Showing papers in "Atmosfera in 2007"

Detection of the urban heat island in Mexicali, B.C., México and its relationship with land use

Abstract: In this paper the urban heat islands (UHI), both atmospheric and surface, and their relationship with the land use in the city of Mexicali, Baja California, Mexico, were examined by means of direct in situ measurements

Human thermal comfort over three different land surfaces during summer in the city of Erzurum, Turkey

Abstract: In the present study an attempt has been made to compare the differences in human bioclimatological conditions 2 m above the ground between three different land surfaces: asphalt concrete, soil and grass surfaces, using a data set obtained on 15 clear and calm days in August 2005, and an appropriate bioclimatological index, the thermohygrometric index (THI) in the city of Erzurum, Turkey. In the respect of human thermal comfort, soil surface was found to be the most advantageous surface but for the mean THI values grass surface exhibits more favourable features while the least favourable features were presented by the asphalt concrete surface.

Tropical cyclone statistics in the Northeastern Pacific

Abstract: LA PRINCIPAL REGION DE LA FORMACION DE CICLONES EN EL OCEANO PACIFICO ESTE ES EL GOLFO DE TEHUANTEPEC, ENTRE LOS 8 Y LOS 15° N. EN SU FASE INICIAL LOS CICLONES SE MUEVEN HACIA EL OESTE Y EL NOROESTE. EL ANALISIS HISTORICO DE LOS CICLONES QUE SE HAN GENERADO DURANTE LOS ULTIMOS 38 ANOS (DE 1966 A 2004) MUESTRA UN PROMEDIO DE 16.2 CICLONES POR ANO, CONSISTENTES EN 8.8 HURACANES Y 7.4 TORMENTAS TROPICALES. EL ANALISIS MUESTRA UNA GRAN VARIABILIDAD GEOGRAFICA EN LA TRAYECTORIA DE LOS CICLONES, DE LOS CUALES UN GRAN NUMERO IMPACTA LAS COSTAS DE MEXICO. ALREDEDOR DEL 50% DE LOS CICLONES TROPICALES QUE SE GENERAN EN EL PACIFICO ESTE RECURVA HACIA EL NORESTE. LOS CICLONES RARA VEZ PASAN DE LOS 30° DE LATITUD NORTE DEBIDO A LA CORRIENTE FRIA DE CALIFORNIA. LAS TRAYECTORIAS DE LOS CICLONES DEL PACIFICO ESTE PUEDEN SEPARARSE EN 5 GRUPOS. LOS DATOS HISTORICOS DE LAS ANOMALIAS EN LA TEMPERATURA SUPERFICIAL DEL MAR (SST) RELACIONADOS CON LOS EVENTOS DE EL NINO, FUERON COMPARADOS CON UN CONJUNTO DE DATOS DE CICLONES TROPICALES, INCLUYENDO FRECUENCIA, INTENSIDAD, TRAYECTORIA Y DURACION. AUNQUE LA DEPENDENCIA ESTADISTICA ENTRE LA FRECUENCIA DE LOS CICLONES TROPICALES DE LAS CATEGORIAS MAS ABUNDANTES EN ESTA REGION, 1 Y 2, Y LOS DATOS DE SST NO FUE SIGNIFICATIVA, EL PORCENTAJE DE HURACANES DE ALTA INTENSIDAD (CATEGORIAS 4 Y 5) Y LOS HURACANES CON UNA LARGA DURACION (MAYOR A 12 DIAS) FUE MAYOR DURANTE LOS ANOS NINO QUE DURANTE LOS ANOS NO NINO.

Evolution of atmospheric pollutants in the city of Sfax (Tunisia) (October 1996-June 1997)

Abstract: The descriptive study related to the evolution of O 3 , NO, NO 2 , CO, SO 2 , CH 4 , NMHC and PM 10 concentrations in downtown Sfax showed, during the period October 1996-June 1997, that the city is significantly influenced by many sources and meteorological factors. The diurnal average concentrations of these species let appear at times some peculiarities due to the population local customs and also to particular meteorological conditions associated with predominant strong cyclonic situations (cut-off lows). Based on NO and CH 4 , two species selected respectively as local and synoptic tracers, this descriptive study which is refined by a principal component analysis showed, out from these particular meteorological conditions, three components of the atmospheric pollution: a first component formed by CH 4 and in less degree NMHC showing the impact of synoptic sources, a second component containing NO, NO 2 , CO, SO 2 and in less degree PM 10 and NMHC displaying the impact of local sources (vehicle and industrial sources), and finally a third component constituted by O 3 and in less degree PM 10 presenting the impact of regional sources. Under the above quoted cyclonic situations, the distribution of such components was shown considerably modified.

