Who's who in our street?

En la misma calle varias familias conviven, se relacionan, se echan una mano cuando alguien lo necesita. Aún con su agitada vida, encuentran momentos para reunirse, reír, jugar, comer, ver la televisión y divertirse.

Comunicación didáctica en la programación infantil de RTVE : Sesame street : un ejemplo.

Analizar el acercamiento desde la perspectiva didáctica a la TV infantil en circuito abierto (TVCA). Estudiar el modelo comunicativo en el fondo el modelo didáctico que subyace y estructura a la programación infantil de TVE. Así como unas consideraciones sobre las semejanzas de este modelo comunicativo con el de la enseñanza tradicional. Aproximación a la experiencia de Sesame Street a fin de descubrir sus principales aportaciones, tanto en la producción como elaboración psicopedagógica de programas instructivos de TV dirigidos a niños en edad preescolar. Repasar lo más extensamente posible el material bibliográfico que haya publicado sobre estas cuestiones. Se ha trabajado partiendo de un supuesto general que funciona un poco como el hilo conductor de todas las indagaciones y a la vez ofrece coherencia a las muchas cuestiones que se dan cita inevitablemente en un problema tan complejo como es el de la televisión infantil. La hipótesis se formula siguiendo los siguientes términos: el modelo didáctico que se configura a través de la TVCA se basa en un esquema comunicativo de tipo vertical, unidireccional en forma y fondo. La participación requerida del telespectador es un mero recurso para asegurarse la audiencia. Los pasos seguidos en el trabajo más importantes son los siguientes: 1. consulta de una amplia bibliografía sobre el tema, unas veces sobre aspectos muy concretos y en otras sobre cuestiones generales; 2. contactos y entrevistas frecuentes con el equipo asesor y productor del Barrio Sésamo, que como se sabe es la versión española y realizada en coproducción, del Sesame Street. También asistir a un seminario reorganizado para el equipo de Barrió Sésamo. En el cual durante tres días se pudo contactar con un asesor pedagógico, el jefe de investigación y un productor de la CTW. Este contacto directo con la experiencia Sesame Street resulto de gran interés; 3. Análisis de los programas apuntados. Tal vez sea el paso más endeble por las numerosas dificultades a que se ha tenido que hacer frente como la de esperar casi año y medio para poder ver -ábrete sésamo-. Se ha intentado demostrar que la relación escuela-alumnos y TV-telespectador se montan sobre un proceso de comunicación. En ambos casos este proceso es manejado en uno y otro sentido en función del logro de unos objetivos que no siempre están explícitamente formulados. Pero en qué cualquier caso esto lleva a formular la hipótesis de que puede hablarse de un acto didáctico televisual, cuyas semejanzas (en la teoría y en la práctica) son harto significativas tal como ya se expuso en el punto correspondiente del trabajo. Con mayor o menor dignidad la escuela y la TV al menos según se les ha conocido hasta hoy funciona con un modelo de comunicación vertical. No sólo lo elaborar los de arriba que son los que saben y de acuerdo con lo que creen que saben, sino que además utilizan códigos que son inaccesibles para la mayoría de los niños y sobre todo los de clases más desafortunadas. Por otro lado, son unos mensajes elaborados a partir de la experiencia, de la improvisación. De donde se deduce fácilmente que los condicionamientos que van a aflorar en tales mensajes serán de muy dignos del más detallado estudio psicológico. Los telespectadores son los que irremediablemente, tendrán que soportar las proyecciones frustrantes que sobre ellos lanzan unos adultos que la fortuna o la casualidad les ha puesto donde están, ante telespectadores o ante alumnos.

Modeled and observed atmospheric radiation balance during the West African dry season: role of mineral dust, biomass burning aerosol, and surface albedo

The global radiation balance of the atmosphere is still poorly observed, particularly at the surface. We investigate the observed radiation balance at (1) the surface using the ARM Mobile Facility in Niamey, Niger, and (2) the top of the atmosphere (TOA) over West Africa using data from the Geostationary Earth Radiation Budget (GERB) instrument on board Meteosat-8. Observed radiative fluxes are compared with predictions from the global numerical weather prediction (NWP) version of the Met Office Unified Model (MetUM). The evaluation points to major shortcomings in the NWP model's radiative fluxes during the dry season (December 2005 to April 2006) arising from (1) a lack of absorbing aerosol in the model (mineral dust and biomass burning aerosol) and (2) a poor specification of the surface albedo. A case study of the major Saharan dust outbreak of 6–12 March 2006 is used to evaluate a parameterization of mineral dust for use in the NWP models. The model shows good predictability of the large-scale flow out to 4–5 days with the dust parameterization providing reasonable dust uplift, spatial distribution, and temporal evolution for this strongly forced dust event. The direct radiative impact of the dust reduces net downward shortwave (SW) flux at the surface (TOA) by a maximum of 200 W m−2 (150 W m−2), with a SW heating of the atmospheric column. The impacts of dust on terrestrial radiation are smaller. Comparisons of TOA (surface) radiation balance with GERB (ARM) show the “dusty” forecasts reduce biases in the radiative fluxes and improve surface temperatures and vertical thermodynamic structure.

