Regional flow frequency analysis of river basin with headwaters at the Andes cordillera

El objetivo es determinar la magnitud del caudal anual y estacional, para periodos de retorno mucho mayores que los observados y obtener el cuantil correspondiente en sitios sin información, a partir del Análisis Regional de Frecuencias basadas en la estadística de momentos $L$ ($ARF-LM$). El área de estudio abarca las cuencas cordilleranas desde el río Bermejo hasta el río Santa Cruz. Los sitios analizados fueron 32 y se determinaron 5 variables: caudal anual ($Q_{a tilde{n}o}$) y caudales estacionales: invierno $Q_I$ (julio, agosto, setiembre), primavera $Q_P$ (octubre, noviembre, diciembre), verano $Q_V$ (enero, febrero, marzo) y otoño $Q_O$ (abril, mayo, junio), a partir del caudal medio diario observado. Se verificaron las condiciones de independencia, aleatoriedad, normalidad y homogeneidad. La normalidad es rechazada en el 60 % de los casos, particularmente en los caudales de verano y otoño; la ausencia de independencia y aleatoriedad ocurre en el 34 % de las series analizadas, destacándose el caudal de invierno y otoño, para un nivel de significancia de $alpha=5$. Los ríos Los Patos, San Juan, Las Cuevas, Diamante, Atuel, Grande, Valenzuela, Poti Malal, Neuquén y Santa Cruz no mostraron tendencias significativas en ninguna de las variables. Se detectaron tendencia creciente significativa en variables y sitios del noroeste y centro-oeste argentino y tendencia decreciente en variables y sitios de Los Andes patagónicos. Los caudales $Q_a tilde{n}o$, $Q_I$ y $Q_V$ muestran cambios abruptos en el 65 % de los casos, el $Q_P$, en un 44 %. El salto en los valores medios generalmente se produce en la década del 70. Se identificaron las regiones homogéneas para las 5 variables analizadas. La homogeneidad se verificó mediante pruebas de Discordancia y Heterogeneidad y la adopción de la distribución de mejor ajuste por medio de la medida $Z^{DIST}$ y $PUM_T$. Las distribuciones empleadas son: Generalizada de Valores Extremos, Logística Generalizada, Generalizada Normal, Normal, Gumbel, Pareto Generalizada, Exponencial y Pearson III. En todos los casos, la región homogénea encontrada incluye solamente estaciones de Los Andes Centrales sur, desde el río Tunuyan al Colorado. La función Pearson III y Gumbel, son las que presentan el mejor ajuste.The aim is to determine the magnitude of flow variables for return periods much longer than the observed and to obtain the correspondent quantil for sites with scarce data using a Regional Frequency Analysis approach based on $L-moment$ statistics ($ARF-LM$). The area under analysis comprises mountain basins between the Bermejo and the Santa Cruz rivers. Thirty-two gauging stations were analyzed and five variables were determined: annual flow ($Q_{a tilde{n}o}$) and seasonal flows: winter $Q_I$ (july, august, september), spring $Q_P$ (october, november, december), summer $Q_V$ (january, february, march) and autumn $Q_O$ (april, may, june), from the average daily flow observed. Independence, randomness, normalcy, and homogeneity conditions were verified. Normalcy is rejected in 60 % of the cases, summer and autumn flows being the variables with the least degree of normalcy. Lack of both independence and randomness occurs in 34 % of the series analyzed, notably the winter and autumn flows with a level of significance of 5 %. The Los Patos, San Juan, Cuevas, Diamante, Atuel, Grande, Valenzuela, Poti Malal, Neuquén and Santa Cruz rivers did not show any significant trends in the variables analyzed. A statistically significant increasing trend was detected in some variables and locations of northwestern and central-western of Argentina while a decreasing trend was observed in some variables and locations in the Patagonian Andes. Flows $Q_{a tilde{n}o}$), $Q_I$ and $Q_V$ show abrupt changes in over 65 % of the cases while $Q_P$ only in 44 %. In general, the jump in mean values took place in the 1970s.A homogeneous region was identified for each of the five variables. Homogeneity was verified by means of discordance and heterogeneity tests and the best-fit distribution through $Z^{DIST}$ and $PUM_T$ measures. The distributions used were: generalized extreme values, generalized logistic, generalized normal, normal, Gumbel, generalized Pareto, exponential, and Pearson III. In all cases the homogeneous region includes only stations in the southern Central Andes, from the Tunuyan to the Colorado river. The Pearson III and Gumbel distributions exhibit the best fit.Fil: Vich, Alberto Ismael Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina. Universidad Nacional de Cuyo. Facultad de Filosofía y Letras. Instituto de Estudios del Ambiente y Los Recursos Naturales; ArgentinaFil: Norte, Federico Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Lauro, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentin

The potential of food fortification to add micronutrients in young children and women of reproductive age - findings from a cross-sectional survey in Abidjan, Côte d'Ivoire

Poor micronutrient intakes are a major contributing factor to the high burden of micronutrient deficiencies in Côte d'Ivoire. Large-scale food fortification is considered a cost-effective approach to deliver micronutrients, and fortification of salt (iodine), wheat flour (iron and folic acid), and vegetable oil (vitamin A) is mandatory in Côte d'Ivoire. A cross-sectional survey on households with at least one child 6-23 months was conducted to update coverage figures with adequately fortified food vehicles in Abidjan, the capital of and largest urban community in Côte d'Ivoire, and to evaluate whether additional iron and vitamin A intake is sufficient to bear the potential to reduce micronutrient malnutrition. Information on demographics and food consumption was collected, along with samples of salt and oil. Wheat flour was sampled from bakeries and retailers residing in the selected clusters. In Abidjan, 86% and 97% of salt and vegetable oil samples, respectively, were adequately fortified, while only 32% of wheat flour samples were adequately fortified, but all samples contained some added iron. There were no major differences in additional vitamin A and iron intake between poor and non-poor households. For vitamin A in oil, the additional percentage of the recommended nutrient intake was 27% and 40% for children 6-23 months and women of reproductive age, respectively, while for iron from wheat flour, only 13% and 19% could be covered. Compared to previous estimates, coverage has remained stable for salt and wheat flour, but improved for vegetable oil. Fortification of vegetable oil clearly provides a meaningful additional amount of vitamin A. This is not currently the case for iron, due to the low fortification levels. Iron levels in wheat flour should be increased and monitored, and additional vehicles should be explored to add iron to the Ivorian diet

High awareness butlow coverage of a locally produced fortified complementary food in Abidjan, Côte d'Ivoire : findings from a cross-sectional survey

Poor complementary feeding practices among infants and young children in Côte d'Ivoire are major contributing factors to the country's high burden of malnutrition. As part of a broad effort to address this issue, an affordable, nutritious, and locally produced fortified complementary food product was launched in the Côte d'Ivoire in 2011. The objective of the current research was to assess various levels of coverage of the program and to identify coverage barriers. A cross-sectional household survey was conducted among caregivers of children less than 2-years of age living in Abidjan, Côte d'Ivoire. Four measures of coverage were assessed: "message coverage" (i.e., has the caregiver ever heard of the product?), "contact coverage" (i.e., has the caregiver ever fed the child the product?), "partial coverage" (i.e., has the caregiver fed the child the product in the previous month?), and "effective coverage" (i.e., has the caregiver fed the child the product in the previous 7 days?). A total of 1,113 caregivers with children between 0 and 23 months of age were interviewed. Results showed high message coverage (85.0%), moderate contact coverage (37.8%), and poor partial and effective coverages (8.8% and 4.6%, respectively). Product awareness was lower among caregivers from poorer households, but partial and effective coverages were comparable in both poor and non-poor groups. Infant and young child feeding (IYCF) practices were generally poor and did not appear to have improved since previous assessments. In conclusion, the results from the present study indicate that availability on the market and high awareness among the target population is not sufficient to achieve high and effective coverage. With market-based delivery models, significant efforts are needed to improve demand. Moreover, given the high prevalence of malnutrition and poor IYCF practices, additional modes of delivering IYCF interventions and improving IYCF practices should be considered