Regionalization and classification of bioclimatic zones in the central-northeastern region of México using principal component analysis (PCA)

Abstract: UTILIZANDO UN ANALISIS DE COMPONENTES PRINCIPALES, DETERMINAMOS ZONAS CLIMATICAS EN UN GRADIENTE TOPOGRAFICO EN LA ZONA CENTRO-NORESTE DE MEXICO. SE EMPLEARON DATOS DE PRECIPITACION Y TEMPERATURA MEDIAS MENSUALES POR UN PERIODO DE 30 ANOS DE 173 ESTACIONES METEOROLOGICAS. LA CLASIFICACION DEL CLIMA FUE LLEVADA A CABO DE ACUERDO CON EL SISTEMA DE KPPEN MODIFICADO PARA LAS CONDICIONES DE MEXICO. EL ANALISIS DE COMPONENTES PRINCIPALES INDICO UNA REGIONALIZACION QUE CONCUERDA CON CARACTERISTICAS DE TOPOGRAFIA Y VEGETACION. SE DESCRIBEN ZONAS BIOCLIMATICAS, ASOCIADAS A VEGETACION TIPICA PARA CADA CLIMA, USANDO SISTEMAS DE INFORMACION GEOGRAFICA (SIG).

Methodological approach to the study of the daily persistence of the sea breeze in Alicante (Spain)

Abstract: ESTE ESTUDIO EXAMINA EL GRADO DE PERSISTENCIA DE LA BRISA MARINA EN ALICANTE. ESTA INVESTIGACION ESTA BASADA EN LA SECUENCIA DE DATOS SEMI-HORARIOS DE DIRECCION Y VELOCIDAD DE VIENTO CORRESPONDIENTES AL PERIODO QUINQUENAL 1999-2003 (BASE DE DATOS DE DIAS DE BRISA MARINA). EL COMPORTAMIENTO REPETIDO DE ESTA VARIABLE METEOROLOGICA (DIAS CONSECUTIVOS CON VIENTOS EN REGIMEN DE BRISA MARINA) ES ESTUDIADO MEDIANTE LA APLICACION DE VARIOS METODOS Y TECNICAS ESTADISTICAS: ANALISIS DEL NUMERO Y LONGITUD DE LAS RACHAS DE DIAS CON BRISA MARINA; DISTRIBUCION DE FRECUENCIAS DE LAS RACHAS SEGUN LA DURACION (CURVAS DE CONCENTRACION O DE LORENZ); CALCULO DE COEFICIENTES DE PERSISTENCIA (PROBABILIDADES EMPIRICAS Y CONDICIONADAS), Y ENSAYO DE PROBABILIDADES DE DURACION DE LAS RACHAS DE BRISA MARINA UTILIZANDO EL MODELO DE LAS CADENAS DE MARKOV DE PRIMER Y SEGUNDO ORDEN (CM1 Y CM2). LOS RESULTADOS DEMUESTRAN EL ELEVADO GRADO DE PERSISTENCIA DE ESTE MECANISMO DE VIENTOS EN EL SURESTE DE LA PENINSULA IBERICA, PARTICULARMENTE EN VERANO. LA PERSISTENCIA DE LA BRISA MARINA SE RELACIONA CON DOS FACTORES PRINCIPALES: LAS CONDICIONES SINOPTICAS REGIONALES (DEBIL GRADIENTE DE PRESION EN SUPERFICIE) Y LAS CARACTERISTICAS DEL TERRENO ""TOPOGRAFIA"". LA CARACTERIZACION ESTADISTICA DE LA PERSISTENCIA DE LA BRISA MARINA PODRIA SER UNA HERRAMIENTA UTIL EN EL ANALISIS DE LA VARIABILIDAD ANUAL Y ESTACIONAL DE LOS NIVELES DE CONTAMINACION ATMOSFERICA EN LA CUENCA DEL MEDITERRANEO.

