and background condition). The PM concentrations were generally high, with yearly average PM 2.5 and PM 10 values of 85 ± 12 and 170 ± 25 μg/m -3 , respectively. On an annual scale, the high PM levels were due to many sources that included traffic, waste burning and wind blown dust particles emitted from the desert outside GC and the Moqattam hill inside GC. On a seasonal scale, the PM concentrations were highest in the industrial sector during spring, the dusty season, due to the combined effect of dust storm events and anthropogenic emissions over GC. The lowest seasonal concentrations were recorded in the summer season at the background sites. There was a marked increase in PM levels during the period October to December due to burning of waste from harvested rice in the agriculture area in the Nile Delta (north of Cairo). The highest PM 2.5 /PM 10 ratio was recorded in the urban sector (0.59) while the lowest ratio was recorded in the residential sector (0.32). The PM 2.5 and PM 10 samples were also analyzed for Pb in order to address the influence of different emission sources. The monthly average concentrations of Pb in both PM2.5 (Pb2.5) and PM 10 (Pb 10 ) varied between 0.4 and 1.8 ± μg m -3 at the non industrial sites. The concentrations were significantly higher in the industrial areas, where concentration up to a maximum of 16 ± g m -3 could be observed. Both the high lead and PM concentrations measured are contributing to local environmental pollution. GC is subjected to high concentrations of particulates most of the year. There is no annual limit for PM 10 concentrations in the Egyptian law of environment, but comparing to the 24 hour average, PM 10 is representing health risks on the long-term that will give both regionally and globally environmental effects. High volume samplers measuring PM 10 as daily average shows that the air quality limit value has been exceeded at sites Heliopolis (35), Maadi (6) and 6th October (13) during 60.47, 79.07, and 62.96% of the measuring period of 2001, and at Shoubra El-Kheima (20), El-Qolaly Sq (1), and Abbasiya (36) during 100.0, 91.7, and 89.8% of the measuring period of 2002. Thus, the evaluation of the data presented in this paper will serve as a basis for future regional and global modelling and source apportionment.

Oceanographic characterization of the Veracruz reefs system

Abstract: An analysis based on the compilation of bibliographic information for the southwestern Gulf of Mexico led to the establishment of an integrated oceanographic framework useful to assess the processes that take place at different spatial and temporal scales. Those scales are related to the survival of the Sistema Arrecifal Veracruzano (SAV). This study should help us understand the multidisciplinary approach necessary to understand the marine environment of the area. The information was analyzed considering two main dynamic scales: the basin and the coastal zone, both included in a conceptual model, which states that the circulation in the SAV is the result of the interaction between the different components of the circulation and atmospheric processes. Both processes influence the generation of gradients of scalar properties, which, in turn, influence the coral reef community of the SAV.

Spatial estimation of mean temperature and precipitation in areas of scarce meteorological information

Abstract: In regions of complex relief and scarce meteorological information it becomes difficult to implement techniques and models of numerical interpolation to elaborate reliable maps of climatic variables essential for the study of natural resources using the new tools of the geographic information systems. This paper presents a method for estimating annual and monthly mean values of temperature and precipitation, taking elements from simple interpolation methods and complementing them with some characteristics of more sophisticated methods. To determine temperature, simple linear regression equations were generated associating temperature with altitude of weather stations in the study region, which had been previously subdivided in accordance with humidity conditions and then applying such equations to the area’s digital elevation model to obtain temperatures. The estimation of precipitation was based on the graphic method through the analysis of the meteorological systems that affect the regions of the study area throughout the year and considering the influence of mountain ridges on the movement of prevailing winds. Weather stations with data in nearby regions were analyzed according to their position in the landscape, exposure to humid winds, and false color associated with vegetation types. Weather station sites were used to reference the amount of rainfall; interpolation was attained using analogies with satellite images of false color to which a model of digital elevation was incorporated to find similar conditions within the study area.

Multi-model ensemble forecasting of rainfall over Indian monsoon region

Abstract: In the present study, a method is proposed for the ensemble forecasting of rainfall over the Indian monsoon region based on daily outputs of four operational numerical weather prediction (NWP) models in the shortrange time scale (up to 48 hours). The method is applied to prepare 24 and 48 hours ensemble forecastings of rainfall in the test mode daily during the summer monsoon 2006, using the rainfall prediction of constituent models with the pre-assigned grid point weights. The prediction skill of the ensemble forecasts is examined against observations and corresponding outputs of each constituent model. The intercomparison reveals that the method is capable to improve the forecast by taking the strength of each constituent model. The method has the potential for operational application.

