Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (p. 89-92).

No description available.

No description available.

Diss. no. 13300 nat. sc. SFIT Zurich. / Literaturverz.

Universiẗat, Diss., 2000--München.

Universiẗat, Diss., 2003--München.

Thesis (M. S.)--Florida State University, 2006. / Advisor: Philip Cunningham, Florida State University, College of Arts and Sciences, Dept. of Meteorology. Title and description from dissertation home page (viewed June 7, 2006). Document formatted into pages; contains viii, 53 pages. Includes bibliographical references.

Tropospheric ozone plays an important role in the atmosphere especially towards climate change and air quality. In this study, characteristics of tropospheric ozone over the South African Highveld are investigated using the ozonesonde data collected at Irene weather station (25.9°S, 28.2°E, and 1523 m asl) for the period 1990 to 1993 and 1999 to 2003. It was found that synoptic systems have an effect on the vertical distribution of tropospheric ozone. Ozone stratification appeared during anticyclonic conditions as displayed by a continental high ozone profile. During the ridging high, low ozone concentrations are observed with a strong ozone gradient between 10 and 12 km. Ozone enhancement appeared in the lower altitudes, <4 km, in both the ridging high and the westerly disturbance ozone profiles. Ozone profiles exhibited higher ozone concentrations during the westerly wave conditions. Tropospheric ozone over the South African Highveld region follows a clear annual cycle with lower ozone concentrations observed during autumn and higher ozone concentrations during spring. Summer ozone profiles had high ozone concentrations from the earth’s surface up to 9 km compared to winter ozone profiles. However, winter ozone profiles exhibited higher ozone concentrations than summer ozone profiles and they were characterised by a strong ozone gradient at 12 km. Ozone profiles obtained during the Southern African Fire-Atmosphere Research Initiative conducted in 1992 (SAFARI-92) displayed lower ozone concentrations than ozone profiles from the Southern African Regional Science Initiative conducted during 2000 (SAFARI- 2000). Therefore, it is apparent tropospheric ozone over the South African Highveld has increased over the past decade.

Universiẗat, Diss., 2003--Frankfurt am Main.

Two mechanisms appear to be primarily responsible for the formation of cirrus clouds in Tropical Tropopause Layer (TTL): detrainment from deep convective anvils and in situ initiation. Here we propose to identify TTL cirrus clouds by analyzing water content measurements from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) and Aura Microwave Limb Sounder (MLS). Using ice water content (IWC) and water vapor (H2O) abundances we identify TTL cirrus clouds that contain too much ice to have been formed in situ — and therefore must be of convective origin. We use two methods to infer amounts of water vapor available for in situ formation. Clouds with IWC greater than this threshold are categorized as being of convective origin; clouds with IWC below the threshold are ambiguous — they could either form from in situ or still be of convective origin. Applying the thresholds from December 2008 to November 2009, we found that at least 19.2% of tropical cirrus were definitively of convective origin at the tropopause (375 K) during boreal winter. At each level, we found three maxima in the occurrence of convective cirrus: western Pacific, equatorial Africa, and South America. Averaged over the entire tropics (30oS to 30oN), we found convective cirrus occurs more frequently in boreal winter and less frequently in boreal summer, basically following the a decreasing trend from DJF, MAM, SON, to JJA. During boreal summer, we found that only 4.6% of tropical cirrus come from convection. Sensitivity tests show that the thresholds derived at 390 K have the largest uncertainty. At lower levels, especially 375 K, our thresholds are robust.