Interannual and interdecadal variability in the predominant Pacific region SST anomaly patterns and their impact on climate in the mid-Mississippi valley region

Abstract: Previous research has demonstrated that Pacific Region SSTs and SST anomalies can be separated into seven general synoptic classifications (clusters) (A-G). Clusters B and G (C, D, and F) [A and E] were shown to be generally representative of La Nina (El Nino) [neutral] type SST distributions. Further, an analysis of the SST patterns in 1955-1993 demonstrated that clusters A-D were prominent in 1955-1977, while types E and F dominated the later period. Type G clusters were comparatively rare, but occurred during both periods. In retrospect, this shift during 1977 corresponds roughly with a change in phase of the Pacific Decadal Oscillation (PDO). After updating the analysis to include the 1994 to 2005 period, there was a corresponding change in the predominant SSTs associated with a change in phase of the PDO during 1999 and 2000. The results show that SST patterns did evolve from predominantly E and F-type anomalies in 1994 to A, B, D and G-type anomalies through 2005. Thus, these results suggest that A through D-type (C, E, and F-type) SST clusters are characteristic of the negative (positive) phase of the PDO. Also, using a modified technique for generating phase diagrams, it is shown that there are interannual and interdecadal variations in the mid-Mississippi region monthly mean surface temperature and precipitation records that can be associated with the ENSO and PDO. Additionally, an analysis was performed to see if there was any statistical association between temperature and precipitation anomalies in the mid-Mississippi region and prolonged SST regimes. B, D and G anomalies were associated with warmer-than-normal conditions, while C and E type anomalies tended to be associated with cooler-than-normal conditions across the region. C, D, F, and G anomalies were associated with drier than normal conditions.

The nature of the rainfall onset over central South America

Abstract: The objective of this work is to provide a detailed description of the onset of the South American Monsoon based on precipitation observations available over tropical and subtropical South America. The analysis was also performed using outgoing longwave radiation (OLR) data in order to assess the ability of this particular dataset to reproduce the main features associated with precipitation evolution during austral spring. Results show that both OLR and precipitation data agree in describing the progression of convection from the northwest and southeast into central Brazil by the beginning of October. Moreover the assessment of available methods to identify onset dates shows that the method of Kousky (1988), based on the OLR evolution, provides the onset date in most of South America, without regionally adaptation, as the methods based on rainfall generally require. Composite fields show that rainfall in central Brazil begins with moderate rates, which are still lower than those observed over the northwestern and southeastern tropical regions. After the rainfall jump, that on average occurs three pentads later than the onset of rainfall, precipitation rates increase over central Brazil and similar rates are observed over the entire tropical region. It is suggested that transient activity, which occurs around the onset period when the atmospheric mean conditions are getting more unstable as they approach summer-like conditions, is the one that imprints a rainfall-jump feature in the precipitation evolution. The character of changes in the precipitation rate, as the rainy season develops, provides complementary information that can be used together with onset date.

The global and UV-B radiation over Egypt

Abstract: This work studies the relation between UV-B radiation and global radiation over Egypt. The relationships between the global solar radiation and UV-B radiation at four stations in Egypt have been studied, and linear empirical formulas for estimating UV-B from global radiation at these stations has been deduced. The deduced equations were applied to calculate the UV-B radiation for other stations where measurements were unavailable, using records of global radiation at these stations. Because of the periodicity of variations in solar radiation, global and UV-B radiation, the non-dimensional values are expanded in Fourier series. Fourier coefficients were determined by using measured global solar radiation data of the selected stations. These coefficients were used to calculate UV-B radiation based on global solar radiation for the same stations. A comparison between observed and calculated UV-B radiation arising from the two methods of estimation is presented. The comparison showed a good agreement between the observed and estimated UV-B radiation. The application of linear regression method to calculate solar radiation for other stations where UV-B radiation measurements were unavailable was better than Fourier coefficients method.

Some implications of time series analysis for describing climatologic conditions and for forecasting: An illustrative case: Veracruz, México

Abstract: The common practice of using 30-year sub-samples of climatological data for describing past, present and future conditions has been widely applied, in many cases without considering the properties of the time series analyzed. This paper shows that this practice can lead to an inefficient use of the information contained in the data and to an inaccurate characterization of present, and especially future, climatological conditions because parameters are time and sub-sample size dependent. Furthermore, this approach can lead to the detection of spurious changes in distribution parameters. The time series analysis of observed monthly temperature in Veracruz, Mexico, is used to illustrate the fact that these techniques permit to make a better description of the mean and variability of the series, which in turn allows (depending on the class of process) to restrain uncertainty of forecasts, and therefore provides a better estimation of present and future risk of observing values outside a given coping range. Results presented in this paper show that, although a significant trend is found in the temperatures, giving possible evidence of observed climate change in the region, there is no evidence to support changes in the variability of the series and therefore there is neither observed evidence to support that monthly temperature variability will increase (or decrease) in the future. That is, if climate change is already occurring, it has manifested itself as a change-in-the-mean of these processes and has not affected other moments of their distributions (homogeneous non-stationary processes). The Magicc-Scengen, a software useful for constructing climate change scenarios, uses 20-year sub-samples to estimate future climate variability. For comparison purposes, possible future probability density functions are constructed following two different approaches: one, using solely the Magicc-Scengen output, and another one using a combination of this information and the time series analysis. It is shown that sub-sample estimations can lead to an inaccurate estimation of the potential impacts of present climate variability and of climate change scenarios in terms of the probabilities of obtaining values outside a given coping range.