Determination of temperature differences between asphalt concrete, soil and grass surfaces of the City of Erzurum, Turkey

Abstract: t is known that cities are warmer and drier that the surrounding, vegetated areas. In addition to their aesthetic aspects, plants play important roles in urban ecosystems function by providing various favourable effects. The City or Erzurum has extreme continental climatic features and is very hot in summer time, i.e., the period between June and September. There are few tree species capable of growing in the city; it is thought that in such cities, grass may have superior effects to the trees. The present study was carried out to determine temperature differences between asphalt concrete (AC), soil and grass surfaces on and 2m above them and to show the advantages of the use of grass surfaces in this kind of new developing cities. After the study, it was seen a mean temperature difference of 6.5 oC between AC and soil, 5.3 oC between soil and grass, and 11.79 oC between AC and grass surfaces respectively, while temperature differences 2m above the surfaces were 5.22 oC between AC and soil, 2.32 oC between soil and grass, and 7.54 oC between AC and grass surfaces. It was suggested at the end of the study that in the new developing cities having the same features as Erzurum, open spaces between the structures and areas along the roads must be covered with grass surfaces and recreational and aesthetical spaces must be left.

Universal multifractal description of an hourly rainfall time series from a location in southern Spain

Abstract: EL FORMALISMO MULTIFRACTAL DE TURBULENCIA HA SIDO USADO PARA LLEVAR A CABO EL ANALISIS DE LA ESTRUCTURA TEMPORAL, PARA ESCALAS DESDE 1 HORA HASTA CASI 6 MESES, DE LA SERIE DE DATOS DE LLUVIA HORARIA REGISTRADA DURANTE VEINTICUATRO ANOS EN CORDOBA, LOCALIDAD SITUADA EN EL SUR DE ESPANA. LOS PARAMETROS DEL MODELO MULTIFRACTAL UNIVERSAL FUERON ESTIMADOS Y SE OBTUVO LA FUNCION TEORICA DE LOS MOMENTOS ESTADISTICOS. SE ENCONTRO UN BUEN AJUSTE A LA FUNCION EMPIRICA PARA UN INTERVALO DE VALORES DE MOMENTOS, DEMOSTRANDOSE QUE EL MODELO MULTIFRACTAL UNIVERSAL RESULTA ADECUADO PARA DESCRIBIR ESTADISTICAMENTE LA SERIE TEMPORAL DE LLUVIA REGISTRADA EN CORDOBA.

Statistical analysis of the precipitation trends in the Patagonia region in southern South America

Abstract: This paper describes the rainfall climatology in Argentinean Patagonia and faces with rainfall trends. Gridded precipitation dataset from Delaware University is used as an alternative data and they seem to reflect the same patterns that the observed ones. The mean annual precipitation shows maximum amplitude in Patagonia, winter values greater than in summer in the northwest, especially in the west and over the Andes. Both, principal component analysis (PCA) applied to the monthly anomalous precipitations and linear annual rainfall trends, show positive trends in north and south of Patagonia, meanwhile precipitation tends to decrease in the western and central zone. An alternative nonlinear methodology, a piecewise linear function, is used to detect a number of breakpoints in order to identify the moments at which the tendency changes its behavior.

The effects of canopy cover on throughfall and soil chemistry in two forest sites in the México City air basin

Abstract: Throughfall and soil chemistry were compared in two sites with differing atmospheric deposition: Desierto de los Leones National Park (high atmospheric deposition) and Zoquiapan National Park (low atmospheric deposition). Throughfall fluxes of NO 3 - , SO4 2 - , Ca, Mg and K were compared under two canopy cover types: Abies religiosa Schl. (fir) and Pinus hartwegii Lindl. (pine), in comparison with sites without cover canopy, e.g. forests clearings. Throughfall fluxes decreased in the following order: fir > pine > forest clearing. Nitrogen balance under canopy of fir and pine resulted in negative values for net throughfall of NH 4 + at Desierto de los Leones and Zoquiapan, while NO 3 - , only resulted in negative values under canopy cover at the low deposition site. With few exceptions, concentrations of total C, N and S, soluble SO 4 2- , and Ca 2+ were higher in soil under fir canopies than under pine or in forest clearings. In polluted sites, the densely foliated fir canopies generally resulted in higher throughfall fluxes and soil accumulation of N, S and Mg compared to pine canopies or open areas. The elevated atmospheric depositions affect the functional process of forest ecosystem, particularly the throughfall and nutrients intern cycle, and these effects depend of the cover and present tree species.

