Everyday vulnerabilities and ''social dispositions'' in the Malian Sahel, an indication for evaluating future adaptability to water crises?

International audienceSince the 1970s, precipitation in the Sahel has decreased and become very irregular, leading to widespread drought, whilst the human need for water has rapidly increased. A new ''dispositions''-based approach was adapted in order to analyse human interactions with environmental hazards and applied to the case of Hombori village in northeastern Mali. This article explores how the population and political stakeholders perceive, live with and respond to the increasing scarcity of water. It also explores how their current vulnerability and ability to cope with variations in available water resources indicate future adaptability to climate shocks. On the one hand, this research shows how the population copes with variations in water resource availability: the population's socio-spatial organisation explains the inhabitants' exposure to this problem and some of the factors affecting vulnerability, the elderly and women being the hardest hit. The water issue is generally managed on a ''day-to-day'' basis and considered a big problem only in the dry season, thus lowering any incentive for self-protection. The main two variables that could explain this kind of risk management are the conflicting local governance and current social rules. On the other hand, the discussion of results, based on a conceptual model of social responses, explains why these current ''social dispositions'' to cope with and even address the water scarcity issue do not guarantee future adaptability to climate change

Characteristics and conditions of production of transient luminous events observed over a maritime storm

International audienceOn the night of 15/16 November 2007, cameras in southern France detected 30 transient luminous events (TLEs) over a storm located in the Corsican region (France). Among these TLEs, 19 were sprites, 6 were halos, and 5 were elves. For 26 of them, a positive “parent” cloud‐to‐ground lightning (P+CG) flash was identified. The peak current of the P+CG flashes for the sprites had an average value of 63 kA and had a maximum value of 125 kA. The flashes for the halos and the elves had average values of 272 and 351 kA, respectively, and they had maximum values of 312 and 384 kA, respectively. No TLEs were detected after negative CG flashes with very large peak currents. Among the 26 P+CG flashes, 23 were located in a stratiform region with reflectivity values lower than 45 dBZ. The CG flashes in this region were classified into two groups according to the time interval separating them from the following flash: one group with values less than 2 s and one with values greater than 2 s. About 79% of all CGs were produced in a sequence of at least two flashes less than 2 s apart. For 65.5% of the sequences, the first flash was positive with an average peak current of 73 kA, while the later +CG flashes in a sequence had much lower peak currents. Several triangulated sprites were found to be shifted from their P+CG flashes by about 10 to 50 km and preferentially downstream. The observations suggest that the P+CG flashes can initiate both sprites and other CG flashes in a storm

A New Videosonde with a Particle Charge Measurement Device for In Situ Observation of Precipitation Particles

A new videosonde designed for microphysical soundings inside thunderclouds is described. This sensor makes use of a charge-coupled device (CCD) camera and can provide the phase (liquid or ice), the shape, the size, and the electric charge of each precipitating particle detected singly, the size of which ranges from 0.5 mm to 2 cm and the electric charge from ±1 to ±400 pC. The performances of the videosonde are analyzed and evaluated. It is found that the accuracy on the size measurement varies between about 13% for the smaller sizes and less than 2.6% for the larger sizes; meanwhile the average accuracy on the charge measurement is 3.2%. The determination of several large-scale parameters deduced from the videosonde data and comparable with radar observations and electrical soundings is presented. An intercomparison experiment with a disdrometer at the ground shows that the size distribution is perfectly restituted for large drops, even though the video permits filming at a maximum rate of only 50 images per second. The discrepancies that appear for smaller sizes are probably due to windy conditions to which small particles are much more sensitive, but it does not affect the rainfall-rate determination

A New Videosonde with a Particle Charge Measurement Device for In Situ Observation of Precipitation Particles

A new videosonde designed for microphysical soundings inside thunderclouds is described. This sensor makes use of a charge-coupled device (CCD) camera and can provide the phase (liquid or ice), the shape, the size, and the electric charge of each precipitating particle detected singly, the size of which ranges from 0.5 mm to 2 cm and the electric charge from ±1 to ±400 pC. The performances of the videosonde are analyzed and evaluated. It is found that the accuracy on the size measurement varies between about 13% for the smaller sizes and less than 2.6% for the larger sizes; meanwhile the average accuracy on the charge measurement is 3.2%. The determination of several large-scale parameters deduced from the videosonde data and comparable with radar observations and electrical soundings is presented. An intercomparison experiment with a disdrometer at the ground shows that the size distribution is perfectly restituted for large drops, even though the video permits filming at a maximum rate of only 50 images per second. The discrepancies that appear for smaller sizes are probably due to windy conditions to which small particles are much more sensitive, but it does not affect the rainfall-rate determination

A new videosonde for in situ observation of precipitation particles.

9-13 juin 200

Implementation of the citizen science part of the NanoEnvi project: monitoring indoor air particulate pollution with passive bio-captors

International audienceExposition to air pollution in urban environments is now associated with a wide range of adverse health effects, including respiratory and cardiovascular diseases. For a medium-sized European city like Toulouse in France, with a population of approx. 500,000, road traffic contributes to fine particles concentrations and plays an important role in the exceedance of European limits happening several times a year. The goal of the NanoEnvi project is to track fine and ultrafine particle emitted by the vehicles and their fate at the street level and inside homes. A collaboration between researchers and citizens has been set up in the NanoEnvi project to allow the monitoring of indoor air pollution. Involved citizen also bring their appraisal on their local environment. Closing the gap between the scientific and citizen expertise will hopefully lead to collect better data and to develop better strategies (individual and institutional) regarding air quality. In the NanoEnvi project, we use magnetic method on low-cost and easy to implement passive sensors made with small pieces (around 2cm*2cm) of plane tree bark. Participating citizen in the city of Toulouse host two passive sensors for one year: one inside their home and one outside, mostly on the facade or in a balcony. More than 150 inhabitants have joined the project in the 2018-2019 campaign. Our study involves researchers from different fields: atmospheric sciences, earth and environmental sciences, physics, humanities and social sciences. This transdisciplinary team shares the goal to test and calibrate the environmental magnetic method as a new proxy for airborne nanoparticles. People got into the project through outreach meetings with scientists organized by the project or in the frame of other scientific events as well as in community centers and schools. This allows to involve a broad community of motivated people in the project, with different level of awareness of air pollution issues

Characteristics and conditions of production of transient luminous events observed over a maritime storm

On the night of 15/16 November 2007, cameras in southern France detected 30 transient luminous events (TLEs) over a storm located in the Corsican region (France). Among these TLEs, 19 were sprites, 6 were halos, and 5 were elves. For 26 of them, a positive “parent” cloud-to-ground lightning (P+CG) flash was identified. The peak current of the P+CG flashes for the sprites had an average value of 63 kA and had a maximum value of 125 kA. The flashes for the halos and the elves had average values of 272 and 351 kA, respectively, and they had maximum values of 312 and 384 kA, respectively. No TLEs were detected after negative CG flashes with very large peak currents. Among the 26 P+CG flashes, 23 were located in a stratiform region with reflectivity values lower than 45 dBZ. The CG flashes in this region were classified into two groups according to the time interval separating them from the following flash: one group with values less than 2 s and one with values greater than 2 s. About 79% of all CGs were produced in a sequence of at least two flashes less than 2 s apart. For 65.5% of the sequences, the first flash was positive with an average peak current of 73 kA, while the later +CG flashes in a sequence had much lower peak currents. Several triangulated sprites were found to be shifted from their P+CG flashes by about 10 to 50 km and preferentially downstream. The observations suggest that the P+CG flashes can initiate both sprites and other CG flashes in a storm.Peer Reviewe