Toward a climate-dependent paradigm of ammonia emission & deposition.

Existing descriptions of bi-directional ammonia (NH3) land–atmosphere exchange incorporate temperature and moisture controls, and are beginning to be used in regional chemical transport models. However, such models have typically applied simpler emission factors to upscale the main NH3 emission terms. While this approach has successfully simulated the main spatial patterns on local to global scales, it fails to address the environment- and climate-dependence of emissions. To handle these issues, we outline the basis for a new modelling paradigm where both NH3 emissions and deposition are calculated online according to diurnal, seasonal and spatial differences in meteorology. We show how measurements reveal a strong, but complex pattern of climatic dependence, which is increasingly being characterized using ground-based NH3 monitoring and satellite observations, while advances in process-based modelling are illustrated for agricultural and natural sources, including a global application for seabird colonies. A future architecture for NH3 emission–deposition modelling is proposed that integrates the spatio-temporal interactions, and provides the necessary foundation to assess the consequences of climate change. Based on available measurements, a first empirical estimate suggests that 5°C warming would increase emissions by 42 per cent (28–67%). Together with increased anthropogenic activity, global NH3 emissions may increase from 65 (45–85) Tg N in 2008 to reach 132 (89–179) Tg by 2100.

James Turrell y Robert Irwin. Coincidencias, Manhattan, 2013

Durante el verano de 2013 Manhattan albergó las muestras de dos artistas que trabajan con la luz y el espacio: una amplia exposición retrospectiva de James Turrell en el Museo Guggenheim y una instalación de Robert Irwin para el Museo Withney de Arte Americano. Ambos han hecho de la percepción el elemento fundamental de sus obras en una investigación que comenzó en los años sesenta y que han continuado desarrollando a lo largo de los últimos cuarenta y cinco años. Los dos compartieron en sus comienzos una línea de investigación conjunta, sis investigaciones sobre las sensaciones en el espacio y su estudio empírico fueron cruciales para el desarrollo de sus obras que hacen de la experiencia espacial un mecanismo de trascendencia. Sus trabajos son de gran interés para la arquitectura poarque los dos hacen de la percepción en el espacio el argumento fundamental de su investigación artística.