Variability of rainfall from tropical cyclones in northwestern México and its relation to SOI and PDO

Abstract: Tropical cyclones during September affect the semi-arid northwestern region of Mexico with a relatively high frequency, bringing much-needed precipitation. This study provided a better understanding of tropical cyclone inter-annual variability, their relationships with other atmospheric-oceanic phenomena, and their inter-decadal occurrences. Daily rain data from 534 meteorological stations were analyzed and used to calculate the percentage of the annual precipitation related to tropical cyclones of the eastern North Pacific Ocean affecting the region from 1949 to 2002. Using interpolation techniques, the stations were grouped in 1o × 1o areas, and the area structure of the tropical cyclone influence was obtained using empirical orthogonal function (EOF) variable analysis to identify five regions. Representative inter-annual variation series from each region were analyzed to identify changes in the influence of tropical cyclones as part of the annual precipitation. A gradient of tropical cyclone influence was found declining from south to north, mainly in the peninsula area. A regime shift in 1976 is coincident with a shift trend in series from areas with larger tropical cyclones influence. The Southern Oscillation Index (SOI) driving is stronger for the northern part of the region, while the southern part has stronger Pacific Decadal Oscillation (PDO) influence.

Temporal and spatial behavior of temperature and precipitation during the canícula (midsummer drought) under El Niño conditions in central México

Abstract: Relatively few studies have been performed about the onset, duration, and intensity of the canicula (midsummer drought) within central Mexico in response to El Nino/Southern Oscillation (ENSO) events. The objective of our research is to assess the impact of the El Nino (EN) phase of ENSO upon air temperature

Influence of synoptic scale in the generation of extremely cold days in Europe

Abstract: UNA BASE DE DATOS HOMOGENEOS DE TEMPERATURAS MINIMAS DE 135 OBSERVATORIOS DISTRIBUIDOS EN EUROPA HA SIDO ANALIZADA CON EL OBJETIVO DE ESTIMAR LAS VARIACIONES DE TENDENCIAS E IDENTIFICAR LAS PRINCIPALES SITUACIONES SINOPTICAS QUE CONTRIBUYEN EN UN DIA DE FRIO EXTREMO (DFE). SE HA CONSIDERADO UN DIA DE FRIO EXTREMO (DFE) DEFINIDO POR EL PERCENTIL 5% DE LA SERIE DE TEMPERATURA MINIMA DIARIA DE CADA OBSERVATORIO; VALORES QUE TIENE EFECTOS SOBRE LA SALUD. PARA ESTE ANALISIS SE UTILIZA EL PERIODO DE 1 DE ENERO DE 1955 HASTA EL 31 DE DICIEMBRE DE 1998; PERIODO QUE PRESENTA EL MAYOR NUMERO DE ESTACIONES DE MEDIDAS CON SERIES COMPLETAS. LA CONEXION ENTRE LOS DFE CON LA CIRCULACION GENERAL DE LA ATMOSFERA, ESTA BASADA EN UN ANALISIS DETALLADO OBTENIENDO UN COEFICIENTE DE EFICACIA PARA CADA PATRON SINOPTICO. PARA SIMPLIFICAR LA INFORMACION OBTENIDA, SE APLICA UN ANALISIS DE COMPONENTES PRINCIPALES ROTADAS (RPC) Y SE OBTIENEN LOS PATRONES SINOPTICOS CON MAYOR CONTRIBUCION A LOS DFE. AL MISMO TIEMPO SE HA HECHO UN ANALISIS DE TENDENCIA EN CADA UNO DE LOS PATRONES SINOPTICOS Y TAMBIEN UN ESTUDIO COMPARATIVO ENTRE LOS DIFERENTES DFE DE LAS SITUACIONES SINOPTICAS.

Erythemal irradiance at the Magellan's region and Antarctic ozone hole 1999-2005

Abstract: The most austral zone of the Southern Cone of South America, which is sometimes under the influence of the Antarctic Ozone Hole (AOH), occasionally receives enhanced levels of ultraviolet B radiation (UV-B: 280-320 nm). Ultraviolet erythemal irradiance measurements began in 1999 by the University of Magallanes in Punta Arenas (Lat. 53.0o S; Lon. 70.9o W), Chile, with the installation of four instruments in different locations in the Magallanes region, which is the southernmost region in Chile and the nearest to the Antarctic Continent. Data from Solar Light instruments, the Brewer spectrophotometer (Serial 180) and the Total Ozone Mapping Spectrometer (TOMS) from 1999 to 2005 for the Magellan’s Region is presented in this paper. These data show a significant number of days in 2004 with low ozone concentrations, specifying that recovery of the ozone column at these latitudes is still uncertain. Data of erythemal measurements from the stations that are part of the Magallanes network were analyzed, with extra attention given to the spring-summer period when the activity of the AOH is more intense. On several occasions important decreases down to 20-53% in the total ozone column were observed. Along with these decreases, increased levels of UV-B radiation were observed. When compared to normal daily concentration values of the total ozone, the days with increased UV-B levels reached values between ~50 and ~200% above normal at the different stations.

