Three studies of precipitable water using the Global Positioning System are presented. The first study finds that precipitable water in Hawaiʻi is best described by a lognormal distribution. The long-term average value of precipitable water declines exponentially with height, but the dispersion of precipitable water declines more linearly. The change in skewness of the distributions is also linear, although in this case it increases with elevation. The second and third studies use GPS meteorology to investigate a climatological and a meteorological event respectively. First, the effect of the 1997-1998 El Nino on precipitable water in the western tropical Pacific is studied and found to be consistent with a model relating the formation of an anomalous high-pressure ridge to the El Nino episode. Finally, the details of the precipitable water field for the Kaʻu Storm, November 2000 are examined. The results highlight the role of topography in controlling the location of convection, The observed correlation between the precipitable water and rainfall is used to generate estimates of rainfall based on GPS data, Comparing the GPS precipitable water estimates with those from a weather model indicates that the underestimates of rainfall produced by the weather model are probably due to correlated underestimates of precipitable water. / Thesis (Ph. D.)--University of Hawaii at Manoa, 2002. / Mode of access: World Wide Web. / Includes bibliographical references (leaves 62-66). / Electronic reproduction. / Also available by subscription via World Wide Web / ix, 66 leaves, bound ill. 29 cm

Thesis (Ph.D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2008. / Committee Chair: Dr. Paul G. Steffes; Committee Member: Dr. Gregory D. Durgin; Committee Member: Dr. Robert D. Braun; Committee Member: Dr. Thomas K. Gaylord; Committee Member: Dr. Waymond R. Scott

Thesis (Ph. D.)--University of California, San Diego, 2000. / Vita. Includes bibliographical references.

No description available.

Water vapour content and transport over southern Africa and adjacent oceans are examined. Early summer rainfall over the northern and central interior of South Africa tends to be associated with baroclinic controls whereas late-summer rainfall is barotropic in origin. This is reflected in the northwesterly water vapour transport from an Atlantic Ocean source by middle and upper tropospheric westerly waves in early summer. A thermally indirect Ferrel cell, indicated-from energetics, COpIU1nSthe· temperate nature of the early-summer atmosphere over southern Africa. Late summer water vapour transport, in contrast, is strongly from the tropics, with' a reduced eddy component, indicating an important tropical control on late SUmmerrainfall especially in terms of fluctuations in the position of the ascending limb of .the Walker cell Over southern Africa. The Hadley cell is of importance to the late summer rainfall in that dry (wet) years are associated with an anomalous cell OVereastern (central) South Africa such that low level vapour transport is southerly (northerly). The anticyclone over the eastern parts of southern Africa, coupled with. a trough over the interior (especially at the 700 hPa pressure level), is important for the introduction of water vapour over the subcontinent in wet and dry years and for tropical-temperate trough case studies. Water vapour source regions differ from early summer (Atlantic Ocean) to late summer (Indian Ocean), which reflects the temperate. control on early and the tropical control on late summer circulation. The convergence of water vapour over southern Africa in wet years and during tropical-temperate troughs is not only important for cloud formation and precipitation, but also for latent heat release associated with convergent water vapour. Diabatic heating decreases the stability of the tropical atmosphere thereby resulting in increased vertical motion. It also forces an anomalous Badley circulation during wet late summers and tropical-temperate trough .cases as a result of complex energy transformations. Heating increases eddy available potential energy which is converted to zonal available potential energy by a thermally indirect circulation found in the tropics. The zonal potential energy is then converted to kinetic energy by the thermally direct Badley cell. Water vapour and its variations are thus important for the precipitation, heating and SUbsequent energy of the subtropical southern African atmosphere, / GR 2017

