No description available.

Thesis (M.S.C.I.T.)--Regis University, Denver, Colo., 2006. / Title from PDF title page (viewed on Apr. 7, 2006). Includes bibliographical references.

In this work, snow data, collected at the Centre for Atmospheric Research Experiments (CARE) site during the winter of 2005/06 as part of the Canadian CALIPSO/CloudSat Validation Project (C3VP) were analyzed with various goals in mind: 1) investigate the effects of surface temperature and system depth on the snow fall velocity and particle size distribution, 2) find the variables that control the relationships between snow fall velocity and size (control variables), 3) retrieve the coefficient and the exponent in the power-law mass-size relations used in snow reflectivity, 4) estimate vertical air motion and 5) describe the shape of snowflakes that can be used in polarimetric studies of snow. It also includes considerable calibration work on the Hydrometeor Velocity and Shape Detector (HVSD); as well as sensitivity testing for radar calibration and Mie-scattering effect on snow density. / Snow events were classified into several categories according to the radar echo vertical extent (H), surface and echo top temperatures (T s, Tt), to find their effects on snow fall velocity and particle size distribution. Several case studies, including situations of strong turbulence, were also examined. / Simple and multiple correlation analyses between control variables and parameters of the power-law size-velocity relationship were carried out for 13 snow cases having a high R2 between their mean snowflakes fall velocity and the v-D fitted curve, in order to find the control variables of power-law v-D relations. Those cases were all characterized by single layered precipitation with different echo depth, surface and echo top temperatures. Results show that the exponent "b" in v-D power-law relationship has little effect on the variability of snow fall velocity; all control variables (T s, Tt, H) correlate much better to the coefficient "a" than to the exponent "b", leading to a snow fall velocity that can be simulated with a varying coefficient "a" and a fixed exponent "b" (v=aD0.15) with good accuracy. Coefficient "a" and exponent "b" for a generic snow v-D relationship were also examined. The results indicate that coefficient "a" of generic snow represents the most frequent coefficient "a" during the events, while the exponent "b" does not show any representative. / Retrieval of the coefficient "a" and exponent "b" in a power-law mass-size relation, which eventually affects the snow reflectivity, was conducted by minimizing the root mean square (RMS) of differences in reflectivity between Vertically pointing McGill X-band Radar (VertiX) and HVSD. Minima of reflectivity differences lay on a diagonal direction of a diagram of the coefficient "a" (x-axis) versus exponent "b" (y-axis). It is shown that as the system deepens, the slope gets less steep. In addition, coefficient and exponent for this mass-size relation change with time, and snow density derived from several combined snow events does not explain the average snow density of the period. / A method to retrieve vertical air motion with good accuracy using VertiX and HVSD is suggested. Several snow shape parameters and relations between the area ratio (Ar) and size of snowflakes (Ar-D relation) are investigated with snow dimensions defined in various ways. These Ar-D relations will be used as a guideline in snow density models.

Thesis (M.S.)--Wisconsin. / Includes bibliographical references (leaves 46-48).

No description available.

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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.

Recently, the high radiance of synchrotron sources was used to enhance FTIR spectrometer performance. However, excessive channel spectra when synchrotron sources are used degrade the quality of retrieved spectral parameters. In the research reported in this thesis, seven different techniques for handling channel spectra were investigated. These techniques were used to reduce channel spectra for a test group of seven samples of CO2 mixed with air recorded using the synchrotron source at the Canadian Light Source. The increases in signal to noise ratio (SNR) of spectra handled with each technique were calculated. SNR results showed that transmission spectra, produced using synthetic background spectra with simulated channel spectra, achieved the highest SNR improvement. However, when the spectra groups were fitted using nonlinear least square fit algorithm, the technique using channel spectra fitting produced the smallest fitting residual. Moreover, the retrieved intensities and air broadening coefficients of 21 spectral lines showed that the spectral fitting technique produced the most accurate values as compared to the HITRAN 2008 database. Although the spectral fitting technique was accurate in retrieving spectral line parameters, applying the technique at wider spectral ranges was less accurate. A modification to the channel spectra fitting technique by performing iterations of channel fitting was introduced to process wider spectral ranges. Carbon dioxide laser band I centred at 961 wavenumber was analyzed using 24 spectra recorded under different experimental conditions. The intensity and air-and self-broadening coefficients were retrieved for 48 spectral lines with average deviations from HITRAN database values of 2.11%, 1.25% and 4.14%, respectively, using the Voigt profile. These average deviations lie within the uncertainty limits listed by the database. The deviation between our results and other results reported in the literature were also examined and it is found to be also within the range of HITRAN uncertainties. The effect of errors in fitting channel spectra parameters was examined and found to be mitigated by the inclusion of channel-free spectra in the multispectral fit. / xiv, 134 leaves : ill. ; 29 cm