Climate change scenarios of extreme temperatures and atmospheric humidity for México

Abstract: EN ESTE ARTICULO SE PRESENTAN ESCENARIOS DE CAMBIO CLIMATICO REFERIDOS A TEMPERATURAS EXTREMAS Y HUMEDAD ATMOSFERICA PARA LAS DECADAS DE 2020 Y 2050. FUERON GENERADOS PARA MEXICO A PARTIR DE LOS MODELOS DE CIRCULACION GENERAL GFDLR30, ECHAM4 Y HADCM2. EL ESCENARIO BASE CORRESPONDE A LAS NORMALES CLIMATOLOGICAS DEL PERIODO 1961-1990 PARA 50 OBSERVATORIOS DE SUPERFICIE. PARA LA MITAD DE ELLOS FUE NECESARIO ESTIMAR EMPIRICAMENTE LA PRESION ATMOSFERICA A PARTIR DE LA ALTITUD Y PARA LA TOTALIDAD SE OBTUVIERON MODELOS ESTADISTICOS DE LOS PROMEDIOS MENSUALES DE TEMPERATURAS MAXIMA Y MINIMA ASI COMO DE HUMEDAD ATMOSFERICA (RELATIVA Y ESPECIFICA). ESOS MODELOS ESTADISTICOS, COMBINADOS CON LAS SALIDAS DE LOS MODELOS DE CIRCULACION GENERAL MENCIONADOS, PRODUJERON ESCENARIOS FUTUROS DE MEDIAS MENSUALES DE TEMPERATURAS EXTREMAS Y DE HUMEDAD BAJO CONDICIONES DE CAMBIO CLIMATICO. SE MOSTRARAN LOS RESULTADOS PARA UN MES REPRESENTATIVO DEL INVIERNO (ENERO) Y OTRO DEL VERANO (JULIO).

Bivariate distribution with two-component extreme value marginals to model extreme wind speeds

Abstract: UNA BASE DE DATOS HOMOGENEOS DE TEMPERATURAS MINIMAS DE 135 OBSERVATORIOS DISTRIBUIDOS EN EUROPA HA SIDO ANALIZADA CON EL OBJETIVO DE ESTIMAR LAS VARIACIONES DE TENDENCIAS E IDENTIFICAR LAS PRINCIPALES SITUACIONES SINOPTICAS QUE CONTRIBUYEN EN UN DIA DE FRIO EXTREMO (DFE). SE HA CONSIDERADO UN DIA DE FRIO EXTREMO (DFE) DEFINIDO POR EL PERCENTIL 5% DE LA SERIE DE TEMPERATURA MINIMA DIARIA DE CADA OBSERVATORIO; VALORES QUE TIENE EFECTOS SOBRE LA SALUD. PARA ESTE ANALISIS SE UTILIZA EL PERIODO DE 1 DE ENERO DE 1955 HASTA EL 31 DE DICIEMBRE DE 1998; PERIODO QUE PRESENTA EL MAYOR NUMERO DE ESTACIONES DE MEDIDAS CON SERIES COMPLETAS. LA CONEXION ENTRE LOS DFE CON LA CIRCULACION GENERAL DE LA ATMOSFERA, ESTA BASADA EN UN ANALISIS DETALLADO OBTENIENDO UN COEFICIENTE DE EFICACIA PARA CADA PATRON SINOPTICO. PARA SIMPLIFICAR LA INFORMACION OBTENIDA, SE APLICA UN ANALISIS DE COMPONENTES PRINCIPALES ROTADAS (RPC) Y SE OBTIENEN LOS PATRONES SINOPTICOS CON MAYOR CONTRIBUCION A LOS DFE. AL MISMO TIEMPO SE HA HECHO UN ANALISIS DE TENDENCIA EN CADA UNO DE LOS PATRONES SINOPTICOS Y TAMBIEN UN ESTUDIO COMPARATIVO ENTRE LOS DIFERENTES DFE DE LAS SITUACIONES SINOPTICAS. Abstract A HOMOGENIZED DATABASE OF MINIMUM TEMPERATURES FROM 135 OBSERVATORIES DISTRIBUTED AROUND EUROPE WAS ANALYZED IN ORDER TO ESTIMATE TRENDS AND TO DETERMINE THE MAIN SYNOPTIC WEATHER PATTERNS THAT CONTRIBUTE TO AN EXTREMELY COLD DAY (ECD). AN ECD IS DEFINED AS A DAY WHOSE MINIMUM TEMPERATURE IS WITHIN THE LOWEST 5TH CENTILE OF THE DAILY TEMPERATURE SERIES FOR EACH OBSERVATORY; THESE VALUES REPRESENT TEMPERATURES BELOW WHICH PUBLIC HEALTH CONCERNS MAY BE EXPECTED. THE PERIOD FROM 1 JANUARY 1955 TO 31 DECEMBER 1998 WAS CHOSEN FOR THIS ANALYSIS BECAUSE IT REPRESENTS THE PERIOD FOR WHICH THE GREATEST NUMBER OF MEASURING STATIONS WITH COMPLETE TIME SERIES WAS AVAILABLE. THE RELATIONSHIP BETWEEN THE OCCURRENCE OF AN ECD AND THE GENERAL CIRCULATION OF THE ATMOSPHERE WAS BASED ON A STATISTICAL ANALYSIS IN WHICH A COEFFICIENT OF EFFECTIVENESS FOR EACH SYNOPTIC PATTERN WAS OBTAINED. IN ORDER TO SIMPLIFY THE MANIPULATION OF THE DATA, A ROTATED PRINCIPAL COMPONENTS (RPC) ANALYSIS WAS APPLIED AND THE SYNOPTIC PATTERNS WITH THE GREATEST CONTRIBUTION TO THE ECD WERE OBTAINED. TRENDS FOR EACH SYNOPTIC PATTERN WERE STUDIED IN ORDER TO EXAMINE THE RELATIONSHIP AMONG THE ECD.