Características del viento zonda en la región de Cuyo

En zonas montañosas se observa ocasionalmente un viento fuerte que desciende desde la cresta al valle o al llano. Recibe distintasdenominaciones segun las zonas donde sopla: chinook en Estados Unidos y Canadá; fohn en los Alpes Europeos; Canterbury - northwester en Nueva Zelandia; bers wind en Sud Africa; Zonda en Argentina. El objetivo principal de este trabajo de tesis es determinar laestructura del Viento Zonda y las causas de su aparicion para obtener undiagnóstico de su comportamiento y métodos de pronóstico de alto grado devalidación. Los objetivos parciales o secundarios son: establecer el régimenclimatológico de la ocurrencia del Zonda y los Parámetros meteorológicosque lo acompañan en estaciones de ubicación geográfica y altura diferentes;analizar la estructura tridimensional del fenómeno; investigar sobre losprocesos físicos involucrados en su aparición; establecer reglas depronóstico objetivo en base a parámetros termodinámicos, sinópticos yclimáticos. Existen algunos antecedentes sobre el tema en nuestro país entrabajos específicos y en otros donde si bien el tópico central no es el Zonda, el fenómeno aparece mencionado. En el extranjero existe una bibliografía mucho más abundante referidaal fenómeno, especialmente en Canadá, Estados Unidos y Suiza, Alemania y Austria. Una caracterización geográfica mediante fotos satelitarias permitevisualizar los distintos accidentes orográficos y las laderas montañosasprincipales. Se realizó una climatología del llano, a partir de la selecciónsubjetiva para las estaciones de los días de Viento Zonda con datos diariosde libretas meteorológicas. Este método se desarrolló considerando un conjunto de variables ocombinación de las mismas consideradas relevantes "a Priori" paraidentificar la ocurrencia de Viento Zonda, resultando sersatisfactoriamente eficaz ya que permite hallar casi todos los eventos deuna serie prolongada. Para corroborar la eficiencia de esta forma de identificación decasos, se aplicó el método estadístico del Análisis Discriminante Escalonado que permitió, además, establecer una jerarquia de las variablesrespecto a su mayor o menor incidencia en la discriminación de "días de Viento Zonda" con los de ausencia del mismo. Se aplicó solamente a lasciudades de Mendoza y San Juan clasificando mejor los casos de esta últimapor la mayor frecuencia y mejor definición del fenómeno en esa localidad. Las variaciones hisrotérmicas y el viento máximo alcanzado son loselementos que identifican mejor al día de Viento Zonda. La ausencia de nubes bajas, la nubosidad lenticular y la de "pared ofranja" del Zonda desempeñan un papel importante en El Plumerillo (Aeropuerto de la ciudad de Mendoza). En invierno el calentamiento es lo que mejor discrimina y durante elresto del año la disminución de humedad es el factor mas relevante. En el llano el Viento Zonda es un fenómeno poco frecuente, siendobastante menor la ocurrencia de eventos severos o muy severos. Con respecto a la marcha anual, es entre Mayo a Noviembre que ocurrela mayoria de casos a más de la mitad se registra entre Mayo a Agosto. La menor frecuencia está condicionada a la altura sobre el nivel delmar a la distancia de la estación a la Cordillera o Precordillera. El Viento Zonda tiende a Soplar con mayor frecuencia de tarde, a lahora de la temperatura máxima y con menor frecuencia de madrugada, con unminimo a la hora de la salida del sol. El calentamiento diurno influyesobre el aire frío de capas bajas a disminuye su contraste térmico,permitiendo la irrupción del viento en el llano. Con los datos horarios de termohigrógrafos se realizó una climatologíade Vallecitos (una estación de montaña a 2220 metros sobre el nivel delmar). Se desarrollaron dos métodos indirectos de detección del fenómeno, unoel de Zonda térmico a otro el de Zonda higrico. El método tiene comoobjetivo determinar el incremento de temperatura que es necesario obteneren un intervalo de tiempo fijado para poder decir que se esta en presenciade Zonda termico, teniendo en cuenta la onda climática diaria. El segundo, es semejante al anterior, teniendo como objetivodeterminar la variación de humedad relativa que es necesario obtener a unintervalo de tiempo fijados para decir que se está frente a un caso de Zonda higrico a ver en oue medida coinciden con los de Zonda térmico y losde Viento Zonda real. Los resultados indican que el hígrico identifica mejor que el térmicoa los casos de Zonda real. La mayor frecuencia de horas con Zonda térmico y/o hígrico correspondeal invierno. Inversamente a lo que sucede en el llano las horas de mayorfrecuencia en esta estación de montaña corresponden a las inmediatasposteriores a la salida del sol. Esto podría ser consecuencia del efectode brisa montaña-valle. El Viento Zonda en la montaña presenta períodos contínuos o pulsantesdebido a la masor rafagosidad observada a esas alturas. Existen muchos casos de Viento Zonda en alta montaña, que no aparecenen el llano, que se denominan en este trabajo "Zonda de altura". La estructura tridimensional del fenómeno fue analizada seleccionandoun caso típico de moderada intensidad ocurrido en la Provincia de San Juany norte de la de Mendoza, que llegó a las ciudades capitales de ambasprovincias en la tarde del 23 de Agosto de 1983. La situación sinóptica se caracterizó por una vaguada entrante desdeel oeste a una cuña en el este del país; un frente caliente en el extremonoreste; la Depresión del Noroeste Argentino trasladada más al sur; unflujo moderado del norte en el centro del País y una depresión migratoriaentrando al norte de la Patagonia con un frente frío acercándose a la Cordillera desde el oeste-sudoeste. Se concluye que el Viento Zonda se produjo por el ascenso y posteriormayor descenso orográfico de una masa de aire prefrontal fuertementebaroclínica y que en la cúspide de la Cordillera apareció como un vientofrío que se fue calentando adiabáticamente al descender. El enfriamiento progresivo en las cumbres de la Cordillera se debió alacercamiento de una vaguada. El pasaje frontal fue posterior. El flujo de aire se produjo al estilo de un "chorro descendente" aalguna distancia y a alguna altura del perfil del terreno en la faldaoriental de la cordillera provocando un rotor en ese espacio y la formaciónde lagunas de aire húmedo en las pendientes orientales de la Cordillera Frontal o Cordón del Plata. Se establecieron las similitudes y diferencias entre el caso de Zondamoderado y los eventos severos. En estos el aire no desciende dejandolagunas protegidas sino que lo hace en forma de cascada siguiendo elrelieve y su aparición en el llano esta precedida de un Zonda contínuo yprolongado en estaciones de montaña desde varias horas antes. Con los datos de presión atmosférica reducida al nivel medio del mar,se analizaron los campos medios de presión (el campo medio total, el dedías con Zonda, el del día anterior, el de dos días antes, el dia posteriory los días con Zonda en altura). Hay una alteración significativa en los días con Viento Zonda respectodel desarrollo climatológico de la situación sinóptica en superficie alobservarse: el cinturón de bajas polares desplazado hacia latitudesmenores; un sistema ciclónico sobre la Isla Chiloe y el oeste de Chubut;intensificación notable de la vaguada climatológica al oeste del pais;existencia de un frente frío a una distancia media de 500 km al sudoeste dela ciudad de Mendoza. A ambos lados de la cordillera se observa due la componente zonal delviento es significativamente mayor a la altura de la cresta de lacordillera. La tropósfera media presenta mayor cortante vertical delviento y por ende mayor baroclinicidad indicando estas condiciones elacercamiento de un sistema frontal. Finalmente, de los resultados obtenidos al diagnosticar el Viento Zonda se obtienen reglas y metodos de Pronóstico, algunos de ellos con unalto grado de verificación. Se consideraron procedimientos sencillos como el metodo observacionalempírico a partir de la forma, densidad y ubicación de las nubes quepermiten inferir los desarrollos futuros posibles del fenómeno. Se tuvieron en cuenta también elementos sinópticos y aerológicos depredicción. Mediante la aplicacion del Análisis Discriminante Escalonado a unconjunto de variables, se seleccionaron algunas que fueron asumidas comopredictores. Entre ellas se destacan: la diferencia de presion entre San Juan y La Serena (Chile); la presion atmosférica de Puerto Montt; ladepresión de punto de rocío de 850 hPa en El Plumerillo a la componentemeridional del viento a 250 hPa en Quintero. Todos estos datoscorresponden a las 12 UTC. Se confeccionaron cuatro programas distintos: uno que trabaja con ungradiente espacial meridonal y un gradiente espacial cuasi zonal; otro queutiliza los valores de presión atmosférica a 12 UTC de ciertas estacionesselecciondas; un tercer programa predictor que usa parametros derivadosdel radiosondeo de El Plumerillo y por último, otro pograma predictorrealizado con variables derivadas del radiosondeo de Quintero. La evaluación de estos progranas predictores implementados se realizóconsiderando