The synoptic chart encodes climatological and meteorological information in a highly abstract manner. The pupil's level of cognitive development, the nature of the syllabus and the teaching strategies employed by the geography teacher influence the pupil's conceptualisation of information. The synoptic chart is a valuable tool for consolidating the content of the S.A climatology syllabus. Recent research has established that climatology-meteorology, and especially synoptic chart reading and interpretation, is difficult for the concrete thinker. These pupils find difficulty in visualising the weather processes and systems. Provided that they are simple and clear, models are useful teaching devices that integrate and generalise information in a manner that is easily retrievable. The intention of the author is to provide weather type models and other supporting strategies and aids as a means to improve the senior secondary pupil's assimilation of southern African climatological-meteorological information. This model-based approach is tested in the classroom using an action research framework to judge its efficacy. Conclusions are drawn and recommendations are made.

The surface character of a suburban area is far from the uniform, smooth and flat planes over which current surface-layer theory is valid and where vertical eddy-fluxes can be assumed to be almost constant horizontally and vertically. The complexity of the surface introduces considerable variability into the atmosphere at small spatial scales. This variability is partly reduced and spatially-averaged by turbulent mixing but still leaves the concerns about the spatial representativeness of sensible heat flux measurements over a suburban area. The spatial scales of sensible heat flux variability are discussed in terms of the distribution of surface temperature and roughness elements. It is shown that : (1) an eddy-correlation measurement can be considered spatially representative, if its surface zone of influence (source area) is large enough to include a spatially representative sample of surface temperature and roughness elements. (2) a quantitative measure of spatial representativeness can be estimated by use of the two-dimensional Fourier transform of the surface temperature and roughness element distributions (i.e. by the normalized integrated variance spectrum). (3) the source area of an eddy correlation measurement may be evaluated by a numerical model based on a probability density function plume diffusion model. The source area model developed herein can also be used to estimate the relative influence of specific surface sources or sinks upon an eddy-flux measurement in the surface layer. These concepts are tested in a suburban residential area in Vancouver, B.C., Canada. Remotely sensed surface temperatures and a digitized roughness element inventory are used as data-bases for the Fourier transforms to develop representativeness criteria for eddy-flux measurements. A set of sensible heat flux measurements at six sites and the corresponding source area calculations are used to formulate recommendations for the objective evaluation of the spatial representativeness of sensible heat flux measurements over a suburban area. The validity of the suggested evaluation methods is confirmed by the observations. Internal boundary layer growth, estimated by the source area model, compares well with existing work. Some consequences of complex surfaces on the surface layer structure are briefly discussed. / Arts, Faculty of / Geography, Department of / Graduate

Philosophiae Doctor - PhD / This thesis characterises and discusses two continuous coastal Southern Hemispheric (SH) atmospheric radon (222Rn) signals. Large-scale atmospheric circulation patterns are important components of the climate system implicated in driving catastrophic events such as extreme droughts and mega-wildfires and radon measurements at coastal sites provide valuable information on interactions of terrestrial and oceanic air masses on regional to hemispheric scales. The main collaborating SH atmospheric observatories in this study are located at Cape Grim (CGO, Tasmania, 1992-2017) and Cape Point (CPO, South Africa, 1999-2017). The radon signal from a high-altitude remote island oceanic site in the Northern Hemisphere Mauna Loa Observatory (MLO, Hawaii, 2004-2015) is also incorporated for comparison purposes. The CGO radon signal is the longest and most sensitive in current existence. A variety of statistical, spectral, trend, back-trajectory and trajectory density methods are utilized in this study to illuminate features of the datasets on multiple scales. Strongly skewed radon distributions occur, with a large number of events falling into a compact range of low values (corresponding to marine air-masses) and a smaller number of events spread over a wide range of high-radon values (continental air-masses). Making use of Fast Fourier Transform power spectral analysis, prominent periodicities are identified on diurnal and annual scales. Inter-annual variations in seasonal and diurnal radon and meteorological characteristics, indicating changes in the continental/oceanic atmospheric mixing state, are evident especially during the period from 2012 to 2017, perhaps associated with the strong El-Niño southern oscillation centred on 2015. A slow but systematic decline in CGO and CPO radon levels is evident over the dataset, associated with fewer continental and more marine air-masses impacting the coastal stations. The long-term trends observed in the atmospheric radon signal may indicate changes in SH circulation patterns over time, perhaps associated with climate change effects.

A thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy (Agroclimatology) at the University of Witwatersrand, 2017. / Plant development is inherently linked to meteorological variability. The phenology, distribution and production of crops and wild relatives has already altered in response to climate change. Recent years have produced the warmest mean annual global temperatures since 1880, with 2016 setting the highest record thus far. Such profound changes have sparked investigations into the impact of temperature and rainfall on crop development, particularly those with profound economic importance such as coffee (C. arabica). The crop is a fundamental source of income for smallholder farming communities and governments throughout the tropical highlands. However, the impact of climate change on C. arabica has yet to be quantified using empirical data in East Africa, leaving uncertainty in the cultivable future of the crop. Therefore, the objective of this thesis is to investigate the influence of climate change and variability on C. arabica yields and phenology in East Africa. Using a spatio-temporal approach, trends and relationships between coffee performance and meteorological variables were analysed at different scales and time periods ranging from the macroclimatic national scale (49 year), to the meso- and microclimatic farm level (3 year) scale, and finally to the microclimatic canopy and leaf level (hourly) scales. Data from all three climatic continua reveal for the first time that temperatures, and particularly rapidly advancing night time temperatures, are having a substantial negative impact on C. arabica yields. Forecasting models based on these biophysical relationships indicate that by the year 2050, smallholder farmers would on average harvest approximately 50% of the yield they are achieving today. Warming night time temperatures are also responsible for advancing ripening and harvest phenology. As a result, bean filling and development time is reduced, thereby potentially resulting in lower quality coffee. Trends in precipitation do not appear to have any substantial impact on C. arabica yields or harvest phenology, however, it is proposed that rainfall would act synergistically with temperatures to influence plant development and other phenological phases such as flowering. Finally, thermography is introduced as a novel complementary technique to rapidly analyse the suitability of different agroecological systems on coffee physiology at the leaf level. High temporal resolution (hourly) data, illustrate the success of the method in variable meteorological and environmental conditions. The findings contribute to advancing the protocol for use at the canopy and plantation level on coffee, so that appropriate microenvironment designs and adaptation mechanisms be put in place to accommodate climatic change. Avoiding increments in night time temperatures is key to maintaining or improving yields and fruiting development. Farming at higher altitudes and novel agroforestry systems may assist in achieving lower night time temperatures. Importantly, data reveal that careful analysis of various cropping systems, particularly at lower altitudes, is critical for providing suitable microenvironments for the crop. / XL2017

Wind and waves play a major role in important ocean dynamical processes, such as the exchange of heat, momentum and gases between atmosphere and ocean, that greatly contributes to the earth climate and marine lives. Knowledge on wind and wave weather and climate is crucial for a wide range of applications, including oceanographic studies, maritime activities and ocean engineering. Despite being one of the important world shipping routes, the wind-wave characteristics in the Red Sea are yet to be fully explored. Because of the scarcity of waves data in the Red Sea, numerical models become crucial and provide very powerful tools to extrapolate wind and wave data in space, and backward and forward in time. Unlike open oceans, enclosed basins wave have different characteristics, mainly because of their local generation processes. The complex orography on both sides of the Red Sea makes the local wind, and consequently wave, modeling very challenging. This thesis considers the modeling of wind-wave characteristics in the Red Sea, including their climate variability and trends using state-of-the-art numerical models and all available observations. Different approaches are investigated to model and understand the general and unusual wind and wave conditions in the basin using standard global meteorological products and customised regional wind and wave models. After studying and identifying the main characteristics of the wind-wave variability in the Red Sea, we demonstrate the importance of generating accurate atmospheric forcing through data assimilation for reliable wave simulations. In particular, we show that the state-of-the-art physical formulation of wave models is not suitable to model the unique situation of the two opposing wind-waves systems in the Red Sea Convergence Zone, and propose and successfully test a modification to the input and white-capping source functions to address this problem. We further investigate the climate variability and trends of wind and waves in the Red Sea using high-resolution wind and wave reanalyses that have been generated as part of this thesis. An innovative spectral partition technique is first applied to distinguish the dominant wave systems. Our analysis demonstrates that winds, and consequently waves, exhibit a decreasing trend in the Red Sea. This is mainly attributed to a remarkable weakening of the winds protruding from the Mediterranean Sea. We also use these highresolution reanalyses to assess the potential for harvesting wind and wave energy from the Red Sea.