Urban-rural climatic differences over a 2-year period in the City of Erzurum, Turkey

Abstract: This study deals with the climatic differences between rural and urban areas over a two-year-period and three different climatic elements in the conditions of the city of Erzurum; and it was aimed to determine what factors may have affected these differences. It was found in the study that temperature difference between the areas was 1.7 oC, mean relative humidity was 2.5% and rainfall was 4.8 mm/m 2 (urban is wetter). The factors thought to be effective on these differences were surface structures, buildings, smoke prevalent in the urban area and snow cover. Consequently, it was suggested that, in order to obtain more favorable and healthy climatic conditions, green areas amount, which are now not effective in the city center, must be increased.

Analyzing ground ozone formation regimes using a principal axis factoring method: A case study of Kladno (Czech Republic) industrial area

Abstract: Tropospheric ozone is a secondary air pollutant, changes in the ambient content of which are affected by both, the emission rates of primary pollutants and the variability of meteorological conditions. In this paper, we use two multivariate statistical methods to analyze the impact of the meteorological conditions associated with pollutant transformation processes. First, we evaluated the variability of the spatial and temporal distribution of ozone precursor parameters by using discriminant analysis (DA) in locations close to the industrial area of Kladno (a city in the Czech Republic). Second, we interpreted the data set by using factor analysis (FA) to examine the differences between ozone formation processes in summer and in winter. To avoid temperature dependency between the variables, as well as to describe tropospheric washout processes, we used water vapour content rather than the more commonly employed relative humidity parameter. In this way, we were able to successfully determine and subsequently evaluate the various processes of ozone formation, together with the distribution of ozone precursors. High air temperature, radiation and low water content relate to summer pollution episodes, while radiation and wind speed prove to be the most important parameters during winter.

Temporal variations in sun photometer measured precipitable water in near IR band and its comparison with model estimates at a tropical Indian station

Abstract: PARA INVESTIGAR LAS VARIACIONES ESTACIONALES Y TEMPORALES DEL CONTENIDO DE AGUA PRECIPITABLE (PWC, POR SUS SIGLAS EN INGLES) SE HICIERON OBSERVACIONES CON UN FOTOMETRO SOLAR MULTICANAL EN LA BANDA DEL INFRARROJO CERCANO EN LA ESTACION TROPICAL DE PUNE, EN LA INDIA, DURANTE EL PERIODO DE MAYO 1998 A MAYO 2006. PARA LA ESTACION MENCIONADA SE COMPARARON EL AGUA PRECIPITABLE ESTIMADA A PARTIR DE PARAMETROS METEOROLOGICOS DE SUPERFICIE (TEMPERATURA Y HUMEDAD RELATIVA) Y LA OBTENIDA DEL SATELITE MODIS. EXISTE UNA VARIACION ESTACIONAL BIEN DEFINIDA DEL CONTENIDO DE AGUA PRECIPITABLE CON UN MAXIMO DURANTE LOS MESES DEL MONZON DEL SUROESTE (JUNIO-SEPTIEMBRE) Y UN MINIMO DURANTE EL MES DE MARZO. LA VARIABILIDAD DEL PWC ES MAYOR DURANTE EL POST MONZON Y LOS MESES DE INVIERNO (OCTUBRE-FEBRERO) Y MENOR DURANTE LOS MESES DEL PRE MONZON Y MONZON (MARZO-SEPTIEMBRE). LA MEDIA TOTAL DEL PWC ESTIMADA CON EL FOTOMETRO SOLAR EN PUNE ES DE 13.27 MM. EL AGUA PRECIPITABLE CALCULADA CON LOS PARAMETROS METEOROLOGICOS Y LA OBTENIDA DE LOS DATOS DE SATELITE ES MAYOR EN MAGNITUD QUE LAS MEDICIONES OBTENIDAS CON EL FOTOMETRO SOLAR DESDE TIERRA. SIN EMBARGO, LAS VARIACIONES TEMPORALES EN TODAS LAS ESCALAS DE TIEMPO CONCUERDAN MUY BIEN Y SE ENCUENTRAN EN FASE. UN FOTOMETRO SOLAR PORTATIL BIEN CALIBRADO EN LAS LONGITUDES DE ONDA DEL INFRARROJO CERCANO PUEDE PROPORCIONAR OBSERVACIONES TEMPORALES MUY BUENAS DEL AGUA PRECIPITABLE EN CUALQUIER LOCALIDAD.

