title: A simple graphical technique for conditional long range forecasting of below-average rainfall periods in the Tuvalu Islands, Western Pacific

authors: Bardsley, W. Earl

subjects: NINO4

abstract: For the Tuvalu Island group in the western Pacific, a simple graphical method is proposed as a means of forecasting whether rainfall totals for the next 1, 2,…,6 months will be below average. The method is based on scatter plots where the points are color-coded as above- or below-average rainfall, with the plot axes being lag-1 and lag-2 NINO4 sea surface temperatures. Within the scatter plots there are reasonably clear data fields with higher frequencies of below-average rainfalls associated with cooler precursor NINO4 temperatures. These data fields are defined by subjectively emplaced separation lines which bifurcate the scatter plots into “predictable” and “unpredictable” fields. If two precursor NINO4 temperature values define a point located in a predictable field then a warning would be issued for below-average rainfall over the next n-month period, depending on the time scale of the scatter plot. A long rainfall record at Funafuti in Tuvalu indicates that success in predictable-field forecasting of below-average rainfalls would range between 68% for 1-month rainfall totals and 89% for 6-month totals. The forecasting success derives from persistence of cooler NINO4 sea surface temperatures which are associated with lower rainfalls in Tuvalu. However, many dry periods are also located in the unpredictable field and cannot be forecast by this method.

text: A simple graphical technique for conditional long range forecasting of below-average rainfall periods in the Tuvalu Islands, Western Pacific For the Tuvalu Island group in the western Pacific, a simple graphical method is proposed as a means of forecasting whether rainfall totals for the next 1, 2,…,6 months will be below average. The method is based on scatter plots where the points are color-coded as above- or below-average rainfall, with the plot axes being lag-1 and lag-2 NINO4 sea surface temperatures. Within the scatter plots there are reasonably clear data fields with higher frequencies of below-average rainfalls associated with cooler precursor NINO4 temperatures. These data fields are defined by subjectively emplaced separation lines which bifurcate the scatter plots into “predictable” and “unpredictable” fields. If two precursor NINO4 temperature values define a point located in a predictable field then a warning would be issued for below-average rainfall over the next n-month period, depending on the time scale of the scatter plot. A long rainfall record at Funafuti in Tuvalu indicates that success in predictable-field forecasting of below-average rainfalls would range between 68% for 1-month rainfall totals and 89% for 6-month totals. The forecasting success derives from persistence of cooler NINO4 sea surface temperatures which are associated with lower rainfalls in Tuvalu. However, many dry periods are also located in the unpredictable field and cannot be forecast by this method.

year: 2009

title: Power conditioning and power protection for electronic systems

authors: Kularatna, Nihal

abstract: Electrical energy is the most convenient form of energy, and modern society takes it for granted that it is always available by our side. We have a legacy AC power grid where systems were historically developed based on the assumption that electricity is generated in bulk at far-away sites from our cities and neighbourhoods. Nationwide AC transmission and distribution networks use the advantages of line frequency transformers for voltage conversions with ‘adequate’ efficiency.

Given the distributed nature of these AC power networks, with many long-distance high-voltage transmission lines and electrical substations distributed over wider geographical regions, they are naturally exposed to acts of God, such as extreme weather events and lightning strikes. Furthermore, with the increasing complexity of the power networks, complex control systems are utilized at network substations, which could occasionally have accidental failures due to system reliability issues or human errors. The overall effect is that these unexpected random events could create power quality issues and systemic issues such as overloading and sudden load shedding.

text: Power conditioning and power protection for electronic systems Electrical energy is the most convenient form of energy, and modern society takes it for granted that it is always available by our side. We have a legacy AC power grid where systems were historically developed based on the assumption that electricity is generated in bulk at far-away sites from our cities and neighbourhoods. Nationwide AC transmission and distribution networks use the advantages of line frequency transformers for voltage conversions with ‘adequate’ efficiency.