Methane conversion factors from cattle manure in México

Abstract: Methane emission factors from different cattle manure management systems including simulated slurry system fermentation were experimentally determined in this and a previous study (Gonzalez-Avalos and Ruiz-Suarez, 2001). Combining results from both studies, we report values for maximum CH4 yield, called B0, for manure produced by cattle under different production systems and climates, which also implies different quality of feeds and associated methane conversion factors (MCF) for distinct manure management systems. This set of data has the same functionality than that of the current IPCC methodology, but offer a wider set of key parameters to estimate methane emissions from manure, which may be of interest in other countries. In this work, we report MCF can be up to 17.3 times smaller than those suggested in the 1996 Revised IPCC Methodology Guidelines (IPCC, 1997) and Good Practice Guidance (IPCC, 2000).

Characterization of atmospheric transport to the El Tajín archaeological zone in Veracruz, México

Abstract: Features of long- and short-range atmospheric transport to El Tajin, an important archaeological site in Veracruz, Mexico, are investigated. The study is motivated by the need for an increased understanding of the

Analysis of full-scale data obtained in a street canyon

Abstract: EN LAS CIUDADES, PRINCIPALMENTE EN LOS CANONES URBANOS, SE PUEDEN PRESENTAR ALTOS NIVELES DE CONCENTRACION DE CONTAMINANTES EN AIRE. EL FLUJO DEL AIRE EN LOS CANONES URBANOS ESTA MODIFICADO POR EFECTOS AERODINAMICOS Y TERMICOS, Y POR EL MOVIMIENTO DE LOS VEHICULOS QUE INFLUYEN SOBRE LOS NIVELES DE CONTAMINACION. EN ESTE TRABAJO, SE ANALIZAN VALORES HORARIOS DE CONCENTRACIONES DE CO Y NOX MEDIDAS A 1.5 M DE ALTURA EN EL LADO OESTE DE UN CANON URBANO DE GTTINGER STRASSE EN HANNOVER (ALEMANIA) Y DE CONCENTRACIONES DE FONDO DE CO Y NOX OBSERVADAS EN EL TECHO DE UN EDIFICIO LATERAL. ASIMISMO, SE INCLUYEN EN EL ANALISIS LAS OBSERVACIONES HORARIAS DE VELOCIDAD Y DIRECCION DEL VIENTO AMBIENTAL EN EL TECHO DE ESE EDIFICIO LATERAL E INFORMACION HORARIA DE VOLUMEN DE TRANSITO EN LA CALLE DEL CANON. LOS RESULTADOS PERMITEN INFERIR LA PRESENCIA DE UN VORTICE EN EL AIRE DENTRO DEL CANON URBANO, CUANDO EL VIENTO AMBIENTAL ES MAYOR QUE 1.8 M/S Y ES PERPENDICULAR AL EJE DE LA CALLE. SE REALIZAN ALGUNAS EVALUACIONES DE LA INFLUENCIA DE LAS TURBULENCIAS AMBIENTAL E INDUCIDA POR LOS VEHICULOS SOBRE LAS CONCENTRACIONES LOCALES EN EL CANON. LOS RESULTADOS MUESTRAN QUE CUANDO LA VELOCIDAD DEL VIENTO ES MENOR QUE 2 M/S, EL EFECTO DE LA TURBULENCIA INDUCIDA POR LOS VEHICULOS AFECTA LA DISPERSION DE LOS CONTAMINANTES DENTRO DEL CANON URBANO.