A numerical investigation of the atmosphere-ocean thermal contrast over the coastal upwelling region of Cabo Frio, Brazil

Abstract: EN ESTE TRABAJO SE UTILIZA UN MODELO ATMOSFERICO UNIDIMENSIONAL CON UNA CERRADURA DE SEGUNDO ORDEN, CONECTADO A UN MODELO DE CAPA DE MEZCLA OCEANICA, PARA INVESTIGAR LAS VARIACIONES TEMPORALES DE INTERVALO CORTO DE TIEMPO DE LAS CAPAS LIMITE ATMOSFERICA Y OCEANICA EN LA REGION DE SURGENCIA COSTERA DE CABO FRIO, BRASIL (23° S, 42°08"" W). SE REALIZARON SIMULACIONES NUMERICAS PARA EVALUAR EL IMPACTO DE LOS CONTRASTES TERMICOS ENTRE LA ATMOSFERA Y EL OCEANO SOBRE LA EXTENSION VERTICAL Y OTRAS PROPIEDADES DE ESTAS CAPAS LIMITE. LAS SIMULACIONES FUERON DISENADAS TOMANDO EN CONSIDERACION LAS OBSERVACIONES HECHAS DURANTE LA INCURSION DE UN FRENTE FRIO QUE INTERRUMPIO EL REGIMEN DE SURGENCIA EN CABO FRIO EN JULIO DE 1992. LAS SIMULACIONES HAN DEMOSTRADO QUE, TRANSCURRIDAS 10 HORAS DE MEZCLA MECANICA, DEBIDO A UNA CORRIENTE ATMOSFERICA CONSTANTE DE 10 M S-1, AUMENTO LA ALTURA DE LA CAPA LIMITE ATMOSFERICA EN 214 M CUANDO EL CONTRASTE TERMICO INICIAL ES POSITIVO E IGUAL A 2 K (LA ATMOSFERA ES MAS CALIENTE QUE EL OCEANO DURANTE LA SURGENCIA). PARA UN CONTRASTE TERMICO INICIAL NEGATIVO DE -2 K (LA ATMOSFERA ES MAS FRIA QUE EL OCEANO CUANDO EL REGIMEN DE SURGENCIA ESTA ALTERADO), LA INCIPIENTE CONVECCION TERMICA INCREMENTA LA MEZCLA MECANICA INCREMENTANDO LA CAPA LIMITE ATMOSFERICA EN 360 M. LA EVOLUCION VERTICAL DE LA CAPA LIMITE ATMOSFERICA SIMULADA ES CONSISTENTE CON LAS OBSERVACIONES EN CABO FRIO EN REGIMEN DE SURGENCIA. CUANDO LA SURGENCIA NO ESTA PRESENTE, LA ALTURA DE LA CAPA LIMITE ATMOSFERICA SIMULADA ES CERCA DE LA MITAD QUE LA OBSERVADA EN CABO FRIO EN JULIO DE 1992. DURANTE EL PERIODO DE 10 HORAS ANALIZANDO LA CAPA DE MEZCLA OCEANICA SE INCREMENTA EN 2 Y 5.4 M, RESPECTIVAMENTE, PARA LOS CONTRASTES TERMICOS INICIALES POSITIVO Y NEGATIVO DE 2 K Y -2 K. LA EXTENSION VERTICAL DE LA CAPA DE MEZCLA OCEANICA ES CONTROLADA POR LA PRESENCIA DE LA CONVECCION TERMICA EN LA CAPA LIMITE ATMOSFERICA ASOCIADA A LA AUSENCIA DE SURGENCIA Y AL PASO DE FRENTES FRIOS POR CABO FRIO.