The object of this research program has been to provide a baseline for microwave remote sensing of ammonia and water vapor in the atmosphere of Jupiter through laboratory measurements of their microwave absorption properties. Jupiter is not only the largest planet in our solar system, but one of the most interesting and complex. Despite a handful of spacecraft missions and many astronomical measurements, much of Jupiter s atmospheric dynamics and composition remain a mystery. Although constraints have been formed on the amount of certain gases present, the global abundances and distributions of water vapor (H2O) and ammonia (NH3) are relatively unknown. Measurements of H2O and NH3 in the Jovian atmosphere to hundreds of bars of pressure are best accomplished via passive microwave emission measurements. For these measurements to be accurately interpreted, however, the hydrogen and helium pressure-broadened microwave opacities of H2O and NH3 must be well characterized, a task that is very difficult if based solely on theory and limited laboratory measurements. Therefore, accurate laboratory measurements have been taken under a broad range of conditions that mimic those of the Jovian atmosphere. These measurements, performed using a newly redesigned high-accuracy system, and the corresponding models of microwave opacity that have been developed from them comprise the majority of this work. The models allow more accurate retrievals of H2O and NH3 abundances from previous as well as future missions to Jupiter and the outer planets, such as the NASA New Frontiers class Juno mission scheduled for launch in 2011. This information will enable a greater understanding of the concentration and distribution of H2O and NH3 in the Jovian atmosphere, which will reveal much about how Jupiter and our solar system formed and how similar planets could form in other solar systems, even planets that may be hospitable to life.

This document describes the design and deployment of a first generation water vapor density sensing unit, the HumiSense. This device is based on an open, air-filled capacitor which is part of a resonant circuit. The frequency of the resonant circuit mixed with a fixed frequency oscillator is the basis of the method to generate a signal that is associated to the change in water vapor density within the open capacitor with time. The physical testing results were inconclusive given that there were many unresolved artifacts in the data. Several suggestions for improving the device for future device generations were provided. / Graduation date: 2013

La vapeur d’eau est le principal gaz à effet de serre de l’atmosphère et implique un processus de rétroaction climatique positif qui se traduit par une augmentation importante de l’humidité dans la troposphère dans les prochaines décennies. La vapeur d’eau joue également un rôle primordial dans le système climatique, notamment via le transport d’énergie de l’équateur vers les pôles. Malgré ceci, la compréhension des mécanismes qui contrôlent la distribution de la vapeur d’eau sur le globe reste insuffisante, ce qui se répercute sur les prédictions de l’évolution de notre climat. Depuis quelques années, les observations de la composition isotopique de la vapeur d’eau se sont révélées être particulièrement utiles pour aider à mieux comprendre les processus hydrologiques car les différents isotopologues de la vapeur d’eau (H216O, H218O, HDO) se comportent différemment selon les processus en jeu.<p>Dans cette perspective, les mesures de radiances du système terre-atmosphère dans l’infrarouge thermique par l’Interféromètre Atmosphérique de Sondage Infrarouge (IASI) à bord de la plateforme météorologique MetOp, peuvent fournir des observations du rapport isotopique δD (rapport HDO/H216O), à l’échelle globale et à haute résolution spatio-temporelle, pour autant que la restitution du rapport puisse être obtenue avec une précision suffisante.<p>Dans ce travail, nous présentons une méthodologie robuste et précise pour la restitution du profil de δD à partir des spectres IASI. Basée sur la méthode d’estimation optimale, elle consiste à appliquer des contraintes d’inversion adaptées afin d’obtenir des profils de δD fiables. Nous décrivons le choix de celles-ci et nous montrons que la méthode mise en place permet de fournir des profils de δD qui présentent un maximum de sensibilité dans la troposphère libre. L’adéquation de la méthode mise en place est ensuite évaluée grâce à une étude d’inter-comparaison avec des mesures dérivées de l’instrument spatial TES (Tropospheric Emission Spectrometer sur AURA) et FTIR localisés au sol. L’exactitude des profils IASI a aussi pu être déterminée grâce à des comparaisons avec des mesures in situ. <p>Dans une autre partie du travail, nous nous attachons à préciser les applications liées à l’utilisation des nouvelles mesures dans le domaine des géosciences. Nous documentons ainsi les capacités du sondeur IASI à fournir des mesures de δD à une résolution spatio-temporelle inégalée et décrivons les diverses distributions obtenues. Nous montrons et analysons notamment les premières cartes globales à haute résolution de δD dans la troposphère. Les mesures de δD et de l’humidité sont analysées conjointement à l’aide de modèles simples et permettent de démontrer la plus-value mesures de δD depuis les satellites. Parmi les résultats les plus significatifs, citons la mise en évidence de la signature isotopique des différentes sources de la vapeur d’eau (évaporation continentale/océanique), et celle de l’empreinte des différents processus hydrologiques qui contrôlent l’humidification de l’atmosphère (convection, mélange de masse d’air, ré-évaporation des gouttes de pluie). <p> / Doctorat en Sciences / info:eu-repo/semantics/nonPublished