Accounting for anthropic energy flux of traffic in winter urban road surface temperature simulations with the TEB model

Snowfall forecasts help winter maintenance of road networks, ensure better coordination between services, cost control, and a reduction in environmental impacts caused by an inappropriate use of de-icers. In order to determine the possible accumulation of snow on pavements, forecasting the road surface temperature (RST) is mandatory. Weather outstations are used along these networks to identify changes in pavement status, and to make forecasts by analyzing the data they provide. Physical numerical models provide such forecasts, and require an accurate description of the infrastructure along with meteorological parameters. The objective of this study was to build a reliable urban RST forecast with a detailed integration of traffic in the Town Energy Balance (TEB) numerical model for winter maintenance. The study first consisted in generating a physical and consistent description of traffic in the model with two approaches to evaluate traffic incidence on RST. Experiments were then conducted to measure the effect of traffic on RST increase with respect to non-circulated areas. These field data were then used for comparison with the forecast provided by this traffic-implemented TEB version

The Cévennes-Vivarais Mediterranean Hydrometeorological Observatory database

International audienceIntense rain events frequently result in devastating flash floods in Mediterranean regions. To improve the understanding and prediction of these phenomena, the Cévennes‐Vivarais Mediterranean Hydrometeorological Observatory (CVMHO) was set up in 2000. The observation strategies deployed include the detailed and long‐lasting (>10 years) observation in the Cévennes‐Vivarais region (France) using both operational observation systems and research instrumentation. The present note describes the procedures implemented by CVMHO to critically analyze and generate hydrometeorological products for research. The related data can be viewed or downloaded via the Système d'Extraction et de Visualisation des Données de l'Observatoire en Ligne (SEVnOL) interface on the CVMHO Web site

Individual contributions of anthropogenic physical processes associated to urban traffic in improving the road surface temperature forecast using TEB model

International audienceFor years, some work has been undertaken on the traffic heat issue input in the Town Energy Balance (TEB). It has been the subject of many studies related to the summer period and urban heat islands topic. However, during winter conditions, the traffic energy input was marginally integrated into the modeling of the road surface parameters. This deficiency, may explain the differences between forecast and observations for road surface status (RSS) during winter season. Over the past decade, identification and quantification of traffic effects were undertaken. However, they have been studied independently, and non-numerical model integrates the energy contribution of traffic into the RSS. Based on the (TEB) model (v7.2), recent research provided a detailed integration of the traffic thermal contribution in the TEB. This study showed traffic increases the road surface temperature (R S T) by 2-3°C, and its heat inputs improve significantly the R S T modeling. This study consists in evaluating the thermal contribution of each traffic process to improve the R S T modeling based on field experiments. Secondly, the most significant physical processes of traffic responsible for R S T changes have been identified and their contributions discussed. Finally, we analyzed the effects of weather conditions onto the thermal contribution of traffic processes

Understanding and modeling the physical processes that govern the melting of the snow cover in tropical mountain environment in Ecuador

International audienceThe ISBA/CROCUS coupled ground-snow model developed for the Alps and subsequently adapted to the outer tropical conditions of Bolivia has been applied to a full set of meteorological data recorded at 4860 m above sea level on a moraine area in Ecuador (Antizana 15 glacier, 0°28′S; 78°09′W) between 16 June 2005 and 30 June 2006 to determine the physical processes involved in the melting and disappearance of transient snow cover in nonglaciated areas of the inner tropics. Although less accurate than in Bolivia, the model is still able to simulate snow behavior over nonglaciated natural surfaces, as long as the modeled turbulent fluxes over bare ground are reduced and a suitable function is included to represent the partitioning of the surface between bare soil and snow cover. The main difference between the two tropical sites is the wind velocity, which is more than 3 times higher at the Antizana site than at the Bolivian site, leading to a nonuniform spatial distribution of snow over nonglaciated areas that is hard to describe with a simple snow partitioning function. Net solar radiation dominates the surface energy balance and is responsible for the energy stored in snow-free areas (albedo = 0.05) and transferred horizontally to adjacent snow patches by conduction within the upper soil layers and by turbulent advection. These processes can prevent the snow cover from lasting more than a few hours or a few days. Sporadically, and at any time of the year, this inner tropical site, much wetter than the outer tropics, experiences heavy snowfalls, covering all the moraine area, and thus limiting horizontal transfers and inducing a significant time lag between precipitation events and runoff