Study of diurnal and seasonal variation of atmospheric NO2, O3, H2O and O4 at Pune, India

Abstract: Study of diurnal and seasonal variation of atmospheric trace gases is essential to understand our atmosphere. For this, daily zenith-sky scattered light observations have been made by UV-visible spectrometer during the period 2000-2003. Slant column densities (SCD) from morning (solar zenith angle SZA = 90o) to evening (SZA = 90o) were retrieved to see the diurnal variation of NO 2 , O 3 , H 2 O and O 4 . For the study of seasonal behavior of NO 2 and O3, vertical column densities (VCD) were retrieved during the above period. For the whole period, NO2 and O 3 VCD are found in a positive correlation of r = 0.72 for the morning data and r = 0.79 for the evening data. Satellites borne observations are compared with the spectroscopic observations, which are found in good correlation. It is seen that highest NO 2 and O 3 VCD are found in summer months (May and June) and lowest in winter months (December and January). Evening NO 2 VCD are found higher compared to morning. There is found an interesting seasonal change that at Pune (18o32´ N, 73o51´ E), the evening-to-morning (PM/AM) ratios of NO 2 as well as temperature maximum/minimum ratios are higher in winter months and lower in summer months during the above period. In winter months NO 2 PM/AM ratio goes up to 3.8 and in summer months lowest ratio is 1.25. During the day, N 2 O 5 can be photolyzed to regenerate NO 2 , which reflects in the evening hours. In the winter, nights are longest; therefore, during night NO 2 to N 2 O 5 conversion is more, hence in the morning NO 2 value will be less that leads to high PM/AM ratio. O 3 PM/AM ratio is slightly higher in winter months compared to summer months.

Seasonal dependence of peroxyacetylnitrate (PAN) concentrations in downtown Santiago, Chile

Abstract: EL OZONO Y EL NITRATO DE PEROXIACETILO (PAN) SON CONTAMINANTES SECUNDARIOS DE ORIGEN FOTOQUIMICO. ES POR LO TANTO ESPERABLE QUE ALCANCEN SUS MAXIMAS CONCENTRACIONES EN PERIODOS DE ALTA IRRADIACION SOLAR (PRIMAVERA Y VERANO). SIN EMBARGO, EN LA CIUDAD DE SANTIAGO DE CHILE SE PRESENTAN ALTAS CONCENTRACIONES DE PAN EN EPOCA DE OTONO. LOS PROMEDIOS DEL VALOR MAXIMO DIARIO SON: 4.0 ± 1.7 PPB, EN OTONO (MAYO Y JUNIO); 0.9 ± 0.5 PPB EN INVIERNO (JULIO Y AGOSTO); 1.9 ± 1.0 PPB EN PRIMAVERA (OCTUBRE Y NOVIEMBRE) Y 3.1 ± 1.4 PPB EN VERANO (ENERO Y MARZO). EN OTONO, LOS VALORES INTEGRADOS DEL PERFIL DIARIO DE CONCENTRACION SON TAMBIEN CONSIDERABLEMENTE MAYORES QUE EN OTROS PERIODOS DEL ANO (PROMEDIO DEL PERFIL DIARIO: 38 PPB-HORA EN MAYO Y 13 PPB HORA EN ENERO). ESTE COMPORTAMIENTO SE RELACIONARIA CON LA MENOR ESTABILIDAD TERMICA DEL PAN EN VERANO. ESTE FACTOR, JUNTO A LA ALTA ESTABILIDAD ATMOSFERICA Y MENORES ALTURAS DE LA CAPA DE MEZCLA EN LOS MESES DE OTONO, EXPLICARIA LOS ALTOS NIVELES DE CONCENTRACIONES MEDIDOS EN PERIODOS DE BAJA IRRADIACION SOLAR

Ensemble lagged forecasts of a monsoon depression over India using a mesoscale model

