title: Storm Surges in Tauranga Harbour

authors: Tyler, Michael Jack

abstract: Understanding the potential elevation of extreme sea-levels at the coast is important for management of hazards, and adaptation to climate change. This poses challenges for coastlines around the globe, with current pressure from sea-level rise and predictions for an increase in the frequency of extreme events, storminess and associated storm surge hazards. Therefore present day extreme sea-levels are likely to occur more frequently in the future, reaching higher elevations. The largest storm surge on record in New Zealand was 0.88 m in Tauranga Harbour during Tropical Cyclone Gisele in 1968. This is lower in comparison to the tide which can be up to 2 m, therefore it is important to consider the role of storm tides on extreme sea-levels in New Zealand.

The main aim of this research is to understand how storm conditions amplify the sea-level variations across Tauranga Harbour. This is one of the first studies that aims to understand how storm conditions amplify the sea-level in the upper regions of the Harbour, and therefore affect the hazards in this zone. The peaks over threshold method was applied to sea-level data at four gauges inside the Harbour, and one on the open coast at Moturiki Island. Extreme storm surges were found to be influenced by the morphology of the coastline, and are largest at Omokoroa. Due to relatively short sea-level records, additional techniques using oral histories and photographic evidence provide additional data which can be used to validate results from extreme value analyses. Storm surge is variable depending on the intensity and track of significant storms relative to Tauranga Harbour.

On the 5th January 2018 a sub-tropical storm passing over Tauranga, coincided with king tide conditions, causing significant inundation around Tauranga Harbour. The event produced maximum recorded storm surge of 0.64 m at Hairini, with an estimated average recurrence interval of 100 years at this sea-level gauge. The combination of storm tide and wave run-up was highest around the southern entrance, indicating significant external wave energy entered the Harbour. This event is an important reminder to monitor weather conditions closely during periods of king tide conditions. 

Stepwise regression was also applied to determine the variance in storm surge explained by atmospheric pressure and wind. Atmospheric pressure explains approximately 50% of the variance in storm surges. Wind from the east was found to explain an additional 3 to 15% of the variance, with the most influence at Omokoroa as it experiences large fetches from the east, being located on the north eastern side of the Peninsula. Waves likely explain the remaining variance in storm surges which is supported by findings from historical events in this study, however further research is needed to quantify the effect of waves. The relationship between storm surge frequency and magnitude with the Southern Oscillation Index was investigated at Moturiki, due to the potential for increased coastal hazards during La Niña. No statistically significant relationship was identified, however the results indicate larger, more frequent surges during La Niña. Since 2012, there has been a greater frequency of storm surge events per year exceeding 0.4 m. This may be the result of the Interdecadal Pacific Oscillation which shifted around 2000, and was predicted to increase the storm surge hazard for several decades based on previous research.

The research provides information and data on sea-levels and storm surges which will be useful in the implementation of the King Tides Project in Tauranga Harbour. This is a tool primarily focused on engaging the community with sea-level related information and coastal hazards, which is crucial for increasing awareness and our ability to adapt to coastal hazards.

text: Storm Surges in Tauranga Harbour Understanding the potential elevation of extreme sea-levels at the coast is important for management of hazards, and adaptation to climate change. This poses challenges for coastlines around the globe, with current pressure from sea-level rise and predictions for an increase in the frequency of extreme events, storminess and associated storm surge hazards. Therefore present day extreme sea-levels are likely to occur more frequently in the future, reaching higher elevations. The largest storm surge on record in New Zealand was 0.88 m in Tauranga Harbour during Tropical Cyclone Gisele in 1968. This is lower in comparison to the tide which can be up to 2 m, therefore it is important to consider the role of storm tides on extreme sea-levels in New Zealand.

The main aim of this research is to understand how storm conditions amplify the sea-level variations across Tauranga Harbour. This is one of the first studies that aims to understand how storm conditions amplify the sea-level in the upper regions of the Harbour, and therefore affect the hazards in this zone. The peaks over threshold method was applied to sea-level data at four gauges inside the Harbour, and one on the open coast at Moturiki Island. Extreme storm surges were found to be influenced by the morphology of the coastline, and are largest at Omokoroa. Due to relatively short sea-level records, additional techniques using oral histories and photographic evidence provide additional data which can be used to validate results from extreme value analyses. Storm surge is variable depending on the intensity and track of significant storms relative to Tauranga Harbour.