Given the distributed nature of these AC power networks, with many long-distance high-voltage transmission lines and electrical substations distributed over wider geographical regions, they are naturally exposed to acts of God, such as extreme weather events and lightning strikes. Furthermore, with the increasing complexity of the power networks, complex control systems are utilized at network substations, which could occasionally have accidental failures due to system reliability issues or human errors. The overall effect is that these unexpected random events could create power quality issues and systemic issues such as overloading and sudden load shedding.

year: 2023-03-01

title: Maori and Pakeha at Te Aroha: the context: 2: Maori in Hauraki in the nineteenth century

authors: Hart, Philip

abstract: After the arrival of Europeans, the Maori population of Hauraki suffered a rapid decline. Some rangatira opposed Pakeha ways, whereas others adopted these for their personal benefit. Keeping ‘the peace of Hauraki’ required government agents to intervene in various disputes between hapu (Ngati Hako in particular causing concern in the 1870s and early 1880s). Although rangatira had links to both Queen Victoria and King Tawhiao, the government was relieved that most remained ‘loyal’ to the new order, and only an intransigent minority opposed the spread of ‘civilisation’ through its roads, telegraph, and the snagging of the Waihou River. A liking for Pakeha goods encouraged collaboration, with Maori joining the cash economy through their involvement in road making, gum digging, and European agriculture to raise money for, in part, traditional gatherings that for a while were more lavish than earlier possible.
Maori of all ranks were quick to stand up for their rights by using the court system, reminding Pakeha of the Treaty of Waitangi, and, in some cases, violence. Tensions were eased by Maori socializing with Pakeha in sport, horse racing, and even the Volunteers, but drinking together in hotels could result in fights, and the lure of alcohol had to be countered by temperance movements. A few Maori children attended school, with Pakeha, and for a time the government provided a (free) doctor and vaccinated them against smallpox (though some preferred traditional ‘cures’ for other ailments). For most, living conditions remained poor. Criminal behaviour was of a minor nature. Christianity had to compete with old beliefs (notably in maketu), newer ones such as ‘Hauhauism’, and by the later years of the century the popularity of the Mormons.
Examples are included of intermarriage, ‘half-castes’, and Pakeha Maori, all being notable features of the time. In a variety of ways, Maori society was sufficiently resilient to adapt and thereby to survive the impact of Pakeha settlement, which produced massive changes and dominated the region well before the end of the century.

text: Maori and Pakeha at Te Aroha: the context: 2: Maori in Hauraki in the nineteenth century After the arrival of Europeans, the Maori population of Hauraki suffered a rapid decline. Some rangatira opposed Pakeha ways, whereas others adopted these for their personal benefit. Keeping ‘the peace of Hauraki’ required government agents to intervene in various disputes between hapu (Ngati Hako in particular causing concern in the 1870s and early 1880s). Although rangatira had links to both Queen Victoria and King Tawhiao, the government was relieved that most remained ‘loyal’ to the new order, and only an intransigent minority opposed the spread of ‘civilisation’ through its roads, telegraph, and the snagging of the Waihou River. A liking for Pakeha goods encouraged collaboration, with Maori joining the cash economy through their involvement in road making, gum digging, and European agriculture to raise money for, in part, traditional gatherings that for a while were more lavish than earlier possible.
Maori of all ranks were quick to stand up for their rights by using the court system, reminding Pakeha of the Treaty of Waitangi, and, in some cases, violence. Tensions were eased by Maori socializing with Pakeha in sport, horse racing, and even the Volunteers, but drinking together in hotels could result in fights, and the lure of alcohol had to be countered by temperance movements. A few Maori children attended school, with Pakeha, and for a time the government provided a (free) doctor and vaccinated them against smallpox (though some preferred traditional ‘cures’ for other ailments). For most, living conditions remained poor. Criminal behaviour was of a minor nature. Christianity had to compete with old beliefs (notably in maketu), newer ones such as ‘Hauhauism’, and by the later years of the century the popularity of the Mormons.
Examples are included of intermarriage, ‘half-castes’, and Pakeha Maori, all being notable features of the time. In a variety of ways, Maori society was sufficiently resilient to adapt and thereby to survive the impact of Pakeha settlement, which produced massive changes and dominated the region well before the end of the century.

year: 2016