pronósticos determinísticos y probabilísticos, resultandoaltamente satisfactoria. Los programas tienden a sobreestimar laprobabilidad de ocurrencia de Zonda en el llano. Los casos de falsasalarmas superaron ampliamente a los de sorpresas. Dada la eficacia a sencillez de los programas, éstos pueden serimplementados en forma operativa en cualquier oficina de pronósticosIn mountainous zones a strong wind can be occasionally observed,descending from the summit to the vallet or to the plain. It isdifferently named, according to where it blows: chinook in the USA and Canada, fóhn in the European Alps, Canterbury-northwester in New Zealand,bers wind in South Africa, Zonda wind in Argentina. The main object of this thesis work is to determine the structure ofthe Zonda wind and the cause of its appeatance, in order to obtain adiagnostic of its behavior and also forecast methods of high valid degree. Other objects are: to establish the climatologic regime of the Zondaoccurence and the meteorologic parameters that go with it, in stations ofdifferent heights and geographic locations; to analyze the ridimensionalstructure of the phenomenon; to investigate the physical processesinvolved in its appearance; to establish objective forecast rules based onthermodynamic, synoptic and climatic parameters. There exist previous studies on this matter in our country, in worksdealing with it specifically and in others, where Zonda may not be thesubject, but it is mentioned. Bibliography regarding this phenomenonabounds outside the country, especially in Canada; USA: Switzerland, Germany and Austria. Geographyc characterization trough satelite image allows to visualizethe diverse orographic features and main mountain slopes. A climatology of the plain was performed, considering the subjectiveselection for the Zonda day stations, with the daily data from meteorologicrecords. This method was developed reckoning with a group of variables or theircombination, which is considered relevant beforehand to identify the Zondaoccurrence, resulting satisfactorily accurate as it leads to find almostall the events of a prolonged series. In order to corroborate how accurate this way of identifyins cases is,the Stepwise Discriminant Analysis statistic method was applied. This allowed to establish a variable scale, respect their major orminor incidence, when discriminating among Zonda days and days lackingit. This was only applied to the cities of Mendoza and San Juan, being theevents of the latter better classified, due to major frecuency and betterdefinition of the phenomenon in that locality. Hygrometric variations and maximum wind reached are the elements thatbetter identify a Zonda day. Absence of low clouds, Zonda lenticular clouds and fohn-wall areimportant at "El Plumerillo" (Mendoza city airport). While warming is whatmakes for a better discrimination during the winter, dwindling humidity isthe most relevant factor the rest of the year. Zonda is not frequent in the plain, and severe or very severe eventsdo not happen often. As for the annual variation, the major incidence isbetween May and Nov, and more than half of all the cases are recordedbetween May and Aus. Minor frecuency is conditioned to height asl and todistance between the station and the cordillera or precordillera. Zonda blows more frecuently in the afternoon, at the maximumtemperature time and less frecuently at dawn, being minimum at sunrisetime. The diurnal warming influences the cold air of lower lasers anddiminishes its thermic contrast, permittins the wind a violent entre intothe plain. A Vallecitos climatology (mountain station at 2220 m a.s.l) wasperformed, based on hourly data from the thermohygrographs. Two indirect methods were developed to detect the phenomenon, one forthermic Zonda and the other for hygric Zonda. The first method tends todetermine the temperature increase which needs to be obtained in a fixedtime lag, in order to establish the presence of thermic Zonda consideringthe daily climatic wave. The second method, similar to the first, tends to ascertain therelative humidity variation needed in a fixed time lag, to precise whetherthere is a case of hygric Zonda, also to observe whether it coincides withthermic Zonda and with real Zonda. The highest frecuencs of hours with thermic and/or hygric Zondacorrespond to winter. Inverse to what happens in the plain, highestfrecuency hours in this mountain station correspon to hors comingimmediately after sunrise. This could result from the mountain-valleybreeze effect. Zonda in the mountain presents continuous or pulsins periods owing tothe more frecuent gustiness observed hish up. There are many cases of Zonda in the high mountains, which do notappear on the plain. In this work they are called "high Zonda". The tridimensional structure of the phenomenon was analyzed selectinga typical case of moderate intensitsy that happened in the province of San Juan and northern Mendoza province, which reached the capital cities ofboth provinces, in the afternoon of Aug. 23rd, 1983. The synoptic situation was characterized by a trough entering throughthe west and a ridge in the east of the country; a warm front on the NE;the NW Argentine Deppression moved south; a moderate northern flow in themiddle of the countrs and a migrators depression entering throush north of Patagonia, with a cold front reachins the Cordillera from the W-SW. Theconclusion is that the Zonda was produced by a trongly baroclinicprefrontal airmass, undergoing an orographic lifting and a major descentafterwards, which appeared at the cordillera summit as a cold wind warmingadiabatically while doing down. The progressive cooling at the cordillerasummit was due to a trough getting near. The frontal passage came lateron. The air flow was similar to a "descending jet stream" not very far andat some height over the terrain profile in the oriental slope of thecordillera, provokins a rotor in that space and the formation of wet airparcels in the oriental slopes of the frontal cordillera or Cordón del Plata. The similitudes and differences among moderate and severe Zonda eventswere ascertained. During the lattery air does not descend leavinsprotected air parcels, but it goes down like a "cascade" following theterrain features, and blows continuously and largely on mountain stationsmany hours before its appearance on the plain. Another stage consists of analyzing the mean, synoptic and aerologicconditions that go linked with it. With the atmospheric pressure data reduced to the mean sea level, themean pressure fields were analezed: mean total field, field belongins to Zonda days, the one of the day before, pressure fields of two days before,and the one of the day after. There is a significant alteration on Zonda days regarding theclimatologic development of the surface synoptic situation. When thishappens, it is observed: the low polar belt is displaced toward lowerlatitudes; the cyclonic system is over Chiloé Island and W of Chubut;there is a noticeable intensification of the climatologic trough, west ofthe country and the existence of a cold front at a mean distance of 500 km SW of the city of Mendoza. The wind zonal component is significantly higher on both sides of the Cordillera, at the summit. The mean troposphere shows a major verticalshear of the wind and therefore, a bigger amount of baroclinicityindicating the arrival of a frontal system. Finally, from the results reached when diagnosing the Zonda,forecasting rules and methods are obtained, some of which are highlyverifiable. Simple procedures, such as the empiric observational method startingfrom shape, density and location of clouds, permit to infer the possiblefuture developments of the phenomenon. Prediction aerological and synoptic elements were also considered. The Stepwise Discriminant Analysis was applied to a group ofvariables, some of which were selected to be assumed as predictors. Thefollowing should be noticed: pressure difference among San Juan and La Serena (Chile); atmospheric pressure of Puerto Montt; dew-pointdepression of El Plumerillo at 850 hPa and meridional wind component at 250hPa at Quintero. All these data correspond to 12 UTC. Four different programs were performed: one works with a meridionalspatial gradient and an almost zonal spatial gradient; another oneutilizes the atmospheric pressure values at 12 UTC from several selectedstations; a third predictor program uses parameters derived from El Plumerillo radio-sonde and finally, another predictor program executed withvariables deriving from Quintero radio-sonde. These predictor programs were evaluated taking into account theprobabilistic and determinstic forecasts, resultins highlysatisfactory. The programs tend to overestimated the probability of Zondaoccuring in the plain. False alarms largely surpassed surprise cases. Because of the efficiencs and simplicity of these programs, they canbe operatively carried out in any forecasting office.Fil: Norte, Federico Augusto. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Understanding and Forecasting Zonda Wind (Andean Foehn) in Argentina: A Review