Operational speciation of Cd, Cr, Cu, Mn, Ni, Pb, V and Zn in dust samples from schools in Caracas, Venezuela

Abstract: A sequential extraction approach has been applied to analyze Cd, Cr, Cu, Mn, Ni, Pb, V and Zn in dust samples from different schools chosen according with their location in areas with different concentrations of total suspended particles (TSP). The aim of this work is to provide information about the chemical fractionation of metal content. Hence, information about the origin, mode of occurrence, mobilization and transport of metals could be obtained. Total and partial metal concentrations were further determined by analyzing the samples

Sensitivity of main downdraft features to vertical wind shear and ice-phase in a microburst-producing thunderstorm

Abstract: EN ESTE TRABAJO SE PRESENTAN LOS RESULTADOS DE SIMULACIONES NUMERICAS DE UNA TORMENTA SEVERA GENERADORA DE UNA RAFAGA DESCENDENTE DE PEQUENA ESCALA, USANDO UN MODELO CONVECTIVO. SE REALIZARON DIFERENTES EXPERIMENTOS NUMERICOS A FIN DE COMPRENDER EL PAPEL DE LA CORTANTE VERTICAL DEL VIENTO EN EL ENTORNO Y LA FASE HIELO EN ORGANIZAR LA DINAMICA DE LA NUBE Y LA INTENSIDAD DE LA RAFAGA. TAMBIEN SE ANALIZAN TRES TIPOS DE DESCENDENTES (LA DE NIVELES MEDIOS, LA PENETRATIVA Y LA DESCENDENTE ASOCIADA CON LA PRECIPITACION) Y SU RELACION CON LA MICROFISICA DE LA NUBE Y LA CORTANTE VERTICAL DEL VIENTO EN EL ENTORNO. CON EL FIN DE CUMPLIMENTAR ESTE OBJETIVO SE UTILIZA COMO CASO DE ESTUDIO UNA TORMENTA EXTENSAMENTE DOCUMENTADA OCURRIDA EL 20 DE JULIO DE 1986 SOBRE EL NORTE DE ALABAMA (EUA). ESTA ELECCION HA SIDO MOTIVADA POR LA SIMILITUD QUE PRESENTAN LAS CONDICIONES EN EL ENTORNO PREVIAS A DICHA TORMENTA, RESPECTO A LAS QUE FAVORECEN LA OCURRENCIA DE TORMENTAS GENERADORAS DE RAFAGAS SEVERAS EN LA REGION NORESTE DE ARGENTINA. EN EL EXPERIMENTO DE CONTROL, LOS RESULTADOS DEL MODELO MOSTRARON UNA CORRECTA REPRESENTACION DE LOS RASGOS PRINCIPALES DE LA TORMENTA DURANTE SU CICLO DE VIDA. LAS SIMULACIONES NUMERICAS CONFIRMAN EL PAPEL DE LA CORTANTE VERTICAL DEL VIENTO, A PESAR DE SER DEBIL, EN LA GENESIS Y MANTENIMIENTO DE LA DESCENDENTE DE NIVELES MEDIOS. LA INCLUSION DE LA FASE HIELO PROVEE UN EMPUJE ADICIONAL QUE PROMUEVE EL CRECIMIENTO VERTICAL Y REDUCE LA CONTRIBUCION DE LA CARGA DE HIDROMETEOROS, VINCULADA A LAS GOTAS DE LLUVIA SOBREENFRIADAS, A LA DESCENDENTE DE NIVELES MEDIOS. LA FUSION PROVEE UN ENFRIAMIENTO ADICIONAL QUE REFUERZA TANTO LA DESCENDENTE ASOCIADA CON LA PRECIPITACION COMO LA DIFERENCIA DE VELOCIDADES EN EL FLUJO SALIENTE DIVERGENTE EN LA RAFAGA.

A Note on Coastally Trapped Waves Generated by the Wind at the Northern Bight of Panama

Abstract: : An operational version of the Navy Layered Ocean Model is used to study the generation of a coastally trapped wave forced by a strong and intermittent wind event at the Northern Bight of Panama. This study identifies the winds at the Northern Bight of Panama as a new source for the generation of coastally trapped waves along the west coast of the North American continent. The results indicate that after its generation, the wave propagated poleward increasing the sea level > 10 cm, producing surface currents > 50 cm/s, and traveling > 1200 km. The generation and existence of the coastally trapped wave and the model results are validated with sea surface height coastal tide gauge observations.

Impact of the use of segregated streets in the elemental carbon concentrations in Santiago de Chile