Seasonal variations of the physical and optical characteristics of Saharan Dust: results from the Dust outflow and Deposition to the Ocean (DODO) experiment

North African dust is important for climate through its direct radiative effect on solar and terrestrial radiation and its role in the biogeochemical system. The Dust Outflow and Deposition to the Ocean project (DODO) aimed to characterize the physical and optical properties of airborne North African dust in two seasons and to use these observations to constrain model simulations, with the ultimate aim of being able to quantify the deposition of iron to the North Atlantic Ocean. The in situ properties of dust from airborne campaigns measured during February and August 2006, based at Dakar, Senegal, are presented here. Average values of the single scattering albedo (0.99, 0.98), mass specific extinction (0.85 m^2 g^-1 , 1.14 m^2 g^-1 ), asymmetry parameter (0.68, 0.68), and refractive index (1.53--0.0005i,1.53--0.0014i) for the accumulation mode were found to differ by varying degrees between the dry and wet season, respectively. It is hypothesized that these differences are due to different source regions and transport processes which also differ between the DODO campaigns. Elemental ratios of Ca/Al were found to differ between the dry and wet season (1.1 and 0.5, respectively). Differences in vertical profiles are found between seasons and between land and ocean locations and reflect the different dynamics of the seasons. Using measurements of the coarse mode size distribution and illustrative Mie calculations, the optical properties are found to be very sensitive to the presence and amount of coarse mode of mineral dust, and the importance of accurate measurements of the coarse mode of dust is highlighted.

Referencing of street-level flows measured during the DAPPLE 2004 campaign

Street-level mean flow and turbulence govern the dispersion of gases away from their sources in urban areas. A suitable reference measurement in the driving flow above the urban canopy is needed to both understand and model complex street-level flow for pollutant dispersion or emergency response purposes. In vegetation canopies, a reference at mean canopy height is often used, but it is unclear whether this is suitable for urban canopies. This paper presents an evaluation of the quality of reference measurements at both roof-top (height = H) and at height z = 9H = 190 m, and their ability to explain mean and turbulent variations of street-level flow. Fast response wind data were measured at street canyon and reference sites during the six-week long DAPPLE project field campaign in spring 2004, in central London, UK, and an averaging time of 10 min was used to distinguish recirculation-type mean flow patterns from turbulence. Flow distortion at each reference site was assessed by considering turbulence intensity and streamline deflection. Then each reference was used as the dependent variable in the model of Dobre et al. (2005) which decomposes street-level flow into channelling and recirculating components. The high reference explained more of the variability of the mean flow. Coupling of turbulent kinetic energy was also stronger between street-level and the high reference flow rather than the roof-top. This coupling was weaker when overnight flow was stratified, and turbulence was suppressed at the high reference site. However, such events were rare (<1% of data) over the six-week long period. The potential usefulness of a centralised, high reference site in London was thus demonstrated with application to emergency response and air quality modelling.

Can desert dust explain the outgoing longwave radiation anomaly over the Sahara during July 2003?

Measurements of the top‐of‐the‐atmosphere outgoing longwave radiation (OLR) for July 2003 from Meteosat‐7 are used to assess the performance of the numerical weather prediction version of the Met Office Unified Model. A significant difference is found over desert regions of northern Africa where the model emits too much OLR by up to 35 Wm−2 in the monthly mean. By cloud‐screening the data we find an error of up to 50 Wm−2 associated with cloud‐free areas, which suggests an error in the model surface temperature, surface emissivity, or atmospheric transmission. By building up a physical model of the radiative properties of mineral dust based on in situ, and surface‐based and satellite remote sensing observations we show that the most plausible explanation for the discrepancy in OLR is due to the neglect of mineral dust in the model. The calculations suggest that mineral dust can exert a longwave radiative forcing by as much as 50 Wm−2 in the monthly mean for 1200 UTC in cloud‐free regions, which accounts for the discrepancy between the model and the Meteosat‐7 observations. This suggests that inclusion of the radiative effects of mineral dust will lead to a significant improvement in the radiation balance of numerical weather prediction models with subsequent improvements in performance.