We used ion drift observations from the DE-2 satellite to study for the first time the longitudinal variations of middle and low latitude F-region zonal plasma drifts during quiet and disturbed conditions. The daytime quiet-time drifts do not change much with longitude. In the dusk-premidnight period, the equinoctial middle latitude westward drifts are smallest in the European sector, and the low latitude eastward drifts are largest in the American-Pacific sector. The longitudinal variations of the late night-early morning drifts during June and December solstice are anti-correlated. During geomagnetically active time s, there are large westward perturbation drifts in the late afternoon-early night sector at upper middle latitudes and in the midnight sector at low latitudes. The largest westward disturbed drifts during equinox occur in the European sector and the smallest in the Pacific region. These results suggest that during equinox, Subauroral Polarization Streams (SAPS) events occur most often at European longitudes. The low latitude perturbation drifts do not show significant longitudinal dependence. We have used five years of measurements on board the ROCSA T-1 satellite to develop a detailed local-time, season, and longitude-dependent quiet-time global empirical model for equatorial F-region vertical plasma drifts. We show that the longitudinal dependence of the daytime and nighttime vertical drifts is much stronger than reported earlier, especially during December and June solstice. The late night downward drift velocities are larger in the eastern than in the western hemisphere at all seasons, the morning and afternoon December solstice drifts have significantly different longitudinal dependence, and the daytime upward drifts have strong wavenumber-four signatures during equinox and June solstice. The largest evening upward drifts occur during equinox and December solstice near the American sector. The longitudinal variations of the evening prereversal velocity peaks during December and June solstice are anti-correlated, which further indicates the importance of conductivity effects on the electrodynamics of the equatorial ionosphere. We have shown that disturbance dynamo largely does not affect daytime drifts. The upward perturbations during the nighttime are largely season independent, but near the prereversal enhancement, the downward perturbation drifts are largest during equinox and smallest during December.

A Rayleigh-scatter lidar has been in operation at Utah State University (41. 7° N, 111.8 ° W) starting in September 1993 until the present (October 2003). The return profiles from the atmosphere have been analyzed to provide temperature measurements of the middle atmosphere from 45 to 90 km. Various methods of averaging were used to construct a temperature climatology of the region based on these observations. The data analysis algorithm has been critically analyzed to find possible sources of error, and has been compared to an independently derived technique. The resulting temperatures have been compared to other mid-latitude lidars with good agreement. Comparisons were made with temperatures from other ground-based instruments at Bear Lake Observatory. Additional comparisons were carried out with two satellite-based instruments, WINDII and SABER The comparison of individual nights with the SABER instrument produced surprisingly good agreement considering the difference in the two methods. With the basic analysis of the temperature climatology completed in this work, an outline is given for future research and upgrades to the facility.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Meteorology and Physical Oceanography, 1982. / Microfiche copy available in Archives and Science / Vita. / Bibliography: leaves 120-127. / by Robert Steven Chen. / M.S.

Thesis. 1977. Ph.D.--Massachusetts Institute of Technology. Dept. of Meteorology. / Microfiche copy available in Archives and Science. / Vita. / Bibliography : leaves 206-218. / Ph.D.

Bryan Tikalsky Department of Geography Master of Science Mountain water resources are essential to those living along the Salt Lake City urban corridor. Water resource planners base their policy on twentieth century climate conditions and streamflow records. Often these records only account for a small amount of the natural variability in streamflow and climate. By utilizing dendrochronology this study seeks to better understand variability of streamflow in the Jordan River Drainage Basin over the last 828 years. A GIS model was used to identify potential sampling sites where tree growth would be sensitive to climate and factors affecting stream run-off. Over eighty samples from ancient limber pine (Pinus flexilis) and Douglas-fir (Pseudotsuga menziesii) were obtained to perform the reconstruction. Results indicate significant correlation between tree growth and streamflow. A multiple linear regression model created with tree-ring width as the predictor of October - March American Fork River streamflow explained 51.7% of streamflow variance. Analysis of the reconstruction indicates that present records do not adequately represent potential streamflow variability, and several droughts of greater severity and length occurred before the instrumental period.