This article gives an overview about the activities of the Leipzig Institute of Meteorology (LIM) within the HALO (High Altitude and Long Range Aircraft) Scientific Priority Program (SPP 1294 funded by DFG). HALO offers unique possibilities for atmospheric research and Earth observations. It can carry a scientific payload of up to 3 t, cover a range of 10000 km and reach a ceiling of 15 km. The LIM contributes to the instrumentation of HALO with the Spectral Modular Airborne Radiation measurement sysTem (SMART). SMART was deployed during the first HALO mission TECHNO in 2010. During subsequent five HALO campaigns SMART measurements provided valuable insights regarding cloud properties and the Earth’s radiative budget. Three further missions, which are scheduled for the coming years, will make use of SMART measurements as well. / Dieser Bericht gibt einen Überblick über die Aktivitäten des Leipziger Instituts für Meteorologie (LIM) im HALO Schwerpunktprogramm (SPP 1294 der DFG). HALO bietet einzigartige Möglichkeiten für die Atmosphärenforschung und Erdbeobachtung. Es kann eine wissenschaftliche Nutzlast von 3 t aufnehmen, eine Reichweite von 10000 km zurücklegen und eine maximale Flughöhe von 15 km erreichen. Das LIM trägt zur Instrumentierung von HALO mit dem Spectral Modular Airborne Radiation measurement sysTem (SMART) bei. SMART wurde 2010 bei der ersten HALO Mission TECHNO eingesetzt. In fünf folgenden HALO Kampagnen verschafften SMART Messungen wertvolle Erkenntnisse bezüglich Wolkeneigenschaften und dem Strahlungsbudget der Erde. Drei weitere HALO Missionen, die für die kommenden Jahre geplant sind, werden ebenfalls SMART nutzen.

Rainfall is one of the central features of Earth’s climate. Understanding the physical mechanisms that control it has deep social impacts on water and food security. In this thesis, we use a series of idealized single column models to reveal mechanisms driving steady-state precipitation both in the tropics and in the global mean. These mechanisms yield a deeper understanding of precipitation in model outputs (Chapter 1), observations (Chapter 2), and projections for a warming climate (Chapter 3). Chapter 1 centers around model development. We use the single column model version of NCAR’s Community Earth System Model (CESM) to better understand its simulation of tropical rainfall under various representations of radiation, convection, and circulation. Using a variety of existing methods – the weak temperature gradient (WTG), damped gravity wave (DGW), and spectral weak temperature gradient (SWTG) method – we parameterize the column’s large-scale dynamics and consider the response of steady-state tropical precipitation to changes in relative sea surface temperature (SST). Radiative cooling is either specified or interactive, and the convective parameterization is run using two different values of a parameter that controls the degree of convective inhibition (CIN) required to cap a convective plume. Under all three methods, circulation strength is decreased when greater CIN is required, that is, when convection is allowed to occur more easily. This effect is shown to come from increased static stability in the column’s reference radiative-convective equilibrium profile and results in decreased rainfall over warm SSTs. This argument can be extended to aquaplanet simulations in CESM, which show that the warmest regions in the tropics rain less when greater CIN is required to cap a convective plume. This suggests that the parameter in CESM which controls the degree of convective inhibition significantly affects the strength of the model’s intertropical convergence zone (ITCZ). In Chapter 2, we use a similar set of idealized models to better understand the observed climatology of tropical rainfall. The distribution of climatological rainfall over tropical oceans can be thought of as primarily the result of two mechanisms: conditional instability in the free troposphere and convergence in the boundary layer. We modify the SWTG method to assess the relative influence of these mechanisms. In its original configuration, the SWTG method applies the weak temperature gradient approximation to the full depth of the troposphere without consideration of the stronger horizontal temperature and pressure gradients in the planetary boundary layer (PBL). To account for convergence in the PBL induced by these stronger pressure gradients, we modify the SWTG method to include an externally-specified vertical mass flux at the PBL top. When forced using the climatological SST and 850 hPa vertical velocity taken from observation-based reanalysis data, the Forced SWTG method reproduces most features of the observed annual mean tropical rainfall climatology. Its predictions remain largely unchanged when it is forced by a spatially uniform SST field. Insofar as the boundary layer convergence field can be interpreted as an external forcing on the column, this would indicate that it controls the precipitation field. However, local column stability likely also plays a role in determining PBL convergence, so this method does not fully untangle the causality behind the climatological precipitation field. In Chapter 3, we shift our perspective from column dynamics to column radiative transfer. Global mean rainfall is known to be constrained by the atmosphere's column-integrated radiative cooling. However, the surface temperature dependence of this radiative constraint on mean rainfall, and the mechanisms which set it, are not well understood. We present a simple spectral model for changes in the clear-sky column-integrated radiative cooling with surface warming. We find that surface warming increases column-integrated radiative cooling – and thus mean rainfall – by decreasing atmospheric transmission in spectral regions with significant longwave emission, that is, by closing the water vapor window. Water vapor's spectroscopy implies a hydrological sensitivity whose magnitude is roughly set by surface Planck emission, and which peaks near tropical surface temperatures. We also examine the role of carbon dioxide and shortwave heating, which primarily act to mute the hydrological response to warming. We validate our findings using line-by-line calculations. Overall, we demonstrate that idealized frameworks, such as those provided by single column models, can elucidate mechanisms controlling tropical and global-mean precipitation. However, the relevance of these results to more complex simulations and observations is tempered by the extent to which our simplifying assumptions neglect important physics.