On the 5th January 2018 a sub-tropical storm passing over Tauranga, coincided with king tide conditions, causing significant inundation around Tauranga Harbour. The event produced maximum recorded storm surge of 0.64 m at Hairini, with an estimated average recurrence interval of 100 years at this sea-level gauge. The combination of storm tide and wave run-up was highest around the southern entrance, indicating significant external wave energy entered the Harbour. This event is an important reminder to monitor weather conditions closely during periods of king tide conditions. 

Stepwise regression was also applied to determine the variance in storm surge explained by atmospheric pressure and wind. Atmospheric pressure explains approximately 50% of the variance in storm surges. Wind from the east was found to explain an additional 3 to 15% of the variance, with the most influence at Omokoroa as it experiences large fetches from the east, being located on the north eastern side of the Peninsula. Waves likely explain the remaining variance in storm surges which is supported by findings from historical events in this study, however further research is needed to quantify the effect of waves. The relationship between storm surge frequency and magnitude with the Southern Oscillation Index was investigated at Moturiki, due to the potential for increased coastal hazards during La Niña. No statistically significant relationship was identified, however the results indicate larger, more frequent surges during La Niña. Since 2012, there has been a greater frequency of storm surge events per year exceeding 0.4 m. This may be the result of the Interdecadal Pacific Oscillation which shifted around 2000, and was predicted to increase the storm surge hazard for several decades based on previous research.

The research provides information and data on sea-levels and storm surges which will be useful in the implementation of the King Tides Project in Tauranga Harbour. This is a tool primarily focused on engaging the community with sea-level related information and coastal hazards, which is crucial for increasing awareness and our ability to adapt to coastal hazards.

year: 2018

title: A single mechanism can explain the speed tuning properties of MT and V1 complex neurons

authors: Perrone, John A.

subjects: speed tuning

abstract: A recent study by Priebe et al., (2006) has shown that a small proportion (27%) of primate directionally selective, complex V1 neurons are tuned for the speed of image motion. In this study, I show that the weighted intersection mechanism (WIM) model, which was previously proposed to explain speed tuning in middle temporal neurons, can also explain the tuning found in complex V1 neurons. With the addition of a contrast gain mechanism, this model is able to replicate the effects of contrast on V1 speed tuning, a phenomenon that was recently discovered by Priebe et al., (2006). The WIM model simulations also indicate that V1 neuron spatiotemporal frequency response maps may be asymmetrical in shape and hence poorly characterized by the symmetrical two-dimensional Gaussian fitting function used by Priebe et al., (2006) to classify their cells. Therefore, the actual proportion of speed tuning among directional complex V1 cells may be higher than the 27% estimate suggested by these authors.

text: A single mechanism can explain the speed tuning properties of MT and V1 complex neurons A recent study by Priebe et al., (2006) has shown that a small proportion (27%) of primate directionally selective, complex V1 neurons are tuned for the speed of image motion. In this study, I show that the weighted intersection mechanism (WIM) model, which was previously proposed to explain speed tuning in middle temporal neurons, can also explain the tuning found in complex V1 neurons. With the addition of a contrast gain mechanism, this model is able to replicate the effects of contrast on V1 speed tuning, a phenomenon that was recently discovered by Priebe et al., (2006). The WIM model simulations also indicate that V1 neuron spatiotemporal frequency response maps may be asymmetrical in shape and hence poorly characterized by the symmetrical two-dimensional Gaussian fitting function used by Priebe et al., (2006) to classify their cells. Therefore, the actual proportion of speed tuning among directional complex V1 cells may be higher than the 27% estimate suggested by these authors.