Abstract: DURANTE EL 27 DE JULIO DE 1999 SE FORMO UNA DEPRESION MONZONICA SOBRE LA BAHIA DE BENGALA, INDIA, QUE CRUZO LA COSTA ESTE DEL PAIS EL 28 DE JULIO DEL MISMO ANO. EL SISTEMA OCASIONO LLUVIAS ABUNDANTES SOBRE LA COSTA ESTE Y REGIONES ADYACENTES Y ES INVESTIGADO EN ESTE TRABAJO UTILIZANDO METODOS DE ENSAMBLE RETRASADOS CON EL MODELO DE MESOESCALA DE QUINTA GENERACION (MM5) DE LA PENNSYLVANIA STATE UNIVERSITY Y EL NATIONAL CENTER FOR ATMOSPHERIC RESEARCH (PSU/NCAR). SE DISENAN DOS GRUPOS DE EXPERIMENTOS CON CINCO MIEMBROS DE ENSAMBLES CADA UNO EMPEZANDO EL 25 DE JULIO DE 1999 A LAS 12 UTC CON INTERVALOS SUBSIGUIENTES DE 3 HORAS. EN EL PRIMER EXPERIMENTO SE UTILIZAN LOS DATOS DEL REANALISIS DEL NACIONAL CENTER FOR ENVIRONMENTAL PREDICTION (NCEP) PARA EL PRONOSTICO DE UN DOMINIO DE MALLA GRUESA Y UN ANIDAJE SUBSECUENTE A UN DOMINIO DE MALLA MAS FINO (30 KM). EN EL SEGUNDO EXPERIMENTO LOS DATOS DEL REANALISIS DEL NCEP SE UTILIZAN DIRECTAMENTE EN EL DOMINIO DE 30 KM COMO CONDICIONES INICIALES Y DE FRONTERA. SE ENCUENTRA QUE EN LOS TIEMPOS INICIALES DE VERIFICACION, EL PROMEDIO DEL ENSAMBLE DEL CAMPO DE PRESION AL NIVEL DEL MAR CORRESPONDIENTE AL SEGUNDO EXPERIMENTO TIENE UNA ESTRUCTURA HORIZONTAL MAS GRANDE Y ES MAS CERCANO AL REANALISIS DEL NCEP. SIN EMBARGO, SE ENCONTRO QUE EN TIEMPOS POSTERIORES DE VERIFICACION EL PROMEDIO DEL ENSAMBLE DEL CAMPO DE PRESION AL NIVEL DEL MAR ES MEJOR EN EL PRIMER EXPERIMENTO. TODOS LOS MIEMBROS DEL ENSAMBLE DEL PRIMER EXPERIMENTO TIENEN VALORES MAYORES EN EL AREA PROMEDIO DE PRECIPITACION ACUMULADA DE 24 HORAS QUE LOS DEL SEGUNDO EXPERIMENTO. ASIMISMO, LOS VALORES DE LA DISPERSION DE TODOS LOS MIEMBROS DEL ENSAMBLE DEL PRIMER EXPERIMENTO PARA EL AREA PROMEDIO DE PRECIPITACION ACUMULADA DE 24 HORAS SON MAYORES QUE LOS DEL PROMEDIO DE SU RESPECTIVO ENSAMBLE EN EL SEGUNDO EXPERIMENTO. LOS RESULTADOS DE ESTE ESTUDIO PUEDEN SER UTILES PARA LOS CENTROS DE PRONOSTICO OPERATIVO DEL TIEMPO EN LA INDIA, YA QUE PUEDEN PROPORCIONAR DIFERENTES MANERAS DE DESARROLLAR Y PROBAR LA IMPORTANCIA DE LOS ENSAMBLES.

The storm of January 1, 2000, north of the city of Mendoza

Abstract: The objective of this paper is the study of the conditions observed before and during the development of the convective storm recorded the last hours of January 1, 2000, that affected an area located north of the city of Mendoza, including the International Airport. The work also attempts to determine the behavior of the dynamic and thermodynamic variables that triggered off this case of severe convection. The hourly surface data and daily radiosoundings of Meteorological Station Mendoza Aero, identified as SAME, were analyzed for the period December 30, 1999 to January 2, 2000. The synoptic scale analysis was done with information of National Center for Enviromental Prediction and National Center for Atmospheric Research (NCEP/NCAR), USA, and the results from Centro de Previsao de Tempo e Estudos Climaticos (CPTEC), Brazil. Mesoscale precipitation information was obtained from Instituto Nacional del Agua (INA) network, Argentina. During one hour of the storm the record in SAME was 66.1 mm, surpassing the historical daily and hourly maximum. Principal results shows that there was an intense advection of warm and humid air on the surface, proceeding from the northeast of the country, while a short wave trough axis came from the Pacific Ocean. Nevertheless wind hodograph showed similar characteristics like a weak isolated storm, the intensity was enhancement by a dynamic trigger represented by the trough. Even though the phenomenon did not differ from the usual storms with respect to the time of occurrence and duration, it had extraordinary features in regards to the precipitation intensity, that surpassed the historical daily values at the SAME. It is necessary to improve research about physical mechanisms of the storms and its climatology for better indentification and predictions, and also to understand the mechanisms that led to the production of intense precipitation.