This paper focuses on the ?state of the art? research of the Argentinian zonda wind at the beginning of 2015. Zonda (similar to foehn) is a strong, warm, very dry wind associated with adiabatic compression upon descending the eastern slopes of the Andes Cordillera in western central Argentina.Particularly, hourly surface meteorological information obtained from the Argentine National Weather Service (Servicio Meteorológico Nacional, SMN) from Mendoza Aero (32˚50?S, 68˚47?W, 704 m ASL) and San Juan Aero (31˚34?S, 68˚25?W, 598 m ASL) airport meteorological stations was used. The paper contains a history of zonda research mentioning the principal papers since the 1950s, the characteristics of zonda wind (conceptual model, a classic event, intensitiescategories) and examples of non-classical episodes. Also zonda dynamics, zonda climatology and forecasting problems are considered. A probabilistic method and the model forecast that are running in operative way are commented. Also the climate impact, air quality and damages caused arementioned. There has been substantial progress in the understanding of this kind of complex wind during the last years, especially since the last decade, accelerated using different models. This paper has highlighted some of these advances by synthesizing some of the major findings. The probabilisticprediction method developed in the 1980s is still very useful to predict zonda in the cities of San Juan and Mendoza. This as well as the new available tools, such as the eta/PRM and GEM models running operatively (continuously) at PRM (Mendoza Regional Meteorology Program), offered the community the possibility to generate an Early Warning System to warn the population particularly in its severe manifestations. The answer to questions regarding time of onset of theevent, place where it will occur first, duration, intensity and offset still poses a great challenge for researchers and forecasters in the region.Fil: Norte, Federico Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentin

Classification methods and statistic of zonda wind in San Juan City

Este trabajo se propone evaluar distintos Métodos de Clasificación Objetiva (MCO) de eventos de viento zonda (foehn) y actualizar la estadística disponible de dicho fenómeno en la ciudad de San Juan. En primer lugar, se realizó una clasificación del viento zonda siguiendo el método de los tres puntos, donde se analizan los cambios temporales en la dirección e intensidad del viento, en la temperatura y temperatura de rocío, para diagnosticar la presencia de zonda. Esta clasificación se utilizó como referencia para evaluar la habilidad de clasificación de otros métodos objetivos, los cuales ayudan a entender cuáles son las variables más relevantes, proporcionando una base física para definir la ocurrencia de viento zonda en la estación. Siguiendo las metodologías de clasificación realizadas por otros autores se seleccionaron las variables más adecuadas, siendo éstas una combinación de la dirección y velocidad del viento y de las anomalías de temperatura y temperatura de rocío. Se proponen tres MCO;el método de la Temperatura Máxima (CTMAX), que incluye las variables de temperatura máxima del día, temperatura máxima media del mes y temperatura de punto de rocío mínima del mismo día; el método de Clasificación por Anomalías Diarias (CAD), que tiene como variables a las anomalías diarias de temperatura y de temperatura de rocío y el método de Clasificación por Anomalías Estacionales (CADE), con anomalías estacionales de temperatura y temperatura de rocío. Todos los métodos lograron identificar gran parte de los eventos de viento zonda en San Juan. Finalmente se realizó una climatología del viento zonda la cual se abordó con los resultados obtenidos por los distintos métodos propuestos. Se analizó el ciclo diurno y anual, la hora de inicio y finalización y la duración de los eventos.This paper intends to evaluate different Objective Classification Methods (OCM) for zonda wind (foehn) events and update the statistics of this phenomenon in the city of San Juan. First, a classification was performed according to the “three point method”, where analyze temporal changes in wind speed and direction, temperature and humidity to diagnose the presence of zonda. This classification was used as a reference for assessing the classification ability for other objective methods, which help us to understand the most important variables that provide a physical basis to define the Zonda wind occurrence at San Juan station. Following the classification methodologies by other authors, the most appropriate variables were selected, being a combination of the speed and direction of wind and temperature anomalies and relative humidity. Three OCM are proposed; The Maximum Temperature Method of the (MTM), including daily maximum temperature, monthly average maximum temperature and minimum dew point temperature for the same day variables; the Daily anomalies Method (DM), which has as variables the daily temperature and dew point temperature anomalies and finally, the Seasonal anomalies Method (SM), with seasonal temperature and dew point temperature anomalies. All methods were able to identify many of the Zonda wind events in San Juan. Finally, Zonda wind climatology where addressed for the different proposed methods, diurnal and annual cycle, onset, offset and the average duration of the events took place in this analysis.Fil: Otero, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Norte, Federico Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentin

Validation of a Statistical Forecast Model for Zonda Wind in West Argentina Based on the Vertical Atmospheric Structure

Zonda is a strong, warm, very dry wind associated with adiabatic compression upon descending the eastern slopes of the Andes Cordillera in western-central Argentina. This research seeks, first, to validate the skill of a statistical forecast of zonda based on the behavior of the vertical structure of the atmosphere and, second, to describe the climatology of the vertical profile leeward of the Andes. The forecast was built for May-August 1974/1983, and was verified against a series of cases recorded in the Mendoza Aero and San Juan Aero weather stations for May-August 2005/2014.It made use of the Stepwise Discriminant Analysis (SDA) and rawinsonde data from Mendoza Aero as predictors, with the following input variables: surface pressure, temperature, dew point, and the zonal and meridional components of the wind on surface and of the fixed levels up to 200 hPa.The variables selected as predictors by the SDA were: surface pressure, dew point depression at 850 hPa, meridional wind component at 850 hPa, and zonal wind component at 400 hPa. Climatology of the vertical profile of the atmosphere leeward of the Andes was built from daily rawinsonde data from Mendoza Aero for May-August 1974/1983. Zonda markedly influences the atmospheric structure leeward of the Andes in western-central Argentina. Its maximum impact occurs at850 to 800 hPa, with significant heating and decrease of humidity. Validation of the prediction program considered deterministic and probabilistic forecasts. Contingency tables show that probability of zonda occurrence in the plains is generally overestimated, and false alarm cases are far more frequent than surprise events. The main contribution of this paper is precisely the validation of the prediction model, which ensures forecasters one more tool to improve zonda forecasting; this, in turn, will aid decision-makers when taking steps to ameliorate zonda wind impact.Fil: Norte, Federico Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Simonelli, Silvia Carmen. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentin

A probability index for surface zonda wind occurrence at Mendoza city through vertical sounding principal components analysis

The aim of this work is to obtain an index for predicting the probability of occurrence of zonda event at surface level from sounding data at Mendoza city, Argentine. To accomplish this goal, surface zonda wind events were previously found with an objective classification method (OCM) only considering the surface station values. Once obtained the dates and the onset time of each event, the prior closest sounding for each event was taken to realize a principal component analysis (PCA) that is used to identify the leading patterns of the vertical structure of the atmosphere previously to a zonda wind event. These components were used to construct the index model. For the PCA an entry matrix of temperature (T) and dew point temperature (Td) anomalies for the standard levels between 850 and 300 hPa was build. The analysis yielded six significant components with a 94 % of the variance explained and the leading patterns of favorable weather conditions for the development of the phenomenon were obtained. A zonda/non-zonda indicator c can be estimated by a logistic multiple regressions depending on the PCA component loadings, determining a zonda probability index ĉ calculable from T and Td profiles and it depends on the climatological features of the region. The index showed 74.7 % efficiency. The same analysis was performed by adding surface values of T and Td from Mendoza Aero station increasing the index efficiency to 87.8 %. The results revealed four significantly correlated PCs with a major improvement in differentiating zonda cases and a reducing of the uncertainty interval.Fil: Otero, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Norte, Federico Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Araneo, Diego Christian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentin

Characteristics of three extreme maximum temperature episodes in Mendoza, Argentina

