L’objectif de cette thèse est d’obtenir une meilleure connaissance des ondes de gravité atmosphériques, de leurs sources et caractéristiques, et de leur propagation au moyen d’observations ballons et de simulations. Les ballons pressurisés (SPBs) utilisés dans cette thèse sont une des meilleures plateformes d’observations des ondes de gravité, et permettent d’obtenir l’ensemble de leurs caractéristiques. Les modèles à haute résolution donnent une description complète de l’écoulement, non seulement des ondes, mais aussi de leurs sources. Nous avons combiné mesures par SPBs et modélisation pour décrire les ondes de gravité et évaluer le réalisme des champs d’ondes de gravité dans des sorties de modèles. En s’appuyant sur les observations de PreConcordiasi (2010), les ondes de gravité convectives sont décrites aux Tropiques sur l’ensemble de la campagne, ainsi que sur un cas de cyclone tropical en développement. Dans un deuxième temps, les observations de la campagne Concordiasi (2010) nous permettent de quantifier le réalisme du champ d’onde de gravité résolu aux hautes latitudes (hémisphère sud) décrit dans les analyses de l’ECMWF. Un bon accord géographique et saisonnier est observé pour les flux de quantité de mouvement et l’intermittence. Cependant, il est montré que la magnitude des flux est sous-estimée dans les analyses de l’ECMWF. Enfin, une contribution aux campagnes opérationnelles ballons est apportée, en se focalisant sur les ballons stratosphériques ouverts qui sont le plus grand défi pour le CNES. Pour des cas d’étude lors de la campagne Strapolété (2009), nous montrons que l’incertitude sur la position de retombée des ballons peut être réduite dans une configuration simple en assimilant des observations par radiosondages. / The goal of this thesis is to obtain a better knowledge of the atmospheric gravity waves in the atmosphere, of their sources and characteristics, and their propagation using balloon observations and modeling. The superpressure balloons (SPBs) used in this thesis are one of the best platform to observe gravity waves, and allow us to retrieve the ensemble of their characteristics. High-resolution models provide a complete description of the flow, not only of the waves, but also of their sources. We have combined SPB measurements and modeling in order to describe the gravity waves and evaluate the gravity wave field in model outputs. Using the observations from PreConcordiasi (2010), the convective gravity waves are described in the Tropics during the whole campaign, and also for a case of developing Tropical Cyclone. Second, observations from the Concordiasi campaign (2010) allow us to quantify the realism of the resolved gravity wave field in the ECMWF analyses at high latitudes (Southern Hemisphere). A good geographical and seasonal agreement is found for the momentum fluxes and the intermittency. However, it is shown that the magnitude is underestimated in the ECMWF. Finally, we bring a contribution to the operational balloon campaigns, with a focus on the open stratospheric balloons, which constitute the greatest challenge for the CNES. For cases during the Strapolété campaign, we show that the uncertainty on the final touchdown position of the balloons can be reduced using a simple setup that assimilates radiosoundings.

No description available.

Scientific stratospheric balloons offer a valuable service to scientists wishing to test or demonstrate developing technological instruments, or to run fully operational instruments with short preparation times and for a cheap price compared to other similar services. The ballooning industry is therefore a vital part of the scientific community as it enables less funded and experienced scientific organisations to actively engage in the development of their technologies. In the context of scientific stratospheric balloons, the speed of permeation affects among other things the flight time and the flight planning, as these are determined by the rate of loss of the buoyancy force keeping the balloon afloat. Most balloons today use helium as lifting gas, but the ballooning industry is today facing increased pressure to switch to hydrogen gas. Before making this switch, understanding how hydrogen gas behaves differently, in terms of permeation or otherwise, is important to prevent unexpected flight paths among other things. In this thesis, two experiments were conducted in order to attempt to determine the ratio of permeation speed between hydrogen gas and helium through balloon membranes. One experiment used a manometric method, where the pressure of permeant in a diffusion chamber was measured over time. The other experiment measured the buoyancy force of permeant-filled balloons over time. The resulting ratio of permeation speed may give more confidence in predicting how much faster or slower a stratospheric balloon filled with hydrogen will lose buoyancy force.