Sensitivity of cloud albedo to aerosol concentration and spectral dispersion of cloud droplet size distribution

Abstract: Both the enhancement of the aerosol number concentration and the relative dispersion of the cloud droplet size distribution (spectral dispersion) on a regional scale can modify the cloud reflectivity. This work is focused on the role that pre-cloud aerosol plays in cloud reflectivity. Log-normal aerosol size distributions were used to describe two aerosol types: marine and rural. The number of aerosols that activate to droplets was obtained based on Abdul-Razzak and Ghan’s (2000) activation parameterization. The cloud albedo taking into account the spectral dispersion effect in the parameterization of cloud effective radius and in the scattering asymmetry factor has been estimated. Two different scaling factors to account for dispersion were used. The sensitivity of cloud albedo to spectral dispersion-cloud droplet number concentration relationship in connection to the changes in liquid water content (LWC), and the cloud droplet effective radius has been also investigated. We obtained higher values of effective radius when dispersion is taken into account, with respect to the base case (without considering dispersion). The inferred absolute differences in effective radius values between calculations with each of the scaling factors are below 0.8 μm as LWC ranges between 0.1 and 1.0 g m -3 . The optical depth decreased by up to 14% (marine), and up to 29% (continental) when dispersion is considered in both effective radius and asymmetry factor (β LDR scaling factor). Correspondingly, the relative change in cloud albedo is up to 6% (marine) and up to 11% (continental) clouds. For continental clouds, the calculated effective radius when dispersion is considered fits well within the measured range of effective radius in SCAR-B project. The calculated cloud albedo when dispersion is considered shows better agreement with the estimated cloud albedo from measured effective radius in SCAR-B project than the cloud albedo calculated without dispersion. In cleaner conditions of marine clouds, only β PL -scaled albedo fits satisfactory within the validity range of albedo inferred using an effective radius-liquid water content relationship proposed by Reid et al. (1999) from ASTEX project. The low correlation coefficient of the effective radius-liquid water content parameterization in ASTEX may also play a role within.

Differences in the monthly evolution of the Antarctic ozone hole size

Abstract: We study here the evolution of the ozone hole size (OHS) with the aim of contributing to understand the long term evolution and the origin of the discrepancies between modeled and observed size. Using the September, October and November monthly average data of the OHS, for the years 1982-2003, we separate the series into two components: a linear and a residual one. The residual OHS components for October-November, shows a tendency to decrease after 1997, whereas the residual component of September does not show a clear decrease. The OHS during September evolve different, in relation to the other months. Therefore, the earlier results for the OHS analysis obtained with an annual approach may be refined.

A short communication on meteorological observations at Mt. Everest 6523 m

Abstract: Mt. Everest is relatively inaccessible and little is known about its meteorology. On 27 April 2005, an automatic weather station was displayed on the north column (28°01′0.95″N, 86°57′48.4″E, 6523 masl) of Mt. Everest. This paper summarizes the meteorological data collected from 1 May to 22 July 2005. The measured variables included long-wave radiation, air temperature, relative humidity and baromteric pressure. The daily record indicates synoptic scale variability in the thermodynamic variables, while short-wave radiation and wind speed decrease gradually at different degree, net radiation changes little with a slight increase, and wind direction turns from north to south.

Prediction of binary tropical cyclones path on northeastern Pacific Ocean

Abstract: In this article, some results of numerical prediction of binary tropical cyclones (or binary systems) paths are presented. The analyzed systems were produced between 1984 and 2005, southward of 20o North latitude on northeastern Pacific Ocean adjacent to Mexico. In this zone, it is common that tropical cyclones be accompanied by cloud clusters or another tropical cyclone that might be a mesoscale convective system, (MCS), a tropical depression, a tropical storm or a hurricane, establishing an interaction that is able to affect their typical tracks. When simulating a binary system in this work, the ability of the model to predict the path of this kind of tropical cyclones was improved. In all cases, western coast of Mexico was affected by this kind of systems.