In Argentina heat waves have regular frequency specially during summer-time. There are two of them with an important recurrence period: one observed at the end of December, known as Christmas Heat Wave (CHW), and the other during the second fortnight of January, generally after the 20th. A heat wave is defined when the minimum temperature is greater than the average of the higher minimum temperature, and when the maximum temperature is greater than the average of the lower maximum temperature. This definition is valid for the central west of Argentina and must occur at least during two days. During CHW of December 1994 maximum temperature reached 41.9°C on 30th in Mendoza Aero (SAME) located at 32.50\ub0S 68.47°W; on CHW of December 2000 maximum temperature reached 40.1\ub0C on 25th. On January 30th 2003 was registered 44.4 °C, the highest maximum temperature in SAME since records exist. The goal of this work is to analyze the prevailing meteorological conditions during the occurrence of three Extreme Maximum Temperature Episodes (EMTE) from synoptic, thermodynamic and dynamic point of view in order to establish differences and similitudes between them. Surface data were obtained from Servicio Meteorológico Nacional (SMN) Argentina and Dirección Meteorológica de Chile (DMC); the aerological data reconstructed from NOAA Air Resources Laboratory Real Time Environmental Aplications and Display System (ARL). Reanalysis from the National Center for Enviromental Prediction and the National Center for Atmospheric Research (NCEP/NCAR) , and ETA model from Centro de Previsao e Estudos Climaticos (CPTEC) Brazil. The principal results were obtained at the following levels: at 850 hPa the height pattern in the continent is similar in all EMTE´s analyzed. Height value in 33\ub0S is almost 50 mgp less on December 2000, justifying the presence of the Norwestern Argentinian Low (NAL) and the displacement toward the south for it habitual position helping to the occurrence of Zonda wind in surface. At SAME latitude the height pattern at 600 hPa level shows a downward trough in the EMTE December 25th 2000, zonal flow on Decembre 30th 1994 and the presence of a height wedge with a cut off high in January 30th 2003. The EMTE 1994 occured at the end of a long heat wave started at the beginning of December; the zonda wind was detected above 600 hPa level. The Christmas EMTE 2000 was a classic zonda wind event, like in winter, characterized by a cold front approaching and a deep trough associated over Pacific Ocean close to the continent. All EMTE´s analyzed were produced by heat waves events and reforcing by zonda wind episodes of different intensity. To improve the prediction of this kind of EMTE, in a global warming scenary that is coming up, it would be necessary to adjust regional mesoscale models and use satellite imagery.Pages: 1877-188

Synoptic and thermodynamic analysis of an extreme heat wave over subtropical South America

During the last week of February of 2003 an intense and extensive heat wave occurred over most of the subtropical South America, affecting especially central Argentina Uruguay and Southern Brazil. In particular, the highest maximum temperature since record exists (44°C at 20:15 UTC on January 30, 2003) was reported at the Mendoza Airport (located approximately at 33°S near the Andean foothills). The studied period took place during the South American Low-Level Jet Experiment (SALLJEX) and a fly mission by the NOAA P3 plane was performed during the demise phase of the episode, on February 1st 2003. The goal of this work is to analyze the prevailing meteorological conditions during the last week of January 2003 from a synoptic, dynamic and thermodynamic point of view in order to establish the physical processes that contributed to the heat wave. To this purpose surface and aerological data were employed and also complemented with NCEP/NCAR reanalysis and forecast/simulations performed with the Eta/CPTEC regional model. During the lat week of January, the atmospheric circulation over subtropical latitudes was dominated by a rather barotropic pattern. The main baroclinic zone was located further south, between 35°S and 40°S, fostering the development of the Thermal-Orographic Low (NAL) and, consequently, the warm and humid advection from the north. The synoptic-scale pattern was immerse in a large-scale wedge that provoked slice but sustained subsidence over most of the subtropical South America and contributed to keep the sky clear during the whole considered period. Dynamic and thermodynamic analysis evidenced that the moderate but persistent warming was principally restricted to the middle-lower troposphere (below 700 hPa). This warming was stronger during the last three days of the analyzed record (28-30 January). The close inspection to the therms of the thermodynamic equation allows concluding that the extreme temperatures were the consequence of a combination of different factors. Warm horizontal advection was a very important effect especially south of 35-37°S, as the result of sustained northerly winds superimposed to the relatively baroclinic region. Slice to moderate larger-scale adiabatic warming by subsidence dominated over most of the subtropical latitudes but additional orographic forced subsidence, locally know as Zonda wind, was also detected to the end of the period significantly increasing the heating rate near the 850 hPa level. Surface heat fluxes were also important to close the thermal balance. Modest but not irrelevant warming was due to sensible heating from the surface, especially close to the eastern Andean slopes, when semi desert environment features prevail.Pages: 2009-201