HR: 1400h
AN: OS23E-02    [Abstracts]
TI: Statistical Modelling of New Zealands Southland Front From Space
AU: * Hopkins, J E
EM: jeh200@noc.soton.ac.uk
AF: National Oceanography Centre, Southampton, European Way, Southampton, SO14 3ZH, United Kingdom
AU: Challenor, P
EM: P.Challenor@noc.soton.ac.uk
AF: National Oceanography Centre, Southampton, European Way, Southampton, SO14 3ZH, United Kingdom
AU: Shaw, A G
EM: agps@noc.soton.ac.uk
AF: National Oceanography Centre, Southampton, European Way, Southampton, SO14 3ZH, United Kingdom
AB: The Southland Front is a localised section of the global southern Subtropical Front that runs along the southeast coast of South Island, New Zealand. It is the boundary between warmer subtropical water in the north and colder subantarctic water from the south. It is associated with strong physical and nutrient gradients which lead to enhanced biological productivity. In this paper we discuss a new method to determine the position and gradient (i.e.strength) of a thermal ocean front. A weighted local likelihood estimation technique in which estimates of frontal parameters (position and strength) are based upon weighted contributions from surrounding points is described. We use this new technique to study the characteristics of the Southland Front and the variation in its properties over the period 1985-2005 from AVHRR imagery. We find the mean path of the Southland Front to be bounded by the 500m isobath and observe a gradual increase in meandering intensity northwards along its path. Its mean width increases from 17 to 30 km and its thermal gradient decreases from 0.22 to 0.13 ° C.km^-1 as it flows northwards from Otago Peninsula towards the Chatham Rise. These trends are maintained throughout the seasons, with the exception of winter, where a constant width and gradient of 20 km and 0.17 ° C.km^-1 respectively are observed along the length of the front. Spectral analysis of the 21 year time series reveals evidence for possible links with the El Nino Southern Oscillation.
DE: 1640 Remote sensing (1855)
DE: 4223 Descriptive and regional oceanography
DE: 4522 ENSO (4922)
DE: 4528 Fronts and jets
DE: 4594 Instruments and techniques
SC: Ocean Sciences [OS]
MN: 2007 Joint Assembly