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The relevance of ship based routeing is discussed. Data collected at sea are analysed to produce vessel response characteristics Meteorological data are analysed in a conventional manner to establish effective steering criteria with respect to 500 mb flow. For the first time a routeing model is formulated which recognises the three spatial dimensions of a middle latitude storm. A theoretical analysis of relative flow in a growing baroclinic wave is undertaken. Reference to displacement of the wave trough affords a measure of both storm development and steering effectiveness. Short, medium and long term planning elements are combined in a model. The effectiveness of this approach is demonstrated by actually "weather routeing" a vessel, whilst comparing progress of a sister ship navigated conventionally. Sources of error and limitations of the model are discussed.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. Johannesburg, 2016. / The diaries of Jan van Riebeeck contains one of the oldest documentary records of weather phenomena for the southwestern Cape. They contain descriptions of daily wind direction and strength and daily rainfall events. The primary aim of this research is to reconstruct a comprehensive weather chronology for the southwestern Cape region from these diaries, spanning the period 1652-1665, and place this in context with the 20th-21st C climate for the region. The study further aims to examine the relationships between the 17th C society and natural environment. All climate and environmental information is extracted from the diaries and tabulated. Qualitative information on wind and rain was classified and transformed into quantitative data. Contemporary data retrieved from the Royal Observatory and the South African Weather Services are used to make comparisons between the historical study period and contemporary conditions. However, due to the qualitative nature of the historical data, statistical analysis demonstrated that such comparisons are limited. Within the historical period, analysis of the number of rain days demonstrated a distinct wet period in the first half followed by progressive drying. Wind data from the diaries reflected distinct seasonality linked to shifts in the position of the ITCZ. Additionally, unusual events including snow, hail, the Black south-easterly and ‘dirty rain’ are explored. Qualitative data revealed a heavy reliance on climate to support crops and livestock, and a range of environmental stresses to human health, infrastructure and food security. / LG2017

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During summertime Saharan heat low, a region of low pressure system, is formed as a result of large solar insolation superimposed with the convergence of west African South westerly monsoon flow and dry north easterly Harmattan flow along the intertropical discontinuity. This region plays significant role in the initiation and development of the West African Monsoon. The Saharan heat low is co-located with region of maximum load of dust aerosol which is known to have impact on the climate. Further the Saharan heat low plays key role in the global circulations including its role in formation of African Easterly Jets and African Easterly Waves. Despite its role in influencing the dynamic and thermodynamics of the region, the Saharan Heat low is not extensively studied partly due to lack of comprehensive data due to the harsh weather conditions of the region. Climate system of the Saharan heat low is a result of different complicated atmospheric and land surface processes most dominantly immense solar input at the surface, large convergence of sensible heat flux from the ground into the atmosphere, and low level cooling by horizontal advection of moisture from the surrounding area. These dynamical and thermodynamical processes take part in transport and redistribution of heat and transport of the moisture in the region. This thesis aims at providing a detailed analysis of the physical processes responsible for the development, maintenance, and decadal variability of the Saharan heat low region. I investigate three specific aspects of the Saharan heat low region. 1. Heat and Moisture Budget: Heat and moisture are drivers of dynamics and thermodynamics of a region. Previous studies presented heat and moisture budget of the Saharan heat Low without attributing to the detailed mechanisms by which heat and moisture is transported from the surrounding area to the Sahara heat low and vice versa. This thesis presents components of heat and moisture budget resulting from mean and transient flows that are responsible for heating/cooling and moistening/drying of the Sahara heat low region. Heat and moisture budget are derived using commonly used reanalyses simulations (ERA-I, NCEP, and MERRA) and comparison of the results between the three reanalyses are made. I investigate the mechanisms responsible for the decadal variability of intensity of the Sahara heat low and provide implications. This work has not been done previously to the best of knowledge. 2. Role of Dust and Water vapor in controlling the radiative flux: Recent studies show that water vapour greenhouse forcing is responsible for intensification of the Saharan heat low and as a consequence recovery of Sahel rainfall. Dust aerosol is known to have impact on the climate through its interaction with radiation. The large dust load in the Sahara heat low makes it important in controlling the variability in the radiative budget of the region. Previous studies have quantified the role of dust and water vapour in the region in controlling day to day variability in the radiative flux in the heat low. There is still uncertainty in the radiative forcing and associated variability partly due to lack of observational data. Furthermore separating the radiative effect of dust from that of water vapour is challenging due to the co-variability of dust and water vapour. This thesis quantifies separate and combined effect of dust and water vapour in controlling the radiative flux of the Saharan heat low using the recently made FENNEC observations of meteorological variables and dust loading. Theoretical experiments are made to study sensitivity of radiative flux to variations in dust and water vapour. 3. Characteristics of convective density currents: Convective down drafting density currents (cold pools) are ubiquitous features of the Saharan Heat low region which are shown to play important role in the transport of moisture and emission of dust in the region. Despite this, the characteristics of these atmospheric processes are not well studied in the Sahara Heat Low. Improving our knowledge of properties of convective density currents is imperative to better understand atmospheric processes within boundary layer of the Saharan heat low and thus improve model simulation performance. Here I provide magnitude, spatial distribution, and seasonal variability of cold pools using data from the Automatic weather Station (AWS) spread over the Sahara desert. I implement a unique identification method which is further verified by satellite observations of cold pool signatures. Once cold pools are identified at all stations, statistical description of the occurrence frequency and distribution are presented. Finally I asses reanalyses model simulation of convection triggered cold pool outflows through comparison with measurements.