Simultaneous occurrence of the North Atlantic Seesaw and El Niño

Abstract: SE APLICAN MODELOS DE REGRESION LOGISTICA DICOTOMICA Y POLITOMICA EN SERIES DE REGISTROS HISTORICOS DE SIGLO Y MEDIO (1840-1990) DEL SEESAW DEL ATLANTICO NORTE Y EL NINO, BUSCANDO PROBABILIDADES DE OCURRENCIA SIMULTANEA DE AMBOS FENOMENOS EN LOS MESES INVERNALES BOREALES Y CLASIFICANDO EL SEESAW EN CUATRO MODALIDADES Y EL NINO EN TRES INTENSIDADES. EL SEESAW SE REFIERE A LAS ANOMALIAS DE TEMPERATURA EN GROENLANDIA Y NORUEGA; SUS MODALIDADES SON: AMBAS POSITIVAS (AP), AMBAS NEGATIVAS (AN), GROENLANDIA POSITIVA CON NORUEGA NEGATIVA (GP) Y GROENLANDIA NEGATIVA CON NORUEGA POSITIVA (GN). SE ENCUENTRA UNA INCIDENCIA MAYOR DEL SEESAW CONFORME AVANZA EL INVIERNO, ASI COMO UNA SIMULTANEIDAD DE OCURRENCIA DEL 61% DEL SEESAW Y EL NINO. LAS MODALIDADES HETEROGENEAS DEL SEESAW (GP Y GN) COINCIDEN EN 71% CON EL NINO, MIENTRAS QUE LAS HOMOGENEAS (AP Y AN) LO HACEN EN 29%. LAS MODALIDADES HETEROGENEAS TIENEN UNA COINCIDENCIA MAYOR CON EL NINO DE INTENSIDAD MAS ELEVADA (3). AL APLICAR UNA PRUEBA DE BONDAD DE AJUSTE PARA LAS PROBABILIDADES ESTIMADAS POR EL MODELO LOGISTICO POLITOMICO, EN COMPARACION CON LAS FRECUENCIAS OBSERVADAS, SE OBTUVO UN AJUSTE MUY BUENO AL ANALIZAR LAS TEMPORADAS INVERNALES COMPLETAS.

Total peroxides and sulfate in rainwater in the Mexican eastern Pacific Ocean during the Climatic Experiment in the Americas Warm Water Pools

Abstract: Total peroxides were analyzed in 26 rainwater samples collected on board of the R/V El Puma of the National Autonomous University of Mexico (UNAM) during the Climatic Experiment in the Americas Warm Water Pools (ECAC-1) over the eastern Pacific Ocean between 12 and 14o N, and between 98 and 100o W, from May 23 to 25, 2001. The volume weighted mean concentration of total peroxides was 13.1 ± 1.94 μM. Also, sulfate ion was analyzed. The volume weighted mean concentrations for sulfate and sea-salt sulfate were 0.76 ± 0.59 and 0.04 ± 0.06 mg L -1 , respectively. Excess sulfate (non-sea-salt sulfate) represented 95% of the total sulfate. The total peroxides concentration in rainwater correlated significantly with total sulfate and excess sulfate (0.560 and 0.586 at a p < 0.05, respectively) possibly because most of the excess sulfate and hydrogen peroxide, observed in the Mexican eastern Pacific Ocean, could have been produced from the oxidation of biogenic sulfur compounds. The non-significant correlation between sea-salt sulfate and total peroxides was due to the fact that H 2 O 2 does not react with the sulfate already present in sea salt aerosols. Also, the concentration of total peroxides did not correlate with rain intensity probably because a significant fraction of H 2 O 2 could have been generated within cloud droplets.

On the usefulness of atmospheric measurements for air quality evaluation in the context of recent urban meteorology findings in México City

Abstract: In many cities, the main tool used to assess pollution abatement policies is the air quality information obtain-ed from local monitoring network. However, in the context of a complex meteorology and land use such as those prevailing in Mexico City, the point-wise character and lack of detailed chemistry of this information may confer conflictive or biased information. The approach to understand the problem could be not based on solid ground. It is not until the measurement effort is complemented with detailed meteorological and air quality modeling that proper use of the information can be assured. In order to provide an example of this assertion, the usefulness of measured air quality data is gauged in a simplified manner, constructing three dimensional graphs containing local emission concentrations of nitrogen oxides (NO x ), volatile organic compounds (VOC) and maximum ozone (O 3 ) concentrations, that we call “ozone isopleths”, for three sites in Mexico City. Together with corresponding wind rose data, an interpretation of the air pollution transport in the Valley of Mexico using only measured data is attempted. This interpretation, based on measured information subject to local influences, is compared with recent air quality modeling results showing that when measured data is used in conjunction with air quality modeling a better interpretation of air pollution problem can be obtained. A correct strategy to study the air quality problem, especially in the case of Mexico City where complex meteorology and land use is present, should be that both endeavors, measuring and modeling, are pursued with equal vigor.