Au départ, j’ai développé un code d’inversion en se basant sur l’exemple donné au laboratoire. Ensuite, j’ai eu l’opportunité de l’appliquer en participant à la campagne de mesure in situ StratoScience 2015 au Canada. Durant cette campagne, on a aussi réalisé quelques comparaisons de l’Amulse avec d’autres instruments de mesure de CH4 et CO2 (PicoSDLA, Picarro, AirCore). Ce fut une expérience très enrichissante ainsi qu’un premier test pour l’Amulse. A partir des résultats de ce premier vol, on constate qu’il y a encore des améliorations à apporter, que ce soit au niveau instrumental qu’au niveau d’inversion. Sur le plan instrumental, on fait quelques interventions au niveau de l’intelligence de l’instrument (acquisition et stockage) et son optique, d’une part, d’autre part le code d’inversion a besoin de certaines modifications qui englobent la ligne de base et la détermination de la raie spectrale. Pour ce fait, j’essaye d’appliquer plusieurs méthodes pour obtenir un bon fit et par conséquent une bonne concentration. Concernant les travaux en cours, j’essaye toujours d’améliorer mon code d’inversion pour avoir un meilleur profil vertical, qui va être utilisé par la suite dans ma publication sur la mesure du méthane. Dans le cadre de la rédaction de la publication, j’ai fait une première calibration au laboratoire du senseur laser Amulse CH4 en attendant la deuxième. En outre, je développe un autre code d’inversion pour le projet Strateole 2 qui va durer 2 mois. J’interviens aussi au niveau de l’inversion des données de la calibration du nouveau senseur laser bi gaz APOGEE (CH4 et CO2), qui est prévue pour le mois de juin à Toulouse. Dernièrement, j’ai participé au congrès EGU à Vienne et dans un avenir proche, je vais participer à la campagne de Kiruna avec PicoSDLA, Amulse et APOGEE. / In the first place, I developed a code based on the example given in the laboratory. I had the opportunity to apply my program by participating in the in situ measurement campaign called StratoScience 2015, located in Canada. During this campaign, we also made some comparisons of Amulse with other CH4 and CO2 measurement instruments such as PicoSDLA, Picarro and AirCore. As matter of fact, it was a very rewarding experience and a first test for Amulse. From the results of this first flight, we decide to add some improvements on both sides: the instrumental and the process data part. Instrumentally, some changes has been required note only on the intelligence of the instrument including acquisition and storage but also on the optical part. Besides, the process data needs also some changes which include baseline and the determination of the spectral line. In fact, I try to apply several methods to get a good fit and therefore a good concentration. To this end, my current work is mainly focusing on improving my program for better vertical profile, because it will be used later in my publication on the measurement of methane. In the same context, I made a first calibration in the laboratory of Amulse CH4 laser sensor and preparing a second one. In addition, I developed another code for Stratéole 2 project which will last two months. I’ll also do the process data of the new dual laser sensor APOGEE (CH4 and CO2), which is scheduled for June in Toulouse. At last, I recently participate in the EGU congress in Vienna and in the near future, I will participate in a new campaign of in situ measurement in Kiruna with both sensors: PicoSDLA, and APOGEE Amulse.

International Telemetering Conference Proceedings / October 30-November 02, 1995 / Riviera Hotel, Las Vegas, Nevada / After briefly presenting the TRANSMED mission, the configuration of the Telemetry and Telecommand links is illustrated and the their dimensioning is analyzed. Both links operate at S-band with satellite grade standards. The system composition, the main equipment and the system growth potential are thereafter presented.

Purpose: This study evaluated the effect of lung volume at the catch position to force and power outputs during single maximal effort strokes in rowing. Responses were compared when the participants were ‘fresh’ and following specific inspiratory muscle fatigue (IMF). In addition, a single subject pilot study was performed to characterise the changes in intra-thoracic (ITP), intra-abdominal (IAP) and trans-diaphragmatic (Pdi) pressures during a 30 second maximal effort piece on a rowing ergometer. Methods: Nine male rowers of international standard participated in the research. Static force, as well as the power produced during a single stroke were assessed at residual volume (RV), 25%TLC, 50%TLC, 75%TLC, total lung capacity (TLC), and a self-selected lung volume (S-S). Lung volumes were derived from maximal flow-volume loops (MFVLs) and achieved using online real-time feedback. Inspiratory muscle fatigue (IMF) was induced by breathing against an inspiratory load equivalent to 80% baseline maximal inspiratory pressure (MIP), at a breathing frequency (fB) of 15 breaths per minute, and a duty cycle of 0.6. Expiration was unimpeded. The single subject pilot study was undertaken using balloon catheters to measure ITP, IAP, and Pdi during a 30 second maximal effort free-rating piece on the ergometer. Results: There was no significant effect of lung volume upon either force or power production. The RMF protocol induced a significant reduction in MIP (159.9 ± 70.8 vs. 106.8 ± 58.7 cmH2O; p = 0.000), but not maximal expiratory pressure (MEP; 159.9 ± 79.2 vs. 166.6 ± 53.0 cmH2O; p = 0.376). RMF induced a significant reduction in force output with increasing lung volume, across all lung volumes (mean force 1313.4 ± 31.9 vs. 1209.6 ± 45.0N; p < 0.008), but not power (mean power 598.6 ± 31.9 vs. 592.7 ± 45.0W; p > 0.05). Self-selected lung volumes were consistent across all tests for force and power (mean 38.1 ± 6.9% [Force] vs. 28.2 ± 0.6% [Power]; p > 0.017). The pilot study indicated that internal pressures fluctuate markedly during maximal effort rowing (pressure, [max, min, average] cmH2O; IAP [144.69, 7.46, 73.59], ITP [75, -22.65, 15.34], Pdi [111.84, 7.09, 58.83]), suggesting that the trunk muscles play an active role in power production during rowing. Conclusion: The present study suggests that there is no significant effect of lung volume on force or power when athletes are in a fresh condition. However, a decrement in force production is present with inspiratory muscle fatigue. Combined with evidence of high internal pressures during maximal effort rowing, these data may indicate a role for the inspiratory muscles in force production during rowing.