Graduation date: 1955

Thesis (M.S.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 87-88). Also available on the World Wide Web.

A new high-resolution climatology and volumetric θ-S census (Δθ = 0.1°C, ΔS = 0.01) is constructed for the Ross Sea. Property maps (potential temperature, salinity, and dissolved oxygen) along 40 depth levels and 21 neutral density (γn) surfaces are analyzed. A major inflow of Antarctic Surface Water (AASW) is observed branching off the westward-flowing coastal current near Cape Colbeck. One portion continues poleward hugging the coast while the other follows the shelf break to the west. The characteristic “V” shape of the Antarctic Slope Front over the western Ross Sea is indicated by a narrow stream of thickened AASW. The entire AASW layer shoals from east to west. Two major shoreward inflows of Lower Circumpolar Deep Water (LCDW) are inferred. A warm and salty tongue from the Balleny Gyre enters the Drygalski and Joides troughs. A similar tongue is exported from the Ross Gyre and enters the Glomar Challenger Trough. No significant LCDW inflow is observed over the eastern slope of the Ross Sea. The thickest outflows of Shelf Water (SW: θ ≤ -1.85°C, S > 34.5) and new Antarctic Bottom Water (AABW: θ > -1.85°C, γn > 28.27 kg m-3) are found along the Drygalski and Joides troughs. Their saltiest (S > 34.7) components are concentrated in the western Ross Sea, whereas the low-salinity varieties are found throughout the Ross Sea shelf. The most voluminous water mass in the Ross Sea is LCDW. The least abundant is AABW found primarily over the western slope. Modified CDW (MCDW) in the western Ross is inferred to be a mixture of 30% AASW and 70% LCDW; whereas central (eastern) MCDW is 40% (60%) AASW and 60% (40%) LCDW. The same water mass composition is inferred for new AABW in the western and central Ross Sea: 25% SW and 75% MCDW. A 40-year freshening trend is detected at different sites along the coastal transit of AASW from Cape Colbeck to Ross Island. In addition to a freshening, the MCDW and high-salinity SW also reveal a cooling trend. Conversely, a warming and salinification is indicated at the main inflows of LCDW.

Thesis (Ph. D.)--School of Electrical and Computer Engineering, Georgia Institute of Technology, 2004. Directed by Linda M. Wills. / Vita. Includes bibliographical references (leaves 169-175).

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