Abstract: LAS ALTAS CONCENTRACIONES DE MATERIAL PARTICULADO QUE SE OBSERVAN EN SANTIAGO DE CHILE DURANTE EL INVIERNO HAN IMPULSADO AL GOBIERNO A IMPLEMENTAR VARIAS MEDIDAS PARA REDUCIR LA CONTAMINACION. UNA DE LAS ESTRATEGIAS FUE CAMBIAR LAS DIRECCIONES DE TRANSITO, Y LOS PRIVILEGIOS EN VARIAS CALLES. LA AVENIDA PRINCIPAL (ALAMEDA) CON CINCO LINEAS POR LADO, FUE SEGREGADA DE TAL MANERA QUE EN TRES DE ELLAS, SOLO PUEDEN CIRCULAR BUSES PUBLICOS Y LAS OTRAS DOS PUEDEN SER UTILIZADAS POR LOS DEMAS VEHICULOS. AL CIRCULAR LOS BUSES MAS LIBREMENTE, PUEDEN REDUCIR SUS EMISIONES. DURANTE EL INVIERNO DEL 2001, SE HAN DETERMINADO LAS CONCENTRACIONES DE CARBONO ELEMENTAL (CE) EN LA ALAMEDA Y VARIAS OTRAS CALLES CON UN EQUIPO QUE MIDE LA ABSORCION OPTICA DEL AIRE CONSTRUIDO EN LA UNIVERSIDAD DE SANTIAGO. EL PICO DE LA HORA PUNTA DE LA MANANA PUEDE VERSE CLARAMENTE TODOS LOS MESES DEL ANO, INDICANDO QUE LA INFLUENCIA DEL TRAFICO ES ALTA. LA CONCENTRACION DE CE DURANTE LA HORA PUNTA REPRESENTA EN PROMEDIO UN 25% DE LA CONCENTRACION TOTAL. ADEMAS, EL PROMEDIO DE CONCENTRACIONES DE CARBONO ELEMENTAL EN LAS VIAS SIN TRAFICO SEGREGADO DURANTE LA HORA PUNTA ES MAS ALTO QUE EL AUMENTO EN LAS VIAS SEGREGADAS. SIN EMBARGO, LA GRAN VARIABILIDAD EN LOS DATOS NO NOS PERMITE CONCLUIR CON SIGNIFICANCIA ESTADISTICA QUE HAY UNA REDUCCION EN LA CONTAMINACION POR CE DURANTE LA HORA PUNTA. SE HAN DETERMINADO LAS CONCENTRACIONES DE CE EN CUATRO ESTACIONES, Y DOS DE ELLAS TIENEN CONCENTRACIONES MAS ALTAS, LAS OTRAS DOS TIENEN VALORES MENORES QUE DEPENDEN DE LA UBICACION DENTRO DE LA CIUDAD. ESTOS RESULTADOS PERMITEN DIBUJAR LOS LIMITES APROXIMADOS DE UN SECTOR CON ALTAS CONCENTRACIONES DE CARBONO ELEMENTAL.

Simple air quality model for a plane source

Abstract: The goal of this article is to show simple, analytical solutions of the general dispersion equation for an homogeneous plane source, parallel to the surface of the earth. At a first step, we construct a one-dimensional model, where a perfect vertical mixture is assumed (PVMM). At a second step, vertical diffusion is added to the problem (GM). Both models predict that the concentration increases downwind and, due to deposition, it remains bounded. In order to analyze the validity of the models, the space distribution of particulate matter PM10 in the saturated zone Temuco-Padre Las Casas, Chile (38.77o S, 72.63o W) is analyzed and compared with the prediction of the models.

Combined IR-microwave satellite retrieval of temperature and moisture profiles using the ICI inversion system and its application in the MM5 model

Abstract: Radiance measurements from satellites offer the opportunity to retrieve atmospheric variables at much higher horizontal resolution than is presently afforded by in-situ measurements (e.g., radiosondes). However, the accuracy of these retrievals is crucial to their usefulness, and the ill-posed nature of the problem precludes a straightforward solution. A number of retrieval approaches have been investigated, including empirical techniques, coupling with numerical weather prediction models, and data analysis techniques such as regression. In this paper, the inversion coupled with imager (ICI) scheme is used to retrieve vertical temperature and moisture profiles from infrared and microwave brightness temperatures from a polar-orbiting satellite. The bias and root mean square (RMS) deviations were assessed for the winter and summer conditions over land and sea, separately, using the National Center for Environmental Prediction (NCEP) reanalysis data. The results showed the RMS error of temperature in the lower troposphere to be about 2 K. On the other hand, the RMS errors of the moisture profiles are found to be about 1 g kg -1 . However, below 850 hPa the errors were of the order of about 3.5 K and 3 g kg -1 for the temperature and moisture profiles over the land and about 2.5 K and 2.0 g kg -1 over the sea. Two numerical experiments are designed, one control simulation without assimilation of observations, and another in which the advanced microwave sounding unit (AMSU) together with high-resolution infrared radiacion sounder (HIRS) retrieved temperature and moisture profiles are assimilated for the prediction of two tropical cyclones, which formed over the Bay of Bengal during 24 to 27 November 2002 and during 16 to 18 May 2004. The model run with assimilation of AMSU and HIRS could simulate the wind and thermodynamic structures associated with a tropical cyclone better than the control run. The spatial pattern of the precipitation simulated by the model with assimilation is in good agreement with the Tropical Rainfall Measuring Mission (TRMM) rainfall observations for the November 2002 cyclone case. The time series of minimum sea level pressure and maximum wind speed simulated by the model run with assimilation are closer to the corresponding observations when compared with the control simulation.