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Using synoptic type analysis to understand New Zealand climate during the Mid-Holocene

Citation

Ackerly, D and Lorrey, A and Renwick, JA and Phipps, SJ and Wagner, S and Dean, S and Singarayer, J and Valdes, P and Abe-Ouchi, A and Ohgaito, R and Jones, JM, Using synoptic type analysis to understand New Zealand climate during the Mid-Holocene, Climate of the Past, 7 pp. 1189-1207. ISSN 1814-9324 (2011) [Refereed Article]


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Copyright 2011 The Authors Licensed under Creative Commons Attribution 3.0 Unported http://creativecommons.org/licenses/by/3.0/legalcode

DOI: doi:10.5194/cp-7-1189-2011

Abstract

Diagnosing the climate of New Zealand from low-resolution General Circulation Models (GCMs) is notoriously difficult due to the interaction of the complex topography and the Southern Hemisphere (SH) mid-latitude westerly winds. Therefore, methods of downscaling synoptic scale model data for New Zealand are useful to help understand past climate. New Zealand also has a wealth of palaeoclimate-proxy data to which the downscaled model output can be compared, and to provide a qualitative method of assessing the capability of GCMs to represent, in this case, the climate 6000 yr ago in the Mid-Holocene. In this paper, a synoptic weather and climate regime classification system using Empirical Orthogonal Function (EOF) analysis of GCM and reanalysis data was used. The climate regimes are associated with surface air temperature and precipitation anomalies over New Zealand. From the analysis in this study, we find at 6000 BP that increased trough activity in summer and autumn led to increased precipitation, with an increased north-south pressure gradient ("zonal events") in winter and spring leading to drier conditions. Opposing effects of increased (decreased) temperature are also seen in spring (autumn) in the South Island, which are associated with the increased zonal (trough) events; however, the circulation induced changes in temperature are likely to have been of secondary importance to the insolation induced changes. Evidence from the palaeoclimate-proxy data suggests that the Mid-Holocene was characterized by increased westerly wind events in New Zealand, which agrees with the preference for trough and zonal regimes in the models.

Item Details

Item Type:Refereed Article
Keywords:New Zealand, palaeoclimate
Research Division:Earth Sciences
Research Group:Physical Geography and Environmental Geoscience
Research Field:Palaeoclimatology
Objective Division:Environment
Objective Group:Climate and Climate Change
Objective Field:Effects of Climate Change and Variability on New Zealand (excl. Social Impacts)
Author:Phipps, SJ (Dr Steven Phipps)
ID Code:104711
Year Published:2011
Web of Science® Times Cited:12
Deposited By:IMAS Research and Education Centre
Deposited On:2015-11-18
Last Modified:2017-10-30
Downloads:43 View Download Statistics

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