year: 2006

title: Te taiao: Te titiro a te Māori

authors: Kirby, Dean Robert

subjects: Cosmology

abstract: Ko te kaupapa o tēnei tuhinga ko te titiro a te Māori ki te taiao. He mea tuhi i runga i te aroha, i te whakapono ki ngēnei mea, ki te ātaahua o te taiao me ngā kōrero mōna. E whakatangatatia ana ngā āhuatanga o te taiao, ngā rākau, ngā manu, ngā ika, te kohu, ngā kapua, ngā maunga, otirā ngā mea katoa. Ara noa atu ngā kōrero, he whakapapa ō rātou, he huānga tētehi mea ki tētehi, he mauri tō tēnā mea tō tēnā mea. E ora ana ngā mea katoa o te ao, ka whai tamariki, he mātua he tūpuna anō, te katoa tae atu hoki ki te tangata, he wāhanga ia nō te taiao.
Hei aha tēnei tuhinga? Ko tāna mahi he whakaatu i ngēnei āhuatanga. Ā he whakamātau hoki ki te whakautu i te pātai he aha i whērā ai te titiro a ngā tūpuna ki tō rātou taiao. He kohikohingā tēnei nō ngā kōrero maha e takoto mai naka i roto i ngā pukapuka kua tāia kētia. Ehake i te mea ka kōrerotia ngā mea katoa, otiia ka tirohia noatia ngētehi āhuatanga o tēnei hanga te taiao. Kāhore i tuhia i runga i ngā kōrero ā waha a ngētehi kaikōrero, whēnā i ngētehi atu tuhinga roa. He mahi nui tērā mā tētehi atu hei whai, heoi anō tēnei he huihuinga nō ngētehi kōrero kua tuhia i mua atu.
Ka whakarārangitia ngā kōrero neki i muri ake nei. Ko tōna timatanga kei te Ōrokohanga, ko te timatanga tērā o te taiao. Ko te whenua ka whai mai me ngā kōrero mōna. Muri iho ko te wai me ngōna āhuatanga katoa. Ko te rangi, ngā mea katoa o te rangi ka whai mai i muri i tēnā. Muri iho anō ko ngā manu, ko ngā ngārara me ngā ngāngara, ngā rākau me ngā ika. Ka mutu atu i ngā tupua, i ngā taniwha me ngā patupaiarehe, i ngā kōrero mō ngērā. E iwa wāhanga nui te katoa o tēnei tuhinga. Kei te timatanga tētehi wāhanga hei whakamārama i te tuhinga ā kei te mutunga tētehi atu wāhanga hei whakatōpū, hei whakarāpopoto i ngā kōrero o roto i te puku o te tuhinga nei.
Kei ngā wāhanga o te pukapuka nei he kōrero mō tēnā mea, mō tēnā mea i raro i tōna ūpoko anō, me ngā whakaāhua e rite ana mōna. Ko te tūmanako ka kite te kaipānui i te pūrotutanga o te taiao o te Māori.

text: Te taiao: Te titiro a te Māori Ko te kaupapa o tēnei tuhinga ko te titiro a te Māori ki te taiao. He mea tuhi i runga i te aroha, i te whakapono ki ngēnei mea, ki te ātaahua o te taiao me ngā kōrero mōna. E whakatangatatia ana ngā āhuatanga o te taiao, ngā rākau, ngā manu, ngā ika, te kohu, ngā kapua, ngā maunga, otirā ngā mea katoa. Ara noa atu ngā kōrero, he whakapapa ō rātou, he huānga tētehi mea ki tētehi, he mauri tō tēnā mea tō tēnā mea. E ora ana ngā mea katoa o te ao, ka whai tamariki, he mātua he tūpuna anō, te katoa tae atu hoki ki te tangata, he wāhanga ia nō te taiao.
Hei aha tēnei tuhinga? Ko tāna mahi he whakaatu i ngēnei āhuatanga. Ā he whakamātau hoki ki te whakautu i te pātai he aha i whērā ai te titiro a ngā tūpuna ki tō rātou taiao. He kohikohingā tēnei nō ngā kōrero maha e takoto mai naka i roto i ngā pukapuka kua tāia kētia. Ehake i te mea ka kōrerotia ngā mea katoa, otiia ka tirohia noatia ngētehi āhuatanga o tēnei hanga te taiao. Kāhore i tuhia i runga i ngā kōrero ā waha a ngētehi kaikōrero, whēnā i ngētehi atu tuhinga roa. He mahi nui tērā mā tētehi atu hei whai, heoi anō tēnei he huihuinga nō ngētehi kōrero kua tuhia i mua atu.
Ka whakarārangitia ngā kōrero neki i muri ake nei. Ko tōna timatanga kei te Ōrokohanga, ko te timatanga tērā o te taiao. Ko te whenua ka whai mai me ngā kōrero mōna. Muri iho ko te wai me ngōna āhuatanga katoa. Ko te rangi, ngā mea katoa o te rangi ka whai mai i muri i tēnā. Muri iho anō ko ngā manu, ko ngā ngārara me ngā ngāngara, ngā rākau me ngā ika. Ka mutu atu i ngā tupua, i ngā taniwha me ngā patupaiarehe, i ngā kōrero mō ngērā. E iwa wāhanga nui te katoa o tēnei tuhinga. Kei te timatanga tētehi wāhanga hei whakamārama i te tuhinga ā kei te mutunga tētehi atu wāhanga hei whakatōpū, hei whakarāpopoto i ngā kōrero o roto i te puku o te tuhinga nei.
Kei ngā wāhanga o te pukapuka nei he kōrero mō tēnā mea, mō tēnā mea i raro i tōna ūpoko anō, me ngā whakaāhua e rite ana mōna. Ko te tūmanako ka kite te kaipānui i te pūrotutanga o te taiao o te Māori.

year: 1992