Thesis (Master').

Les travaux exposés dans ce manuscrit concernent le développement de spectromètres laser pour la mesure in-situ de CH4, CO2 et H2O dans l'atmosphère moyenne ainsi que la spectroscopie associée, l'inversion des données atmosphériques et les premières campagnes ballon. La première partie de ce manuscrit décrit le contexte scientifique qui a conduit au développement des spectromètres laser et donne un état de l'art en matière instrumentale. La seconde partie décrit deux études spectroscopiques portant sur le multiplet R(6) du méthane à 3.24µm et sur les transitions R18e et R20e du dioxyde de carbone à 2.68µm pour l'inversion des mesures atmosphériques. La troisième partie de ce manuscrit porte sur le développement des spectromètres PicoSDLA-CH4 dédié à la mesure de CH4 dans l'atmosphère à 3.24µm, utilisant une source laser à différence de fréquence, et PicoSDLA-CO2 dédié à la mesure de CO2 à 2.68µm avec une diode à antimoniure. Ces spectromètres ont réalisé plusieurs vols sous ballons stratosphériques en 2010, 2011 et 2012. Les résultats de ces campagnes sont exposés dans la quatrième partie du manuscrit. / This thesis reports the development of laser spectrometers dedicated to in-situ measurements of CH4, CO2 et H2O in the middle atmosphere. It includes the development of the prototypes, the associated spectroscopy, the concentration data retrieval as well as the first balloon campaigns. The first part of the thesis describes the scientific framework and it further gives a state of art of the instrumental field. The second part gives the results from a spectroscopic study on the R(6) manifold of CH4 at 3.24µm and on the R18e and R20e lines of CO2 at 2.68µm in order to allow an accurate concentration retrieval. The third part details the development of the PicoSDLA-CH4 spectrometer dedicated to the in-situ measurements of CH4 at 3.24µm, using a difference frequency generation (DFG) laser source, and the development of PicoSDLA-CO2, a sensor dedicated to measurements of CO2 at 2.68µm using antimonide laser diodes. Both spectrometers were involved in three balloon campaigns in 2010, 2011 and 2012; the results are presented in the fourth part of the thesis.

This thesis describes the development of an autonomous recovery system for stratospheric balloons, focusing on the novel pressurised balloon prototype BALMAN of CNES. Stratospheric balloons, reaching altitudes of up to 40 km, are utilised for scientific experiments, with recovery of payloads being a critical aspect. While traditional recovery methods involve separating the balloon envelope and deploying a parachute, BALMAN's parachute will be deployed in free fall. The proposed autonomous system comprises decision-making and electronics components. The decision-making segment employs microcontrollers and environmental sensors to recognise the balloon's descent, triggering the release decision. The electronics section, responsible for providing energy to a pyro cutter, is designed with electrical switches and capacitors. Thermal simulations guide the placement of heaters, maintaining system temperature within operational limits. The final prototype, tested for functionality on-ground, exhibits a measured energy release of 24 mJ, double the requirement for pyro cutter activation. However, environmental and flight testing remain pending. The system's potential applications extend beyond BALMAN, offering a standardised autonomous recovery solution for various balloons. This innovation promises enhanced landing accuracy, obviates the need for telecommunication in recovery, and facilitates payload descent deceleration. Future endeavors involve comprehensive testing and potential integration into BALMAN missions, showcasing the system's adaptability and operational simplicity across diverse stratospheric endeavors.

No description available.